Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
2001-12-20
2003-08-26
Lillis, Eileen D. (Department: 3652)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
C294S065000, C029S743000
Reexamination Certificate
active
06609741
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a parts suction head having a non-contact sealing structure, and in particular to an improved parts suction head having a non-contact sealing structure which can precisely control rotation of a rotation shaft in a surface mount device.
2. Description of the Background Art
In general, a surface mount device is used to rapidly precisely mount a plurality of parts on a printed circuit board. The surface mount device for rapidly precisely mounting parts on the printed circuit board includes an X-Y gantry, a printed circuit board conveyor, a parts feeder and a head unit. The head unit is installed in the X-Y gantry, for mounting the parts on the printed circuit board transferred to a parts mounting operation position by the printed circuit board conveyor. The head unit receives the parts from the parts feeder to be mounted on the printed circuit board.
The head unit adsorbing the parts supplied from the parts feeder includes a plurality of parts suction heads. Each of the respective parts suction heads includes a motor, a ball spline and a socket unit. The parts suction head composed of a motor, a ball spline unit and a rotation shaft unit will now be described in detail with reference to the accompanying drawings.
FIG. 1
is a side view illustrating a conventional parts suction head of a surface mount device. Referring to
FIG. 1
, the parts suction head includes a motor
10
, a ball spline unit
20
and a rotation shaft unit
30
. A rotation central axis
11
of the motor
10
is connected to one end portion of the ball spline unit
20
by a coupling
1
. The other end portion of the ball spline unit
20
is connected to the rotation shaft unit
30
. The ball spline unit
20
connected to the rotation shaft unit
30
includes a ball spline
21
and a ball spline nut
22
. The ball spline unit
20
performs a rotation movement due to a rotary force generated by the motor
10
, and performs reciprocation in a vertical direction. When the parts suction head is moved in a vertical direction, the ball spline unit
20
prevents a load of the motor
10
from being transmitted to the rotation shaft unit
30
.
The rotation shaft unit
30
connected to the other end portion of the ball spline unit
20
performing the rotation movement and the reciprocation includes a rotation shaft
31
, a socket
32
, an LM guide
33
, a moving block
34
and flanges
35
. The socket
32
is installed at one end portion of the rotation shaft
31
, and the moving block
34
is disposed at the outer portion thereof. The flanges
35
are provided to both end portions of the moving block
34
. Here, the rotation shaft
31
is assembled in the moving block
34
. The LM guide
33
is positioned on the rear surface of the moving block
34
in order to vertically reciprocate the rotation shaft
31
assembled in the moving block
34
.
The LM guide
33
guides the vertical reciprocation of the rotation shaft
31
, the ball spline
21
and the moving block
34
, so that the parts suction head of the rotation shaft
31
can suck the parts and mount it on the printed circuit board. When the parts to be mounted on the printed circuit board is not precisely sucked to the parts suction head, the rotation shaft
31
is rotated by the motor
10
in a predetermined radius, thereby correcting suction of the parts.
The structure of the conventional rotation shaft unit
30
correcting the suction of the parts by rotating the rotation shaft
31
will now be explained with reference to FIG.
2
.
FIG. 2
is a cross-sectional view illustrating the conventional rotation shaft unit having the contact sealing structure in FIG.
1
. As depicted in
FIG. 2
, when the rotation shaft
31
is inserted into the moving block
34
, both end portions of the moving block
34
are sealed up by a sealing material
36
to prevent pressure reinforcement from being generated due to external air inputted from both end portions of the moving block
34
. Here, air is flowed in and out in an arrow A direction through an air passage
34
a
of the moving block
34
, and a hollow unit
31
a
and an air passage
31
b
of the rotation shaft
31
so as to generate a pressure for the parts suction.
The conventional rotation shaft has the contact structure. That is, the rotation shaft is inserted into the moving block, and both end portions of the moving block are sealed up by the sealing material. Accordingly, when the rotation shaft is rotated, a non-linear frictional force is generated between the sealing material containing rubber and the rotation shaft. In the case that the rotation shaft is precisely rotated, it is impossible to stabilize a rotation angle in a wanted time due to the non-linear frictional force.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a parts suction head having a non-contact sealing structure which can prevent a non-linear frictional force from being generated in rotation of a rotation shaft inserted into a moving block in a rotation shaft unit of a surface mount device.
It is another object of the present invention to stabilize rotation of a rotation shaft in a wanted time in precise rotation, by rotating a moving block and a rotation shaft in a non-contact type in a parts suction head.
In order to achieve the above-described object of the invention, there is provided a parts suction head having a non-contact sealing head comprising: a moving block having a plurality of first air passages on its upper surface and having a first hollow unit in a longitudinal direction; a spacer having at least one or more second air passage connected to the first air passage for air flow, and having a second hollow unit in a longitudinal direction; a rotation shaft being inserted into the second hollow unit of the spacer at a predetermined interval and having at least one or more third air passage connected to the second air passage for air flow, and having a third hollow unit in a longitudinal direction; and flanges mounted to both end portions of the moving block to seal up an interval between the spacer and the rotation shaft.
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patent: 6076394 (2000-06-01), Tsuda et al.
patent: 6213528 (2001-04-01), Hufken et al.
patent: 6260898 (2001-07-01), Kano et al.
patent: 6287151 (2001-09-01), Matsuzaki et al.
patent: 6308403 (2001-10-01), Hwang
patent: 6343415 (2002-02-01), Okuda et al.
patent: 6378198 (2002-04-01), Asai et al.
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patent: 46-24328 (1971-07-01), None
patent: 404022198 (1992-01-01), None
patent: 405169385 (1993-07-01), None
patent: 405185391 (1993-07-01), None
Chin Paul T.
Lillis Eileen D.
Mirae Corporation
LandOfFree
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