Title: Shaft tool with fixedly disposed winglike inserts
Abstract: A shank-end tool is described that is simple and economical to manufacture, with permanently attached wing-like inserts for the milling-type machining of chipless materials that remains functional with unavoidable frictional wear and with increasing erosion. The shank-end tool is characterized by a shank (1) rotatable around its longitudinal axis (2) that can be connected detachably to a drive device and is provided at its free end section (6) with at least one groove-shaped recess (7) extending in the axial direction and one flat cutter blade (8), which is provided with a non-cutting blade edge (12) on its leading face viewed in the direction of advance (9). The shank-end tool is used for the manufacture of molds, especially heat-resistant casting molds for the production of metal castings.
Patent Number: 6,984,093 Issued on 01/10/2006 to Hauschild, et al.
| Inventors:
|
Hauschild; Rüdiger (Naundorf, DE);
Hentschel; Bertram (Trebsen, DE);
Wagner; Ralf (Kesselsdorf, DE);
Gantner; Detlev (Freiberg, DE)
|
| Assignee:
|
Actech GmbH Advanced Casting Technologies (Freiberg, DE)
|
| Appl. No.:
|
019749 |
| Filed:
|
June 7, 2000 |
| PCT Filed:
|
June 7, 2000
|
| PCT NO:
|
PCT/DE00/01888
|
| 371 Date:
|
December 21, 2001
|
| 102(e) Date:
|
December 21, 2001
|
| PCT PUB.NO.:
|
WO01/00351 |
| PCT PUB. Date:
|
January 4, 2001 |
Foreign Application Priority Data
| Jun 24, 1999[DE] | 199 28 840 |
| Current U.S. Class: |
407/53; 407/54; 407/56 |
| Current Intern'l Class: |
B23C 5/10 (20060101) |
| Field of Search: |
407/53,54,56,61,62
366/325.92
164/17,701,262
|
References Cited [Referenced By]
U.S. Patent Documents
| 221099 | Oct., 1879 | Putnam.
| |
| 638504 | Dec., 1899 | Galt.
| |
| 717531 | Jan., 1903 | Beynon.
| |
| 1303333 | May., 1919 | Lambert.
| |
| 2621548 | Dec., 1952 | Williams.
| |
| 2637537 | May., 1953 | Arthur.
| |
| 3261095 | Jul., 1966 | Nelson et al.
| |
| 3540315 | Nov., 1970 | Freitag.
| |
| 4034452 | Jul., 1977 | Edming.
| |
| 4060335 | Nov., 1977 | Holloway et al.
| |
| 4116579 | Sep., 1978 | Hamilton.
| |
| 4243348 | Jan., 1981 | Paige.
| |
| 4541757 | Sep., 1985 | Reynolds et al.
| |
| 4623285 | Nov., 1986 | Costil.
| |
| 4924444 | May., 1990 | Castellanos.
| |
| 5222842 | Jun., 1993 | Schweikert et al.
| |
| 5597269 | Jan., 1997 | Ogawa.
| |
| 5653536 | Aug., 1997 | Mandel.
| |
| 6071045 | Jun., 2000 | Janness.
| |
| 6116831 | Sep., 2000 | Simson et al.
| |
| 6146059 | Nov., 2000 | Rohr.
| |
| 6305832 | Oct., 2001 | Huang.
| |
| Foreign Patent Documents |
| 197 21 900 | Dec., 1998 | DE.
| |
Primary Examiner: Ashley; Boyer D.
Assistant Examiner: Ross; Dana
Attorney, Agent or Firm: Neuner; George W., Edwards & Angell LLP
Claims
What is claimed is:
1. A method for the milling-type machining of chipless materials for the manufacture
of heat-resistant sand molds, said method comprising:
providing a shank-end tool comprising:
a shank portion having a longitudinal axis, a first end that can be connected
detachably to a drive device and a second end with a groove-shaped recess extending
in the longitudinal direction; and
a blade as an insert tool in the form of a flat bar in said groove and fixedly
attached to the shank, said cutter blade having a flat leading face with a leading
blade edge in a direction of advance during use,
wherein the blade has a leading blade edge with at least a portion of the leading
edge substantially parallel to said longitudinal axis and the flat bar and is provided
with a non-cutting blade edge on the leading face; and
wherein said leading blade edge is at a right angle to the flat leading face; and
machining a chipless material with the shank-end tool to provide a finished form.
2. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the flat leading face of the blade is more wear resistant then
the rear side of the cutter blade, wherein the blade comprises a steel base material
and is provided with a wear-protective covering on the leading flat face, the wear-protective
covering being a material selected from the group consisting of a hard substance,
a metal composite containing hard substances, and a metal alloy containing a hard substance.
3. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the blade further comprises a trailing edge behind the leading
blade edge when viewed in the direction of advance, wherein the blade edge and
the trailing edge are rounded.
4. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the flat leading face of the blade has a rounded corner or a corner
cut at an angle.
5. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the flat leading face of the blade has an outer contour with a
circular arc or conical shape.
6. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the blade further comprises a curved surface having a convex face
or a bent surface, parallel to the longitudinal axis, with the convex face of the
curved surface or of the bend pointing in a direction of rotation of the shank
in use.
7. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the blade further comprises shovel-like blade folds that are sloped
with a blade angle relative to the longitudinal axis to produce fan-like action.
8. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the blade comprises a material selected from the group consisting
of a metal, a high-strength elastically deformable material, and a springy material.
9. A method for the milling-type machining of chipless materials in accord with
claim 1, wherein the shank comprises a tubular or cylindrical hollow body at least
at the second end.
Description
BACKGROUND OF THE INVENTION
This invention relates to a shank-end tool with permanently attached wing-like
inserts for the milling-type machining of chipless materials for the manufacture
of molds, especially heat-resistant casting molds for producing metal castings.
Primarily sand molds that are made with the help of patterns are used in
practice to produce metal castings. Since it is costly to make patterns, there
has long been a need to make casting molds by direct machining of heat-resistant
molding compositions for small and medium-sized runs.
In DE PS 26 05 687 C3, a cutting and milling tool is used to hollow out a mold
cavity to produce sand molds, which is used in active combination with a duplicating
miller. The milling tool has a knife assembly with a cutter that conforms essentially
to an inverted T-shape and is fastened to an arm that rotates around an axis of
rotation. The cutter is interchangeable, it is curved on the outside to smooth
the mold surface according to the inside diameter of the casting mold to be produced,
and viewed in the direction of rotation it is shaped on the forward edge so that
a cutting edge is formed. A hardenable green sand with low strength of 2-5 kg/cm
2
compacted in a molding box is hollowed out with the cutter before the final
strength of the molding sand after hardening is reached. This is to prevent fast
wear of the cutting edge. The method is relatively difficult to perform because
the proper time for the machining has to be provided for during the hardening of
the mold. Otherwise the mold becomes dirty with low-strength molding sand, or the
cutter quickly becomes unusable with high-strength sand. Furthermore, the milling
tools can be used only to make rotationally symmetrical parts.
On the other hand, it was proposed in DD 275 419 A1 to work out a casting mold
from a single block of mold material with tools that have no cutter geometry. To
produce a cavity in a block of mold material, a device is used that includes a
rod-shaped driver driven around an axis on which at least two non-rigid or semi-rigid
carriers variable in length are guided. Active machining units are fastened to
these carriers and are positioned at identical angular graduations on the driver
to avoid imbalance. Flat parts such as triangular plates, stars, or the like, or
balls or squares or others with or without edges can be used as active machining
units, for example. Cables, wire cables, sheet metal strips, chains, or the like
can be used as non-rigid or semi-rigid carriers, and are provided with additional
guard elements to protect against the wear caused by the eroded sand mold material.
To increase excavating capacity, it is necessary during the machining to achieve
the highest possible stiffness of the carriers by arranging the machining units
to be movable and having them braced against one another. The device can be run
under computer control on the arm of a robot. In the same way, it is also possible
to control the device by a CNC machine. To improve the surface of the castings,
the inner surfaces enclosing the cavity space are sprayed in a concluding step
with a smoothing agent, which has to be distributed evenly over the surface. In
this case also, it is a drawback that essentially only molds that differ only roughly
from rotationally symmetrical parts can be made. The low surface quality of the
castings produced with the casting molds is a drawback that can be attributed to
the more or less beating action of the tools.
Shank-end millers that have a circular contour are customary for the production
of casting molds. The shank-end miller described in DE 197 21 900 A1 has a cutting
plate on the free end that is fastened to the shank with tightening screws. The
shank has a plate seat with a threaded bore, with the cutting plate being provided
with a drilled hole. However, such fastening runs into problems when the dimensions
of the cutting plates are smaller than a minimum size. Therefore, it is difficult
to loosen the cutting plate or to fasten it satisfactorily. It is also a drawback
that the cutting plate is exposed to high wear from chipless materials. This makes
it necessary to change tools constantly, which is associated with correspondingly
high cost.
To reduce the tool cost occurring from high wear, an economically manufactured
milling tool was proposed in DE 3914074 A1 that has a cylindrical shank and a flat
cutter support. The cutter support is provided with cutting edges at its edges
farthest from the axis of the shank. There are additional frontal cutting plates
on the face of the cutter support. The shank is designed as a borer at one end
so that the miller can function as a face mill. The cutters are positioned at the
radially terminal outer edges of the cutter support relative to the axis of the
shank. The cross section of the milling tool shows an S-shaped profile with the
cutting edge pointing in the cutting direction. For this reason the previously
described miller can be used only for chip-forming materials. Use is not possible
for chipless materials.
Foundry sands containing binders bring about a severe degree of wear of the
tool cutters, which is caused by wear of the cutters at the cutting edges and frictional
wear on the open surfaces. For this reason there is cutting action only with new
tools, and there is thus a time limit for it. The cutter wear is manifested as
rounding of the forward edge of the tool, which causes additional frictional wear
in the area behind the cutting edge. This frictional wear increasingly erodes the
outer surfaces and deforms the tool increasingly toward the rear opposite to the
direction of rotation. The energy corresponding to the friction is converted into
heat, which can lead to heating of the tool and to more rapidly increasing wear.
The problem underlying this invention is to design a shank-end tool for milling-type
machining that is simple and economical to manufacture, in such a way that it remains
functional with unavoidable frictional wear and with increasing erosion. The machining
action should be retained for a lengthy period of time. The losses from friction
should be lowered.
SUMMARY OF THE INVENTION
The problem is solved pursuant to the invention with a shank-end tool with a
wing-like cutter blade as a cutter insert that is characterized by a shank (1)
rotatable around its longitudinal axis (2) that can be connected detachably
to a drive device and is provided at its free end section (6) with at least
one groove-shaped recess (7) extending in the axial direction and one flat
cutter blade (8), which is provided with a non-cutting blade edge (12)
on its leading face viewed in the direction of advance (9). The minimal
blade thickness brings about a substantial reduction of friction between the blade
edges and the casting mold surface, which not only reduces the erosion of the cutter
blade but also increases the working life of the tool. Because of this the tool
is particularly suitable for high-speed machining, since it has reduced weight
and the cooling of the blade edges is increased at high speeds of rotation.
The proposed shank-end tool is composed of easily made semifinished parts, and
it can be made economically in this way, which will be described in detail below
with reference to an example of embodiment. Other benefits and refinements of the
invention are shown in the following description. Examples of such other benefits
and refinements include preferred shank-end tools characterized by the fact that
the cutter blade (8) is made as a part punched out of a flat blank made
of steel, wear-resistant steel, or a suitable wear-resistant material, and is provided
with a blade edge (12) at a right angle to the flat face (11); characterized
by the fact that the blade edge (12) and the trailing edge (13) of
the cutter blade (8) behind the blade edge (12) viewed in the direction
of advance (9) are given a radius or are rounded; characterized by the fact
that the cutter blade (8) has the basic form of a square or rectangular
blank, and/or is provided on the face with rounding (17) or corners (18)
cut at an angle; characterized by the fact that the cutter blade (8) is
provided with a circular arc-shaped or conical outer contour; characterized by
the fact that the cutter blade (8) is provided with curvature (22)
or bending (23) parallel to the longitudinal axis (2), with the convex
face of the curvature (22) or of the bend (23) pointing in the direction
of rotation (24); characterized by the fact that the cutter blade (8)
has shovel-like blade folds (25) that are sloped with a blade angle (26)
relative to the longitudinal axis (2), to produce fan-like action; characterized
by the fact that the cutter blade (8) is made of a metallic blade material,
a high-strength elastically deformable blade material, or a springy blade material;
characterized by the fact that the cutter blade (8) has a steel base material
and is provided with a wear-protective covering (15) on its leading flat
face (11) consisting of a hard substance or a metal composite containing
hard substances or a metal alloy containing a hard substance; or characterized
by the fact that the shank (1) has a tubular or cylindrical hollow body
(5) at least in the area of the cutter blade holder (4).
BRIEF DESCRIPTION OF THE DRAWINGS
The attached drawings show:
FIG. 1 a shank-end tool with a rectangular cutter blade,
FIG. 2 a shank-end tool with a cutter blade with arc-shaped blade edge,
FIG. 3 a shank-end tool with a cutter blade with rounded blade edges,
FIG. 4 a shank-end tool with a cutter blade with angled blade edges,
FIG. 5 a shank-end tool with a cutter blade with conical blade edges,
FIG. 6 a shank-end tool with a tubular shank,
FIG. 7 a shank-end tool with cutter blades positioned with double symmetry,
FIG. 8 a shank-end tool with a curved cutter blade convex in the direction of rotation,
FIG. 9 a shank-end tool with angled-back cutter blade convex in the direction
of rotation,
FIG. 10 a shank-end tool with angled-back cutter blade convex in the direction
of rotation with obliquely pitched blade edges in schematic illustration.
DETAILED DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS
The shank-end tool shown in FIG. 1 for the milling-type machining of chipless
materials, which may include coarse-crystalline sand particularly in the manufacture
of heat-resistant casting molds for metal castings, consists essentially of two
simple parts that are assembled in a suitable way, for example by interlocking
assembly, welding, soldering, or cementing.
The elongated and cylindrical shank
1 rotatable around its longitudinal
axis
2 has an upper shank section
3 that can be connected detachably
to a tool holder for rotary cutting tools. According to FIG. 6, the shank
1
is of tubular design with a hollow body
5. A tubular hollow body
5
offers a substantial saving of weight, which becomes a particularly noticeable
advantage especially at high speeds of rotation. Another benefit may consist of
the fact that the shank
1, at least in the area of the cutter blade mount
4, is designed as a tubular hollow body
5. In this way the hollow
body
5 can be lengthened with a fitted cylindrical shank section
3
when machining deep parts.
The shank
1 at its free end section
6 is provided with a groove-shaped
recess
7 in the area of the cutter blade mount
4, extending in the
axial direction, to hold the cutter blade
8. According to FIG. 7, by way
of example, there are two groove-shaped recesses
7 so that two cutter blades
8 can be positioned with double symmetry. In the case of a tubular hollow
body
5, the cutter blades
8 can be interlaced with one another by
two opposite half cutaways in the longitudinal axis
2, and can be fastened
in the recess
7 in an especially simple way, for example by soldering. This
guarantees a secure mount at high speeds of rotation.
The cutter blade
8 can be produced as a punched part by punching from
a flat blank of sheet metal or wear-resistant sheet metal, with the invention not
being limited to the mentioned examples of embodiment. Instead, unmentioned suitable
materials and semifinished products can also be used, if they are within the scope
of the patent claims. In particular, this is true for composite materials, fiber
composition materials, or high-strength materials or ceramic or fiber-composite
ceramic elements.
The cutter blade
8 according to FIG. 1 is provided with a wear resistant
cutting blade edge
12 on the leading flat side
11 viewed in the direction
of advance
9, at a right angle to the flat side
11 when a simple
punched part is used. In this case the blade thickness can be comparatively small.
The blade thickness can be 0.1 mm-5.00 mm. The blade thickness is preferably
0.2-1.00 mm.
In particular, the blade thickness should be no greater so that the tangential
angle of the flank of the leading blade edge
12 is close to or equal to zero.
When high-strength or composite materials are used, the blade edge
12
and the trailing edge
13 behind the blade edge
12 of the cutter blade
8 viewed in the direction of advance
9 are given a radius or are
rounded. Frictional heat and wear are reduced by a small tangential angle and by rounding.
Additional reduction of friction in the area of the trailing edge
13
can be achieved with a cutter blade
8 that has a base material of steel
and is joined to a high-strength wear-protective covering
15 on the leading
flat face
11. Any hard substance or metal composites containing a hard substance,
or a metal alloy or composite material containing a hard substance can be provided
as the wear-protective covering
15. Wear of the blade edge
12 becomes
lower because of the wear-protective covering
15 applied to the leading
flat face
11. The trailing edge
13 on the cutter blade
8 made
of steel erodes more severely because of its low strength, so that the flank that
has low frictional resistance becomes rounded.
The cutter blade
8 can have diverse forms. Thus different shank-end tools
can be used in succession when machining casting molds using CNC-controlled machine
tools with automatic tool change, so that the production of complicated molds can
be substantially simplified. In the basic form, the cutter blade
8 of FIG.
1 and FIGS. 3-10 has a square or rectangular blank. In FIG. 3 the cutter blade
8 is rounded
17 on its face
16, or in FIG. 4 it is provided
with corners
18 cut off at an angle on the face.
The cutter blade
8 of FIG. 2 has an outer contour that has the shape of
a circular arc
19, and in FIG. 5 a trapezoidal contour
21 can be
seen, which produces a cone when rotated around the longitudinal axis
2
of the shank-end tool.
In a particularly beneficial refinement of the shank-end tool, the cutter blade
8 can have convex curvature
22 parallel to the longitudinal axis
2 according to FIG. 8, or in FIG. 9 it can have convex folding
23
in the direction of rotation
24. If the cutter blade
8 is made of
an elastically deformable or springy blade material of low thickness, the curvature
22 can be reduced at higher speeds, as in the case of high-speed machining.
In this way the tool radius can be kept constant with increasing wear of the cutter
blade
8 because of a speed increase. Metal cutter blades
8 that have
high wear resistance are especially suitable for this process. Filigree casting
molds that have a very smooth mold surface can be manufactured with the shank-end
tools shown, using foundry sand.
To eliminate the machining residues formed during the cutting of the material,
it is advantageous for the cutter blade
8 to have shovel-like blade bends
25 according to FIG. 10 to produce fan-like action, by providing a blade
angle
26 relative to the longitudinal axis
2. The eroded material
residues can thus be carried away from the point of machining primarily in the
axial direction.
*
