Method of manufacturing a tool

A method of manufacturing a composite chip-removing tool which includes a tool body of a material which is in its molten state above a predetermined melting temperature, and at least one tipping element secured to the tool body, comprises positioning the tipping element on a model of the tool body that consists of a material that melts at a temperature considerably lower than the predetermined melting temperature, in a position relative to the model which the tipping element is to assume relative to the body, and simultaneously forming the tool body and a durable mechanical connection of the tipping element to the tool body in a precision casting operation involving replacement of the material of the model with the material of the tool body in its molten state. The model may be produced prior to or simultaneously with the positioning of the tipping element on the model. For establishing the durable connection, the tipping element is provided prior to its positioning on the model with at least one aperture which preferably has at least one cross-sectional enlargement and which is subsequently filled with the material of the tool body during the formation of the tool body, so that the material of the tool body which has penetrated into the aperture establishes a durable connection of the tipping element to the tool body. The model has at least one projection received in the aperture of the tipping element.

BACKGROUND OF THE INVENTION 
The present invention relates to tool manufacture in general, and more 
particularly to a method of manufacturing a chip-removing tool. 
Various methods of manufacturing chip-removing tools are already known, 
among them composite tools in which, in order to reduce the consumption of 
high-quality, high-strength materials and/or for other reasons, separate 
tipping elements made of such materials are connected to a tool body which 
is made of a lower quality and hence less expensive material. Upto now, 
the connection of the tipping elements to the tool body was accomplished 
by welding, by hard soldering, or utilizing threaded connections. So, for 
instance, it is known from the German published patent application No. 
DE-OS 21 36 271 to make a tool out of a composite metal, wherein the shank 
and the main portion of a grooved tool body is made of inexpensive, only 
slightly alloyed or non-alloyed carbon steel, and the tipping element, 
which is separate from the shank and body and is made of tool steel, 
cobalt steel or another high-speed steel, is welded to the shank. It is 
also possible to achieve the connection of a carrier part with a tipping 
part of the tool by resorting to hard soldering. What is disadvantageous 
in this kind of connection is the number and complexity of the required 
processing steps and of the equipment needed for performing such 
processing steps, as well as the additional material consumption, such as 
that of the solder, and the energy consumption. 
SUMMARY OF THE INVENTION 
Accordingly, it is a general object of the present invention to avoid the 
disadvantages of the prior art. 
More particularly, it is an object of the present invention to provide a 
method of manufacturing chip-removing tools, which method does not possess 
the disadvantages of the known methods of this kind. 
Still another object of the present invention is to devise the method of 
the type here under consideration so as to avoid the need for the 
performance of any further processing steps in addition to those which are 
required in any event for the production of the tool carrier or body. 
It is yet another object of the present invention to avoid the heretofore 
existing need for performing welding or hard-soldering operation. 
A concomitant object of the present invention is to construct the tool of 
the above type so as to be relatively simple in construction, inexpensive 
to manufacture by utilizing the method of the present invention, easy to 
use, and nevertheless reliable in operation. 
In pursuance of these objects and others which will become apparent 
hereafter, one feature of the present invention resides in a method of 
manufacturing a composite chip-removing tool which includes a tool body of 
a material which is in its molten state above a predetermined melting 
temperature, and at least one tipping element secured to the tool body, 
this method comprising the steps of positioning the tipping element on a 
model of the tool body which consists of a material that melts at a 
temperature considerably lower than the predetermined melting temperature, 
in a position relative to the model which the tipping element is to assume 
relative to the tool body; and simultaneously forming the tool body and a 
durable mechanical connection of the tipping element to the tool body in a 
precision casting operation involving replacement of the material of the 
model with the material of the tool body in its molten state. 
As a result of the use of the method as described so far, there is obtained 
a reduction in the number of the required processing steps. Moreover, the 
need for the highly precise alignment of the tipping element on the tool 
carrier or body prior to the now non-performed soldering or welding step, 
and the high expense of the requisite measuring operation during such 
alignment, are now dispensed with. It is particularly advantageous that 
saving of the consumed material, as well as a reduction in the energy 
consumption, are achieved by the non-use of the heretofore required flux 
and solder and by the avoidance of the welding or soldering operation. 
These savings enhance the series production of the tools when great 
numbers of such tools are to be manufactured. 
The method of the present invention advantageously further comprises 
producing the model prior to the positioning step, in which case the 
positioning includes mounting the tipping element on the thus-produced 
model. However, it is even more advantageous when the positioning step 
includes producing the model at the tipping element with simultaneous 
formation of the connection, since a further reduction in the number of 
the processing steps to be performed in achieved by using this expedient. 
According to an advantageous concept of the present invention, the tipping 
element is provided prior to its positioning on the tool body with at 
least one aperture which may be circular in cross section, or slot shaped. 
The aperture in the tipping element advantageously has at least one 
cross-sectional enlargement which is subsequently filled with the material 
of the tool body during the formation of the tool body to form the 
aforementioned connection. The cross-sectional enlargement may be situated 
within the tipping element. However, according to an advantageous aspect 
of the present invention, the cross-sectional enlargement is situated at a 
major surface of the tipping element which is exposed after the formation 
of the tool body. In this context, it is particularly advantageous when 
the cross-sectional enlargement is a countersink situated at the major 
surface and produced during the drilling of the aperture. In accordance 
with a further advantageous aspect of the present invention, the model has 
at least one projection which has a cross-sectional configuration 
substantially corresponding to that of the aperture and which at least 
partially fills the aperture when the tipping element is mounted on the 
model. 
The manufacturing method of the present invention is particularly suited 
for the low-cost production of tools, especially of milling tools and 
spiral drills, which are intended for the do-it-yourself and craftsman 
market. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved tool 
itself, however, both as to its construction and its method of 
manufacture, together with additional features and advantages thereof, 
will be best understood upon perusal of the following detailed description 
of certain specific embodiments with reference to the accompanying drawing 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing in detail, and first to FIG. 1 thereof, it may 
be seen that the reference numeral 10 has been used therein to identify a 
model of a tool carrier, while the reference numeral 12 denotes a tipping 
element. These two components 10 and 12 will be described here, to give an 
example, as constituent parts of a milling tool. The model 10 of the tool 
carrier then corresponds to the milling tool body and the tipping element 
12 is the cutting bit of the milling tool. The model 10 has two blades 13 
and 14 formed thereon, each of such blades 13 and 14 having a blade 
surface 15. Two projections 16 and 17 are provided at the blade surface 
15. The cutting bit 12 is provided with two apertures 18 and 19, each of 
which is provided with a respective cross-sectional enlargement 21 or 22. 
The cross-sectional enlargements 21 and 22 are provided at an exposed 
surface 25 of the cutting bit 12. 
FIG. 2 of the drawing shows a completed milling tool 23, which consist of a 
metallic milling tool body 11, and of the cutting bit 12 secured to the 
milling tool body 11. The milling tool body 11 is made of a material 24 
which fills the volume of the apertures 18 and 19 and of the enlargements 
or recesses 21 and 22 and forms a part of the exposed cutting bit surface 
25. 
Having so described the construction of the milling tool 23, the method of 
the present invention will now be explained in more detail with respect to 
the manufacture of such milling tool 23. The milling tool 23 is provided 
with at least one cutting bit 12. However, in dependence on the particular 
requirements, a plurality of the cutting bits 12 can be provided. The 
cutting bit 12 consists of a suitable material, in order to obtain a 
high-performance cutting tool, such as of cobalt, carbide or high-speed 
steel. On the other hand, the metallic milling tool body 11 consist of a 
relatively inexpensive material 24, for instance of a non-alloyed carbon 
steel. 
During the manufacture of the milling tool 23, the model 10 of the milling 
tool body 11 is made first. It consists of wax or of a synthetic plastic 
material; however, for the sake of simplicity, the method of the present 
invention will be described here only as performed with wax, it being 
understood that the procedure will be analogous when using a synthetic 
plastic material for the tool body 11 instead of wax. At least one 
projection 16, 17 is provided at the blade surface 15. The projection 16 
or 17 can be configured as a cylinder with a circular cross section. 
However, it can also have a different shape with a cross section that is 
not circular. 
The cutting bit 12 is provided with at least one aperture 18 and/or 19. The 
respective aperture 18 or 19 constitutes a counterpart to the associated 
projection 16 or 17. Therefore, it must have generally the same cross 
section as the associated projection 16 or 17. So, for instance, the 
aperture 18 and/or 19 may have a circular cross section, or it may be 
slot-shaped, and in each instance the associated projection 16 or 17 will 
have a shape substantially complementary to that of the respective 
aperture 18 or 19. A cross-sectional enlargement 21 or 22 is provided at 
least at one location along the course of the aperture 18 or 19. The 
cross-sectional enlargement 21 or 22 can be situated within the cutting 
bit 12. Yet, a very simple fabrication of the cross-sectional enlargement 
21 or 22 results from providing the same as a countersink or counterbore 
at the end of the respective aperture 18 or 19 which opens onto the 
exposed cutting bit surface 25. 
After the production of the model 10, the cutting bit 12 is juxtaposed with 
the blade surface 15. Herein, the projection 16 and/or 17 serves as a 
guide in that it engages in the associated aperture 18 and/or 19. 
During the next stage of the manufacturing process, the model 10 which is 
made of wax is replaced by the metallic milling tool body 11 and 
simultaneously the heretofore loose connection of the cutting bit 12 with 
the model 10 is converted into a strong and durable mechanical connection 
of the cutting bit 12 with the milling tool body 11. This is accomplished 
by resorting to the use of precision casting technology. More 
particularly, the model 10 with the at least one cutting bit 12 mounted 
thereon is inserted into a mold, in which the wax of the model 10 is 
replaced by molten liquid steel which is introduced into the mold under 
pressure, in a so called cire perdue process which will be referred to 
herein as the lost wax process. The liquid steel 24, in addition to 
forming the tool body 11, also fills the volume of the respective aperture 
18 and/or 19 and of the cross-sectional enlargement 21 and/or 22. By using 
this procedure, there is achieved in a secure manner a durable and rigid 
connection of the cutting bit 12 to the tool body 11. It will be 
appreciated that the manufacturing process of the metallic milling tool 
body 11 and the connection thereof with the cutting bit 12 are completely 
accomplished in a single manufacturing step. 
A modification of the manufacturing process is possible in accordance with 
the present invention in the following manner: the mounting of the cutting 
bit 12 on the model 10 of the milling tool body 11 occurs already during 
the fabrication of the model 10 from wax. In this case, the completely 
manufactured cutting bit 12 is positioned in a mold in such a manner that, 
after the filling of the mold with wax during a model-forming step, it 
assumes the same position on the model 10 as it is supposed to assume 
later on the finished milling tool body 11. Analogously to the 
last-discussed process step during which the wax is replaced by the liquid 
metal, the liquid wax introduced into the mold during the model-forming 
step also fills the volume of the respective aperture 18 and/or 19 and of 
the cross-sectional enlargement 21 and/or 22. After the wax has congealed 
or solidified, the cutting bit 12 is rigidly connected with the model 10. 
Subsequently, the model 10 which has been made of wax during the 
above-discussed model-forming step is replaced in the lost wax process by 
the metallic material 24 in the same manner as discussed previously. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
arrangements differing from the type described above. 
While the invention has been illustrated and described as embodied in a 
method of manufacturing a milling tool, it is not intended to be limited 
to the details shown, since various modifications and structural changes 
may be made without departing in any way from the spirit of the present 
invention. So, for instance, the method of the present invention is not 
limited to the manufacture of milling tools. It is also suited for the 
manufacture of other chip-removing tools, for example of drilling tools 
such as spiral, peeling, precision or countersinking or counterboring 
drills. The method of the present invention is of a special interest for 
the manufacture of drilling tools having relatively large dimensions, 
inasmuch as the tool carrier or body need not be made completely of an 
expensive and special steel under these circumstances. In this case, the 
tool carrier 11 consists of a stem to which the tipping element 12 is 
secured. The part on which the drilling or cutting edges are formed is the 
tipping element 12. The tipping element 12 is produced before the 
manufacture of the tool carrier 11 as a sleeve-shaped component. Herein, 
the stem of the tool carrier 11 fills the internal space of the 
sleeve-shaped component 12 after the completion of the lost wax process. 
Here again, the connection of the tipping element 12 with the tool carrier 
11 is achieved simultaneously with the formation of the tool carrier 11 
during the performance of the lost wax process. The apertures 18 and/or 19 
of the drilling bits 12 are advantageously disposed in the chip-receiving 
channels of the drilling tool. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of our contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the claims. 
What is claimed as new and desired to be protected by Letters Patent is set 
forth in the appended claims.