Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-01-15
2001-09-11
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C029S740000
Reexamination Certificate
active
06289256
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for mounting, for instance, electronic parts onto circuit boards, and a part-mounting apparatus executing the method.
High accuracy and high productivity have been demanded in recent part-mounting apparatuses for mounting, age e.g., electronic parts onto circuit boards. For instance, a part-mounting apparatus of a multi-functional type has increased its market share, wherein a part transfer device (referred to as a head member hereinafter) taking out each electronic part from a part feed section and mounting it to a circuit board is moved by an XY robot which is freely movable in X, Y directions. In this type of the apparatus, parts can be supplied from the part feed section with a high degree of freedom in a feed state, a variety of parts can be handled and high accuracy of the mounting is secured because of a simple constitution, and accordingly furthermore development has been attempted with an aim for much higher speed and accuracy. In the meantime, besides the speed-up of mounting of parts by the adoption of a linear motor to the XY robot, a pressure of a part-sucking nozzle of the head member impressed to the parts has been controlled in a nozzle-driving mechanism of some apparatuses, thereby to adjust a mount pressure. Although a mechanism using a mechanically driving clutch has been a mainstream conventionally to take out the electronic parts from the part feed section and correct a posture of each held part simultaneously, the mechanism practically has demerits, that is, a complicated structure and an increased weight with impressing a high stress to the held part, etc. As such, in accordance with the progress of the image recognition technique, an air pressure is primarily utilized today to suck, take out, recognize and correct a position of the parts.
Parts to be mounted to circuit boards have become greatly complicate in shape consequent to the miniaturization of products with the circuit boards incorporated therein. As a result, some of the parts have no face to be able to be sucked by the nozzle. For coping with this, there is a part-mounting apparatus which includes a chucking mechanism with two holding plates moving in opposite directions to each other orthogonally to a thickness direction of the circuit board, wherein the posture of the part held by the holding plates is corrected through the image recognition technique.
A method for mounting parts which is carried out in the above-described part-mounting apparatus of the conventional art will be described with reference to the. drawings.
FIG. 8
is an example of a chucking device
200
set in the conventional part-mounting apparatus. The chucking device
200
generally consists of a chucking mechanism part
201
and a driving part
210
for moving the chucking mechanism part
201
in a thickness direction I of a circuit board. The chucking mechanism part
201
has two holding plates
202
,
203
and an air pressure driving source
204
with, e.g., an air cylinder. The holding plates
202
,
203
are movable in opposite directions II to each other orthogonally to the thickness direction I, and opened/closed by the driving source
204
to hold electronic parts. The driving part
210
and chucking mechanism part
201
are coupled via a spring
205
which absorbs shocks between the part and the chucking mechanism part
201
when the part is held by the chucking device
200
and between the part held by the chucking mechanism part
201
and the circuit board when the part is mounted to the circuit board.
The chucking device
200
in the above constitution is mounted to an XY robot as described earlier.
The method of mounting in the part-mounting apparatus having the above chucking device
200
will be specifically described below.
The chucking device
200
is moved by the XY robot to above a hold position of in the part feed section. The holding plates
202
,
203
are opened by turning ON the air pressure driving source
204
. At this time, the chucking device
200
recognizes an initial height IV of the part feed section from a placing face
421
and a height III of a held part
422
in the chucking mechanism part
201
. The chucking mechanism part
201
is lowered by the driving part
210
a distance (IV-III) obtained by subtracting the height III from the initial height IV in a height direction of the part
422
. A change in amount of the downward movement of the chucking mechanism part
201
as a result of a distortion of the placing face
421
or an error in the height III of the part
422
is absorbed by the spring
205
. Thereafter, simultaneously with when the chucking mechanism part
201
is finished to move down or an operation delay time of the chucking mechanism part
201
earlier than the finish of the movement, the air pressure driving source
204
is turned OFF and the holding plates
202
,
203
are closed thereby to hold the part
422
. The driving part
210
raises the chucking mechanism part
201
concurrently when the part
422
is completely held. Taking out of the part
422
from the part feed section is completed in this manner. The chucking device
200
is then moved by the XY robot to a mount position on the circuit board, and the part
422
is mounted to the circuit board.
According to the conventional mount method as above, in the event that the initial height IV from the part placing face
421
in the chucking mechanism part
201
includes an error, for example, if the height IV in
FIG. 9
is larger than a predetermined value, the chucking mechanism part
201
cannot hold the part
422
at a normal position, but holds the part
422
only at end portions of the holding plates
202
,
203
at the side of the placing face
421
, which gives rise to a gap V. In an extreme case, the chucking mechanism part
201
after holding the part
422
may drop the part
422
in the middle of transferring the part to the circuit board, or shift a posture of the part
422
when moving the part for the correction after the image recognition. In addition, the chucking mechanism part
201
is descended a total distance of an original fall distance and the gap V when mounting the part to the circuit board, and consequently impresses unnecessary impacts between the circuit board and part
422
. On the other hand, if a fall position of the chucking mechanism part
201
to the part feed section is set to be closer to the part placing face
421
than an original position so as to avoid the unnecessary shocks when the part is mounted to the circuit board, the chucking mechanism part
201
in turn applies undesirable shocks to the part
422
when taking out the part
422
.
The placing face
421
sometimes is considerably a fragile tray. As shown in
FIG. 10
, when the chucking mechanism part
201
applies a force to the part
422
unexpectedly from above when taking out the part
422
, a part of the placing face
421
of a tray
423
is deformed, thereby bringing the part
422
into a greatly instable state. The part
422
in such instable state is highly possibly dropped or recognized wrong in any process of holding, image recognition, positional correction and mounting. Further, in such the fragile tray
423
, the force acting to the part
422
may influence other parts on the same tray
423
to change an alignment of the other parts, forcing the other parts outside the tray
423
in the worst case.
SUMMARY OF THE INVENTION
The present invention is devised to solve the aforementioned problems and thus an object of the present invention is to provide a method and an apparatus for mounting parts at high speed with limiting impacts to the parts to minimum.
In accomplishing this object, according to first aspect of the present invention, there is provided a method for mounting a part to a body to be mounted by moving a part holding member in a height direction of the part thereby to hold the part and then mounting the held part to the body to be mounted,
the method comprising:
moving the part holding member at a first speed to a part vicinal po
Kabeshita Akira
Mimura Yoshihiro
Takeda Takeshi
Yoshida Noriaki
Gain, Jr. Edward F.
Grant William
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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