Precision rotating tool mounting device

The invention is the precise mounting of a cutting tool on a rotating spindle to prevent eccentric runout between the spindle and tool and comprises mating non-locking taper surfaces at the inner end of the spindle tool combination and diverging angular taper surfaces at the outer end of the spindle and tool combination. A variable diameter wedge engages the diverging taper surfaces for precise and repeatable accurate mounting of the tool to the spindle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a mode of precisely mounting a tool, such as a 
cutting tool, in a fixed manner to a rotating spindle and to eliminate any 
eccentric runout between the spindle and the precisely mounted tool. 
2. Description of the Prior Art 
It will be understood that the disclosed mode of precisely mounting the 
rotating tool to a rotating spindle may be utilized in many areas of 
manufacture. However, the disclosed invention does, in fact, have 
particular utility in the field of "finger jointing," that is, an area of 
activity where relatively small segments of lumber are precisely milled to 
provide an interfitting joint, which, through the use of adhesives, may 
provide wood products of larger and useful dimensional lengths. A 
particular cutting tool designed especially for finger jointing is 
disclosed in my U.S. Pat. No. 4,009,742, dated Mar. 1, 1977. In any event, 
persons skilled in the finger jointing art are aware that useful products 
can only be produced where the cutting head is precisely rotated in space 
so that joints of precise structure are created which will provide a 
uniform and precision interfit between subsequently joined pieces. 
Conical mounting arrangements generally have been known in the art. For 
example, U.S. Pat. No. 3,951,477, dated Apr. 20, 1976, teaches a general 
mounting arrangement which comprises a pair of opposed cone surfaces on a 
first member of the arrangement in juxtaposition with opposed cone-shaped 
depression on a second segment of the arrangement which provide bearing 
and supporting surfaces. It is also generally known to provide conical 
surfaces on a rotating member and using those surfaces in a locking or 
non-locking mode to support a rotating element or tool. U.S. Pat. No. 
819,824 dated May 8, 1906, teaches a driven axle 28 having a tapered or 
conical segment supporting a wheel and including a split ring 54 having an 
inner cone complimenting the taper and which performs a wedging action to 
tightly mount the wheel thereto. 
Furthermore, it is state of the art practice in the finger jointing 
industry, to provide cutting heads having mounting bores with outwardly 
flaring tapered surfaces at the inner and outer extremities of the head. 
Annular collars in these arrangements, each having outwardly facing 
conical or tapered surfaces, are slideably mounted on a rotating spindle 
and complimentally engage the conical surfaces on the cutting heads at the 
inner and outer aspects of that head. The structure now being described is 
reminiscent of that shown in U.S. Pat. No. 3,951,477 referenced above. The 
structures are specifically known in the industry as removable 
self-centering collets. 
SUMMARY OF THE INVENTION 
It is the purpose and object of the invention to provide a spindle and 
cutting tool assembly wherein the tool is precisely positioned on the 
spindle in such a manner as to completely eliminate eccentric runout 
between the spindle and the cutting head during rotation of the assembly. 
It is a specific object of the invention to achieve precision mounting of 
the tool on the spindle as described above by the provision of a cutting 
head having a central bore with annular inwardly facing conical surfaces 
at opposed ends of the bore which overlie, in assembled relationship, 
annular tapered surfaces formed on the spindle in angular relation with 
the axis of spindle rotation and which face in a common direction toward 
the outer extremity of the spindle. The annular taper at the inner aspect 
of the spindle is in direct engagement with the annular conical surface at 
the inner aspect of the cutting head while the annular aligning taper at 
the outer aspect of the spindle is in spaced relationship with the conical 
surface at the outer aspect of the cutting head which defines there 
between an annular volume adapted to be filled by a radially expansible 
and contractible wedge element which engages both the spindle and the 
cutting head and thereby precisely aligns the cutting head on the spindle 
and in determined relation to the axis of rotation of the spindle. 
It will be understood by those skilled in the art that any conventional 
locking device may be utilized to hold the cutting head in position on the 
spindle. However, a particularly useful locking arrangement which is 
entirely compatible with the invention herein disclosed is shown and 
described in my application filed Apr. 23, 1981, and entitled "Force 
Multiplying Locking Arrangement." 
These and other objects and advantages of the invention will become 
apparent in the course of the following description and explanation of a 
presently preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Directing attention to the drawings, the numeral 2 indcates a spindle which 
is mounted, in a conventional manner not shown, for accurate rotation 
about its axis indicated by the centerline 4. Spindle 2 has a tool 
mounting segment 6 which is adapted to carry any conventional cutting 
equipment and which is shown schematically at 8. The spindle 2 is provided 
with an integral driving flange which includes drive pins 12,12 
cooperatively disposed in key slots 15,15 whereby the tool 8 will rotate 
at high speed concurrently with the rotation of the spindle 2. 
At its left terminus the spindle 2 is provided with a threaded projection 
or segment 14 which is adapted to receive an assembly locking arrangement 
indicated generally at 16. The locking arrangement 16 may comprise the 
main body 17 having a central aperture internally threaded to 
cooperatively mount on threaded projection 14. The main body 17 threadably 
carries locking nut 19 which will suffice to hold the entire arrangement 
together. Again, it is noted, however, that the force multiplying and 
locking arrangement disclosed in my reference application may be used for 
this purpose. 
To accommodate precision mounting of the cutting head 8 on the spindle 6 an 
annular taper or conical alignment surface 18 is formed at the inner 
aspect of the spindle. A second alignment surface 20 is formed in the 
spindle adjacent the outer aspect thereof again as an annular taper or 
cone, it being understood that the alignment surfaces 18 and 20 are in 
angular relation to the axis of rotation 4 of the spindle 2. The cutter 
head 8 is provided with precisely formed annular conical areas, 22 and 24, 
adjacent the inner and outer aspects of the cutter bore 25. 
In the spindle-cutting head assembly the alignment surface 18 is in 
intimate engagement with the conical area 22 and the alignment surface 20 
defines, with the conical area 24, an annular volume in which is disposed 
a wedge element 26. The wedge element 26 is provided with the wedge faces 
29 and 31 which are in intimate engagement with the alignment surface 20 
and the conical area 24. As the locking arrangement 16 drives the wedge 
element 26 inwardly of the arrangement it is necessary to provide means to 
allow wedge element 26 to expand and contract radially. For this purpose 
wedge element 26, as shown in FIG. 2, is slotted as is 27 which will allow 
radial variation. 
Alternately, the wedge element 26a shown in FIGS. 4 and 5 may be utilized. 
In this embodiment the wedge element 26a is formed of three identical 
segments which are joined by flexible elements, for example, elastomeric 
pins 27a, again allowing diametral variation in use. 
From the above it will be readily apparent to those skilled in the art that 
precise and repeatable positioning of a cutting tool on a spindle has been 
achieved by the utilization of non-locking tapers in intimate face-to-face 
engagement, thus eliminating any possibility of eccentric runout between 
the spindle and cutting head during the arrangement operation, removal for 
sharpening and subsequent remounting. 
Having described the presently preferred embodiment, it is understood that 
such description is by way of illustration and not limitation and that the 
described invention may be subject to certain modifications all within the 
spirit and scope thereof.