Gear cutting – milling – or planing – Milling – Cutter spindle or spindle support
Patent
1993-07-08
1995-04-18
Bishop, Steven C.
Gear cutting, milling, or planing
Milling
Cutter spindle or spindle support
279103, 409234, B23B 31117
Patent
active
054073081
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a tool holder coupling apparatus for attaching a tool holder to a machine spindle.
BACKGROUND
A tool holder normally includes a tool, a tapered portion and a pull stud bolt. When the tool holder is attached to a machine spindle, the pull stud bolt is drawn inwardly by way of a collet chuck in preloading. The tapered portion of the conventional tool holder is defined by a single continuous smooth tapered surface. An opening for receiving the taper portion of the tool holder is formed on the machine spindle. The opening in the machine spindle is defined by a single continuous smooth tapered surface. The tool holder is attached to the machine spindle in such a manner that the tapered portion of the tool holder is engaged with the corresponding tapered surface of the reception opening of the spindle over its entire length.
Nowadays a workpiece to be machined is often made of aluminum, non-ferrous metal containing resins, hard alloys and so on. These materials require high speed cutting or very high speed cutting. Even when a normal metal workpiece is machined, high speed cutting is desirable for accurate machining.
When the tool holder attached to the machine spindle is driven at high rate of rotation, the outer (entry) area of the tapered reception opening of the spindle is enlarged, e.g. by few micron meters. As a result, only the smaller diameter (end) area of the tapered support portion of the tool holder is engaged with the interior surface of the spindle, therefore play of the tool sometimes occurs during machining. Such play in the tool is allowed by the small clearance formed at the large diameter area (end) of the spindle opening. Because the small diameter area is hardly enlarged, the tool holder is supported by only the small diameter end of the support portion. It is hard to machine a workpiece with high accuracy if such tool play occurs. The play will also shorten the tool life. Moreover, severe cutting conditions must be avoided because of the play, to the detriment of productivity.
SUMMARY OF THE INVENTION
An object of the invention is to overcome the above-stated problems of the prior art and provide a tool holder coupling apparatus wherein no play of the tool holder (or tool) occurs even when driven at a high rate of rotation so that high accuracy machining can be performed.
The invention provides a tool holder coupling apparatus for attaching a tool holder to a machine spindle, wherein the tool holder includes a support portion for engaging the interior surface of the spindle and a pull stud bolt. The support portion includes a tapered surface portion of large diameters, a straight surface portion of a small diameter near the pull stud bolt, and a relief surface portion between the tapered surface portion and the straight surface portion. The machine spindle includes a central opening defined by a tapered interior surface portion corresponding to the tapered surface portion of the tool holder, a straight portion corresponding to the straight portion of the tool holder, and a middle portion between the tapered surface portion and the surface portion. The tool holder attaches to the machine spindle in such a manner that the relief portion of the tool holder is spaced from the middle surface portion of the machine spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view showing a first embodiment of the invention; and
FIG. 2 is a sectional view showing a second embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments according to the invention will be explained with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of a tool holder coupling apparatus 1 according to the invention. A tool 16 is mounted at one end of a tool holder 10. A normal pull stud bolt 15 is attached at the other end of the tool holder 10. Between the tool 16 and the pull stud bolt 15 is a support portion to be supported by a machine spindle 21.
The support portion 11 is divided into three portions.
REFERENCES:
patent: 2084801 (1937-06-01), Hall
patent: 3554080 (1971-01-01), Herrmann
patent: 3759536 (1973-09-01), Bronzoni
patent: 4604010 (1986-08-01), Reeves
patent: 4726721 (1988-02-01), Heel et al.
patent: 4772163 (1988-09-01), Scheer et al.
patent: 4856349 (1989-08-01), Huser
Bishop Steven C.
Kitamura Machinery Co. Ltd.
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