Cutters – for shaping – Including holder having seat for inserted tool – With separate means to fasten tool to holder
Reexamination Certificate
2000-07-03
2002-06-25
Tsai, Henry (Department: 3722)
Cutters, for shaping
Including holder having seat for inserted tool
With separate means to fasten tool to holder
C407S107000, C407S112000, C407S109000
Reexamination Certificate
active
06409435
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to cutting tools and, in particular, to cutting inserts and toolholders therefor that effect location of the insert at a selected position on the toolholder with improved accuracy and reliability, and a method of locating such inserts. More particularly, the invention provides inserts and toolholders wherein the inserts are located in the toolholder using reference surface or surfaces close to the active cutting edge and substantially independent of contact between the flanks of the insert and the toolholder.
BACKGROUND OF THE INVENTION
In the cutting tool industry, it is a conventional practice to use cutting toolholders, e.g. mills, drills, lathes, reamers, bores, cutters, blades and other known cutting devices, having replaceable cutting inserts of hard wear resistant material releasably secured thereto. The toolholders are manufactured with recesses or pockets therein, to hold and support the cutting insert, either alone or coupled with an insert-holding cartridge. Generally, the insert has multiple cutting edges or cutting edge portions and only one or two of them are put in contact with the workpiece at any one time. The cutting edge or edges positioned in the toolholder to contact the workpiece are referred to as active cutting edges. In this manner, when the active cutting edges of the insert become dull or the insert otherwise fails, the less expensive insert is indexed to an unused cutting edge which becomes “active” or replaced rather than replacing or repairing an entire tool.
The use of inserts has provided cost savings in materials and labor, as well as allowing use of materials for the cutting insert that are different from the toolholder material. However, the use of replaceable inserts has also created challenges in positioning the insert uniformly, accurately and repeatably in the toolholder in a selected orientation, that is, to locate the insert. Another challenge presented by insert use is to limit movement of the insert relative to the toolholder during use. Location is critical to overall tool performance including the tolerances that can be maintained, reliability of the tool, down time and tool life. Historically, cutting edges integral with a cutting tool, such as the teeth on a hand saw, had a fixed position relative to the tool body and movement of the cutting edge was limited by characteristics of the tool material. The use of inserts as individual parts of a cutting tool, separate from the toolholder, introduced new variables that contribute to inaccuracy in positioning of the active cutting edge. Variables that affect position of the active cutting edge in the toolholder include, but are not limited to, variations in size or shape from insert to insert, variations in the distance between features on the same insert, variations in geometrical forms on the insert, variations in toolholder pocket sidewalls and position of the pocket. Use of inserts also increased the potential for movement of the insert (and hence the cutting edge) relative to the toolholder during use.
Locating an insert involves positioning the insert at a selected location on the toolholder, relative to the x, y and z axes of three-dimensional space, and during use the insert's movement on these axes, translationally and rotationally, relative to the toolholder should approach zero. Additionally, in order to maintain accuracy of a cutting process when a used cutting edge is changed for an unused edge, it is desirable that the user be able to position the insert in the toolholder such that the unused cutting edge is located in nearly the identical place in relation to the toolholder and workpiece as was the former cutting edge. This challenge is multiplied when a tool holds more than one insert since the inserts' positions in the pockets relative to each other also affect cutting. Various known holding means, such as screws and clamps, are used in the industry to secure cutting inserts in toolholders. Heretofore, holding means have been used in conjunction with the sidewalls of the pockets in the toolholder to locate the insert.
Conventionally, an insert positioned in a toolholder has bottom and flank (side) surfaces in contact with the pocket walls, and has at least one cutting edge that is formed by intersection of the top surface with the flanks. A portion of the cutting edge extends beyond the toolholder for contacting the workpiece. The sidewalls of the toolholder pockets are routinely utilized as locating surfaces for the insert. Users push inserts into toolholder pockets until the insert flanks proximate to the pocket sidewalls abut the sidewalls along at least a portion of the flank length. The insert is then releasably secured, with the flanks abutting toolholder pocket sidewalls, by a holding means. In this conventional locating method, the insert flanks determine the position of the insert, relative to the toolholder, by contact between the insert flanks proximate to the pocket sidewalls and the pocket sidewalls, and thereby dictate the position of the active cutting edges on the portion of the insert extending beyond the toolholder. The pocket sidewalls also support the insert and are designed to prevent it from moving out of the selected position due to forces generated by contact with the workpiece. That is, in the prior art, the flanks of the insert and the pocket sidewalls are used to locate the insert. A disadvantage of prior art locating means has been inaccurate location of the active cutting edge of the insert in relation to the workpiece. U.S. Pat. No. 3,813,746 to Price recognized problems that prior art cutting tools have with insert location, noting that as a practical matter, cutting edges will not always be located at exactly the same position in relation to the holder. Price discloses a locking pin used to wedge an insert flank against a toolholder pocket sidewall and seeks to limit variation in cutting edge position by inclining the pocket sidewall to reduce forward and rearward insert displacement. Heretofore other attempts have been made to reduce or eliminate positioning variables, including the following:
U.S. Pat. No. 3,911,543 to Sorice discloses an elongated cutting insert with a locating pin. The insert engages the rear, side and bottom wall of the toolholder pocket.
U.S. Pat. No. 4,028,782 to Stansak discloses an insert having notches in upper and lower surfaces which correspond to the toolholder pocket. Precision indexing is accomplished by indexing surfaces positioned on the flanks of the insert.
U.S. Pat. No. 4,244,666 to Erickson et al. discloses a locking pin that tilts to locate the insert against the back wall of the toolholder pocket.
U.S. Pat. No. 4,420,280 to Gustafson discloses a toolholder with a locking pin on an insert holder engaging the central hole of an insert and a clamping wedge which moves the insert holder. The clamping wedge engages the insert holder thereby moving the locking pin and insert and locating the insert by abutment of the insert flank with a stop on the toolholder. Spring means push the insert away from the stop when the clamp is released.
U.S. Pat. No. 4,525,110 to Stojanovski discloses ball nose end mill inserts having recesses which are acted upon by protuberances on a cap to locate the insert against a toolholder pocket sidewall.
U.S. Pat. No. 5,035,544 to Ikenaga et al. U.S. Pat. No. 3,837,058 to Barkley et al., and U.S. Pat. No. 5,586,844 to Nyman disclose various examples of a toolholder with a locking pin which engages the central hole of an insert and a clamping wedge attached to the toolholder by a screw. A rear end of the clamping wedge assembly engages an inclined supporting surface and a front end of the clamping wedge assembly engages the insert flank. Location of the insert on the pin is made by the wedge with reference to the insert flank. U.S. Pat. No. 5,682,803 to Boianjiu discloses an insert or shim having a pattern of protrusions designed to indent the flat toolholder pocket when a clamp secures the insert to prevent movement during us
Kocherovsky Yevgeny
Powell Foye
Reiterman Lee
Santimaw Edward
Cameron Mary K.
Gregg John W.
Tsai Henry
Valenite Inc.
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