CUT-OFF WHEEL

MEULE TRONCONNEUSE

English Abstract

The invention relates to an abrasive cutoff wheel which comprises a central
disk (2) and a plurality of abrasive segments (4) which subtend between
themselves a straight bonding line (10) that slants inward along a
predetermined disk direction of rotation (12) toward the wheel center of
rotation 14, deviating from a tangent line. Seen in wheel sideview, the
radially outer surface (18) of each abrasive segment (4) preferably also is
straight and slants inward along the wheel direction of rotation (12) toward
the wheel center of rotation (14), deviating from a tangent line.

French Abstract

L'invention concerne une meule tronçonneuse abrasive qui comprend un disque central (2) et plusieurs segments abrasifs (4) qui sous-tendent entre eux une ligne de liaison rectiligne (10) qui s'incline vers l'intérieur le long d'un sens de rotation de disque prédéfini (12) vers le centre de rotation de la meule (14), déviant d'une ligne tangente. Illustrée dans la vue latérale de la meule, la surface radialement externe (18) de chaque segment abrasif (4) est également de préférence rectiligne et s'incline vers l'intérieur le long du sens de rotation de la meule (12) vers le centre de rotation de celle-ci (14) déviant d'une ligne tangente.

Claims

WHAT IS CLAIMED IS:

1. An abrasive cutoff wheel comprising a central disk (2) and a plurality of
abrasive
segments (4) distributed along the circumference of the central disk (2) on
the same number of
disk function faces (6) that are straight as seen in wheel sideview and that
comprise each a
segment junction face (8) which is undetachably affixed to only one of the
disk junction faces
(6),
wherein the abrasive cutoff wheel is driven in a predetermined direction of
rotation (12),
and wherein each disk junction face (6) and the segment junction face (8)
affixed to it when seen
in wheel sideview subtend a straight bonding line (10) which, in the
predetermined direction of
rotation (12) slopes inward toward the wheel center of rotation (14),
deviating from a tangent
line; and
wherein the radially outer surface (18) of each abrasive segment (4) is
straight as seen in
wheel sideview and defines a straight surface line (20) which slants inward in
the direction of
the wheel center of rotation (14), also deviating from a tangent line.


2. The abrasive cutoff wheel as claimed in claim 1, wherein the surface line
(20) and the
bonding line (10) of the particular abrasive segment (4) are mutually
parallel.


3. The abrasive cutoff wheel as claimed in claims 1 or 2, wherein the central
disk (2)
comprises a circumferential notch (22, 24) at every two adjacent disk junction
faces (6).


4. The abrasive cutoff wheel as claimed in claim 3, wherein the depths of the
circumferential
notches (22, 24) are different, a deeper circumferential notch (24) and a
shallower circumferential
notch (22) alternating in the wheel circumferential direction.



5

Description

CA 02603270 2009-10-23

CUT-OFF WHEEL

The present invention relates to an abrasive cutoff wheel defined in the
preamble of claim
1 to cut off building materials, in particular concrete, bricks, roof tiles,
and to cut apart natural
stone.
An abrasive cutoff wheel of this kind is known from the German patent document
DE
44 24 093 C2. It comprises both a central disk and segments. The segments are
undetachably
affixed by laser welding to the central disk circumference which is continuous
of which is sub-
divided by circumferential clearances into projecting tabs. The line
connecting the segments and
the outer contour of the central disk runs tangentially to the central disk
origin or is constituted
by two corresponding tangential straight lines for each segment, said two
lines subtending, in
roof-like manner, between them an angle of less than 180 .
The present invention seeks to provide an improved abrasive cutoff wheel.
In a broad aspect, the invention pertains to an abrasive cutoff wheel
comprising a central
disk and a plurality of abrasive segments distributed along the circumference
of the central disk
on the same number of disk function faces that are straight, as seen in wheel
sideview, and that
comprise each a segment junction face which is undetachably affixed to only
one of the disk
junction faces. The abrasive cutoff wheel is driven into a predetermined
direction of rotation.
Each disk junction face and the segment junction face affixed to it, when seen
in wheel sideview,
subtend a straight bonding line which, in the predetermined direction of
rotation, slopes inward
toward the wheel center of rotation, deviating from a tangent line. The
radially outer surface
of each abrasive segment is straight, as seen in wheel sideview, and defines a
straight surface
line which slants inward in the direction of the wheel center of rotation,
deviating from a tangent
line.
The invention offers improved distribution of forces at the bonding line
between the
abrasive segments and the central disk, allowing higher loading on the
abrasive cutoff wheel.
The present invention converts a substantial portion of the shearing forces
arising in the dry
severing method into compressive forces that are applied in the bonding line
between the
abrasive segments and the central disk.

1


CA 02603270 2007-09-19
WO 2006/106391 PCT/IB2006/000638
In one preferred embodiment mode of the present invention, the radially outer
surface of each abrasive segment is straight when seen in wheel side view and
this
outer surface of each segment defines a surface line sloping inward in the
direction
of disk rotation toward the center of the wheel, deviating from a tangent
line. As a
result, when the abrasive cutoff wheel is used for the first time, only a
minute part of
each abrasive cutoff segment makes contact with the work piece to be cut, and
thereby allows automatically honing the abrasive segments during first time
use.

The abrasive segments are composed of at least in their top zones of an
imbedding material containing imbedded diamond elements illustratively
sintered into
said imbedding material. Before an abrasive cutoff wheel is used for the first
time,
the diamond elements do not protrude from the imbedding material, so that the
abra-
sive cutoff wheel must be honed before or by means of first use to assure the
dia-
mond elements shall project above the imbedding material.

In another preferred embodiment mode of the present invention, the surface
line and the bonding line of the particular abrasive segment are always
mutually par-
allel.

In a further preferred embodiment mode of the present invention, the central
disk is fitted with one circumferential notch between all adjoining disk
junction faces.
In this manner material abraded from a workpiece more easily escapes from the
notch formed in the workpiece.

The present invention is elucidated below by means of a preferred embodi-
ment and in relation to the appended drawing.

Fig. 1 is a sector-like cutaway of a sideview of an abrasive cutoff wheel of
the
invention.

2


CA 02603270 2010-08-27

The abrasive cutoff wheel of the invention shown in Fig. 1 substantially
comprises a
circular central disk 2 and a plurality of abrasive segments 4. The abrasive
segments 4 are
distributed preferably symmetrically along the full outer circumference of the
central disk 2 on
the same plurality of straight (as seen in wheel sideview) disk junction faces
6 and each segment
is fitted with its own segment junction face 8 that is undetachably joined,
for instance by brazing,
welding or laser processing, to one of the disk junction faces 6. The central
disk 2 preferably
is made of steel.
The abrasive cutoff wheel of the invention does its cutoff work in a
predetermined
direction of rotation 12.
Each disk junction face 6 and the segment junction face 8 joined to it
determine between
them a straight bonding line 10 (as seen in wheel sideview), this bonding line
sloping inward
along the predetermined direction of wheel rotation 12, relative to wheel
center of rotation 14,
that is, deviating from a line tangent to the wheel center of rotation. A
conceptual radial line
from the wheel center of rotation 14 to the center (in sideview) of a disk
junction face 6 subtends
an angle with said surface 6 that deviates from 90 .
The radially outer surface 18 of each abrasive segment 4 is straight when seen
in wheel
sideview and defines a straight surface line 20 which. as seen in wheel
sideview, slants in the
direction of rotation of the wheel toward the wheel center of rotation 14,
deviating from a tangent
line. The surface line 20 and the bonding line 10 of the particular abrasive
segment 4 preferably
are mutually parallel.
Between every two mutually adjacent disk junction faces 6, the central disk 2
is fitted
with circumferential notches 22 and 24 respectively.

3


CA 02603270 2007-09-19
WO 2006/106391 PCT/IB2006/000638
In the preferred embodiment mode shown in Fig. 1, the circumferential
notches 22 and 24 differ in depth, a deeper circumferential notch 24 and a
shallower
circumferential notch 22 alternating along the circumference. The
configuration of
circumferential notches of different depths lowers the danger of cracks in the
central
disk.

A spacer gap 26 is subtended in all embodiment modes of the invention be-
tween the circumferentially sequential abrasive segments 4 to facilitate
eliminating
ground material when grinding the workpiece.

The bonding line 10 and a radial line 30 subtend an angle deviating from 90
at least at the longitudinal center point of the disk junction face 6,
preferably however
also at any other point along the length of the segment junction face 8. As a
result
the angle a situated in the predetermined wheel direction of rotation 12 in
front of the
radial line 30 is less than 90 and the angle (3 situated behind is larger
than 90 .

The circumferential notches 22 and 24 preferably are slots open at the outer
central disk circumference. Said notches subtend a defined angle y preferably
larger
than 90 with the connecting line 10, respectively the disk junction surface
6, pre-
ceding them in the wheel's direction of rotation 12.

4

Representative Drawing