[0001] The present invention relates to an electro-deposited thin-blade grindstone used
for grinding, cutting and grooving a metallic material, a nonmetallic material and
the like.
[0002] Conventionally, in order to cut a difficult-to- machine material such as ceramics,
FRP or the like, as disclosed in JP-A-2000-210872 or as shown in Fig. 1, a thin-blade
grindstone 6 on which super-abrasive grains 2 made of diamond, CBN or the like are
electro-deposited by plating method has been used. This thin-blade grindstone 6 is
made, for example, by dispersing the super-abrasive grains 2 in a nickel- plating
tank and by electrodepositing the super-abrasive grains 2 near the edge portion of
a disc-shaped base metal 4 by a nonelectrolytic plating method and an electrolytic
plating method. In the thin-blade grindstone 6, the super-abrasive grains 2 are electro-deposited
in a single layer on the surface of the outer peripheral edge portion of the base
metal 4.
[0003] However, in the thin-blade grindstone 6 in the related art, as shown in Fig. 1, letting
the thickness of the base metal 4 be t and the diameter of the super-abrasive grain
2 be d, a grinding width w in cutting or grooving is expressed as W = t + 2d. Accordingly,
in order to reduce the cutting width w, the thickness of the base metal 4 needs to
be thinned. However, the thickness t of the base metal 4 can not be thinned too much
because of the strength of the base metal 4. Therefore, there is presented a problem
that because the cutting width w of a material 8 to be ground becomes large, a grinding
force becomes large and a yield decreases in the cutting of a precious material.
[0004] Further, the actual machining portion of the grinding and grooving grindstone of
this type in which the super-abrasive grains 2 are electro-deposited on the peripheral
edge portion of the disc-shaped base metal 4 is only the outermost peripheral end
face of the edge portion and the abrasive grains electro-deposited on both side surfaces
do not have a cutting action. Therefore, when the abrasive grains on the outermost
peripheral end surface wear out or drop, the outer peripheral end surface of the base
metal 4 is exposed to lose the cutting action.
[0005] Still further, because the super-abrasive grains 2 are electro-deposited in a single
layer on the outermost peripheral end surface of the edge portion of the base metal
4, when the super-abrasive grains 2 on the base metal 4 wear out or drop, the outer
peripheral end face, with no super-abrasive grains 2, of the base metal 4 is exposed.
As a result, even if the base metal 4 has no problem, the thin-blade grindstone 6
can not be used. Therefore, this wastes the precious base metal 4, increases the frequency
of replacement of the grindstone in a cutting work, and thus reduces work efficiency.
[0006] The invention has been made in view of the above-mentioned problem in the related
art. It is the object of the invention to provide an electro-deposited thin-blade
grindstone capable of reducing a cutting width, increasing a tool life, reducing the
frequency of replacement, and improving efficiency in the cutting and grinding work.
[0007] The invention relates to an electro-deposited thin-blade grindstone, characterized
by including a plate-shaped base metal, depressed portions that are open from near
the edge portion of the base metal to edge portion and are formed alternately on both
side surfaces of the base metal, and a number of abrasive grains deposited on the
depressed portions and protruded from the side surfaces and, optionally, from end
portion of the base metal. The above-mentioned abrasive grain may be a super-abrasive
grain made of diamond, CBN or the like. The depressed portion may be formed in a depth
of 1/2 or more of the thickness of the base metal. It is preferable that the abrasive
grain has a grain size nearly equal to the thickness of the base metal.
[0008] Between the respective depressed portions adjacent to each other along the edge portion
of the base metal may be formed a cutout in which the edge portion of the disc-shaped
base metal is cut away by a predetermined amount in the radial direction of the disc,
and the edge portions of the abrasive grains on the depressed portions are exposed
by the cutout.
[0009] The abrasive grains may be electro-deposited on the depressed portions formed on
both the side surfaces of the base metal overlap each other on an outer peripheral
envelope and the outer periphery of the base metal is actually positioned completely
inside the envelope of the abrasive grains. Even if the abrasive grains on the outermost
periphery wear out or drop, the edge portion of the base metal is brought into contact
with a material to be ground or chips, thereby being worn out, whereby the abrasive
grains are exposed one after another in the radial direction or the like of the disc-shaped
base metal. This action is similar to the wearing mechanism of a metal-bonded diamond
grindstone.
[0010] Further, an electro-deposited thin-blade grindstone in accordance with the invention
may have the depressed portions that are open from near the edge portion of the disc-shaped
base metal to the edge portion and are formed alternately on both the side surfaces
of the base metal are formed by a chemical treatment such as an electrolytic machining,
an etching, or the like, and a number of abrasive grains protruded from the side surfaces
and edge portion of the base metal are fixedly electro-deposited on the depressed
portions by a nonelectrolytic plating, an electrolytic plating, or the like.
Embodiments of the invention will now be described, by way of example only, with reference
to the accompanying drawings, of which:
Fig. 1 is an enlarged cross-sectional view to show the state of use of an electro-deposited
thin-blade grindstone in the related art.
Fig. 2 is a plan view of the electro-deposited thin-blade grindstone in accordance
with the first embodiment of the invention.
Fig. 3 is a front view of the electro-deposited thin-blade grindstone in accordance
with the first embodiment of the invention.
Fig. 4 is an enlarged cross-sectional view to show the state of use of the electro-deposited
thin-blade grindstone in accordance with the first embodiment of the invention.
Fig. 5 is a plan view of an electro-deposited thin-blade grindstone in accordance
with the second embodiment of the invention.
Fig. 6 is a front view of the electro-deposited thin-blade grindstone in accordance
with the second embodiment of the invention.
Fig. 7 is an enlarged cross-sectional view taken on a line A-A in Fig. 5.
[0011] Modes for carrying out the invention will be hereinafter described with reference
to the drawings. Fig. 2 to Fig. 4 show an electro-deposited thin-blade grindstone
10 in accordance with the first embodiment of the invention. The electro-deposited
thin-blade grindstone 10 in accordance with the present embodiment is made of a base
metal 12 made of a disc-shaped metallic plate having a thickness of from about 0.05
mm to 0.5 mm, for example, 0.2 mm. The base metal 12 has depressed portions 14 which
are formed at predetermined pitches in the vicinity of its edge portion and are open
to its edge portion 12a of the base metal 12 and are formed in a concentric manner
alternately on both side surfaces of the base metal 12. The depressed portions 14
are formed in a depth of 1/2 or more of the thickness of the base metal 12. A shaft
hole 18 for clamping is concentrically formed at the center of the base metal 12.
The base metal 12 is made of a tough and hard metal and thus can be reduced in thickness.
Further, the peripheral portions of the depressed portions 14 of the base metal 12
may be made of a comparatively soft material or a brittle material as compared with
a material to be ground so that they are easy to wear out.
[0012] A number of abrasive grains 16 that protrude by a predetermined amount from the side
surfaces and edge portion 12a of the base metal 12 are fixedly electro-deposited on
the depressed portions 14. The abrasive grains 16 are hard super-abrasive grains made
of diamond, CBN or the like. The abrasive grain size is preferably, for example, from
about 50 µm to 300 µm, and more preferably, nearly equal to the thickness of the base
metal 12, depending on the thickness of the base metal 12. It is recommended that
the amount of protrusion of the abrasive grains 16 from the both side surfaces of
the base metal 12 be, for example, about from 5 % to 20 % of the grain size of the
abrasive grain 16. It is recommended that the amount of protrusion of the abrasive
grains 16 from the edge portion 12a of the base metal 12 be appropriately set, for
example, at a value ranging from about 0 %, ie no protrusion initially, to 50 % of
the grain size of the abrasive grain 16. Here, the amount of protrusion of the abrasive
grains 16 from the edge portion 12a is autonomously formed during cutting, that is,
the metal portion of the base metal 12 is worn out more quickly to protrude the abrasive
grains 16 from about 5% to 20 % of the grain size.
[0013] In a method for manufacturing an electro-deposited thin-blade grindstone 10 in accordance
with the present embodiment, depressed portions 14 that are open from near the edge
portion of a disc-shaped base to the edge portion and are formed in a concentric manner
alternately on both side surfaces of the base metal 12 are formed by an electrolytic
grinding. The depressed portions 14 are formed by facing electrodes each corresponding
to the shape of the depressed portion 14 to the both side surfaces near the edge portion
of the base metal 12. First, the electrodes that are formed in the circumferential
direction of the base metal 12 in the same shape as the depressed portion 14 and are
symmetric to each other are faced to the edge portion of the base metal 12. Then,
the opposed electrodes are turned by a half pitch of the depressed portion 14, thereby
being arranged in a staggered manner to form the depressed portions at the same time
on both the sides of the base metal 12. Here, the depressed portions 14 may be formed
by a chemical treatment such as an etching or the like.
[0014] Next, a number of abrasive grains 16 are fixedly electro-deposited on the depressed
portions such that they are protruded by a small amount from the side surfaces and
edge portion 12a of the base metal 12. The abrasive grains 16 are electro-deposited
by giving a usual chemical plating and then by giving an electrolytic plating thereon.
A heat treatment after the electrodeposition leads to the distortion of the base metal
12 and hence it is preferable to avoid the heat treatment.
[0015] After the electrodeposition, the abrasive grains 16 are dressed up to make the grain
size even with each other. The dressing of the abrasive grains 16 is to remove portions
protruding 30 % or more than a desired value from the surface of the base metal 12.
A method for dressing the abrasive grains 16 is to polish the abrasive grains 16 protruding
from the depressed portions 14 by means of a diamond grindstone.
[0016] In the electro-deposited thin-blade grindstone 10 in accordance with the present
embodiment, as shown in Fig. 4, letting the thickness of the base metal 12 be t, the
diameter of the super abrasive grain 2 or the thickness of a plated layer be d, the
depth of the depressed portion 14 be a, the grinding width w of cutting or grooving
is expressed as W = t + 2(d-a). Therefore, the cutting width w can be reduced by 2
times the depth of the depressed portion 14 as compared with the conventional technology.
Further, in the electro-deposited thin-blade grindstone 10 in accordance with the
present embodiment, even if the abrasive grains 16 wear out and drop as the grinding
proceeds, the edge portion 12a of the base metal 12 wears out in the radial direction
of the base metal 12 and hence the abrasive grains 16 inside in the radial direction
of the base metal 12 are exposed and can grind a material 8 to be ground until the
width in the radial direction of the base metal 12 in the depressed portion 14 becomes
zero. This makes it possible to extremely elongate the tool life of the electro-deposited
thin-blade grindstone 10 and thus to continuously cut the material 8 for a long time
without replacing the tool of the electro-deposited thin-blade grindstone 10 even
if the material 8 is hard to cut. Further, since the edge portion 12a of the base
metal 12 is worn out by the material 8 to be ground as the grinding proceeds, it does
not affect a cutting or grinding work. Still further, by making the base metal 12
around the depressed portions 14 of a material softer or more brittle than the material
8 to be ground, the reproducing of the abrasive grains 16 can be speeded up.
[0017] As an example of this electro-deposited thin-blade grindstone 10 was formed a grindstone
of the type in which the diameter of a base metal 12 was 80 mm, the diameter of a
shaft hole 18 was 20 mm, the thickness of the base metal 12 was 0.3 mm, the depth
of the depression was 0.24 mm, the grain size of a diamond abrasive grain was 0.3
mm, the number of divisions on both sides of the base metal 12 (the number of depressed
portions 14) was 36, and the width in the radial direction of the depressed portion
14 was 3 mm. Thereby, the cutting width w was made 0.42 mm and the cutting tool life
of the grindstone 16 was made 100 times or more as compared with the conventional
thin-blade grindstone.
[0018] Next, an electro-deposited thin-blade grindstone 20 in accordance with the second
embodiment of the invention will be described with reference to Fig. 5 to Fig. 7.
Here, the same members as in the above-mentioned embodiment will be denoted by the
same reference characters and the description thereof will be omitted. The electro-deposited
thin-blade grindstone 20 in accordance with the second embodiment has cutouts 22 where
the edge portion 12a is cut away in the radial direction between the neighboring depressed
portions 14 along the edge portion 12a of the base metal 12. The cutouts 22 may be
cut away to an appropriate depth, and they can be cut away, at the maximum depth,
to the width of the depressed portion 14 in the radial direction of the base metal
12, and may be cut to such an extent that part of the abrasive grains 16 are exposed
from the depressed portions 14.
[0019] By these cutouts 22 are exposed the end portions in the grinding direction of the
abrasive grains 16 on the depressed portions 14, whereby the cutting or grinding can
be more effectively performed.
[0020] Incidentally, the electro-deposited thin-blade grindstone in accordance with the
invention is not limited to the embodiments described above, but may be formed in
such a manner that the same depressed portions as described above are formed along
the blade-forming edge portion of a band saw made by forming a slim rectangular steel
plate in the shape of a loop and that abrasive grains are electro-deposited on the
depressed portions. Also by this electro-deposited thin-blade grindstone, it is possible
to produce the same effect as described above and to cut a larger material. Further,
the material and size of the abrasive grain can be appropriately selected.
[0021] Still further, the abrasive grains may be deposited on the depressed portions even
in only a single layer of a single abrasive grain, or it is recommended that abrasive
grains made of sintered bodies of polycrystals or the other grinding particles be
formed in a desired diameter and be deposited on the depressed portions. Still further,
the material of the abrasive grain may be formed even of a hard metal and can be appropriately
selected in accordance with the material to be ground.
[0022] The electro-deposited thin-blade grindstone in accordance with the invention can
reduce the grinding allowance of the material to be ground and greatly expand a tool
life and improve a work efficiency, and further, is easily manufactured and can be
machined with accuracy.
1. An electro-deposited thin-blade grindstone,
characterized by including:
a plate-shaped base metal (12);
depressed portions (14) that are open from near the edge portion of the base metal
(12) to edge portion and are formed alternately on both side surfaces of the base
metal (12); and
a number of abrasive grains (16) deposited on the depressed portions(14) which protrude
from the side surfaces of the base metal (12).
2. An electro-deposited thin-blade grindstone according to claim 1, wherein the depressed
portion (14) is formed in a depth of 1/2 or more of the thickness of the base metal
(12).
3. An electro-deposited thin-blade grindstone according to claim 1 or 2, wherein the
abrasive grain (16) has a grain size nearly equal to the thickness of the base metal
(12).
4. An electro-deposited thin-blade grindstone according to any preceding claim, wherein
a cutout (22) in which the edge portion (12a) of the disc-shaped base metal (12) is
cut away by a predetermined amount in its radial direction is formed between the respective
depressed portions (14) adjacent to each other along the edge portion (12a) of the
base metal (12) and wherein the edge portions (12a) of the abrasive grains on the
depressed portion (14) are exposed to the cutout (22).
5. An electro-deposited thin-blade grindstone as claimed in any preceding claim, in which
a number of the abrasive grains (16) deposited on the depressed portions (14) protrude
from the edge portion of the base metal (16).
6. An electro-deposited thin-blade grindstone according to any preceding claim, wherein
the depressed portions (14) that are open from near the edge portion (12a) of the
disc-shaped base metal (12) to the edge portion (12a) and are formed alternately on
both the side surfaces of the base metal (12) are formed by a chemical treatment and
wherein a number of abrasive grains (16) protruded from the side surfaces or edge
portion (12a) of the base metal (12) are fixedly electro-deposited on the depressed
portions (14).
7. A method of making a grindstone as claimed in any one of claims 1 to 5, in which the
depressed portions (14) that are open from near the edge portion (12a) of the disc-shaped
base metal (12) to the edge portion (12a) and are formed alternately on both the side
surfaces of the base metal (12) are formed by a chemical treatment and wherein a number
of abrasive grains (16) protruded from the side surfaces and edge portion (12a) of
the base metal (12) are fixedly electro-deposited on the depressed portions (14).