Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Metal and nonmetal in final product
Reexamination Certificate
1999-07-07
2001-02-06
Jenkins, Daniel J. (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Metal and nonmetal in final product
C419S028000, C419S036000, C419S037000
Reexamination Certificate
active
06183688
ABSTRACT:
TECHNICAL BACKGROUND
The present invention relates to a tool for rotary, cutting machining, including a tool body, a cutting portion and means for fastening. The tool body has a front surface and the cutting portion has a support surface provided to dismountably abut against each other, substantially in a radial plane. The invention also relates to a separate tool tip, a cutting portion, a tool body as well as to a method for manufacturing a tool tip or a cutting portion.
It is previously known to use interchangeable cutting edges on different types of tools for cutting machining. This technique has however its practical limitation because of strength reasons when it comes to milling- and drilling tools rotating around its longitudinal axis.
Through U.S. Pat. No. 4,684,298 is previously known a drill with a dismountable cutting portion secured in a drill body by two screws, which are provided opposite sides of a central line of the drill. In the known drill, screws transfer torsion which is created during drilling, to the drill body. Such a drill suffers from a number of drawbacks, partly that it becomes statically unstable, which is solved by positioning resilient sleeves around the screws, and partly that the cutting portion is forced to contain less amount of cemented carbide (since the screws need space) whereby the propensity for crack formation increases. In addition the screws are submitted to shear forces and exchange of the cutting portion becomes troublesome.
Furthermore, it is previously known through European Document No. 0 358 901 to provide a drill with a dismountable cutting portion secured in a drill body by means of at least one screw, which is eccentrically positioned relative to the rotational axis of the drill. The cutting portion carries two indexable cutting inserts, and a pilot drill extends centrally therethrough. This known drill has the same drawbacks as mentioned above.
OBJECTS OF THE INVENTION
The present invention has as one object to provide milling or drilling tools with interchangeable cutting edges, which eliminates the problems of prior art tools.
Another object of the present invention is to provide a rigid tool, preferably for drilling or milling, where the cutting portion wedgingly cooperates with the tool body such that the clamping force increases with increasing feed force.
Another object of the present invention is to provide a tool, preferably for drilling or milling, where the cutting portion is firmly held by a central fastening means.
Another object of the present invention is to provide a rigid tool, preferably for drilling or milling, where the cutting portion easily can be exchanged.
Another object of the present invention is to provide a tool and a cutting portion where the advantage with grooves is combined with the production of injection molded cemented carbide.
Still another object of the present invention is to provide a tool and a cutting portion in which the cutting portion can not be positioned obliquely even if one of the cooperating grooved surfaces is worn.
Still another object of the present invention is to provide a tool and a cutting portion where axial or tangential cutting forces are distributed on a large surface such that the risk for breaking the cutting portion, is reduced.
Still another object of the present invention is to provide a tool and a cutting portion where the relative movement between the cutting portion and the tool body is negligible even after wear of the tool body.
Still another method object of the present invention is to provide a method for manufacturing a cutting portion or tool tip whereby the degree of freedom for geometrical appearance is substantially unlimited.
These and other objects have been achieved by a tool comprised of a tool body, a cutting member, and a fastener for securing the cutting member to the tool body. The tool body defines a longitudinal axis and includes a shank terminating in a front surface. The cutting member is formed of cemented carbide and has a cutting edge on a forwardly facing surface thereof. A rearwardly facing support surface of the cutting member includes a screw-threaded blind hole. The support surface and front surface include mutually engaging grooves and ridges. The fastener extends through the tool body and is screw threaded in the blind hole for pulling the cutting member toward the tool body.
The invention also relates to the cutting member per se, and to the tool body per se.
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patent: 5863162 (1999-01-01), Karlsson et al.
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patent: 25 33 495 (1977-01-01), None
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patent: 175 6033 (1992-08-01), None
Bruhn Johnny
Karlsson Ronny
Burns Doane Swecker & Mathis L.L.P.
Jenkins Daniel J.
Seco Tools AB
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