Gyrofinish kobyashi-87

1. P
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1981 69
@ ALL RIGHTS RESERVED
Society of Manufacturing Engineers l One SME Drive l P.O. BOX 930
Dearborn, Michigan 48128 l Phone (313) 271-l 500
MIWI-392
Theory Of Gyrofinishing
and Examples In Deburring
abstract
Cutting velocities and cutting angles are calculated in gyrofinishing, when
both tub and cylindrical workpieces rotate. The metal removal rates, as a
function of combination of cutting velocities and cutting angles, are obtained
by experiments. In summarizing these results, the cutting efficiency in
gyrofinishing is calculated. The results show that the higher the cutting
velocity is, the higher cutting efficiency can be obtained. The limitation in
cutting velocity is discussed, and the optimum working condition in gyro-
finishing is obtained. An example of recently built gyrofinishing unit, and the
workpieces deburred by these units are described.
authors
Masahisa Matsunaga
Professor
Chiba Institute of Technology
Narashino-shi, Chiba-ken, Japan
Hisamine Kobayashi
President
Shikishima Tipton Mfg. Co., Ltd.
Minami-ku, Nagoya, Japan
conference
Deburring & Surface Conditioning ‘81
September 30-October 2, 1981
New Orleans, Louisiana
index terms
Barrel Finishing
Cutting
Cutting Speed
Deburring

2. INTRODUCTION
Gyrofinishing is defined by G. R. Squibb et al, as follows (I):
"a process which consists of submerging the workpieces to be finished
in a revolving mass of free abrasive material." This process was
originally developed by General Motors Co. in mass production scale.
In Japan, some experimental machines were made (2). However, these
machines have never been applied to industrial uses. Recently, the
gyrofinishing is used in many industries, because it is found that
the gyrofinishing is a very efficient method for deburring and the
surface conditioning, and is effective for increasing the wear resist-
ance of machine parts, and thus improving the machine life.
Determination of working conditions for gyrofinishing has been per-
formed empirically, and few fundamental researches have been develop-
ed. The authors reported practical applications (3)141f'5), and a part of
theories (6) on gyrofinishing. In this report, an approacn to the
theory and recently developed techniques on gyrofinishing will be
described.
CUTTING VELOCITY AND CUTTING ANGLE
In usual gyrofinishing, finishing is performed by abrasive grains
moved by revolution of the tub, and the workpieces are also rotated.
Therefore, relative velocity between an abrasive grain and a point on
the workpiece is a resultant of these two movements. This is called
"cutting velocity" in this report. Angle between the striking abrasive
grain and tangent of the workpiece on the striking point is also
influenced by the revolution of both tub and workpiece. This angle is
called "cutting angle" in this report.
It has been known that the cutting angle has much influence onCthe
metal removal rate. For instance, Taniguchi et al made experiments on
metal removal rate in liquid honing, and found that the cutting angle
which gave the maximum removal rate was different with metals and
brittle materials (8).
The cutting velocity and the cutting angle are calculated in gyro-
finishing, when the tub and workpieces revolve around their station-
ary axes. In Fig. 1, 0 and 0' are the centers of the revolving axes
of the tub and workpiece, respectively, taking 00' as X-axis, and
vertical axis to X-axis at 0 as Y-axis, as shown in the figure.
The cutting velocity on a point A on the workpiece is calculated by
equation (1).
V= 2n[( N - n )" q2, + N2q2 e 2NQq( N - n) cos 0]1/2 (1)
or
v= 27~N [(l- ; )2 q2 + 42 + 2Qq ( I- f) cos 8 ]1/2 (2)
where,
N and n are the number of revolution of the tub and the workpiece,
respectively, taking the clockwise direction as positive,
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3. -2-
Fig. 1 Diagram for calculating the cutting velocity
and the cutting angle
Q is distance between the revolving axes of the tub and workpiece.
q is distance between the rotating axis of the workpiece and a point
oti this.
8 is an angle between O'X and O'A, as shown in Fig. 1.
An example of velocity diagram,
respectively,
when Q and q are 0.25 m and 0.075 m,
different n/N,
and the revolution of the tub is 50 rpm, for example, at
is shown in Fig. 2.
Cutting angle is calculated by equation (2).
n
q (1- Q-1 sin 0
@) = 18 - Tan-l n (2)
Q+s(l- 7 ) cos 8
Cutting angle diagram is shown in Fig. 3, at different n/N, and when
Q and q are 0.25m and O.O75m, respectively.
EXPERIMENTAL PROCEDURE
Experiments were performed on a test machine. A schematic drawing of
the structure is shown in Fig. 4, and main specifications are as
follows:
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4. -3-
250hevolution of the tub: 50 rpm
-5
0 Fig. 2
-4-1 Cutting velocity
diagram for each
-3
position on the
-2
workpiece, when the
revolution of the
0 30 60 90 120 150 180 tub is 50 rpm, and
the parameter is
Position of workpiece, 8 degree n/N.
n
N
6
2
-6
1
(1) Tub
Diameter: 0.7 m
Diameter of the center pole: 250 mm
Depth of the tub: 0.17 m
Inner volume: 80 liter
Number of revolution: 32 - 143 rpm
Peripheral velocity: 50 - 225 m/set
(2) Workpiece shaft
Number of revolution: 0 - 120 rpm
In order to examine the effects of the cutting velocity and cutting
angle on the metal removal rate of the workpiece, specimen holder as
shown in Fig. 5 was installed, and 10 )( 9.5 mm specimens were fixed at
the periphery of the holder. These were immersed and rotated in the
revolving abrasive grains, and weight of the removed metal was measured
by a balance. The material of the specimens was brass.
MRSl-392

5. 180
150
0 30 60 90 120 150 180
Position of the workpiece, 8 degree
Fig. 3 Cutting angle on each position of the workpiece, as
a function of n/N.
METAL REMOVAL RATE
Metal removal rate of each specimen on the fixture is shown in Fig. 6.
The circular cordinate corresponds to the position of the specimens,
and length from the periphery towards the center of the circle corres-
ponds to the metal removal.
It is found that the maximum metal removal occurs at the specimen
position of 20° in Fig. 5. The cutting angle is calculted as 14.42'
from the equation (2). This position corresponds to the outer side of
the tub. There is a position, which has the same cutting angle in the
inner side of the tub, but the metal removal is much smaller than that
of the outer side. This discrepancy may be explained by the flowing
pattern of the abrasive. When the cutting angle is small, that is,
tangential to the surface, and the cutting angle near 90°, that is,
vertical to the surface of the specimens, the removal decreases,
When the metal removal is put
u - L”
(3)
m can be obtained from the experiments,
Fig. 7 in each cutting angle.
and the results are shown in
A master curve of the metal removal is
obtained at different cutting angle,
city, as shown in Fig. 8.
in considering the cutting velo-
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6. -5-
Fig. ,4 A schematic drawing
of the test machine.
Tub
Workpiece
Motor for workpiece
Handle for liftinq (3-I
the workpiece -
-
Driving sprocket for
I WI
the tub
C1
These experiments were performed when the fixture was stationary. The
metal removal with rotating fixture were anticipated from a calculation
based on the stationary values, in considering the cutting angle and
n-values. That means, the cutting angle and cutting velocity on each
position of the specimens can be calculated, when the fixture rotates.
Then, the metal removal rate per unit time at each of the specimens can
be calculated, and the total removal rate is summation of these values.
The results are shown in Fig. 9, and the experimental data are plotted
in Figs. 10 (A) to (cl. The coincidence between the experimental and
estimated values is not always good. It is also noted that the removal
rate at n/N = 0 is always larger than that at n/N = -1, although the
estimated value are smaller. The discrepancy will beoriginated from the
flow characteristics of the mass. Further works are necessary for this
subject.
Another problem is the velocity limit on the metal removal. In this
estimation,, the higher the velocity is, the more the metai removal
would be obtained. However, there will be a limitation on the highest
velocity.
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7. -6-
180
Fig. 5
Specimens and a fixture for
these in the case of an
experiment on metal removal
rate, at different cutting
velocity and cutting angle.
a Fig. 6 Metal removal rate at
DIRECTION OF different positions of the
FLOW stationary fixture.
100" 80°
260° 280"
LIMITATION OF TSE CUTTING VELOCITY
The first limitation of the relative velocity between abrasive and work-
piece is determined to be 100 m/min by the authors. The reasons are:
(1) Jamping of abrasives. Abrasive of higher velocity jump up, when
they hit the workpiece. (2) Climbing up of abrasive along the tub wall.
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8. -7-
2.0-0 0
E 0
i Fig. 7
Value of exponent n
al 0
1.0 at each2 - 0
in equation (3),0 0 0 position of the specimens.
2 0
w 0
OJ
0 60 120 180
Position of the specimen, 8 degree
Numberof revolutionNumberof revolution
30 rpm30 rpm 00
0 60 120 180 240 300 360
Cutting angle @
Fig. 8
A master curve of
metal removal, as
a function of the
.cutting angle,
obtained -from the
experiments.
When the revolution of the tub is rapid,
up the abrasive along the tub wall,
the centrifugal force swifts
for returning the abrasive into the
and other apparatus is necessary
tub.
of the cutting efficiency.
(3) Lowering the increase rate
The effect of cutting velocity on metal
removal rate is expressed by Q = cvm , as shown in the equation (3),
and m decreases as the velocity increases. For instance, m was deter-
mined to be 0.73 between 90 and 224 m/min by other experiment. That
means prominent gain is not always obtained by increasing the cutting
velocity. (5) Rigidity of the machine.
of course,
Higher rigidity must be needed,
in order to drive the machine at higher velocity. (6) Surface
roughness.
abrasive,
Surface roughness is not improved, at higher velocity of
defects.
and impact force produces indentation and the other surface
(7) Danger.
m/min.
The driving condition is very suitabLe at under 100
Handling is more dangerous, as the velocity increases.
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9. -a-
4
‘
b
h
‘
Number Of
revolution of
the tub
* 30 rpm
--+(- 40 rpm
--&- 50 rpm
Fig. 9
Estimated weight of metal
removal as affected by n/N.
I I I I I 1 ’ ’ ’ ’ ’ ’ ’
-6 -4 -2 0 2 4 6
Revolution ratio, n/N
IMPOVEMENTS ON GYROFINISHING MACHINES
One of the reasons why the gyrofinishing machines are widely used is
that the improvements have been performed on the machine and their sys-
tems. These improvements are as follows:
(1) Stream adjusting apparatus. The apparatus is very effective for
preventing the eneven accumulation and the sticking of abrasive on the
inner wall of the tub, during working. This is also effective to pre-
serve the abrasive and water in proper mixed condition, so that the most
effective finishing is continuously performed.
(2) Development of minute cutting abrasive. Sintered aluminum oxide
abrasive, which is effective for both producing good surface and high
metal removal rate, have been developed (91 .
(3) Establishment of the working conditions, including the design of
the fixtures. AS the results of many experiments, the working conditions
have been established.
(4) Automation and no-man system. Increase of the labor cost has ad-
vanced the automation and no-man system. The gyrofinishing machines are
fully automated, and no-man system is completed. All working sequences,
for instance, conveying apparatus of workpieces, charging these to the
gyrofinishing machine by robot hands, finishing these in the machine,
and returning to the conveying apparatus, are fully automated.
maI--392
i

10. -9-
*
Number of revolution
of the tub:
30 rpm
Estimated -+-
Experimental -O-
(Al
0 ’
I I I I I I I I I
-4 -2 0 2 4
Revolution ratio, n/N
Number of revoltion
of the tub:
50 rpm
t
Estimated -*-
Experimental -d-
(Cl
t ‘ -A
0' I I I I 1
-2 0 2
Revolution ratio, n/N
Number of
revolution of
tha tub:
40 rpm
150 -
i?
Estimated --%-
r;
Experimental +
z
;
k"
100 -
l-l
s
2
s-l
0 50 -
2
-?
:
01
-2 0 2
Revolution ratio, n/N
.
Fig. 10
Estimated and experimental metal
removal in gyrofinishing, at
various number of revolution of
the tub.
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11. -lO-
(5) Continuous feeding system for finished workpieces. In the past, all
barrel finishing methods could finish workpieces by a "batch system",
that means, many workpieces were completed their finishing, simultane-
ously . However, in modern mass production system, the batch system is
not recommended. One of the reasons of this is space and cost of stock-
ing half-finished workpieces.
A system, which completes the finishing of workpieces every definite
and short intervals, is called, here,"continuous system". One of the
designs that makes the gyrofinishing to be a "continuous system" is that
the turret is continuously rotated or rotated for 3600/n at a definite
interval, which is the same as that of completion of finishing the
workpieces.
(6) Non-stop working system. In the former times, all workpiece shafts
must be lifted up, when the workpieces were exchanged, at the comple-
tion of finishing. Therefore, the finishing must be interrupted during
the exchange periods. In the present system, only one workpiece shaft
is lifted at the front opening of the machine, at the exchange of the
workpieces. In this case, the other workpieces are being finished in
the abrasive.
Not only one shaft is lifted, but another one or more shafts can be
lifted, for instance, just before the exchange and at the completion of
finishing to be washed, or before charging into the abrasive, to remove
grease etc.
AN EXAMPLE OF MACHINE AND ITS SPECIFICATIONS
Many types of gyrofinishing machines are working now. Examples have been
published in the previous reports 13) (41, and especially fully automatic
gyrofinishing units combined with deburring heads are effectively used
15)(6)(7). Another example is shown in Fig. 11, and its specifications
are shown in Table 1.
Examples of workpieces finished by these units are shown in Fig. 12.
Shafts with cams and/or gears were preferably finished by gyrofinish-
ing machines having multi-tub and multi-'spindle, but these are now
finished by these units
CONCLUSIONS
Gyrofinishing has been found to be powerful method, not only in deburr-
ing, but in surface conditioning. By applying the method, whole appli-
ance has advantages, for instance, less noise and high durability.
Many kinds of gyrofinishing machines have been built and applied to
industrial uses. Many kinds of workpieces have been successfully gyro-
finished. Finally, a combination machine with gyrofinishing and deburr-
ing heads have been built, which can deburr even large and thick burrs,
and can finish surface, including washing and rust prevention, auto-
matically.
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12. -ll-
Brushing heads Gyrofinishing Washing and rust stock
Machine prevention
Fig. I.1 Photograph and schematic drawing of a combined
machine with gyrofinishing, brushing, washing
and rust prevention.
Table 1 Specification of the gyrofinishing unit shown in Fig. 11.
(1) 'rub (3) Finishing time 48 set
Diameter 1.6 m (4) Finishing interval
Capacity 400 liter 8 set
Perpheral
velocity 90 through
117 m/min
(2) Workpiece shafts
No. of shafts 8
No. of rotation 10 rpm
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13. -12-
.:... _
Fig. 12 Examples of workpieces finished by gyrofinishing units.
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14. -13-
REFERENCES
(1; G.
(2) M.
(3) H.
(4) H.
(5) H.
(6) M.
(7) H.
(8) N.
(9) M.
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(1956)
Matsunaga, Barrel Finishing in Japan, CIRI? Annal., 11, 4, 221
(1964)
Kobayashi and M. Matsunaga, Automation in Barrel Finishing and
Deburring by Barrels, in "Automation in Buffing and Barrel
Finishing", SME Tech. Pap. MR75-481 (1975)
Kobayashi, F. Kobayashi, Jr. and M. Matsunaga, Deburring and
Finishing by Recipro-Finishing and Gyro-Finishing Machines,
SME Tech. Pap., MR77-464 (1977)
Kobayashi and M. Matsunaga, Deburring and Surface Finishing by
a Gyrofinishing Unit combined with Polishing Heads, SME Tech.
Pap. MR79-728 (1979)
Matsunaga and H. Kobayashi, Recent Developments on Deburring and
Surface Finishing by Fully Automatic Gyrofinishing Machines,
Proc. 4th Intl. Conf. Production Engg. Tokyo, 620 (1980).
Japan Sot. Precision Engg.
Kobayashi and M. Matsunaga, Recent Developments on Barrel
Finishing, Proc. INTERFINISH 80, 412 (1980). Metal Finishing
sot. Japan.
Taniguchi et al, Machining of Hard and Brittle Materials by the
Liquid Honing Method,Tech. Report of Faculty of Engg., Yama-
nashi Univ., No. 6, 51 (1955), in Japanese.
Matsunaga, Micro-Crystalline Abrasive Media for Mass Finishing,
Metal Finishing, 69, 5, 97 (1971)
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