Technical field
[0001] The present invention relates to tool bits for grinding materials such as concrete,
granite, stone, marble or the like and grinding segments to be connected on such tool
bits for grinding, and more particularly to grinding segments in which superabrasive
particles are distributed according to a predetermined particle design in a bond material
and by which the grinding performance and service life of the tool bit can be improved.
Background of the invention
[0002] Tool bits for grinding are composed of a disc-shaped or cup-shaped basic body, a
plurality of grinding segments connected to the basic body, and a plurality of suction
holes arranged in the basic body and configured to discharge removed particles. The
basic body includes an outer circumferential section, an inner section configured
to connect the tool bit to a motorized power tool, and a transition section arranged
between the circumferential section and inner section. The grinding segments are connected
to the basic body by brazing, soldering, welding or the like, and the suction holes
are arranged in at least one of the circumferential section and the transition section
of the basic body.
[0003] Typical grinding segments are manufactured by mixing superabrasive particles with
a suitable bond material (e.g., powder). The mixture is compressed in a mold to form
a green body, which is then consolidated by free-form sintering, hot-pressing, or
infiltrating to form a single grinding segment. Finally, the grinding segments are
connected by brazing, soldering, welding or the like to the basic body to form the
final tool bit for grinding.
[0004] During the process of mixing the superabrasive particles with the bond material,
the superabrasive particles have a much larger size compared to the particles of the
bond material and so tend to freely flow, so that under the condition of a finite
overall blending ratio of the superabrasive particles to the bond material, the superabrasive
particles may be highly concentrated in certain regions or very deficient below the
average concentration in other regions to cause irregular or non-uniform distribution
of the superabrasive particles within the grinding segments.
[0005] During grinding operation, the grinding wheel rotates at a certain speed and removes
surface parts of stone, concrete, marble, or the like with the torque originating
from the motorized power tool, and during the course, the superabrasive particles
on the grinding segments experience severe load due to the reactive force of the object
in the form of friction, with the result that the superabrasive particles can be worn
out, loosened, or even broken.
[0006] When such load of friction with the object exceeds the force binding the bond material
with the superabrasive particles, the superabrasive particles pull out and newly emerging
superabrasive particles take over the machining duty, and thus in such a manner the
self-regeneration process repeats itself to enable continuation of machining operation
with the depleted thickness of the grinding segments.
[0007] In the case the superabrasive particles are segregated to certain regions, the load
of friction imposed on an individual superabrasive particle would be decreased. However,
during initial time after the start of grinding, the superabrasive particles would
be in active working and so dulled in the sharp grinding segments or can be subjected
to a degradation together with the bond material due to an abrupt frictional heat
generation, however the self-regeneration remains at a low level, so that deformation
or unevenness on the surface of the grinding wheel can result.
[0008] In contrast, the superabrasive particles in the sections of the grinding segments,
where the concentration of the superabrasive particles is relatively low, are subjected
to larger load of friction or impact per unit particle and therefore the superabrasive
particles are easily broken, constituting a cause of decreasing the service life of
the tool bit.
Summary of the invention
[0009] Therefore, the present invention was created to resolve the problems with the prior
art as described above, and the object of the present invention is to provide a grinding
segment and a tool bit for grinding equipped with the grinding segments, which allow
precise grinding operation thanks to the defined distribution of the superabrasive
particles, and which make possible the marked improvement in the grinding performance
and/or in the service life of tool bits for grinding.
[0010] The object is achieved according to an aspect of the invention by a grinding segment
characterized in that each of the M layers of the bond material has at least one of
a structured lower surface and a structured upper surface, wherein the structured
lower surfaces and/or structured upper surfaces of the M layers have a first structure
that corresponds to the predetermined particle design of the superabrasive particles.
[0011] The grinding segment is fabricated via powder metallurgy, in which a green body is
build up layer by layer and then the green body is further processed by free-form
sintering, by hot-pressing and/or by infiltrating to form the final grinding segment.
The grinding segment includes a bond material that is at least one of free-form sintered,
hot pressed and infiltrated and a plurality of superabrasive particles being arranged
according to a predetermined particle design and bonded in the bond material.
[0012] The grinding segment according to the present invention is composed of at least two
layers of the bond material and of at least one pattern of the superabrasive particles,
the layers and patterns being stacked in the height direction of the grinding segment.
Each of the layers of the bond material has a lower surface and an upper surface and
at least one of the lower and upper surfaces of each layer is a structured surface
having a first structure that corresponds to the predetermined particle design of
the superabrasive particles. The structured lower and/or upper surfaces of each layer
enable that the superabrasive particles of a pattern can be arranged on different
height levels with height differences between adjacent height levels. The height levels
will preferably be selected such that the superabrasive particles of a following height
level will be opened at a certain wearout of the superabrasive particles of the previous
height level. During grinding with the tool bit for grinding, the active superabrasive
particles wear out and their size in the height direction is reduced.
[0013] In a preferred embodiment, the M layers of the bond material include at least a first
layer having a first lower surface and a first upper surface, wherein the first upper
surface has the first structure, and the first lower surface is non-structured. The
first layer has a non-structured first lower surface and a structured first upper
surface. The non-structured first lower surface may be used as front side of the grinding
segment, the front side being opposite of a back side of the grinding segment, and
the grinding segment being connected via the back side to the basic body of a tool
bit.
[0014] In another preferred embodiment, the M layers of the bond material include at least
a first layer having a first lower surface and a first upper surface, wherein the
first upper surface has the first structure, and the first lower surface has a second
structure that is different from the first structure of the first upper surface. The
first layer has a structured first upper surface and a structured first lower surface,
the first structure of the first upper surface being different from the second structure
of the first lower surface. The structured first lower surface may be used as front
side of the grinding segment, the front side being opposite of a back side of the
grinding segment, and the grinding segment being connected via the back side to a
basic body of a tool bit. The use of a structured first lower surface as front side
may have the advantage that the surface area of the front side that is in contact
with the basic body of the tool bit is reduced. In case of connecting the grinding
segments via methods such as resistance welding to the basic body of the tool bit,
a decreased surface area may be preferred.
[0015] Preferably, the M layers of the bond material include at least a M-th layer having
a M-th lower surface and a M-th upper surface, wherein the M-th lower surface and
the M-th upper surface have the first structure. The structured M-th upper surface
may be used as back side of the grinding segment, the grinding segment being connected
via the back side to a basic body of a tool bit.
[0016] Preferably, the bond material is at least one of a first bond material and a second
bond material, the second bond material being different from the first bond material.
The grinding segment is composed of at least two layers of the bond material and of
at least two patterns of the superabrasive particles. The superabrasive particles
are arranged according to a predetermined particle design and fixed by the bond material
that is at least one of free-form sintered and hot-pressed. The first bond material
may be used to fix the superabrasive particles and the second bond material may be
used in a contact area with the connection face to allow welding of the grinding segment.
Alternatively, or additionally, the layers of bond material may comprise a first bond
material and second bond material, the first bond material may be applied to inner
regions of the layers to fix the superabrasive particles and the second bond material
may be applied to outer regions of the layers to strengthen the side surfaces of the
grinding segment.
[0017] Preferably, each pattern of superabrasive particles includes at least two groups
of K, K ≥ 2 lines of the superabrasive particles, the superabrasive particles of adjacent
lines being arranged on different height levels in the height direction. The grinding
segment is composed of at least one pattern of the superabrasive particles, the patterns
being stacked in the height direction. In each pattern, the superabrasive particles
are arranged according to the predetermined particle design that includes two or more
groups of at least two lines of the superabrasive particles. The number of groups
is preferably adapted to the abrasiveness of the workpiece to be grinded and/or the
expected lifetime of the grinding segment. In a line, the superabrasive particles
are arranged on a similar height level in the height direction, and the superabrasive
particles of adjacent lines are arranged on different height levels. The number of
lines and the height levels of the different types of lines may be selected such that
the superabrasive particles of the next type of lines are opened before the superabrasive
particles positioned just above have been worn out at a certain percentage, so that
self-regeneration of the superabrasive particles may be repeated for the service time
of the grinding segment.
[0018] When all lines of a pattern were fallen out, the next pattern of superabrasive particles
will become active. The height levels of the last type of lines of a previous pattern
and the first type of lines of a following pattern may be selected such that the superabrasive
particles of the next type of lines are opened before the superabrasive particles
of the last line positioned just above have been worn out at a certain percentage,
so that self-regeneration of the superabrasive particles may be repeated for the service
time of the grinding segment.
[0019] Preferably, each of the at least two groups comprises a first line of superabrasive
particles, a second line of superabrasive particles, and a third line of superabrasive
particles, wherein the first lines being arranged on a first height level, the second
lines being arranged on a second height level, and the third lines being arranged
on a third height level, and wherein the first height level, second height level and
third height level being different from each other in the height direction. In each
pattern of the grinding segment, the superabrasive particles are arranged according
to the predetermined particle design that includes two or more groups of a first line,
a second line, and a third line of superabrasive particles, wherein the superabrasive
particles of the first, second, and third line are arranged on the first, second,
and third height level.
[0020] In a first preferred embodiment, the height differences between the first and second
height level and between the second and third height level are substantially equal.
The lines of superabrasive particles of each group define a linear arrangement and
the superabrasive particles of the adjacent lines will become active one after the
other.
[0021] In a second preferred embodiment, the height differences between the first and second
height level and between the second and third height level are different from each
other. The lines of superabrasive particles of each group define a non-linear arrangement
that helps in retaining a more uniform wearout at the edges of the grinding segment
and keeping the tool bit grinding for the service life.
[0022] Preferably, each of the at least two groups further comprises a fourth line of superabrasive
particles, wherein the fourth lines being arranged on a fourth height level, and wherein
the fourth height level is different from the first height level, second height level
and third height level in the height direction. By using four lines of superabrasive
particles arranged on different height levels the height difference between the lines
can be reduced. Preferably, the number of lines of each group and the height differences
between the lines may be selected such that the superabrasive particles of a line
will be opened at a certain wearout of the superabrasive particles of the previous
line.
[0023] Preferably, each of the at least two groups may further comprise a fifth line of
superabrasive particles, wherein the fifth lines being arranged on a fifth height
level, and wherein the fifth height level is different from the first height level,
second height level, third height level, and fourth height level in the height direction.
By using five lines of superabrasive particles arranged on different height levels
the height differences between the lines can be reduced. Preferably, the number of
lines of each group and the height differences between the lines may be selected such
that the superabrasive particles of a line will be opened at a certain wearout of
the superabrasive particles of the previous line.
[0024] The object is also achieved according to another aspect of the invention by a tool
bit for grinding, comprising a basic body including an inner section configured to
connect the tool bit to a power tool, and a circumferential section with a connection
surface, and two or more grinding segments according to the invention, wherein the
grinding segments are connected to the connection surface.
[0025] The tool bit comprises a disc-shaped or cup-shaped basic body and two or more grinding
segments. The grinding segments comprise a front side and a back side opposite of
the front side, and the grinding segments being connected via the back side to the
basic body. A tool bit according to the invention may have a similar performance over
the lifetime since the superabrasive particles are distributed in the grinding segment
according to the predetermined particle design.
[0026] Preferably, the grinding segments are connected to the connection surface with the
upper surface of the M-th layer of the bond material. The grinding segments are composed
of M, M ≥ 2 layers of the bond material and of N, N ≥ 1 patterns of the superabrasive
particles, the layers and patterns being stacked in the height direction of the grinding
segment. Each of the M layers of the bond material has at least one of a structured
lower surface and a structured upper surface. By using the structured upper surface
of the M-th layer as back side ....
[0027] Preferably, the tool bit further comprises a plurality of suction holes being arranged
in at least one of the circumferential section or a transition section that is arranged
between the circumferential section and inner section.
Brief Description of the drawings
[0028] The aspects of the invention are described or explained in more detail below, purely
by way of example, with reference to working examples shown schematically in the drawing.
Identical elements are labelled with the same reference numerals in the figures. The
described embodiments are generally not shown true in scale, and they are also not
to be interpreted as limiting the invention. Specifically,
- FIGS. 1A, B
- show a grinding wheel including a basic body and a plurality of grinding segments
in a view on a front side of the grinding segments (FIG. 1A) and in a cross-section
parallel to an axis of rotation of the grinding wheel (FIG. 1B),
- FIGS. 2A, B
- show one of the grinding segments of the grinding wheel of FIG. 1 in a view on a back
side of the grinding segment (FIG. 2A), the grinding segment being composed of a bond
material and superabrasive particles being arranged according to a predetermined particle
design (FIG. 2B),
- FIGS. 3A, B
- show a cross-section of the grinding segment of FIG. 2A in a plane parallel to a height
direction of the grinding segment (FIG. 3A) and a detail of FIG. 3A (FIG. 3B),
- FIG. 4
- shows how a green body for the grinding segment of FIG. 2A can be manufactured stepwise,
- FIGS. 5A, B
- show an alternative grinding segment for the grinding wheel of FIG. 1 (FIG. 5A), the
grinding segment being composed of a bond material and superabrasive particles being
arranged according to a predetermined particle design (FIG. 5B),
- FIGS. 6A, B
- show a cross-section of the grinding segment of FIG. 5A in a plane parallel to a height
direction of the grinding segment (FIG. 6A) and a detail of FIG. 6A (FIG. 6B),
- FIG. 7
- shows a further grinding wheel including a basic body and a plurality of grinding
segments in a view on a front side of the grinding segments,
- FIGS. 8A, B
- show a first variant of a grinding segment (FIG. 8A) and a second variant of a grinding
segment (FIG. 8B) for the further grinding wheel of FIG. 7,
- FIGS. 9A, B
- show the grinding segments of FIGS. 8A, B, which are composed of a bond material and
superabrasive particles being arranged according to a first predetermined particle
design (FIG. 9A) and a second predetermined particle design (FIG. 9B),
- FIGS. 10A, B
- show a cross-section of a further grinding segment in a plane parallel to a height
direction of the grinding segment, the grinding segment including a nonstructured
first lower surface (FIG. 10A) and a structured first lower surface (FIG. 10B).
Detailed Description
[0029] Reference will now be made in detail to the present preferred embodiment, an example
of which is illustrated in the accompanying drawings. It is to be understood that
the technology disclosed herein is not limited in its application to the details of
construction and the arrangement of components set forth in the following description
or illustrated in the drawings. The technology disclosed herein is capable of other
embodiments and of being practiced or of being carried out in various ways.
[0030] Also, it is to be understood that the phraseology and terminology used herein is
for the purpose of description and should not be regarded as limiting. All definitions,
as defined and used herein, should be understood to control over dictionary definitions,
definitions in documents incorporated by reference, and/or ordinary meanings of the
defined terms. The indefinite articles "a" and "an", as used herein in the specification
and in the claims, unless clearly indicated to the contrary, should be understood
to mean "at least one". The phrase "and/or", as used herein in the specification and
in the claims, should be understood to mean "either or both" of the elements so conjoined,
i.e., elements that are conjunctively present in some cases and disjunctively present
in other cases. Multiple elements listed with "and/or" should be construed in the
same fashion, i.e., "one or more" of the elements so conjoined. Other elements may
optionally be present other than the elements specifically identified by the "and/or"
clause, whether related or unrelated to those elements specifically identified.
[0031] As used herein in the specification and in the claims, "or" should be understood
to have the same meaning as "and/or" as defined above. For example, when separating
items in a list, "or" or "and/or" shall be interpreted as being inclusive, i.e., the
inclusion of at least one, but also including more than one of a number or list of
elements, and, optionally, additional unlisted items. Only terms clearly indicated
to the contrary, such as "only one of" or "exactly one of", or, when used in the claims,
"consisting of" will refer to the inclusion of exactly one element of a number or
list of elements. In general, the term "or" as used herein shall only be interpreted
as indicating exclusive alternatives (ke. "one or the other but not both") when preceded
by terms of exclusivity, such as "either", "one of", "only one of", or "exactly one
of", "consisting essentially of", when used in the claims, shall have its ordinary
meaning as used in the field of patent law.
[0032] As used herein in the specification and in the claims, the phrase "at least one"
in reference to a list of one or more elements, should be understood to mean at least
one element selected from any one or more of the elements in the list of elements,
but not necessarily including at least one of each and every element specifically
listed within the list of elements and not excluding any combinations of elements
in the list of elements. This definition also allows that elements may optionally
be present other than the elements specifically identified within the list of elements
to which the phrase "at least one" refers, whether related or unrelated to those elements
specifically identified.
[0033] The use of "including, or "comprising, or "having" and variations thereof herein
is meant to encompass the items listed thereafter and equivalents thereof as well
as additional items. Unless limited otherwise, the terms "connected", "coupled", and
"mounted", and variations thereof herein are used broadly and encompass direct and
indirect connections, couplings, and mountings. In addition, the terms "connected"
and "coupled", and variations thereof are not restricted to physical or mechanical
connections or couplings.
[0034] As used herein, the term "segment" means a piece or fragment substantially in the
form of a sector, particularly used for the purpose of cutting, grinding, sawing,
drilling or the like as well. The term "bond material" refers to a material to which
superabrasive particles may be bonded. Bond materials typically consist of a base
powder, which is combined with compression auxiliaries and additives which serve to
optimize the properties of the base powder material with regard to the strength and
wear rate of the segments. The base powder may consist of one base material or be
composed of several base materials.
[0035] Th term "superabrasive particles" refer to particles of either natural or synthetic
diamond, super hard crystalline, or polycrystalline substance, or mixtures of substances
and include but are not limited to diamond, polycrystalline diamond (PCD), cubic boron
nitride (CBN), and polycrystalline cubic boron nitride (PCBN). The term "predetermined
particle design" refers to a non-random particle design of the superabrasive particles
that is identified prior to construction of a tool bit, and which individually places
or locates each superabrasive particle in a defined relationship with the other superabrasive
particles, and with the configuration of the tool bit.
[0036] FIGS. 1A, B show a tool bit
10 for grinding according to the present invention. The tool bit 10 is formed as cup-shaped
grinding wheel and comprises a cup-shaped basic body
11, a plurality of grinding segments
12 according to the present invention, and a plurality of suction holes
13. The grinding segments 12 are connected via a back side
14 to the basic body 11. FIG. 1A shows the grinding wheel 10 in a view on a front side
15 opposite to the back side 14 of the grinding segments 12 and FIG. 1B the grinding
wheel 10 in a cross-section parallel to an axis of rotation
16 of the grinding wheel 10.
[0037] The basic body 11 is composed of an outer circumferential section
17, an inner section
18, and a conical transition section
19 that is arranged between the circumferential section 17 and inner section 18. The
circumferential section 17 is ring-shaped and includes several concentrical grooves
21, which form a structured connection surface
22, to which the grinding segments 12 are fixed, e.g., by brazing, soldering, welding,
or the like as well. Alternatively, the circumferential section 17 may include a plane
connection surface, to which the grinding segments 12 can be fixed. The grinding segments
12 may have a L-shaped, boomerang-shaped, rectangular, triangular or the like as well
cross-section perpendicular to a height direction of the grinding segment.
[0038] The suction holes 13 may be arranged in the circumferential section 17 or in the
transition section 19 and may be equally distributed in one row or in two concentric
rows; alternatively, first suction holes may be arranged in the circumferential section
17 and second suction holes in the transition section 19. In the embodiment of FIG.
1, the grinding segments 12 and suction holes 13 are equally spaced along the circumferential
section 17, and in the circumferential direction, each of the suction holes 13 is
arranged between two adjacent grinding segments 12. The number, size and/or position
of the suction holes 13 may vary and be selected such that a discharge of particles
removed by the grinding wheel 10 can be optimized. The suction holes 13 can create
an airstream, which allows to cool the grinding segments 12 and to discharge removed
particles during grinding operation.
[0039] There are a variety of styles of grinding wheels for different workpieces to be grinded
and different requirements. The dimension and number of their grinding segments determine
how aggressive the grinding wheel is.
[0040] FIGS. 2A, B show one of the grinding segments 12 of the grinding wheel 10 in a view on the back
side 13 of the grinding segment 12 (FIG. 2A), which is composed of a bond material
23 and superabrasive particles
24 being arranged according to a predetermined particle design (FIG. 2B).
[0041] The grinding segment 12 is fabricated via powder metallurgy, in which a green body
is build up layer by layer from a powdery or granular bond material and a plurality
of the superabrasive particles 24 and the green body is further processed to form
the grinding segment 12 by free-form sintering, hot-pressing, or infiltrating. The
grinding segment 12 comprises a substantially triangular cross-section with rounded
edges perpendicular to a height direction
H of the grinding segment 12. The back side 13 of the grinding segment 12 is structured
and the front side 14 is non-structured.
[0042] FIG. 2B shows the predetermined particle design of the superabrasive particles 24,
which are arranged in two patterns. Each pattern includes a first group
G1, a second group
G2 and a third group
G3 of four (K = 4) lines of superabrasive particles 24. Each of the three groups G
1, G
2, G
3 includes a first line
l1, a second line
l2, a third line
l3, and a fourth line
l4 of superabrasive particles 24.
[0043] The number of the superabrasive particles 24 in a line can vary and may depend on
the cross-section of the grinding segment 12. As an example, the fourth line l
4 comprises seven superabrasive particles 24 in the first group G
1, eight superabrasive particles 24 in the second group G
2, and three superabrasive particles 24 in the third group G
3. The distances between adjacent superabrasive particles 24 in a line can vary and
may be adapted to the application of the grinding wheel 10 and the workpiece to be
grinded.
[0044] As different workpieces to be grinded, such as concrete, granite, stone, marble,
and the like, have different natures, the bond material and superabrasive particles
used for the grinding segments should also be different. When the workpiece to be
grinded is hard, the bond material should be softer to let the new superabrasive particles
be exposed more easily and participate in grinding, and, when the workpiece to be
grinded is soft, the bond material should be harder to hold the superabrasive particles
longer to extend the service life of the grinding segments.
[0045] FIGS. 3A, B show a cross-section of the grinding segment 12 of FIG. 2A in a plane parallel to
the height direction H of the grinding segment 12 (FIG. 3A) and a detail of FIG. 3A
(FIG. 3B). The grinding segment 12 is made of the bond material 23 that is free-form
sintered, hot-pressed or infiltrated and of the superabrasive particles 24 being arranged
according to the predetermined particle design shown in FIG. 2B.
[0046] The grinding segment 12 is composed of two (M = 2) layers of the bond material 23
and of two (N = 2) patterns of the superabrasive particles 24, the two layers and
two patterns being stacked in a direction of stacking that is parallel to the height
direction H of the grinding segment 12. The two layers of the bond material 23 are
called first layer
L1 and second layer
L2, and the two pattern of the superabrasive particles 24 are called first pattern
P1 and second pattern
P2.
[0047] The first layer L
1 has a lower surface that is called first lower surface
LS1 and an upper surface that is called first upper surface
US1, wherein the first lower surface LS
1 is a non-structured lower surface and the first upper surface US
1 is a structured upper surface, and the second layer L
2 has a lower surface that is called second lower surface
LS2 and an upper surface that is called second upper surface
US2, wherein the second lower surface LS
2 is a structured lower surface and the second upper surface US
2 is a structured upper surface. The back side 13 of the grinding segment 12 is predetermined
by the second upper surface US
2, and the front side 14 by the first lower surface LS
1.
[0048] Each of the first pattern P
1 and second pattern P
2 include the three groups G
1, G
2, G
3 of the four lines l
1, l
2, l
3, l
4 of superabrasive particles 24. Each group G
1, G
2, G
3 includes a first line l
1, a second line l
2, a third line l
3, and a fourth line l
4 of superabrasive particles 24, wherein the four lines l
1, l
2, l
3, l
4 of each group are arranged on different height levels. In each pattern P
1, P
2, the first lines l
1 of the first, second and third group G
1, G
2, G
3 are arranged on a first height level
h1, the second lines l
2 of the first, second and third group G
1, G
2, G
3 are arranged on a second height level
h2, the third lines l
3 of the first, second and third group G
1, G
2, G
3 are arranged on a third height level
h3, and the fourth lines l
4 of the first, second and third group G
1, G
2, G
3 are arranged on a fourth height level
h4.
[0049] Because the superabrasive particles 24 of the four lines l
1, l
2, l
3, l
4 are arranged on different height levels h
1, h
2, h
3, h
4, they start grinding at different points of time. During grinding with the grinding
segment 12, the superabrasive particles 24 of the fourth lines l
4 start grinding, the superabrasive particles 24 of the third lines l
3 take over grinding, then the superabrasive particles 24 of the second lines l
2 continue grinding and last the superabrasive particles 24 of the first lines l
1 take over grinding.
[0050] In each pattern of superabrasive particles 24, the superabrasive particles 24 of
the first line l
1 and second line l
2 differ in the height direction H by a height distance
δ12, the superabrasive particles 24 of the second line l
2 and third line l
3 differ in the height direction H by a height distance
δ23, and the superabrasive particles 24 of the third line l
3 and fourth line l
4 differ in the height direction H by a height distance
δ34. The superabrasive particles 24 are arranged such that in a group of lines the height
distances δ
12, δ
23, δ
34 are nearly equal.
[0051] The bond material 23 is at least one of a first bond material and a second bond material,
the second bond material being different from the first bond material. In the embodiment
shown in FIG. 3B, the first layer L
1 and second layer L
2 may be made from the first bond material that is preferably adapted to the material
of the workpiece that should be grinded and selected such that the superabrasive particles
24 are fixed in the first bond material as necessary.
[0052] If the grinding segment 12 should be connected to the basic body 11 by welding, the
bond material used in the contact area to the connection face 17 must be weldable.
The use of a third layer of the second bond material could support welding of the
grinding segment 12 to the basic body 11. The third layer of the second bond material
would be applied on the structured upper surface US
2 of the second layer L
2 and would have a structured upper surface.
[0053] Instead of using only the first bond material for the first layer L
1 and second layer L
2, the first bond material and second bond material could be used for the first layer
L
1 and second layer L
2. The first bond material could be selected to fix the superabrasive particles 24
and could be applied to inner regions of the first layer L
1 and second layer L
2, and the second bond material could be selected to strengthen the side surfaces of
the grinding segment and could be applied to outer regions of the first layer L
1 and second layer L
2.
[0054] FIG. 4 shows how a green body
31 for the grinding segment 12 of FIG. 2A may be manufactured stepwise from a powdery
bond material
32 and the superabrasive particles 24. To manufacture the green body 31, a sequence
of a first step, a second step and a third step is performed two times as a first
sequence and a second sequence. Generally, the sequence of the first step, second
step and third step is performed n-times (n ≥ 2) to manufacture a green body for a
segment according to the invention.
[0055] In the first step of the first sequence, a first portion of the powdery bond material
32 is applied to a lower punch (
step 1-1). In the second step of the first sequence, a first plurality of the superabrasive
particles 24 is arranged on the first portion of powdery bond material 32 according
to the predetermined particle design shown in FIG. 2B to build a first layer construction
LC1 (
step 1-2), wherein the superabrasive particles 24 are arranged on the same height level in
the height direction H. In the third step of the first sequence, the first layer construction
LC
1 is compacted via an upper punch that has a structured punching surface (
step 1-3).
[0056] By compacting the first layer construction LC
1 with the structured upper punch, the superabrasive particles 24 are shifted in the
height direction H such that superabrasive particles 24 of adjacent lines are arranged
on different height levels and a structured upper surface
33 is formed. After step 1-3, the superabrasive particles 24 are arranged in three groups
of four lines. Each group comprises a first line
l1 of superabrasive particles 24, a second line
l2 of superabrasive particles 24, a third line
l3 of superabrasive particles 24, and a fourth line
l4 of superabrasive particles 24.
[0057] After the first sequence, the second sequence of the first step, second step and
third step is performed. In the first step of the second sequence, a second portion
of the powdery bond material 32 is applied to the first layer construction LC
1 (
step 2-1). In the second step of the second sequence, a second plurality of the superabrasive
particles 24 is arranged according to the predetermined particle design on the second
portion of the powdery bond material 32 to build a second layer construction
LC2 (
step 2-2), wherein the superabrasive particles 24 are arranged on the same height level in
the height direction H. In the third step of the second sequence, the second layer
construction LC
2 is compacted via the structured upper punch (
step 2-3). By compacting the second layer construction LC
2 with the structured upper punch, the superabrasive particles 24 are shifted in the
height direction H such that superabrasive particles 24 of adjacent lines are arranged
on different height levels and a structured upper surface
34 is formed.
[0058] The green body 31 will be further processed to form the grinding segment 12 by free-form
sintering, by hot-pressing and/or by infiltrating. The green body 31 includes a plane
lower surface
35 and the structured upper surface 34. After free-form sintering, hot-pressing, or
infiltrating, the lower surface 35 will define the front side 14 of the grinding segment
12 and the upper surface 34 will define the back side 13 of the grinding segment 12.
[0059] FIGS. 5A, B show an alternative grinding segment
42 (FIG. 5A) for the grinding wheel 10 of FIG. 1, the grinding segment 42 being composed
of a bond material and superabrasive particles being arranged according to a predetermined
particle design (FIG. 5B). The grinding segment 42 includes a backside
44 that may be used to connect the grinding segment 42 to the connection surface 22
of the basic body 11 and a front side
45 that may be used to grind a workpiece via the grinding wheel 10.
[0060] The grinding segment 42 may substitute the grinding segment 12 and may be connected
to the basic body 11 of the grinding wheel 10. The grinding segment 12 and the alternative
grinding segment 42 are both made of the bond material 23 that is at least one of
free-form sintered, hot-pressed, and infiltrated and of the superabrasive particles
24 being arranged according to a predetermined particle design. The number of superabrasive
particles 24 used for a pattern and the position of the superabrasive particles 24
in a horizontal plane perpendicular to the height direction H are the same for the
grinding segments 12, 42, but the height levels of adjacent lines of superabrasive
particles 24 and the structure of the backside is different for the grinding segment
12 and the alternative grinding segment 42.
[0061] FIG. 5B shows the predetermined particle design of the superabrasive particles 24,
which are arranged in patterns. Each of the pattern includes a first group
G1, second group
G2 and third group
G3 of four (K = 4) lines of superabrasive particles 24, and each group G
1, G
2, G
3 includes a first line
l1, second line
l2, third line
l3, and fourth line
l4 of superabrasive particles 24.
[0062] FIGS. 6A, B show a cross-section of the grinding segment 42 of FIG. 5A in a plane parallel to
the height direction H of the grinding segment 42 (FIG. 6A) and a detail of FIG. 6A
(FIG. 6B).
[0063] The grinding segment 42 is made of the bond material 23 that is free-form sintered
or hot-pressed and of the superabrasive particles 24 being arranged according to the
predetermined particle design shown in FIG. 5B. The grinding segment 42 is composed
of two (M = 2) layers
L1,
L2 of the bond material 23 and of two (N = 2) patterns
P1,
P2 of superabrasive particles 24, the two layers L
1, L
2 and two patterns P
1, P
2 being stacked in a direction of stacking that is parallel to the height direction
H of the grinding segment 42.
[0064] The first layer L
1 has a lower surface that is called first lower surface
LS1 and an upper surface that is called first upper surface
US1, wherein the first lower surface LS
1 is a non-structured lower surface and the first upper surface US
1 is a structured upper surface, and the second layer L
2 has a lower surface that is called second lower surface
LS2 and an upper surface that is called second upper surface
US2, wherein the second lower surface LS
2 is a structured lower surface and the second upper surface US
2 is a structured upper surface. The backside 44 of the grinding segment 42 is defined
by the second upper surface US
2, and the front side 45 by the first lower surface LS
1.
[0065] Each of the first pattern P
1 and second pattern P
2 include the first, second and third group G
1, G
2, G
3 of the four lines l
1, l
2, l
3, l
4 of superabrasive particles 24. Each group G
1, G
2, G
3 includes a first line l
1 of superabrasive particles 24 arranged on a first height level
h1, a second line l
2 of superabrasive particles 24 arranged on a second height level
h2, a third line l
3 of superabrasive particles 24 arranged on a third height level
h3, and a fourth line l
4 of superabrasive particles 24 arranged on a fourth height level
h4.
[0066] Because the superabrasive particles 24 of the four lines l
1, l
2, l
3, l
4 are arranged on different height levels, they start grinding at different points
of time. During grinding with the grinding segment 42, the superabrasive particles
24 of the fourth lines l
4 start grinding, the superabrasive particles 24 of the second lines l
2 take over grinding, then the superabrasive particles 24 of the third lines l
3 continue grinding and last the superabrasive particles 24 of the first lines l
1 take over grinding.
[0067] In each pattern P
1, P
2 of superabrasive particles 24, the superabrasive particles 24 of the first line l
1 and second line l
2 differ in the height direction H by a height distance
δ12, the superabrasive particles 24 of the second line l
2 and third line l
3 differ in the height direction H by a height distance
δ23, and the superabrasive particles 24 of the third line l
3 and fourth line l
4 differ in the height direction H by a height distance
δ34. The superabrasive particles 24 are arranged such that in a group of lines the height
distances δ
12, δ
23, δ
34 are not equal.
[0068] The grinding segment 42 differs in the height distances δ
12, δ
23, δ
34 from the grinding segment 12. For the grinding segment 12, the height distances δ
12, δ
23, δ
34 are nearly equal, and, for the grinding segment 42, the height distances δ
12, δ
23, δ
34 vary.
[0069] FIG. 7 shows a further grinding wheel
50 including the cup-shaped basic body 11 and a plurality of grinding segments
52 according to the present invention, the grinding segments 52 being connected via
a backside
54 to the basic body 11. FIG. 7 shows the grinding wheel 50 in a view on a front side
55 of the grinding segments 52. The grinding wheel 50 differs from the grinding wheel
10 in the cross-section of the grinding segments 52 and in the predetermined particle
design.
[0070] FIGS. 8A, B show a first variant of a grinding segment (FIG. 8A)
62-1 and a second variant of a grinding segment
62-2 (FIG. 8B) for the further grinding wheel 50 of FIG. 7. The grinding segments 62-1,
62-2 may substitute the grinding segment 12 of the grinding wheel 10 or the grinding
segment 52 of the grinding wheel 50.
[0071] The grinding segments 62-1, 62-2 may be connected via a back side
64-1, 64-2 to the connection face 17 of the basic body 11 and grinding with the grinding wheel
50 may be performed via a front side
65-1, 65-2 of the grinding segments 62-1, 62-2, the front side 64-1, 64-2 being opposite of
the back side 64-1, 64-2.
[0072] The grinding segments 62-1, 62-2 are fabricated via powder metallurgy, in which a
green body is build up layer by layer from a powdery or granular bond material and
a plurality of superabrasive particles and the green body is further processed to
form the grinding segments 62-1, 62-2 by free-form sintering, by hot-pressing, and/or
by infiltrating. The grinding segment 62-1 differs from the grinding segment 62-2
in the back side.
[0073] FIGS. 9A, B show the grinding segments 62-1, 62-2 of FIGS. 8A, B, which are composed of a bond
material
66 that is free-form sintered or hot-pressed and of superabrasive particles
67 being arranged according to a first predetermined particle design (FIG. 9A) or a
second predetermined particle design (FIG. 9B).
[0074] According to the first and second predetermined particle designs, the superabrasive
particles 67 are arranged in four groups
G1, G2, G3,
G3 of lines. Each group G
1, G
2, G
3, G
4 includes a first line
l1 of superabrasive particles 67 arranged on a first height level, a second line
l2 of superabrasive particles 67 arranged on a second height level, a third line
l3 of superabrasive particles 67 arranged on a third height level, and a fourth line
l4 of superabrasive particles 67 arranged on a fourth height level, wherein the four
lines l
1, l
2, l
3, l
4 of each group are arranged on different height levels in the height direction.
[0075] The number of superabrasive particles 67 in a line can vary and may depend on the
cross-section of the grinding segment. As an example, in the first predetermined particle
design shown in FIG. 9A, the first line l
1 comprises one superabrasive particle 67 in the first group G
1, five superabrasive particles 67 in the second group G
2, seven superabrasive particles 67 in the third group G
3, and three superabrasive particles 67 in the fourth group G
4, and, in the second predetermined particle design shown in FIG. 9B, the first line
l
1 comprises one superabrasive particle 67 in the first group G
1, seven superabrasive particles 67 in the second group G
2, ten superabrasive particles 67 in the third group G
3, and five superabrasive particles 67 in the fourth group G
4.
[0076] FIGS. 10A, B show a cross-section of further grinding segments
72-1, 72-2 in a plane parallel to a height direction
H of the grinding segments 72-1, 72-2, the grinding segment 72-1 including a non-structured
first lower surface (FIG. 10A) and the grinding segment 72-2 including a structured
first lower surface (FIG. 10B). The grinding segments 72-1, 72-2 may substitute the
grinding segment 12 of the grinding wheel 10 or the grinding segment 52 of the grinding
wheel 50.
[0077] The grinding segments 72-1, 72-2 are both made of a bond material
73 that is at least one of free-form sintered and hot-pressed and of superabrasive particles
74 being arranged according to a predetermined particle design. The grinding segments
72-1, 72-2 are composed of four (M = 4) layers of the bond material 73 and four (N
= 4) patterns of superabrasive particles 74, the four layers and four patterns being
stacked in a direction of stacking that is parallel to the height direction H of the
grinding segments 72-1, 72-2. The four layers of the bond material 73 are called first
layer
L1, second layer
L2, third layer
L3, and fourth layer
L4, and the four pattern of the superabrasive particles 74 are called first pattern
P1, second pattern
P2, third pattern
P3, and fourth pattern
P4.
[0078] The first layer L
1 has a lower surface that is called first lower surface
LS1 and an upper surface that is called first upper surface
US1, the second layer L
2 has a lower surface that is called second lower surface
LS2 and an upper surface that is called second upper surface
US2, the third layer L
3 has a lower surface that is called third lower surface
LS3 and an upper surface that is called third upper surface
US3, and the fourth layer L
4 has a lower surface that is called fourth lower surface
LS4 and an upper surface that is called fourth upper surface
US4.
[0079] Both grinding segments 72-1, 72-2 have structured second, third, and fourth lower
surfaces LS
2, LS
3, LS
4 and structured first, second, third, and fourth upper surfaces US
1, US
2, US
3, US
4, wherein the structured lower surfaces LS
2, LS
3, LS
4 and structured upper surfaces US
1, US
2, US
3, US
4 have a first structure that corresponds to the predetermined particle design. The
grinding segments 72-1, 72-2 differ in the first lower surface LS
1. Whereas the grinding segment 72-1 (FIG. 10A) has a non-structured first lower surface
LS
1, the grinding segment 72-2 (FIG. 10B) has a structured first lower surface LS
1.
[0080] The structured lower surfaces and structured upper surfaces having the first structure
are created by compacting the green body via the structured upper punch (see FIG.
4). The first lower surface LS
1 is created by compacting the green body via the lower upper punch (see FIG. 4), the
lower punch may be non-structured to generate the grinding segment 72-1 of FIG. 10A
or may have a second structure to generate the grinding segment 72-2 of FIG. 10B.
[0081] Each of the four pattern P
1, P
2, P
3, P
4 includes three groups
G1, G2, G3 of four (K = 4) lines of superabrasive particles 74. Each group G
1, G
2, G
3 includes a first line
l1 of superabrasive particles 74 arranged on a first height level
h1, a second line
l2 of superabrasive particles 74 arranged on a second height level
h2, a third line
l3 of superabrasive particles 74 arranged on a third height level
h3, and a fourth line
l4 of superabrasive particles 74 arranged on a fourth height level
h4.
[0082] The grinding segments 72-1, 72-2 may be connected via a back side
75-1, 75-2 to a connection face of a basic body and grinding may be performed via a front side
76-1, 76-2 of the grinding segments 72-1, 72-2, the front side 76-1, 76-2 being opposite of
the back side 75-1, 75-2. The back sides 75-1, 75-2 of the grinding segments 72-1,
72-2 are defined by the fourth upper surface US
4, and the front sides 76-1, 76-2 of the grinding segments 72-1, 72-2 are defined by
the first lower surface LS
1.
[0083] The grinding segment 72-2 may have the advantage that the surface area of the front
side 76-1 is reduced compared to the grinding segment 72-1. The structure of the first
lower surface LS
1 has no impact on the distribution of the superabrasive particles 74.
1. A grinding segment (12; 42; 52; 62-1, 62-2; 72-1, 72-2) made of a bond material (23;
66; 73) that is at least one of free-form sintered, hot-pressed and infiltrated and
of superabrasive particles (24; 67; 74) being arranged according to a predetermined
particle design, the grinding segment having a height in a height direction (H) and
the grinding segment being configured to be connected to a connection surface (22)
of a basic body (11) of a tool bit (10; 50), the grinding segment (12; 42; 52; 62-1,
62-2; 72-1, 72-2) comprising:
▪ M, M ≥ 2, layers (L1, L2; L1, L2, L3, L4) of the bond material (23; 66; 73), the layers being stacked in the height direction
(H), and
▪ N, N ≥ 1, patterns (P1, P2; P1, P2, P3, P4) of the superabrasive particles (24; 67; 74), the patterns being stacked in the height
direction (H),
wherein each of the M layers (L
1, L
2; L
1, L
2, L
3, L
4) of the bond material (23; 66; 73) has at least one of a structured lower surface
(LS
2; LS
2, LS
3, LS
4) and a structured upper surface (US
1, US
2; US
1, US
2, US
3, US
4), wherein the structured lower surfaces and/or structured upper surfaces of the M
layers have a first structure that corresponds to the predetermined particle design
of the superabrasive particles (24; 67; 74).
2. The grinding segment of claim 1, wherein the M layers of the bond material (23; 66;
73) include at least a first layer (L1) having a first lower surface (LS1) and a first upper surface (US1), wherein the first upper surface (US1) has the first structure, and the first lower surface (LS1) is non-structured.
3. The grinding segment of claim 1, wherein the M layers of the bond material (23; 66;
73) include at least a first layer (L1) having a first lower surface (LS1) and a first upper surface (US1), wherein the first upper surface (US1) has the first structure, and the first lower surface (LS1) has a second structure that is different from the first structure of the first upper
surface (US1).
4. The grinding segment of any one of claims 1 to 3, wherein the M layers of the bond
material (23; 66; 73) include at least a M-th layer (LM) having a M-th lower surface (LSM) and a M-th upper surface (LSM), wherein the M-th lower surface (LSM) and the M-th upper surface (LSM) have the first structure.
5. The grinding segment of any one of claims 1 to 4, wherein the bond material (23; 66;
73) is at least one of a first bond material and a second bond material, the second
bond material being different from the first bond material.
6. The grinding segment of any one of claims 1 to 5, wherein each pattern (Pi, P2; P1, P2, P3, P4) of the superabrasive particles (24; 67; 74) includes at least two groups (G1, G2, G3; G1, G2, G3, G4) of K, K ≥ 2, lines (l1, l2; l1, l2, l3, l4) of superabrasive particles (24; 67; 74), the superabrasive particles (24; 67; 74)
of adjacent lines being arranged on different height levels (hi, h2, h3, h4) in the height direction (H).
7. The grinding segment of claim 6, wherein each of the at least two groups comprises
a first line (l1) of superabrasive particles (24; 67; 74), a second line (l2) of superabrasive particles (24; 67; 74), and a third line (l3) of superabrasive particles (24; 67; 74), wherein the first lines (l1) being arranged on a first height level (hi), the second lines (l2) being arranged on a second height level (h2), and the third lines (l3) being arranged on a third height level (h3), and wherein the first height level (hi), second height level (h2) and third height level (h3) being different from each other in the height direction (H).
8. The grinding segment of claim 7, wherein each of the at least two groups further comprises
a fourth line (l4) of superabrasive particles (24; 67; 74), wherein the fourth lines (14) being arranged
on a fourth height level (h4), and wherein the fourth height level (h4) is different from the first height level (hi), second height level (h2) and third height level (h3) in the height direction (H).
9. A tool bit (10; 50) for grinding, comprising:
▪ a basic body (11) including an inner section (18) configured to connect the tool
bit to a power tool, and a circumferential section (17) with a connection surface
(22), and
▪ two or more grinding segments (12; 42; 52; 62-1, 62-2; 72-1, 72-2) according to
any one of claims 1 to 8, wherein the grinding segments (12; 42; 52; 62-1, 62-2; 72-1,
72-2) are connected to the connection surface (22).
10. The tool bit of claim 9, wherein the grinding segments (12; 42; 52; 62-1, 62-2; 72-1)
are connected to the connection surface (22) with the upper surface (USM) of the M-th layer (LM) of the bond material (23; 66; 73).
11. The tool bit of any one of claims 9 to 10, further comprising a plurality of suction
holes (13) being arranged in at least one of the circumferential section (17) or a
transition section (19) that is arranged between the circumferential section (17)
and inner section (18).