Note: Descriptions are shown in the official language in which they were submitted.
CA 02336843 2000-12-28
A Process for Manufacturing a Cutting Too) which aids the Metal-Cutting
Machining Operation of Metal Tools
Description
The invention concerns a process for manufacturing a cutting tool which aids
the metal-cutting
s machining operation of metal tools according to the characterising clause of
claim 1, in addition a
cutting tool blank according to the characterising clause of claim 6 and a
cutting tool according to the
characterising clause of claim 9.
Cutting tools for metal cutting machining operations of metal work pieces as
well as processes
for their manufacture are known. In what follows here starts with cutting
tools which have a metallic
,o base, for example a metal plate, and a crystalline wear-resistant coating
bonded to the latter. The
wear-resistant coating contains diamond crystals (polycrystalline diamond I
PCD) and/or cubic boron
nitride crystals (CBN). This coating is deposited on the bottom layer
preferably consisting of a hard
metal and then bonded practically non-detachably to the metallic base in a
sintering process. For
example, powder coatings of the type mentioned here are known to bond at
1500°C and at 50 to
n 60kbar with the hard metal substrate.
One lateral face of the metal plate provided with the wear-resistant coating
is then ground in
order to produce a cutting edge. In the case of cutting tools with more than
one cutting edge, a
corresponding number of lateral faces are subjected to a grinding process.
In the known process described here, the coated metal plate is either
manufactured directly in
zo the form which the future cutting tool is to have. However, also well-known
is the manufacture in the
process described here of larger metal plates, which are also described as
round blanks, and the
cutting-off or cutting-out of cutting tools and then subjecting the lateral
faces thereby produced to a
grinding process in those areas in which the future cutting edge is desired.
This process is relatively costly, and expensive with regard to warehousing.
z5 That is why the aim of the invention is to provide a process of the type
mentioned at the
beginning and which does not have these disadvantages.
To solve this problem, a process including the steps mentioned in claim 1 is
proposed, The
process is characterised by, in a first procedural step, a cutting tool blank
being produced which does
not yet have its final form. It is not yet specifically shaped, pa~iwlarly in
the area in which one or
ao more cutting edges are to be located on the finished cutting tool. So as to
be able to use such a
cutting toot blank as a cutting tool, it is first necessary in a later second
procedural step to produce the
particular area mentioned here in the desired form, which is adapted to a
particular application case.
For instance, an end area (Which is at first rectangular) of the cutting tool
blank is formed into a
~iangular shape, or that is to say provided with a point, so as to be able to
produce a thread-cutting
a5 tool. The shaping of the area of the cutting tool blank provided for the
metal-cutting machining
operation can be carried out in any suitable way. Only then is the cutting
tool blank shaped in this
way ground in the area of the future cutting edge.
The cutting tool blank is thus not yet immediately capable of being used for
the metal-cutting
machining of metal work pieces. At first this appears to be a disadvantage,
because now the finished
ao cutting tool can only be produced in a second further procedural step,
whereby the area in which the
CA 02336843 2000-12-28
2
cutting edges) is/are to be located still requires a special machining
operation and has to be brought
to the desired shape before the cutting edges can be produced through
machining of the lateral faces.
However, it has tamed out that cutting tool blanks of the type mentioned here
are produced in large
numbers and can be supplied to an in-process stock without additional
specification. To produce a
s specific cutting tool from this stock of non-specific cutting tool blanks,
blanks of any type can be taken
which are then brought to the desired shape in the final machining operation
and are provided with at
least one cutting edge by means of a grinding process.
A preferred form of implementing the process is characterised in that the
cutting tool blank is
brought to its desired shape by a grinding process in the area in which at
least one of the cutting
,o edges is to be located. With suitable implementation of the grinding
process, machining of this area
can be undertaken so that grinding of the lateral faces produced thereby can
be carried out to produce
at least one cutting edge directly in the shaping operation, It is therefore
possible to combine the
additional second procedural step with the grinding process for producing a
cutting edge and to
minimise the required processing time for producing the cutting tool.
~s Additional forms of implementing the process emerge from the remaining sub-
claims.
Furthermore the aim of the invention is to provide a cutting tool blank which
is used to
manufacture a Cutting tool and which is characterised by low-cost production.
To solve this problem, a cutting tool blank is proposed which has the features
mentioned in
claim 6 and which is characterised in that it has at first a non-specific
shape. It is therefore not
zo tailored to a specific way of machining, or that is to say it is not
tailored for particular tools.
Warehousing of such a non-specific blank does not require any special
organisational structure and
therefore can be achieved easily and inexpensively.
Additional forms of the cutting tool blank ensue from the remaining sub-
claims.
The invention is explained in more detail below with reference to the
drawings, which show: in
25 Figure 1 a cutting tool in a top view; in Figure 2 a front view of the
cutting tool according to Fgure 1,
and in Figure 3 a side view of the cutting fool represented in Figure 1.
Figure 1 shows in a top view a cutting tool 1 which has an essentially
rectangular basic shape.
One of the longitudinal faces, here the top longitudinal face 3, is provided
with elevations S and
depressions 7 which by way of example are both formed here in essentially
triangular form and by
3o that are used to provide toothing which facilitates the secure fixing of
the cutting tool 1 in a tool. By
means of the same type of formation of elevations 5 and depressions 7 provided
here over the course
of the longitudinal face 3, it is possible to clamp the cutting tool 1 in
different positions in a tool and
consequently to ensure dressing of the cutting tool. If therefore the cutting
tool is blunt, it can be
dressed so that it is fitted once more in the tool and therefore can be used
again.
3s The cutting toot 1 is manufactured from a cutting tool blank 9, which has
essentially the external
profile of the cutting tool 1, but which in the area 11 (in which the cutting
edges 13 and 15 of the
cutting tool 1 are located) is at first basically formed in a rectangular
shape. This is clearly shown in
Figure 1 by a dashed line.
In the example of implementation of the cutting tool 1 represented here, the
cutting edges 13
ao and 1 S in the area 11 are arranged symmetrically to an imaginary centre
line 17 and each forms an
CA 02336843 2000-12-28
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angle of approx. 30° by way of example with the centre line. A dotted
line 19 indicates that a
continuous cutting edge 13', which here purely by way of example forms an
angle of approx. 40° with
the centre line 17, can also be provided extending over the entire height h of
the cutting tool 1.
Obviously it is possible for this cutting edge 13' to also extend in a mirror
image to the centre line.
s From the explanations represented here, it is readily apparent that an
essentially rectangular
area 11 of a cutting fool blank 9 can be shaped in such a way that cutting
edges matched to specific
ways of metal-cutting machining are produced.
Figure 2 shows a front view of the cutting tool 1, that is a view of the area
11.
This representation clearly shows that the cutting tool 1 has a metallic base,
in this case a
~o metal plate 21, preferably a hard metal plate, on which a layer of hard
material, namely a powder
coating 23, is Sintered practically non-detachably and which contains diamond
crystals andlor cubic
boron nitride crystals or similar. This coating is especially hard, wear-
resistant and robust and is
represented in stippled form for clarity.
In the implementation example of the cutting tool 1 depicted here, on the
lower side 25 opposite
the powder coating 23 is provided a rake 27 which aids the defined locating of
the cutting tool 1 on the
tool.
The lateral face 29 located at the bottom in Figure 2 is inclined with respect
to an imaginary
centre plane E. Here it tapers away from the surface 31 of the powder coating
23 to the centre plane
E at an acute angle of 6° for example. The upper surface 33, which
corresponds to the longitudinal
zo face 3 (Figure 1 ), runs parallel to the centre plane E.
Apparent in the top view are the front faces 35 and 37 located in the area 11,
the said front
faces 35 and 37 being subjected to a grinding process to create the cutting
edges 13 and 15. The
representation according to Figure 2 shows that the front faces 35 and 37
intersect in the area of the
centre plane E, and therefore are formed symmetrically.
zs The side view according to Figure 3 shows the uppermost longitudinal face 3
of the cutting tool
1 in Figure 1. In Figures 1 and 2, the elements mentioned of the cutting tool
1 are provided here with
the same reference number, so that the description refers to both Figures 1
and 2.
It can be seen from the representation according to Figure 3 that the
longitudinal face 3 is
provided with elevations 5 and depressions 7, which extend over khe entire
thickness d of the cutting
tool 1 and run essentially parallel to the rear face 39 of the cutting tool 1.
Here it is also clear that the cutting tool 1 comprises a base 21 and a powder
coating 23,
likewise shown here in stippled form.
A dashed line here also indicates that in the area 11 of the cutting tool, 1
parts of a cutting tool
blank 9 have been removed in order to now form cutting edges in this area,
35 The process for manufacturing a cutting tool 1, which aids the metal-
cutting machining
operation of metal work pieces, is gone into below.
In a first procedural step, a powder coating containing diamond Crystals
andlor cubic boron
nitride crystals or similar is applied to a base 21, namely a metal plate,
preferably a hard metal plate.
The powder mating is sinter-fused onto the base 21 in a sintering process, for
example at
uec~T~svea
CA 02336843 2000-12-28
4
temperatures of 1500°C and at a pressure of 50 to 60kbar, which results
in a non-detachable
bonding.
The coated metal plate can have from the outset the shape of the cutting toot
blank 9 described
in Figures 1 and 3. However, it is also possible to cut off or cut out cutting
tool blanks 9 of the type
s mentioned here from a larger coated metal plate. The cutting process can be
achieved by an erosion
process, preferably by wire electrical discharge machining, by which the
elevations 5 and depressions
7 can be provided in the area of the longitudinal face 3.
The area i 1 of the cutting tool blank is non-specifically shaped, that is it
is not especially
tailored to the future application of the cutting tool 1. In the example of
implementation of a cutting tool
o blank 9 represented here, provision is made that the latter is formed in
basically a rectangular shape
in the area 11.
A cutting tool blank 9 of this type can be stored with no exceptional
expenditure, since it is not
assigned to particular tools.
The area 11 of the cutting tool blank 9 cart be brought to a particular shape
as and when
required, so that the cutting tool can be used as a chisel, a lathe tool for
right-hand or left-hand
rotation, a thread-cuffing tool (see Figure 1 ) or even for a drill and/or
reamer.
The area 11 of the cuffing tool blank 9 can be brought to the desired form in
a cutting and/or
grinding process. In this way, lateral faces can be farmed of which at least
one can be subjected to a
grinding process to produce at least one cutting edge,
zo What is clear is that due to the plain basic form of the cutting tool blank
9, its manufacture can
be carried out very simply. This applies of course especially when a
particular form of a longitudinal
edge, in this case the longitudinal edge 3, is dispensed with. The manufacture
of the blank is
therefore possible particularly rapidly and inexpensively. Holding in storage
of such a "neutral" blank
is, as has been said, is likewise feasible at low cost. Finally, it is evident
that the machining of the
z5 cutting tool blank 9 in the area 11 is particularly simple. The procedural
step for producing a cutting
tool 1 therefore is likewise practicable in a rapid and inexpensive manner.
The shaping of the cutting
tool blank in the area 11 can be carved out by a cutting and for grinding
process. In the latter process
it is particularly advantageous that the desired cutting edge can also be
produced in the manufacture
of the desired shape, so that the additional expenditure to produce the
finished cutting tool 1 from the
3o cutting tool blank 9 can be reduced to a minimum.
From what has been said above, it is evident that the cutting tool 1 can be
used universally,
since practically any cutting edge geometry can be produced in the area 11 of
a cutting tool blank 9,
As well, the blank 9 can be formed so generally that it can find application
in any tools and in various
ways of metal-cutting machining operations. In order to make universal
production feasible, the
ss elevations 5 and depressions '7 represented in Figure 1 can be provided as
well on other lateral faces
of the cutting tool 1. In the end, such forms also can be dispensed with
completely, so as to ensure
the universal application of the cutting tool blank 9.
Finally, it should be noted that the cutting tool 1 can be fitted directly
into a tool. It is also
possible to solder the cutting tool 1 onto a base support and then to clamp
the latter in a tool.
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