Patent Application
20060064869
The present invention relates to a tool holder. In particular, the present invention relates to an automotive tool holder and method of using an automotive tool holder wherein the automotive tool holder reduces run out of a tool.
In a high speed machining process, an automotive adaptor is used to adapt “automotive-shank” tool holders to tooling machines which employ a center use process such as a rotating spindle. For high speed machines, centrifugal force of the rotating spindle has a significant impact on the tool processing a work piece. Thus, the tool holder becomes an important component to successful machining.
An automotive shank tool holder consists of a chuck end to hold the tool and a shank end to connect with the spindle. The chuck end typically has a collet for securing the tool, such as a drill, reamer or the like, coaxially to the chuck end. The shank end, in turn, includes an elongated shank which is inserted into a receiving bore on the rotatably driven spindle, wherein the spindle bore rotates coaxial with the axis of rotation of the spindle. Accordingly, the tool secured by the collet to the chuck end rotates hypothetically coaxial with the axis of rotation of the spindle. The shank end of the tool holder also includes threads and a Woodruff key for locating and driving the shank end within the spindle bore. The threads are used to set the desired length that the automotive-shank tool holder can be inserted into the spindle bore by adjusting a collar that travels along the threads.
Integral in machining the work piece is removing the material of the work piece in a controlled manner. Maintaining a smooth and consistent rotation of the tool along the center line of the axis of rotation of the spindle becomes important. Accordingly, the shank end must be properly inserted within the spindle bore. Typical tool holders are configured wherein both the spindle bore as well as the shank end are cylindrical in shape and are simply machined to sufficiently close tolerances to ensure that the axis of the shank end is nearly coaxial with the axis of the spindle. Other typical tool holders configure the spindle bore and the shank end in cooperating engagement pieces.
Once the shank end is inserted into the spindle bore, the shank end must be secured within the spindle bore. In a method of securing the shank end to the spindle bore, referring to
A problem with typical tool holder spindles 10, though, is that the shank end 12 is moved off-center within the spindle bore 14 during rotation. Typical tool holders 10 use a set screw 26 inserted through the spindle bore 14, which passes through the gap 16 between the interior wall 18, to contact the shank end whistle flat 12. The set screw 26 can then be tightened against the shank end 12 to hold the shank end 12 against the interior wall 18. The force of the set screw 26, however, offsets the shank end 12 within the interior of the spindle bore 14. In other words, the set screw 26 pushes the shank end 12 off center causing eccentric run out of the tool holder 10, the run out being defined as the deviation of the eccentric spin of the shank end 12. Thus, there is a differential of the diameter of the spindle bore 14 and the outside diameter of the shank end 12. Accordingly, a center line 28 of the shank end 12 is configured in an eccentric offset 30 with respect to the center line 32 of the spindle bore 14. This eccentric offset 30 creates the run out of the tool 22 which leads to a poor quality interface between the tool 22 and work piece 24 reducing the efficiency and output of the tool holder 10.
Efficient and economic cutting processes are crucial for machining systems. As such, machining systems require tools which process the work piece with maximum but controlled contact with the work piece. Additionally, machining systems require that the tool rotates consistently along the axis of rotation of the spindle. Accordingly, a need exists for tool holder that tightly fits the tool within the spindle bore. The solution, however, must not offset the tool holder within the spindle bore. Additionally, the solution must rotate the tool along the axis of rotation of the spindle while providing controlled contact between the tool and the work piece to provide superior balance and harmonic properties. Thus, the solution must prevent run out of the tool.
The present invention comprises a tool holder including a shank having a first shank portion and a second shank portion. The tool holder also comprises an end component having a first component portion and a second component portion. An expansion member is configured to surround the first shank portion and the first component portion, wherein the expansion member expands as the shank is engaged with the end component.
In an embodiment of the invention, the first shank portion and the first component portion are conical shaped, wherein the first shank portion and the first component portion taper toward the body. Additionally, in an embodiment, the expansion member comprises a first expansion portion and the second expansion portion which are conical shaped tapering toward each other. In an embodiment, the first shank portion nests within the first expansion portion while the first component portion nests within the second expansion portion of the expansion member.
The present invention also relates to a method of fastening a tool. In the method, an expansion member is positioned around a shank and an end component is partially positioned within the expansion member. The end component is connected to the shank wherein the shank is inserted within a spindle bore. An expansion member is expanded against the spindle bore to secure the shank within the spindle bore.
The shank 40, in turn, comprises a first shank portion 50, a second shank portion 52 and a body 54 wherein the body 54 separates the first shank portion 50 and the second shank portion 52. In an embodiment, the first shank portion 50 has a larger surface area than the second shank portion 52 and the body 54, wherein the second shank portion 52 and the body 54 have similar configurations. Although the first shank portion 50 is larger than the second shank portion 52 and the body 54, the components of the shank 40 are aligned coaxially with each other. Consequently, the first shank portion 50, the second shank portion 52 and the body 54 include a coolant bore 56 to supply coolant to the tool 44, if required by the process.
The first shank portion 50 extends/tapers downward toward the body 54 at angles with respect to the adjusting nut 38 and the body 54. Additionally, the outer surface at the first shank portion 50 comprises a smooth finish free from interferences and voids. In an embodiment, the first shank portion 50 is configured in a conical shape wherein the angles extending from the threads of adjusting nut 38 are less than or equal to 45 degrees included. In a further embodiment, the angles from the first shank portion 50 extending from the threads of adjusting nut 38 to the body 54 are approximately 15 degrees.
The second shank portion 52, which is oppositely disposed from the first shank portion 50 by the body 54, comprises a straight configuration. The second shank portion 52 includes fasteners 60, such as but not limited to, threads located on the outer surface of the second shank portion 52. In an embodiment, the threads are fine pitched threads having 20-40 threads per inch machined on the outer surface and surrounding the second shank portion 52.
The body 54 also comprises a straight configuration separating the first shank portion 50 and the second shank portion 52. Accordingly, the length of the shank 40 can be determined by increasing or decreasing length of the body 54. The surface of the body 54 includes a smooth finish free from interferences and voids.
Turning to
The end component 62 further includes a channel 74 disposed within such that the channel 74 includes fasteners 76 such as threads located on an inner surface of the channel 74. In an embodiment, the fasteners 76 may include fine pitched threads having 20 to 40 threads per inch. The fasteners 76 of the channel 74 for the end component 62 are configured to match the fasteners 60 of the second shank portion 52 as will be discussed. The end component 62 further includes a key 78 configured into the top 64 of the end component 62. Turning to
Referring to
In an embodiment, the first expansion portion 86 and the second expansion portion 88 are configured in conical shapes while positioned in opposite directions with respect to each other. Accordingly, the first expansion portion 86 and the second expansion portion 88 form a frusto-conical like configuration such that the first expansion portion 86 tapers downward and toward the second expansion portion 88 while the second expansion portion 88 tapers downward and toward the first expansion portion 86. As illustrated, however, a spaced member 92 may exist between the first expansion portion 86 and the second expansion portion 88.
The angles forming both the first expansion portion 86 and the second expansion portion 88 with respect to the outer wall 82 of the expansion member 80 are less than 45 degrees included. In an embodiment, the angles are approximately 15 degrees. Accordingly, the configuration of the first expansion portion 86 is the same as the configuration of the first shank portion 50 while the configuration of the second expansion portion 88 is the same as the first component portion 68. As shown, the first expansion portion 86 and the second expansion portion 88 are hollow forming an open space through the expansion member 80.
The expansion member 80 further includes a plurality of slots 96 positioned through the outer wall 82 and the inner wall 84. The plurality of slots 96 are positioned in an alternating sequence starting from the first expansion portion 86 and the second expansion portion 88 respectively. As illustrated, the plurality of slots 96 do not extend all the way across the expansion member 80.
Turning to
Referring to
The end component 62 is then positioned around the second shank portion 52 wherein the internal fasteners 76 (
Next, the chuck 36 and shank 40 insert into the spindle bore 98. Then, an operator inserts the tool 44 into the collet 42 and tightens the tool 44 within the collet 42. Next, the operator inserts a fastener tool, such as a wrench, in the flats 46 of the body 36. Once the fastener is attached, the operator rotates the fastener in order to tighten the body 36 which connects with the spindle bore 98 when the shank 40 is inserted into the spindle bore 98. As shown, a gap 100 exists between the spindle bore 98 and the outer wall 82 of the expansion member 80. This gap 100 may include a range from 0.0002 inches up to and including 0.001 inches. The first shank portion 50, the first component portion 68 and the expansion member 80 are configured to eliminate the effect of the gap 100.
When the operator rotates/fastens the body 36, force is applied to the opposing first shank portion 50 and the first component portion 68. Since the first shank portion 50 and the second shank portion 52 are fixed within the spindle bore 98, the force is applied to the expansion member 80 via the first expansion portion 86 and the second expansion portion 88. The applied force results in an outward force against the first expansion member 80 and the second expansion member 88 to force the plurality of slots 96 to expand against an inner spindle wall 102 of the spindle bore 98. Accordingly, the expansion member 80 expands as the shank 40 is tightened within the spindle bore 98. In other words, as the body 36 pushes the first shank portion 50 and the first component portion 68, the force is applied substantially equally in all directions to the expansion member 80. Accordingly, the slots 96 allow the expansion member 80 to uniformly contact the inner spindle wall 102 of the spindle bore 98.
With the uniform contact applied to the spindle bore 98, the shank 40 is fixed within the spindle bore 98. Thus, the shank 40 does not move within the spindle bore 98 during rotation of the spindle bore 98. Accordingly, the axis of rotation of the shank 40 and body 36 has the same center line axis of rotation of the spindle bore 98. Thus, the tool 44 rotates co-axially with the spindle bore 98 preventing run-out of the tool 44. As such, the first shank portion 50, the first component portion 68, the first expansion portion 86 and the second expansion portion 88 are configured to optimize the expansion of the expansion member 80 against the inner spindle wall 102 of the spindle bore 98. After the slots 96 expand and contact the inner spindle wall 102, the spindle bore 98 is activated to rotate the tool 44 in the same axis of rotation as the spindle bore 98.
While the concepts of the present disclosure have been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected by the following claims.
