U.S. patent application number 16/486783 was filed with the patent office on 2019-12-05 for honing tool and fine machining method using the honing tool.
This patent application is currently assigned to Elgan-Diamantwerkzeuge GmbH & Co. KG. The applicant listed for this patent is Elgan-Diamantwerkzeuge GmbH & Co. KG. Invention is credited to Josef Schmid.
Application Number | 20190366504 16/486783 |
Document ID | / |
Family ID | 61168115 |
Filed Date | 2019-12-05 |
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United States Patent
Application |
20190366504 |
Kind Code |
A1 |
Schmid; Josef |
December 5, 2019 |
HONING TOOL AND FINE MACHINING METHOD USING THE HONING TOOL
Abstract
A honing tool (100) for machining an inner face (322) of a bore
(320) in a workpiece (300) with the aid of at least one honing
operation comprises a tool body (110) that defines a tool axis, and
an expandable cutting group (330), attached to the tool body,
having a plurality of radially feedable cutting material body
carriers (150) that each cover a circumferential angle range and
are feedable radially with respect to the tool axis by means of a
cutting group feeding system assigned to the cutting group. Each
cutting material body carrier carries, on its radial outer side, a
plurality of narrow cutting material bodies (140) configured as
cutting material strips (140-1, 140-2, 140-3, 440-1, 440-2) that
are narrow in the circumferential direction and have a width in the
circumferential direction that is small compared with the axial
length of the cutting material strips. The cutting material bodies
are arranged at a mutual spacing from one another. An elastically
resilient intermediate layer (160) is arranged in an intermediate
space between a cutting material body (140) and the cutting
material body carrier (150) carrying the cutting material body,
said intermediate layer (160) filling the intermediate space
between the cutting material body and the cutting material body
carrier. A preferred field of application is the honing of cylinder
surfaces in the production of cylinder blocks or cylinder liners
for reciprocating piston engines.
Inventors: |
Schmid; Josef;
(Grabenstetten, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Elgan-Diamantwerkzeuge GmbH & Co. KG |
Nurtingen |
|
DE |
|
|
Assignee: |
Elgan-Diamantwerkzeuge GmbH &
Co. KG
Nurtingen
DE
|
Family ID: |
61168115 |
Appl. No.: |
16/486783 |
Filed: |
February 6, 2018 |
PCT Filed: |
February 6, 2018 |
PCT NO: |
PCT/EP2018/052943 |
371 Date: |
August 16, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24B 33/088 20130101;
B24B 33/025 20130101 |
International
Class: |
B24B 33/02 20060101
B24B033/02; B24B 33/08 20060101 B24B033/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2017 |
DE |
10 2017 202 573.5 |
Claims
1. A honing tool for machining an inner face of a bore in a
workpiece with the aid of at least one honing operation, in
particular for honing cylinder surfaces in the production of
cylinder blocks or cylinder liners for reciprocating piston
engines, comprising: a tool body that defines a tool axis; an
expandable cutting group, attached to the tool body, having a
plurality of radially feedable cutting material body carriers that
each cover a circumferential angle range and are feedable radially
with respect to the tool axis by means of a cutting group feeding
system assigned to the cutting group, wherein each cutting material
body carrier carries, on its radial outer side, a plurality of
narrow cutting material bodies configured as cutting material
strips that are narrow in the circumferential direction and have a
width (BS) in the circumferential direction that is small compared
with the axial length (LS) of the cutting material strips, wherein
the cutting material bodies are arranged at a mutual spacing from
one another, wherein an elastically resilient intermediate layer is
arranged in an intermediate space between a cutting material body
and the cutting material body carrier carrying the cutting material
body, said intermediate layer filling the intermediate space
between the cutting material body and the cutting material body
carrier.
2. The honing tool as claimed in claim 1, wherein the intermediate
layer has a layer thickness (SD) in the range from 0.1 mm to 2 mm,
in particular in the range from 0.5 mm to 1.5 mm.
3. The honing tool as claimed in claim 1, wherein a Shore hardness
of the intermediate layer is in the range from 70 Shore A to 95
Shore A.
4. The honing tool as claimed in claim 1, wherein the intermediate
layer has a layer made of an elastomer, in particular of a
rubber-elastic polyurethane elastomer.
5. The honing tool as claimed in claim 1, wherein the intermediate
layer has been vulcanized directly onto a contact face on the
cutting material body or the outer face of the cutting material
body carrier element.
6. The honing tool as claimed in claim 1, wherein the intermediate
layer has a first layer and at least one second layer connected
extensively thereto, wherein the first layer is a layer made of an
elastomer and the second layer is an adhesive layer connected
extensively to the first layer.
7. The honing tool as claimed in claim 1, wherein the cutting group
has an axial length (LS), measured in the axial direction, that is
less than an effective outside diameter (AD) of the cutting group
with cutting material bodies fully retracted.
8. The honing tool as claimed in claim 7, wherein the honing tool
has at least one of the following properties: (i) the axial length
(LS) of the cutting material bodies is less than 40% of the
effective outside diameter of the cutting group; (ii) the axial
length (LS) of the cutting material bodies is in the range from 5
mm to 40 mm; (iii) the axial length (LS) of the cutting material
bodies is less than 20% of the bore length of the bore; (iv) the
axial length (LS) of the cutting material bodies is in the range
from 20% to 50% of the bore diameter; (v) an aspect ratio between
the axial length (LS) and the width (BS) of the cutting material
bodies is in the range from 4:1 to 20:1.
9. The honing tool as claimed in claim 1, wherein the cutting group
has at least three cutting material body carriers, which are
arranged such that machining forces over the entire effective
outside diameter, available by expansion, of the honing tool are
able to be distributed uniformly around the circumference of the
cutting group, wherein the cutting group has preferably exactly
four, exactly six or exactly eight cutting material body carriers
of the same or different circumferential width.
10. The honing tool as claimed in claim 1, wherein the honing tool
is designed as a honing tool with double expansion, wherein the
cutting group has a first group of cutting material body carriers
and a second group of cutting material body carriers that is
feedable independently of the first group.
11. The honing tool as claimed in claim 10, wherein the cutting
material bodies of the first group differ from the cutting material
bodies of the second group, preferably in that the cutting material
bodies of the two groups have different widths and/or have been
applied to the cutting material body carriers with different
circumferential spacings and/or a different pitch, and/or in that
the cutting material bodies of one of the groups are provided with
coarser grain for rougher machining and the cutting material bodies
of the other group are provided with finer grain for finer
machining.
12. The honing tool as claimed in claim 10, wherein, in the first
group, the cutting material bodies are fastened directly to the
associated cutting material body carrier without interposition of
an elastic intermediate layer and are connected rigidly to the
cutting material body carrier, and in the second group, the cutting
material bodies are fastened to the associated cutting material
body carrier in an individually resilient manner via an elastic
intermediate layer.
13. A fine machining method for machining the inner face of a bore
in a workpiece, in particular for fine machining cylinder surfaces
in the production of cylinder blocks or cylinder liners for
reciprocating piston engines, wherein the fine machining method
comprises at least one honing operation in which an expandable
honing tool is moved up and down within the bore in order to create
a reciprocating movement in the axial direction of the bore and at
the same time is rotated in order to create a rotary movement
superimposed on the reciprocating movement, wherein a honing tool
having the features of at least one of the preceding claims is used
in the honing operation.
14. The fine machining method as claimed in claim 13, wherein,
before the start of the honing operation, a bore shape that differs
from the circular-cylindrical shape is created by fine boring
and/or honing, and in that a honing operation for creating the
desired surface structure on the bore inner face is carried out
using the honing tool, substantially without changing the macro
shape of the bore.
15. The fine machining method as claimed in claim 13, wherein a
honing tool with double expansion is used, in which a cutting group
of the honing tool has a first group of cutting material body
carriers and a second group of cutting material body carriers that
is feedable independently of the first group, wherein in each case
the cutting material body carriers of one group are radially fed
and retracted jointly, wherein a prior first honing operation is
carried out with the first group, this group is then retracted, the
other group is radially fed, and then a following second honing
operation is carried out with the cutting material bodies of the
second group.
16. The fine machining method as claimed in claim 13, wherein the
first group has cutting material bodies rigidly connected to the
cutting material body carriers, and the first honing operation is a
contour honing operation, and in that the second group is provided
with cutting material bodies that are fastened to the associated
cutting material body carriers in an elastically resilient manner
via an elastically resilient intermediate layer, wherein the second
honing operation is a tracking honing operation.
Description
FIELD OF APPLICATION AND PRIOR ART
[0001] The invention relates to a honing tool according to the
preamble of claim 1 and to a fine machining method according to the
preamble of claim 13. A preferred field of application is the fine
machining of cylinder surfaces in the production of cylinder blocks
or cylinder liners for reciprocating piston engines.
[0002] The cylinder surfaces in cylinder blocks (engine blocks) or
cylinder liners of internal combustion engines or other
reciprocating piston engines are exposed to high tribological
stress during operation. Therefore, in the production of cylinder
blocks or cylinder liners, it is necessary to machine these
cylinder surfaces such that sufficient lubrication by a lubricant
film is subsequently ensured under all operating conditions and the
frictional resistance between parts that move relative to one
another is kept as low as possible.
[0003] The quality-determining finishing of such tribologically
stressable inner faces generally takes place with suitable honing
methods, which typically comprise a plurality of successive honing
operations. Honing is a metal cutting method with geometrically
undetermined cutting edges. In a honing operation, an expandable
honing tool is moved up and down or back and forth within the bore
to be machined in order to create a reciprocating movement in the
axial direction of the bore with a stroke frequency, and at the
same time rotated in order to create a rotary movement,
superimposed on the reciprocating movement, with a rotation
frequency. The cutting material bodies applied to the honing tool
are pressed against the inner face to be machined with a feeding
force acting radially with respect to the tool axis via a cutting
material body feeding system. During honing, a cross-hatch pattern
that is typical for machining by honing and has intersecting
machining lines, which are also known as "honing scores", generally
arises on the inner face.
[0004] In order to prepare the workpieces to be machined for
honing, there can be a prior pre-machining operation by fine
boring, which is sometimes also referred to as fine turning or fine
spindling. Fine boring operations, which are carried out with fine
boring tools with a geometrically determined cutting edge,
generally serve to define the desired position and angular position
of the bore, optionally also to create bore shapes that differ from
a circular-cylindrical form. An essential object of the honing
operation with a smaller allowance compared with fine boring is the
creation of the required surface structure.
[0005] With increasing demands being made of the economy and
environmental friendliness of engines, the optimization of the
piston/piston rings/cylinder surface tribological system is of
particular importance in order to achieve a low level of friction,
a low level of wear and low oil consumption. The macroscopic form
(macro shape) of the bores and the surface structure are accorded
particular importance here.
[0006] In some fine machining methods, a bore shape that differs in
a defined manner from the circular-cylindrical shape is created by
means of fine boring and/or honing. Such bore shapes are generally
asymmetric in the axial direction and/or in the circumferential
direction, because the deformations of the cylinder block are
generally not symmetric either. In the operating state, a
circular-cylindrical shape that is as ideal as possible is usually
intended to result, such that the piston ring set can seal off well
around the entire bore circumference.
[0007] On account of a wide variety of demands, different honing
tool types have been developed. They can be categorized as honing
tools that are feedable during machining and honing tools that are
presettable. Honing tools that are feedable during machining can be
subdivided further into strip honing tools, such as one-strip
honing tools, multi-strip honing tools and special tools, and into
largely full-faced tools, such as shell tools and shank tools. The
category of presettable honing tools includes what are known as
mandrel tools or precidor honing tools.
[0008] One-strip honing tools are frequently used in the machining
of high-precision small parts. Multi-strip honing tools are
available in a wide variety of forms for a variety of possible
uses. On account of the high abrasive capacity and the operating
parameters thereof, high cutting efficiency is achievable during
honing.
[0009] In the case of bores with large interruptions, the use of
conventional strip honing tools can result in problems. Although
the individually guided honing strips can ensure concentric
widening and optimal roundness of the bore, when there are large
interruptions, there is the risk that they will get caught in the
workpiece. The shell tools, as they are known, were developed for
this purpose, inter alia, in the case of which abrasives are
arranged on a cutting material body carrier that is relatively wide
in the circumferential direction. A shell tool can be constructed
for example with only two cutting material body carriers (half
shells), and optionally also with three or four or more cutting
material body carriers of correspondingly smaller circumferential
width.
[0010] Shell tools can be designed with different structures.
[0011] The laid-open application DE 1652074 describes a honing tool
having shell segments that have been produced from one piece as a
sintered part with a cutting coating and that can have, as carriers
for the cutting coating, a multiplicity of outwardly protruding
ribs.
[0012] DE 102013204714 A1 discloses honing tools designed for
example as shell tools, which are suitable for machining
rotationally symmetric bores that have bore portions with different
diameters and/or forms. In that case, it is possible for bores with
a bottle shape, cone shape or barrel shape, for example, to be
machined and/or created. The corresponding honing methods are
occasionally referred to as "contour honing". The honing tool has
an expandable annular cutting group with a plurality of cutting
material bodies distributed around the circumference of the tool
body, the axial length of said cutting material bodies as measured
in the axial direction being less than an effective outside
diameter of the cutting group with cutting material bodies fully
retracted. The cutting group has a plurality of radially feedable
cutting material body carriers, which each cover a circumferential
angle range that is greater than the axial length of the cutting
group.
[0013] On account of the relatively short axial length of the
cutting group, such honing tools are particularly suitable for the
creation of an axial contour and/or for following an already
existing axial contour of the bore. Furthermore, small axial
lengths of the cutting group can be advantageous in order to create
sufficient surface pressure for machining Since the cutting group
has a plurality of radially feedable cutting material body
carriers, which each cover a circumferential angle range that is
greater than the axial length of the cutting group, it is possible,
inter alia, for cross bores, for example, in the wall of a cylinder
running surface to be bridged in the circumferential direction
during honing, such that, in spite of axially short cutting
material bodies, there is no risk of irregular machining in the
region of cross bores. When such honing tools are used, it is
furthermore possible to work with a very small honing overrun at
the axial ends of a bore, without problems with irregular cutting
body wear arising. However, it has been found that, in certain
cases, during the machining of non-cylindrical bores (for example
bores with a bottle shape, cone shape or barrel shape), locally
different surface structures can be created on account of different
cutting depths. These can cause technical problems. In the case of
undesired excessively high local roughness, oil consumption and
blow-by, for example, can be increased. If too little material
removal is created locally, it is possible, on account of
inadequate remedying of material damage from upstream machining
stages, for the risk of seizing during operation of a combustion
engine to increase. Close to the axial ends of a bore, deviations
of the grinding pattern from the grinding pattern in the rest of
the bore can occur.
PROBLEM AND SOLUTION
[0014] The problem addressed by the present invention is to provide
a honing tool of the type in question and a fine machining
operation able to be carried out therewith, which make it possible
to machine bores of different form such that the machined bore
faces have a readily definable surface structure along the entire
bore length.
[0015] To solve this problem, the invention provides a honing tool
having the features of claim 1. Furthermore, a fine machining
method having the features of claim 13 is provided. Advantageous
developments are specified in the dependent claims. The wording of
all the claims is made part of the content of the description by
reference.
[0016] The expandable cutting group attached to the tool body has a
plurality of radially feedable cutting material body carriers that
each cover a circumferential angle range and are feedable radially
with respect to the tool axis by means of a cutting group feeding
system assigned to the cutting group. The circumferential angle
range can be for example 30.degree. or more, 40.degree. or more, or
about 60.degree. or more, or even 90.degree. or more. Each cutting
material body carrier carries, on its radial outer side, a
plurality of narrow cutting material bodies that are arranged at a
mutual lateral spacing from one another and each cover only a
fraction of the circumferential angle range. Therefore,
intermediate spaces or gaps without cutting material remain between
the cutting material bodies. As a result, even in the event of
heavy material removal, reliable lubrication with cooling lubricant
and sufficient discharge of machining residues can be ensured.
[0017] The cutting material bodies are configured as cutting
material strips that are narrow in the circumferential direction
and have a width in the circumferential direction that is small
compared with the axial length of the cutting material strips. By
means of cutting material strips, it is possible, if necessary, to
achieve particularly uniform coverage along the entire bore length,
even at the bore ends, where a honing overrun may be desired. An
aspect ratio between the axial length and the width to be measured
in the circumferential direction may be for example in the range
from 4:1 to 20:1.
[0018] The cutting material bodies can consist entirely of abrasive
or have a carrier that consists for example of metal and bears the
abrasive. The abrasive can exhibit for example cutting grains made
of diamond or cubic boron nitride (CBN), which are bound in a
metallic or ceramic matrix.
[0019] The cutting group has cutting material bodies that have not
been applied directly to the radial outer side of the associated
cutting material body carrier and have not been rigidly or firmly
connected thereto either. Rather, an elastically resilient
intermediate layer is arranged in an intermediate space between a
cutting material body and the cutting material body carrier
carrying the cutting material body, said intermediate layer filling
the intermediate space between the cutting material body and the
cutting material body carrier.
[0020] Such an intermediate layer can be provided at all cutting
material bodies of a cutting group. It is also possible for only
some cutting material bodies of a cutting group to be carried by
such an intermediate layer and for others to be connected rigidly
to the cutting material body carrying them. Preferably, either all
the cutting material bodies of a cutting material body carrier are
connected to the associated cutting material body carrier in a
resilient manner via an elastic intermediate layer or they are all
fastened rigidly thereto, such that there is no mixture of rigidly
and resiliently coupled cutting material bodies at one cutting
material body carrier.
[0021] Each cutting material body carrier therefore carries a
cutting material body group with two, three, four, five, six,
seven, eight or more in each case relatively narrow cutting
material bodies, between which gaps remain in the circumferential
direction. The cutting material body group (group of cutting
material bodies) is carried by the inherently substantially rigid
cutting material body carrier such that all cutting material bodies
of the cutting material body group are radially fed jointly when
the cutting material body carrier is radially fed. The requirement
of radial feedability of the cutting material body carrier means
that the carrier has to be mounted in a movable manner with respect
to the workpiece body, wherein especially movability in a radial
direction is necessary. A certain amount of tilting of a cutting
material body carrier, for example in the region of the honing
overrun, cannot be completely ruled out, however, since uneven
loading of the cutting material bodies and thus of the associated
cutting material body carrier arises there as seen in the axial
direction.
[0022] As a result of the elastically resilient intermediate layers
between the cutting material bodies and the cutting material body
carrier carrying them, there is, to a certain extent, individual
flexibility or movability of the cutting material bodies with
respect to the (rigid) cutting material body carrier carrying them
and relative to other cutting material bodies of the cutting
material body group. It has been found that, as a result, the
adaptability of the honing tool or of the cutting material bodies
to different orientations of the surface to be machined can be
improved even further compared with conventional solutions.
[0023] Improvements can result in particular in the case of conical
shapes and/or in the region of axial transitions between
cylindrical and conical bore portions and/or in the region of axial
transitions between portions of different cone angle. Furthermore,
the cutting material bodies can better follow deviations, which may
also be present, from the roundness of the bore in the case of oval
bore shapes or higher-order roundness deviations. Potentially,
there may be improvements even in the region of the turning point
of the axially back and forth honing movement, i.e. where a tilting
moment can arise on the arrangement of cutting material bodies and
the carrying cutting material body carrier during the change in
direction.
[0024] As a result of the intermediate layer, it is possible, inter
alia, for a cutting material body to remain oriented largely
parallel to the machined bore surface in spite of any tilting
moment acting on the overall arrangement (cutting material body
carrier with cutting material bodies), with the result that a
readily definable uniform surface structure can be ensured even in
axial transition regions of different surface orientation and as
far as the axial bore ends. Since the intermediate layer fills the
intermediate space between the cutting material body and the
cutting material body carrier, no abrasion dust can pass between
the cutting material body and cutting material body carrier and so
the individual flexibility is maintained even in the event of heavy
material removal throughout the honing process. Likewise, surface
damage by scratches and/or scores, which can occur as a result of
abrasion dust and/or course cutting grains or foreign bodies
collecting in the cutouts of sprung strip carriers, can be
prevented thereby.
[0025] Honing tools according to the invention are particularly
suitable for honing bores with an axial contour. The individually
flexibly or resiliently mounted cutting material bodies can adapt
particularly readily to inclinations of the bore inner face that
change in the axial direction of the bore, for example at the
transition between a circular-cylindrical bore portion and a
conical bore portion. Honing operations in which the cutting
material bodies are intended to track the contour of the bore as
well as possible, without changing the macroscopic form of the
bore, are also referred to as "tracking honing" here. The
advantages of honing tools according to the invention can be used
in the machining by honing of non-round bore shapes with deviations
from the rotational symmetry, too.
[0026] Numerous tests have shown that it is generally favorable for
the intermediate layer to have a layer thickness in the range from
0.1 mm to 2 mm, in particular in the range from 0.5 mm to 1.5 mm At
layer thicknesses that are significantly below the lower limit, the
tiltability of the cutting material bodies with respect to the
cutting material body carrier element that is achievable thereby is
generally insufficient for it to be possible to compensate for all
misorientations that occur. At layer thicknesses that are
significantly above the upper limit, it is harder to obtain
sufficient stability of the cutting material strips with respect to
transverse loads.
[0027] In order to allow a good compromise between sufficient
stability of the intermediate layer with respect to transverse
loads and sufficient flexibility for compensating for
misorientations, it has been found to be advantageous for a Shore
hardness of the intermediate layer to be in the range from 70 Shore
A to 95 Shore A. At greater hardnesses, there is generally no
longer sufficient resilience. At significantly lower hardnesses,
the arrangement of the cutting material strips on the cutting
material body carrier element can become too unstable, and so
sufficient machining forces can no longer be applied to the surface
to be machined during machining by honing.
[0028] In preferred embodiments, the intermediate layer has an
elastic layer made of an elastomer, in particular of a
rubber-elastic polyurethane elastomer. The term "elastomer" stands
here for dimensionally stable but elastically deformable plastics,
the glass transition point of which is below the application
temperature. An elastomer can deform elastically under tensile and
compressive load but then returns to its original undeformed shape.
Such elastomers can be produced for example by vulcanization of
natural rubber or silicone rubber. Adhesive elastomers are
particularly good to use. An advantage of polyurethane elastomers
is the particularly high resistance of the material properties to
the influence of typical cooling lubricants.
[0029] In some embodiments, the intermediate layer has been
vulcanized directly onto a contact face on the cutting material
body or the outer face of the cutting material body carrier
element. In this case, in order to establish the connection between
the intermediate layer and the element adjoining the latter, no
further material (for example an adhesion promoter or an adhesive)
is required. The extensive connection to the other element (cutting
material body or outer face of the cutting material body carrier
element) can be realized for example by a thin adhesive layer.
[0030] In some embodiments, the intermediate layer has a multi-ply
or multilayer structure. In particular, the intermediate layer can
have been constructed such that it has a first layer and at least
one second layer connected extensively thereto, wherein the first
layer is a layer made of an elastomer and the second layer is an
adhesive layer connected extensively to the first layer.
[0031] Although it is possible for the adhesive layer (second
layer) to be thicker than the elastomer layer (first layer), it is
preferable for the layer thickness of the first layer to be greater
than the layer thickness of the second layer. As a result, it is
possible for the essential contribution to the desired elasticity
or flexibility of the cutting material body with respect to the
cutting material body carrier element to be determined by the
properties of the first layer (elastomer layer).
[0032] It is possible for a potentially relatively small
contribution to the overall elasticity of the intermediate layer to
be made by the adhesive layer. This can be achieved in that the
adhesive layer itself is inherently elastically deformable. In
order to produce the adhesive layer, it is possible to use for
example viscoplastic adhesives, for example an acrylate-based
viscoplastic two-component plastic adhesive. When selecting the
material for the adhesive layer, care should preferably be taken to
ensure good adhesive strength with respect to the material of the
cutting material bodies and/or with respect to the material of the
outer side of the cutting material body carrier element.
[0033] In order to improve the adhesive strength at an adhesive
joint, at least one of the faces adjoining the adhesive layer can
be roughened by sand blasting or sanding or in some other way prior
to application of the adhesive. Preferably, the average roughness
depth R.sub.z of a face, adjoining the adhesive layer, of a cutting
material body carrier produced for example from steel and/or of the
cutting material body is in the range from R.sub.z=10 .mu.m to
R.sub.z=30 .mu.m. As a result, high adhesive strengths are
achievable in a long-lasting manner The face of the intermediate
layer material (for example plate or strip made of polyurethane
elastomer) that comes into contact with the adhesive can also be
roughened beforehand. In this case, average roughness depths in the
range from R.sub.z=15 .mu.m to R.sub.z=40 .mu.m have been found to
be particularly favorable.
[0034] The invention can be used in different types of honing tool.
For example, the cutting material body carriers can be longer in
the axial direction than in the circumferential direction. In many
embodiments, the cutting group has, by contrast, an axial length,
measured in the axial direction, that is less than an effective
outside diameter of the cutting group with cutting material bodies
fully retracted. Such a cutting group can be referred to as an
annular cutting group. In the case of an annular cutting group,
too, cutting material bodies can be configured as cutting material
strips that are narrow in the circumferential direction and have a
width in the circumferential direction that is small compared with
the axial length of the cutting material strips.
[0035] The honing tool has preferably exactly one annular cutting
group. An annular cutting group can be designed such that, in the
axial portion covered by the annular cutting group, substantially
more contact area can exist between cutting material bodies and
bore inner face than in a comparatively narrow axial portion of a
conventional honing tool with relatively narrow honing strips.
[0036] The axial length of the cutting material bodies can be for
example less than 40% or less than 30% of the effective outside
diameter of the honing tool, in particular between 15% and 30% of
this outside diameter. In honing tools for machining typical
cylinder bores in engine blocks for passenger cars or trucks, the
axial length can be for example in the range from 5 mm to 40 mm, in
particular 10 mm to 35 mm With regard to the bore length of a bore
to be machined, the axial length can be for example less than 20%
or less than 10% of this bore length. With regard to the bore
diameter of a bore to be machined, the axial length can be for
example in the range from 20% to 50% of the bore diameter.
[0037] Since, in such an annular cutting group, the cutting
material bodies are relatively short in the axial direction
compared to conventional honing strips, it is possible, even in the
case of stable intermediate layers with a relatively small
thickness (for example 0.5 mm to 1.5 mm), for sufficiently large
inclination angles to be established between the cutting material
body and tool axis, with the result that a particular
contour-following capability is favored.
[0038] If at least three cutting material body carriers are
provided in the cutting group, the machining forces over the entire
effective outside diameter, available by expansion, of the honing
tool can be distributed well and relatively uniformly around the
circumference of the cutting group. It is possible for example for
exactly three, exactly four, exactly five, exactly six, exactly
seven or exactly eight cutting material body carriers of the same
or different circumferential width to be provided in the cutting
group. Although more than eight cutting material body carriers
within a cutting group are possible, they make the construction
more complicated and are generally not required. In some cases, it
may even be sufficient for the honing tool to have only two cutting
material body carriers.
[0039] There are exemplary embodiments in which all the cutting
material body carriers or all the cutting material bodies of the
honing tool can be radially fed with a single common feed. Such
honing tools are referred to as honing tools with single expansion.
Other embodiments are characterized in that the honing tool is
designed as a honing tool with double expansion. In such honing
tools, the cutting group comprises a first group of cutting
material body carriers and a second group of cutting material body
carriers that is separate therefrom, wherein the first group and
the second group are feedable independently of one another. When a
honing tool with double expansion is used, fine machining methods
are possible in which in each case the cutting body material
carriers of one group are radially fed and retracted jointly. As a
result, it is possible for example for one of the groups to be
taken out of engagement with the bore inner face by retraction,
such that the bore inner face is machined only by the other group.
It is also possible to machine the bore inner face simultaneously
with all cutting material bodies of the first and the second
group.
[0040] The use of a honing tool with double expansion provides
potential for shortening cycle times, since tool changes between
successive different honing operations can potentially be dispensed
with. In some embodiments, a prior first honing operation is first
of all carried out with the first group, this first group is then
retracted, the other group (second group) is radially fed outwards,
preferably at the same time as the retraction of the first group,
and then a following second honing operation is carried out with
the cutting material bodies of the second group.
[0041] Overall, the cutting material bodies of the first and the
second group can have different removal characteristics or other
properties intended for material removal. For example, the cutting
material bodies of the two groups can have different widths and/or
have been applied to the respectively associated cutting material
body carriers with different circumferential spacings and/or a
different pitch. Alternatively or additionally, it is also possible
for the cutting material bodies of one of the groups to be provided
with coarser grain for rougher machining and the cutting material
bodies of the other group to be provided with finer grain for finer
machining Therefore, it is possible, for example, to carry out a
pre-honing operation with substantial material removal and a
following finish-honing operation with less or almost no material
removal, mainly to smooth the previously structured surface, one
after the other with the same honing tool.
[0042] Some embodiments of honing tools with double expansion are
distinguished by the fact that, in the first group, the cutting
material bodies are fastened directly to the associated cutting
material body carrier without interposition of an elastic
intermediate layer and as a result are connected rigidly to the
cutting material body carrier, whereas, in the second group, the
cutting material bodies are fastened to the associated cutting
material body carrier in an individually elastically resilient
manner via an elastically resilient intermediate layer. With the
double expansion, it is possible, for example, to use the first
group first of all in order to carry out a first honing operation,
which is designed as a contour honing operation, in order to change
the axial contour of the bore in a targeted manner starting from a
prior machining operation. Then, the first group can be taken out
of engagement and the second group put into engagement with the
bore inner face, in order to carry out a second honing operation in
the form of a tracking honing operation with the second group, in
which only weakly abrasive cutting material bodies that are held in
an elastically resilient manner substantially track the previously
created contour and primarily improve the surface structure.
[0043] The invention also relates to a fine machining method for
machining the inner face of a bore in a workpiece, in particular
for fine machining cylinder surfaces in the production of cylinder
blocks or cylinder liners for reciprocating piston engines. In the
course of the fine machining method, at least one honing operation
is carried out in which an expandable honing tool is moved up and
down within the bore in order to create a reciprocating movement in
the axial direction of the bore and at the same time is rotated in
order to create a rotary movement superimposed on the reciprocating
movement. In this honing operation, a honing tool according to the
claimed invention is used. This honing operation is preferably the
last fine machining operation of a multistage fine machining method
and determines substantially the surface structure of the end
product.
[0044] Before the start of the honing operation, a bore shape that
differs significantly from a circular-cylindrical shape can be
created by fine boring (with a geometrically determined cutting
edge), honing (with geometrically undetermined cutting edges) or by
a combination of both fine machining methods (for example first
fine boring, then honing). The bore can be premachined for example
such that, before the start of the honing operation, it is given an
axial contour profile (for example barrel shape, bottle shape or
cone shape) and/or one or more portions with a deliberately
non-round shape (for example oval shape or trefoil shape). The
honing operation can then be carried out in a substantially
shape-maintaining way such that the finally desired surface
structure is created at the bore inner face, using the honing tool,
substantially without changing the macro shape of the bore. In the
process, the cutting material bodies track the previously defined
surface form or follow the latter, wherein the individually
resilient mounting of the individual cutting material bodies
results in a particularly good suitability for tracking.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Further advantages and aspects of the invention will become
apparent from the claims and from the following description of
preferred exemplary embodiments of the invention, which are
explained in the following text with reference to the figures, in
which:
[0046] FIG. 1 shows an oblique perspective schematic view of one
embodiment of a honing tool according to the claimed invention;
[0047] FIG. 2 shows a schematic sectional illustration through a
part of a cutting material body carrier, on the outer side of which
a plurality of cutting material strips are fastened in each case
with interposition of an elastically resilient intermediate
layer;
[0048] FIG. 3 shows a schematic illustration of a machining
situation in the region of a transition between a cylindrical and a
conical portion of a rotationally symmetric bore with an axial
contour profile;
[0049] FIG. 4 shows an axial view of another embodiment of a honing
tool;
[0050] FIG. 5 shows a schematic sectional illustration through a
part of a cutting material body carrier, on the outer side of which
an elastically resilient layer has been applied, which carries a
plurality of cutting material bodies, and an enlarged detail;
[0051] FIG. 6 shows, in 6A and 6B, a first exemplary embodiment
with a laterally inhomogeneous intermediate layer; and
[0052] FIGS. 7-9 show further exemplary embodiments with a
laterally inhomogeneous intermediate layer.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0053] The schematic FIG. 1 shows an oblique perspective
illustration of a honing tool 100 according to one embodiment of
the invention. The honing tool serves to machine an inner face of a
bore in a workpiece by means of honing and, in the case of the
example, is designed to hone cylinder surfaces in the production of
cylinder blocks or cylinder liners for reciprocating piston
engines. The honing tool is particularly suitable for also
machining rotationally symmetric bores that have bore portions with
different diameters and/or different forms, for example
bottle-shaped bores, barrel-shaped bores and/or bores that have at
least one conical bore portion with an axially continuously
changing diameter. However, the honing tool can also be used to
machine circular-cylindrical bores, i.e. rotationally symmetric
bores without an axial contour profile.
[0054] The honing tool has a tool body 110, manufactured from a
steel material, that defines a tool axis 112, which is at the same
time the axis of rotation of the honing tool during machining by
honing. Located at the spindle-side end of the honing tool is a
coupling structure 120 for coupling the honing tool to a drive rod
or a working spindle of a honing machine or some other machine tool
that has a working spindle which is rotatable about the spindle
axis and is also movable back and forth in an oscillating manner
parallel to the spindle axis.
[0055] In exemplary embodiments, for use on the working spindle of
a machining center, it is possible for example for a coupling
structure in the manner of a hollow shank taper or a cone of some
other type to be provided.
[0056] Located in the end portion of the tool body that is remote
from the spindle is an expandable annular cutting group 130 having
a multiplicity of cutting material bodies 140-1, 140-2 etc. that
are distributed around the circumference of the tool body and have
an axial length LS, measured in the axial direction, that is
smaller by a multiple than an effective outside diameter AD of the
cutting group 130 with cutting material bodies fully retracted in
the radial direction. The cutting material bodies 140-1 etc. are in
the form of cutting material strips that are narrow in the
circumferential direction and have a width BS, measured in the
circumferential direction, that is small compared with the axial
length LS of the cutting material strips. An aspect ratio between
length LS and width BS can be for example in the range from 4:1 to
20:1. Expressed in absolute terms, the length can be for example in
the range from 10 mm to 20 mm and the width in the range from 2 mm
to 5 mm.
[0057] The honing tool has only one annular cutting group 130. The
latter is arranged more or less flush with the end of the tool body
remote from the spindle, such that it is also possible, if
required, to machine blind bores right to the bottom of the bore.
Illustrated by dashed lines is an optionally present slender
coupling portion at the end of the honing tool remote from the
spindle. This coupling portion can be used as a coding element for
example during an automatic tool change.
[0058] The cutting group or the cutting material bodies of the
cutting group are feedable radially with respect to the tool axis
by means of a cutting group feeding system assigned to the cutting
group. Since this functionality, which is typical for honing tools,
is known per se, the components (for example feeding rod(s),
expansion cone etc.) provided for this purpose are not described in
more detail here.
[0059] The expandable annular cutting group 130 comprises a
plurality of radially feedable cutting material body carriers
150-1, 150-2 etc., which each cover a circumferential angle range
that is greater than the axial length LS of the cutting material
bodies or of the cutting group. In the case of the example in FIG.
1, six cutting material body carriers 150-1 to 150-6 are provided,
which each cover a circumferential angle range of between
45.degree. and 60.degree. and are arranged regularly around the
circumference of the honing tool.
[0060] Between directly adjacent cutting material body carriers,
respective non-cutting guide strips 115-1 etc. are fastened to the
tool body. FIG. 1 shows the honing tool 100 with retracted cutting
material bodies, such that the outer faces, serving as guide faces,
of the guide strips project beyond the abrasive outer faces of the
cutting material bodies in a radial direction. Before and/or during
the machining by honing, the cutting material body carrier elements
are fed radially outward, such that they pass into engagement with
the inner face to be machined of the bore.
[0061] The cutting material body carriers are, in the case of the
example, produced in one piece from a steel material and are
therefore inherently substantially rigid. Each cutting material
body carrier has a carrier portion 152-1 etc. that is relatively
wide in the circumferential direction and has a cylindrically
curved outer side 154 and a substantially planar inner side, facing
the tool body, from which a plate-form feeding portion 156 projects
inwardly. Located on the inner side, remote from the outer side
154, of the feeding portion is a sloping surface that cooperates
with a corresponding sloping surface of an axially displaceable
feeding cone in the manner of a wedge drive, such that an axial
movement of the feeding rod in the interior of the tool body causes
a radial movement of the cutting material body carrier. The feeding
portion 156 of the cutting material body carrier sits in a radially
movable manner in a substantially rectangular cutout in the tool
body, such that a radial movement is possible but tilting movements
in a transverse direction thereto are largely avoided. The cutting
material body carriers are pretensioned into the inwardly retracted
position with the aid of a plurality of encircling coil springs,
such that the radial outward feeding takes place counter to the
force of these restoring springs.
[0062] There are exemplary embodiments in which all of the cutting
material body carriers or all of the cutting material bodies of the
honing tool can be fed radially with a single common feed (honing
tools with single expansion).
[0063] The exemplary embodiment of the honing tool 100 in FIG. 1 is
a honing tool with double expansion. The annular cutting group 130
has two mutually independently feedable groups of cutting material
body carriers, wherein the three cutting material body carriers of
one group are each circumferentially offset through 120.degree.
with respect to one another such that, between two adjacent cutting
material body carriers of one of the groups, a cutting material
body carrier of the other group is arranged.
[0064] For the honing tool, particular design precautions are
taken, which can help to optimize the machining result on the bores
machined with the honing tool, such that the desired surface
structure can be created with relatively uniform quality along the
entire bore length, in particular including in the region of
transitions between bore portions of different form and/or in the
region of turning points of the axial honing movement.
[0065] As is apparent from FIG. 1, each cutting material body
carrier has, on its radial outer side 154, a plurality of cutting
material bodies in the form of cutting material strips, which are
arranged at a mutual circumferential spacing from one another.
These cutting material body groups or strip groups of cutting
material strips applied jointly to a cutting material body carrier
can consist for example of between three and ten cutting material
strips. In the case of the example, seven cutting material strips
are arranged at a uniform circumferential spacing from one another
on each cutting material body carrier. The circumferential spacing
in the case of the narrower cutting material strips is
approximately of a similar size to or greater than the width of the
cutting material strips, and in the case of the wider cutting
material strips is approximately the same size as or less than the
width of the cutting material strips.
[0066] The cutting material bodies are not connected rigidly to the
cutting material body carriers carrying them. Rather, between each
of the cutting material strips and the cutting material body
carrier carrying the cutting material strip, there is an
intermediate space in which an elastically resilient intermediate
layer 160 is arranged, which fills the intermediate space between
the cutting material strip and the cutting material body carrier
element substantially completely. The elastically resilient
intermediate layer has the effect that the cutting material bodies,
when externally loaded, can move to a limited extent relative to
the cutting material body carrier and to a limited extent counter
to the restoring force by the intermediate layer. The cutting
material strips in this case each have individual flexibility, in
other words can each move slightly, independently of the adjacent
cutting material strips.
[0067] In the case of the example, the intermediate layer has a
layer thickness SD of about 1 mm, with the result that a good
compromise between sufficient resilience and sufficient stability
of the cutting material bodies to transverse forces is achievable.
The intermediate layer consists substantially of a rubber-elastic
polyurethane elastomer with a hardness in the hardness range of
between 75 and 85 Shore A. Suitable elastic polyurethane plastics
are commercially available for example under the trade names
Vulkollan.RTM. or Urepan.RTM.. The intermediate layer material is
pore-free, i.e. impermeable, and so no cooling lubricant can
penetrate and the elastic properties are maintained in a
long-lasting manner The material is also chemically resistant to
cooling lubricants and also sufficiently mechanically resistant, in
the harsh machining environment, to the abrasion caused by the
machining by honing.
[0068] It is possible, in the production of the honing tool, to
first of all stick prefabricated narrow thin strips of the
intermediate layer material to the outer side of the cutting
material body carrier and then to stick on the strip-form cutting
material bodies (cutting material strips), provided therefor, with
a suitable adhesive.
[0069] In one variant of the production, there is no adhesion
promoter between the intermediate layer material and the cutting
material bodies. In this variant, first of all a plate made of
cutting material body material is produced. Then, a layer made of
the precursor of the finished intermediate layer material is
vulcanized onto the side intended to be the fastening side (contact
side), such that, as a result of the vulcanization, mechanically
firm adhesive contact arises between the cutting material body
material and the intermediate layer material. Subsequently, the
individual cutting material bodies, each provided with an
intermediate layer, can be produced by dividing up the coated
cutting material body plate. It would also be possible to provide
individual cutting material strips in each case on one side with a
vulcanized-on elastomer layer and then to stick them to the cutting
material body carrier element.
[0070] It is also possible to first of all coat the outer side of a
cutting material body carrier element with a layer of intermediate
layer material more or less over its entire surface (for example by
sticking it on) and then to fasten the cutting material strips at
the points provided therefor by adhesive bonding. The intermediate
layer material is then exposed between adjacent cutting material
strips (cf. FIG. 5).
[0071] For the production of an extensive adhesive bond between a
cutting material body and a strip made of elastic intermediate
layer material and/or an adhesive bond between an intermediate
layer made of polyurethane plastic and the outer side of the
cutting material body carrier element, in preferred embodiments, an
acrylate-based viscoplastic two-component construction adhesive is
used. The adhesion that is obtainable as a result is distinguished
by high adhesive strength. Furthermore, the adhesive layer is
inherently slightly elastic, such that a multilayer elastically
resilient intermediate layer is produced, which affords good
adhesion even after long-term alternating stress.
[0072] An improvement in the adhesive strength can be achieved when
those faces of the intermediate layer material, of the cutting
material body carrier and/or of the cutting material body that come
into contact with the adhesive have a relatively rough surface
structure. The surfaces can potentially be roughened before
adhesive application by sanding, sand blasting or in some other
way, for example to average roughness depths in the range from
R.sub.z=15 .mu.m to R.sub.z=30 .mu.m.
[0073] As a result of the interposition of an elastically resilient
intermediate layer between the cutting material strips and the
cutting material body carrier elements, the contour-following
capability of the honing tool during machining and/or the creation
of bores with an axial contour profile can be generally improved,
since the cutting material strips align themselves to some extent
with the rigid cutting material body carrier element and can thus
achieve more uniform contact pressure with the bore inner face.
[0074] A particular phase of the machining is schematically
illustrated in FIG. 3. A detail of a workpiece 300 in the form of
an engine block (crankcase) for an internal combustion engine can
be seen. The bore 320 to be machined is delimited by a bore inner
face 322. The bore inner face is the workpiece surface to be
machined during the machining by honing. The bore 320 is
rotationally symmetric with respect to its bore axis (not
illustrated) and extends along a bore length from the illustrated
bore inlet 314, facing the cylinder head in the installed state, to
an axially opposite bore outlet. The bore can be subdivided into a
plurality of bore portions of different function that axially
adjoin one another and transition into one another seamlessly, i.e.
without forming steps or edges. Directly at the bore inlet 314
there begins a first bore portion 322, which, after completion of
machining, is intended to have a substantially circular-cylindrical
form, i.e. not to have an axial contour profile. This
circular-cylindrical bore portion is adjoined in the direction of
the opposite bore end by a conical second bore portion 324, in
which the bore diameter increases continuously from the inlet side
in the direction of the outlet side. The conical bore portion can
extend as far as the bore outlet. It is also possible for a further
substantially circular-cylindrical portion to adjoin the conical
bore portion, said substantially circular-cylindrical portion then
having a larger diameter than the inlet-side first bore portion
322. In such a case, the bore would then at least approximately
have a bottle shape. The transition regions between the bore
portions are (unlike in the schematic drawing) continuously curved.
There can be convex or concave transition regions.
[0075] FIG. 3 shows a phase of the machining by honing, in which
the annular cutting group 330, for example during a downward
movement from the bore inlet 314 in the direction of the bore
outlet, is located at the level of a transition portion 323 between
the circular-cylindrical first bore portion 322 and the downwardly
following conical second bore portion 324. The transition portion
generally has a slight rounding with a suitable transition radius,
i.e. is not sharp-edged. A leading part of the cutting material
bodies 140, coming from the cylindrical bore portion, has already
reached the conical bore portion, in which the bore is widened and
the lateral surface of the bore is at an angle or inclined with
respect to the bore axis. Here, axially irregular loading can occur
and this can result in a tilting moment and potentially slight
tilting of the cutting material carrier 150. The elastically
resilient intermediate layer 160 can compensate for some of this
tilting in that the upper part is compressed more greatly than the
leading lower part towards the bore end. As a result, even during
the machining by honing of the conical bore portion, relatively
uniformly distributed machining forces can arise, and so the
surface structure can remain relatively uniform along the entire
bore length, i.e. including both the cylindrical bore portion and
the conical bore portion and the transition portion.
[0076] On account of the elastically resilient intermediate layer,
the cutting material bodies are tiltable with respect to the
cutting material body carrier in an axial direction (about a
tilting axis extending tangentially to the honing tool), as is
schematically shown in FIG. 3. Moreover, tilting in the
circumferential direction is also possible to a certain extent.
This tilting movement can take place for example about a
substantially axially parallel tilting axis. As a result, the
cutting material bodies can follow the bore inner face almost
without constraining forces even when the macroscopic form of the
bore inner face differs significantly from a rotationally symmetric
form in the machined portion. Thus, it is possible for example for
bore portions with an oval form or with a trefoil shape or
higher-order non-roundness or having irregular non-rotationally
symmetric shapes to be machined by means of honing, by virtue of
the individual flexibility of the cutting material bodies, such
that a relatively uniform surface structure can be achieved around
the entire circumference and/or along the entire length of the
bore. This is achieved, inter alia, in that the cutting material
bodies can track the defined surface form to a certain extent on
account of the elastically resilient intermediate layer, such that
contact pressure force peaks, as could occur in the case of cutting
material bodies fastened rigidly to the cutting material body
carrier, are alleviated or avoided. Thus, in spite of a non-round
bore and/or axial bore contour, a relatively uniform cutting depth
can be achieved over the entire bore inner face. This can be
favorable both for largely smooth final surfaces and for surfaces
with a plateau structure. In this connection, it is also worth
mentioning that the expansion force is generally a multiple of the
"spring force" of the intermediate layer. This results in a
relatively uniform cutting depth even at "bulges", which generally
represent only radial deviations of a few .mu.m.
[0077] In the honing tool 100 with double expansion, the three
cutting material body carriers of one group are each
circumferentially offset through 120.degree. with respect to one
another. The cutting material bodies of one group are preferably
identical to one another. The cutting material bodies of a first
group differ preferably from the cutting material bodies of a
second group. For example, the cutting material bodies of the two
groups can have different widths and/or they can have been attached
to the cutting material body carriers with different
circumferential spacings and/or a different pitch. It is possible
for the cutting material bodies of one of the groups to be provided
with coarser grain for rougher machining and for the cutting
material bodies of the other group to be provided with finer grain
for finer machining It is also possible for not all cutting
material bodies of an annular cutting group to have been fastened
to the associated cutting material body carriers by means of an
elastically resilient intermediate layer. It may for example be the
case that, in a first group, the cutting material bodies sit
directly on the cutting material body carrier without interposition
of an elastic intermediate layer and are thus rigidly connected
thereto, while, in the other group, the cutting material bodies
have been fastened to the cutting material body carrier in an
individually resilient manner via an elastic intermediate layer.
For example, a first group can be provided, which is provided for
contour honing and has cutting strips connected rigidly to the
cutting material body carriers, while the second group is provided
for a following finishing honing process and is provided with
cutting material bodies that are fastened in an elastically
resilient manner relative to the cutting material body carrier. In
another process chain, it is also possible to configure a first
group for an intermediate honing process and the second group for
the following finishing honing process, wherein the cutting
material bodies of the two cutting groups are fastened to the
associated cutting material body carriers in an elastically
resilient manner
[0078] With reference to FIG. 4, a honing tool 400 according to
another exemplary embodiment is explained. FIG. 4 shows the honing
tool in an axial view from the end that is remote from the spindle.
The honing tool has a single annular cutting group 430, which is
arranged in the end region of the tool body remote from the spindle
and has a total of eight cutting material body carriers 450-1 to
450-8 that are each feedable radially with respect to the tool axis
412 and each cover a circumferential angle range that is greater
than the axial length of the cutting material bodies or of the
cutting group. Each of the cutting material body carriers covers a
circumferential range of about 40.degree..
[0079] The cutting material body carriers 450-1 and 450-2, together
with the respectively diametrically opposite cutting material body
carriers 450-5 and 450-6, form a first group of cutting material
body carriers that carry relatively narrow cutting strips 440-1.
The cutting material body carriers 450-3, 450-4, 450-7 and 450-8
belong to a second group of cutting material body carriers, the
cutting material body carriers of which each carry cutting strips
440-2 with a somewhat greater circumferential width. Fastened
between directly adjacent pairs of cutting material body carriers
are in each case non-cutting guide strips 415-1 etc. Thus, directly
adjacent cutting material body carriers of the same group are
located next to one another in the circumferential direction
without an interposed guide strip, while in each case one of the
guide strips is arranged between adjacent cutting material body
carriers of different groups.
[0080] The four cutting material body carriers of one group can
each be radially fed and retracted jointly, and the two groups can
be radially fed and retracted independently of one another. Thus,
it is possible, with a first group, to carry out a prior first
honing operation, then to retract this group, to radially feed the
other group, and then to carry out a following second honing
operation with the cutting material bodies of the second group.
[0081] With reference to FIG. 5, another possible way of fastening
individual strip-form cutting material bodies 540-1 etc. to a
common cutting material body carrier 552 is explained. In this
exemplary embodiment, a thin flexible plate 560' made of an
elastomer (thickness about 1 mm) has been vulcanized or adhesively
bonded onto the cylindrically curved outer side 554 of the metal
cutting material body carrier 552. The individual cutting material
bodies 540-1 etc. are then adhesively bonded onto the outer side of
the elastomer layer. To this end, first of all the outer side 562
is roughened by sand blasting, sanding or in some other way to an
average roughness depth of e.g. 20 to 40 .mu.m. Furthermore, the
rear side 542 of the cutting material body, which is intended to be
connected to the elastic intermediate layer, is likewise roughened
by means of sand blasting, sanding or in some other way, wherein
typical roughness depths are usually in the range between 10 .mu.m
and 20 .mu.m. The adhesive for the adhesive layer 565 can be
applied on one side or both sides before the respective cutting
material body is pressed at the intended point onto the outer side
of the elastomer plate until the adhesive has cured. As a result of
the surfaces of the cutting material body and of the elastomer
plate that adjoin the adhesive layer 565 being roughened, the
long-term adhesive strength can be increased considerably compared
with surfaces that have not been roughened. This flexible plate
560' forms an elastomer layer that forms a multilayer intermediate
layer 560 with an (or at least one) adjoining adhesive layer
565.
[0082] In the region between the cutting material body carrier and
the cutting material body carried by the intermediate layer, the
intermediate layer can have spatially homogeneous elasticity
properties, this being able to be achieved for example in that an
intermediate layer made of homogeneous elastic material completely
fills the intermediate space. It is also possible for the
intermediate layer to be designed such that, in that region that
carries a cutting material body, it is designed in a spatially
inhomogeneous manner and/or has inhomogeneous elasticity
properties, i.e. elasticity properties that can change from place
to place over the face used for carrying a cutting material
body.
[0083] By way of example, FIGS. 6A and 6B and FIG. 7 to FIG. 9 show
a number of variants of exemplary embodiments with spatially, in
particular laterally inhomogeneous intermediate layers. The
intermediate layer 660, which is shown in FIG. 6A in vertical
section and in FIG. 6B in plan view, was manufactured from a flat
plane-parallel piece of elastomer material, into which blind bores
662 of different depth and/or size were introduced at a defined
pitch from the side intended for carrying a cutting material body
640, for example by mechanical boring or by laser machining The
holes can be distributed regularly or irregularly. They can also
all have the same depth and/or the same diameter. The cutting
material body 640 is adhesively bonded to the multiply perforated
free surface and closes the holes off from the outside such that
the intermediate layer is protected circumferentially and from
above and below from the penetration of honing sludge or the like
into the cavities.
[0084] FIG. 7 shows a plan view of a flat intermediate layer 760
manufactured from elastomer material, which is configured in the
manner of a circumferentially closed frame with a single long inner
cavity 762. After the associated cutting material body has been
stuck on, this cavity is also closed off on all sides.
[0085] In the variant of the intermediate layer 860 in FIG. 8,
obliquely extending slots 862 have been introduced into the
original flat material made of elastomer, these slots 862, in a
similar manner to the bores in FIG. 6A, being circumferentially
closed and thus protected from the penetration of honing sludge
etc. after the carried cutting material body has been stuck on.
[0086] These are a number of examples of intermediate layers that
have more or less large cavities of different and/or identical
shape and/or size and as a result tend to be more elastically
resilient than the corresponding solid elastomer material, into
which the cavities (bores, slots or the like) have been introduced.
Intermediate layers made of closed-pore elastomer material are also
possible, i.e. elastomer material in which there are already
cavities that are enclosed on all sides (closed pores) after
manufacturing.
[0087] In an embodiment in FIG. 9, the elastomer material of the
intermediate layer 960 completely fills the intermediate space
between the cutting material body carrier and cutting material body
940. The elastomer material is laterally structured and has a
sequence of mutually adjacent strips 964-1 made of a relatively
softer elastomer material and 964-2 made of a relatively harder
elastomer material.
[0088] The examples in FIGS. 6 to 9 illustrate that there are
different possible ways of adapting the elasticity properties of
the intermediate layer exactly to the intended use of the honing
tool provided therewith by way of simple means. In the examples, to
this end, in each case one layer of elastomer material that has
been laterally structured by means of cavities and/or irregular
material distribution is provided. The layer thicknesses that
determine the spacing between the cutting material body carrier and
cutting material body in the unloaded state are usually in the
range from 0.1 to 2 mm, in particular in the range from 0.5 to 1.5
mm.
[0089] The advantages of honing tools according to the invention
can be achieved regardless of the type of pre-machining of the bore
to be honed. Before the start of the honing operation in which the
honing tool is used, a bore shape that differs significantly from
the circular-cylindrical shape can be created by fine boring and/or
by honing. With the aid of the honing operation, it is then
possible, on account of the use of a honing tool with individually
elastically resilient cutting material bodies, to produce the
surface structure desired on the bore inner face, substantially
without changing the previously defined macro shape of the
bore.
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