Abrading – Abrading process – With tool treating or forming
Reexamination Certificate
2002-04-23
2004-09-21
Nguyen, Dung Van (Department: 3723)
Abrading
Abrading process
With tool treating or forming
C451S005000
Reexamination Certificate
active
06793562
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of and apparatus for non-contact conditioning of tools, for truing, dressing or cleaning tools such as a grinder or a cutting tool, by using a laser. More particularly, this invention relates to a grinder used for side machining of a scroll (spiral vane) built in an air-conditioning scroll compressor, or for finish machining of a mold.
BACKGROUND OF THE INVENTION
One of the tools used for side machining of a scroll built in a scroll compressor is an end mill.
FIG. 25
shows an end mill
100
used for side machining of the scroll (spiral vane). In
FIG. 25
,
102
denotes a cutting edge,
103
denotes a groove between the cutting edges
102
,
104
denotes a core diameter,
105
denotes a shank serving as a portion which holds the end mill
100
with a jig or the like, and
106
denotes an angle of torsion of the cutting edge.
FIG. 26
shows a scroll
107
, being a workpiece to be machined, and the scroll
107
has a scroll tooth
108
.
When side machining of the scroll tooth
108
of the scroll
107
is to be carried out by the end mill
100
, the shank
105
of the end mill
100
is fitted to a rotation unit such as a motor, to rotate the end mill
100
by the rotation unit. At this time, the scroll
107
or the end mill
100
is shifted so as to follow the scroll shape, while the cutting edge
102
of the end mill
100
is brought into contact with the side face of the scroll tooth
108
, thereby side machining of the scroll tooth
108
is carried out.
In the side machining by the end mill
100
, however, the position where the cutting edge
102
contacts with the machined surface of the scroll tooth
108
changes due to the torsion of the cutting edge
102
. Particularly, as the angle of torsion
106
decreases, the change of the contact position of the cutting edge
102
increases. As described above, in the side machining by the end mill
100
, since the distance between the position where the shank
105
is fitted and the position where the cutting edge is brought into contact with the scroll tooth changes largely, the machining load varies largely, causing a problem in that high machining accuracy cannot be ensured. With a small-diameter end mill
100
having a large groove
103
and a small core diameter
104
, the rigidity becomes low, and the end mill
100
bends, causing a problem in that the machining accuracy decreases.
Therefore, for this kind of machining, a grinder is often used. An ordinary grinder in which a binder is formed of vitrified or resin, is formed by mixing and stirring abrasive grains and the binder powder, followed by molding into a desired shape, and sintering the molded article. Therefore, minute holes exist therein, and hence the chips discharging property is not so bad. On the other hand, an electrodeposited grinder is produced by holding the abrasive grains by plating, and hence minute holes existing in the ordinary grinder do not exist, thereby deteriorating the chips discharging property.
FIG. 27
shows a columnar electrodeposited grinder
109
used for side machining of the scroll. In
FIG. 27
,
110
denotes a columnar base metal,
111
denotes a plating layer formed of nickel or chromium on the side face of the base metal
110
, and
112
denotes abrasive grains of CBN or diamond arranged in one layer on the surface of the plating layer
111
, and the abrasive grains
112
are put together at random and fixed on the plating layer
111
.
When side machining of the scroll tooth
108
of the scroll
107
is to be carried out, using such an electrodeposited grinder
109
, a portion of the grinder base metal
110
of the electrodeposited grinder
109
where the abrasive grains
112
are not electrodeposited is fitted to a rotation unit such as a motor, and the electrodeposited grinder
109
is rotated by the rotation unit. At this time, the electrodeposited grinder
109
or the scroll
107
is shifted so as to follow the scroll shape, while the abrasive grains
112
, being the cutting edge, are brought into contact with the side face of the scroll tooth
108
, thereby side machining of the scroll tooth
108
is carried out.
In the above electrodeposited grinder
109
in the conventional art, since the abrasive grains
112
are put together at random and fixed on the whole surface of the grinder, lots of abrasive grains as the cutting edge work on the machined surface, regardless of the existence of truing, thereby causing a problem in that the machining load is large. Particularly, since a small-diameter grinder has small shaft rigidity, it easily deforms, and has a problem in that the grinder bends to decrease the machining accuracy, or the grinder life is shortened, due to an increase of the machining load.
As described above, in the conventional electrodeposited grinder, since the abrasive grains are put together at random on the whole surface of the grinder, lots of abrasive grains as the cutting edge work on the machined surface, to increase the machining load, thereby it is difficult to obtain high machining accuracy. The conventional electrodeposited grinder has also poor chips discharging property.
In JISB4130 and JISB4131 in the JIS Standard, there is an indication relating to the grain size of abrasive grains of the CBN or diamond electrodeposited grinder, and the shape of the grinder. This indication, however, relates to the grain size of the abrasive grains
112
and the shape of the grinder base metal
110
, and does not indicate the arrangement of the abrasive grains
112
on the surface of the grinder base metal
110
.
Techniques relating to the truing method and the dressing method of the grinder are shown in JISB4134, JISB4135, JISB4136 or JISB4137 in the JIS Standard. These are for installing tools for truing or dressing so as to come in contact with the grinder to carry out truing and dressing.
These conventional art shown in the JIS Standard is a method for bringing the tool into contact with the grinder, and hence machining resistance is produced at the time of truing or dressing, causing unintended exhaustion of the cutting edge, dropout of abrasive grains or exhaustion of the binder, and further there is a problem of short life span of the tool. Further, there is a disadvantage in that deformation or cracking may occur with respect to a grinder with a small-diameter shaft having low rigidity, a grinder with a thin blade, or a small-diameter end mill.
Therefore, there has been proposed a technique for performing non-contact truing or dressing, using a laser beam. The technique relating to the non-contact truing or dressing is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-285971 shown in FIG.
28
.
In this conventional art, at either a time of stopping or rotating a grinder
113
, a laser beam is irradiated from a laser oscillator
115
to a grinder use plane
114
a
or a grinder auxiliary use plane
114
b
through a lens
116
, to dissolve and evaporate a binder, to thereby adjust the amount of abrasive grains to be protruded and the outline of the abrasive grains. The grinder use plane
114
a
or the grinder auxiliary use plane
114
b
is observed by a portable confocal laser microscope
117
. A feedback mechanism
118
determines the optimum conditions of the maximum laser output and pulse width to obtain a desired amount to be protruded and the optimum conditions of the laser irradiation position to obtain a desired grinder outline, and feeds back the determined optimum conditions to the laser oscillator
115
.
In the conventional non-contact dressing and truing methods, it is disclosed that only the binder on the use plane of the grinder or on the auxiliary use plane of the grinder is dissolved and evaporated without damaging the abrasive grains, by using a laser beam having a wavelength other than the wavelength at which absorption of infrared rays and ultraviolet rays and selective absorption of impurities take place, to thereby control the amount of abrasive grains to be protruded and the grinder outline. However, control
Gunjima Munehisa
Nakasuji Tomoaki
Yokota Kouji
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