Stone working – Turning – Grinding-wheel dressing
Reexamination Certificate
1999-07-09
2001-01-30
Scherbel, David A. (Department: 3723)
Stone working
Turning
Grinding-wheel dressing
C125S016020, C125S012000, C451S104000, C083S764000
Reexamination Certificate
active
06178962
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a saw wire assembly, a cutting method utilizing the same, and a system therefor, and particularly to a saw wire assembly for slicing or cutting a material to be worked in a lump with the use of abrasive grain-bonded saw wires, a cutting method utilizing a saw wire assembly containing such abrasive grain-bonded saw wires, and a system therefor.
BACKGROUND OF THE INVENTION
There are two types of wire saws used generally and two kinds of manners for cutting a material with the use of such wire saws utilized generally at present.
One of the manners is that a saw wire prepared by bonding or fixing continuously or intermittently abrasive grains or cutting blades onto the surface of a wire element is employed. It is mostly in the form of a loop wherein the opposite ends of a saw wire are joined together. A manner for cutting a material to be worked is such that a looped saw wire is allowed to travel and slide simultaneously with respect to the material to be worked, thereby cutting the same.
However, since an abrasive grain-or cutting blade-fixed wire saw in the above described cutting manner is used for cutting a material to be worked in accordance with a single wire traveling, the material cannot be cutoff simultaneously into a number of pieces, so that its cutting efficiency is poor.
In this respect, a free abrasive grain manner wherein an ingot
43
is cut off by allowing a wire element
41
to slidingly travel (for example, reciprocating traveling or unidirectional traveling) with respect to the ingot
43
as shown in
FIGS. 1A and 1B
while pouring a processing slurry
44
prepared by kneading abrasive grains with a processing aid into the sliding position is particularly utilized in recent years for cutting off wafers from ingots (materials to be worked) of silicon, a compound semiconductor or the like. Such free abrasive grain manner is also called a multiple wire saw manner, because the operation is carried out in such that a wire element
41
is wound around a plurality of guide rollers
42
a,
42
b,
and
42
c
with a number of turns, whereby a number of pieces of wafers are sliced from a material in a lump.
In order to elevate slicing performance in a multiple wire saw manner, an inexpensive abrasive grain-bonded saw wire
51
a
which is prepared by bonding abrasive grains
55
on the surface of a wire element
52
a
through a binder
54
, the cross section of which being shown in
FIG. 2A
, and another abrasive grain-bonded saw wire
51
b
which is prepared by bonding abrasive grains
55
on the surface of a covering layer
53
provided on the surface of a wire element
52
b
through a binder
54
, the cross section of which being shown in
FIG. 2B
have been proposed, respectively. (For example, see Japanese Patent Application Nos. 311187/1996 and 328004/1996)
For the sake of using efficiently the abrasive grain-bonded saw wire
51
a
or
51
b,
it is required to afford a tension to the abrasive grain-bonded saw wire
51
a
or
51
b,
whereby a contact force (contact pressure) with respect to a material to be worked is elevated in their sliding portion.
However, in the multiple wire saw manner as shown in
FIGS. 1A and 1B
, although a tension is given to the wire element
41
wound around each of the guide rolls at the opposite ends of the wire element, such tension given to the wire element
41
is not applied merely up to several turns from both of a starting portion of the winding and an ending portion of the winding with respect to each of the guide rollers
42
, since the number of windings of the wire element with respect to each of the guide rollers
42
is as much as 50 to 200 times.
For this reason, a major part of the wire element
41
wound around each of the guide rollers
42
(intermediate windings) constitutes a so-called passive state region with respect to a wire tension, so that the wire tension is in an extremely low state. Accordingly, when the abrasive grain-bonded saw wire
51
a
or
51
b
shown in
FIG. 2A
or
2
B is applied to a multiple saw wire manner, there has been such a problem that a sufficient cutting ability cannot be achieved by the abrasive grain-bonded saw wire
51
a
or
51
b.
In the above case, although it may be also considered that a number of abrasive grain-bonded saw wires are allowed to travel in parallel to each other, so that a constant tension is afforded to each abrasive grain-bonded saw wire in a cutting section, there is a fear of coming the entire system to be very massive, besides workability for setting up the cutting system becomes worse, because each means and function are required in every single abrasive grain-bonded saw wires for delivering the same, affording tension to the same, traveling the same, and winding the same, and further since the number of saw wires are remarkable (50 to 200). On one hand, even if respective abrasive grain-bonded saw wires are collected at positions before and after stages of a cutting section, and further the respective means and functions for affording tension, traveling and winding the saw wires are processed simultaneously in a lump, delivering means are required with the number corresponding to those of the saw wires by all means.
It is to be noted, however, that the above described passive state region with respect to wire tension seems to contribute to improvements in cutting efficiency, because abrasive grains come to easily get into a gap defined between a traveling wire element and a material to be worked in a free abrasive grain manner (multiple wire saw) which is generally employed at present.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention contemplates to solve the problems as described above and to provide a saw wire assembly by which it is possible to easily handle a number of abrasive grain-bonded saw wires in case of cutting a material to be worked with use of such a large number of abrasive grain-bonded saw wires.
A further object of the present invention is to provide a cutting method by utilizing the saw wire assembly having a high cutting efficiency and a simple structure in case of cutting a material to be worked with use of a number of abrasive grain-bonded saw wires, and further to provide a system for applying such cutting method.
According to the first feature of the invention, a saw wire assembly, comprises:
a number of abrasive grain-bonded saw wires being arranged on a long tape base material along the longitudinal direction thereof in such a way that they are disposed side by side in the direction perpendicular to the longitudinal direction; and
these abrasive grain-bonded saw wires being bonded tentatively onto the tape base material through an adhesive in a releasable manner.
In the above described constitution, since a number of abrasive grain-bonded saw wires are bonded tentatively onto the tape base material in a releasable manner, it becomes easy to handle each of the abrasive grain-bonded saw wires, and it is also easy to release the tape base material from the saw wire assembly prior to cutting a material to be worked.
According to the second feature of the invention, a cutting method by the use of an abrasive grain-bonded saw wire assembly, comprises the steps of:
preparing the abrasive grain-bonded saw wire assembly in accordance with such a manner that a number of abrasive grain-bonded saw wires are arranged on a long tape base material along the longitudinal direction thereof in such a way that they are disposed side by side in the direction perpendicular to the longitudinal direction, and these abrasive grain-bonded saw wires are bonded tentatively onto the tape base material through an adhesive in a releasable manner; and
cutting a material to be worked by the use of the abrasive grain-bonded saw wires contained in the saw wire assembly in accordance with such a manner that the tape base material is released from the saw wire assembly before it reaches the material to be worked, and thereafter each of the abrasive grain-bonded saw wires is allowed to reciproc
Matsuzawa Misao
Ohashi Seishiro
Hitachi Cable Ltd.
Nguyen George
Scherbel David A.
Scully Scott Murphy & Presser
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