Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
1998-09-25
2001-06-05
Young, Lee (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S743000, C294S064200
Reexamination Certificate
active
06240628
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a component mounting apparatus which is applied to the mounting of an electronic component onto an electronic circuit substrate, and more particularly, to a nozzle drop prevention device, which is installed in a mounting head equipped with a nozzle for picking up a component.
2. Description of Related Art
With the propagation of leadless electronic components (chip component) in recent years, the shape and size of components have been diversified, and in an electronic component mounting apparatus for mounting these electronic components, there have been demands for high-speed operation, high precision, high productivity, and high reliability.
A conventional electronic component mounting apparatus will be hereinafter described with reference to FIG.
7
. In
FIG. 7
, the electronic component mounting apparatus comprises a mounting head
51
equipped with a nozzle for picking up an electronic component, a suction device
52
for attracting the electronic component with the nozzle, an XY robot
53
for moving the mounting head
51
in the X and Y directions, and a control device
54
which controls actions of the mounting head
51
, the suction device
52
, and the XY robot
53
. It is noted that
FIG. 7
shows only the main elements of the mounting head
51
, and illustration of, for example, a body part is omitted.
Reference numeral
55
represents a spline shaft, to which two nuts
56
,
57
are coupled such as to be movable in a direction of its axis. These nuts
56
,
57
are supported in the body part (not shown) of the mounting head
51
via bearings
58
,
59
, respectively. By this construction, the spline shaft
55
is movable in the direction of its axis as well as rotatable around its axis, and it is driven to rotate by a motor
60
mounted on the mounting head
51
via a pulley
61
, belt
62
, and another pulley
63
.
At the distal end
55
a
of the spline shaft
55
is mounted a nozzle
65
is mounted for picking up the electronic component
64
. Inside the nozzle
65
, a filter
66
is provided for preventing dust from entering into the nozzle when a suctional force. The spline shaft
55
is to be pushed upwards by a compression spring
68
via a bearing
67
which is slidable in a circumferential direction, and by applying a pressing force from a voice coil motor
69
, the spline shaft
55
or the nozzle
65
is lowered to perform pick up and mounting actions of the electronic component
64
.
The actions of the component mounting apparatus with the above described construction will be explained. The control device
54
activates the XY robot
53
to move the mounting head
51
to a component pick-up position where the electronic component is picked up. Then, by the control of the control device
54
, the voice coil motor
69
is driven so as to compress the compression spring
68
, by which the nozzle
65
is lowered via the spline shaft
55
, and at the same time the suction device
52
is driven so that the nozzle
65
picks up the electronic component
64
by suctional force. Next, the nozzle
65
is lifted by means of the voice coil motor
69
. The XY robot
53
is then driven to move the mounting head
51
to a component mounting position above the circuit substrate, after which the nozzle
65
is lowered by means of the voice coil motor
69
so that the electronic component
64
is mounted on the circuit substrate. When the power source is off or at the time of a power failure, the pressing force is not applied from the voice coil motor
69
, and thus the spline shaft
55
or nozzle
65
is prevented from dropping due to the force of the compression spring
68
which is pushing the bearing
67
upwards.
However, in the above described construction, since the spline shaft
55
is urged upwards by the force of the compression spring
68
, the voice coil motor
69
needs to have a pressing force greater than the force of the compression spring
68
alone wherefore there is a problem that precise control of pressing force for the mounting purpose cannot be achieved. Also, the voice coil motor
69
needs to have a capacity greater than necessary, thus causing the size of the voice coil motor or the mounting head
51
to become bulky. Furthermore, in order for minimizing the change of the compression spring
68
due to compression, it is necessary to make enough room for the compression spring
68
, whereby the mounting head
51
becomes elongated in a vertical direction.
BRIEF SUMMARY OF THE INVENTION
In view of the above problems in the prior art, an object of the present invention is to provide a nozzle drop prevention device in a component mounting apparatus by which, without using a compression spring for pushing the nozzle upwards, the nozzle is prevented from falling when power is turned off or cut with a simple and compact construction, and by which a pressing force applied to the nozzle can be precisely controlled with a compact voice coil motor.
The nozzle drop prevention device according to the present invention is used in a component mounting apparatus including a mounting head in which a nozzle is disposed at a distal end of a shaft which is movable upwards and downwards for picking up and mounting a component, and comprises: a shaft driving means for driving the shaft upwards and downwards; a pair of first levers pivotally connected at one end such that the first levers can swing in an open and closed direction and is forced in the close direction by a compression spring to hold the shaft in a gripping manner; a release pin for opening the first levers by engaging release grooves open/close end of the first levers opposite the pivotally connected end; a second lever for driving the release pin toward the open/close end of the first levers by a driving means; and a tension spring for forcing the second lever in a reverse direction with respect to a direction in which the release pin is driven; wherein during an operation of the mounting head is the first levers are opened via the second lever by driving the release pin, only after the shaft driving means is activated and at the end of the operation, the driving of the release pin by the second lever is released, so that the shaft is vertically supported by the first levers. Since the shaft can move upwards and downwards freely when the mounting head is in operation, pressure application control can be precisely made with a compact shaft driving means, and the nozzle can be prevented from dropping since the shaft is supported by the first lever at the end of the the operation, and even when there is a power failure where controlling actions are not effectuated, nozzle drop can be prevented by the action of the spring, by which mechanical damages can be avoided and high reliability is realized.
Instead of providing a spring for forcing the second lever in a reverse direction with respect to a direction in which the release pin is driven, a reciprocating moving means for moving the second lever in a release pin driving direction and in a reverse direction with respect to the driving direction can be provided, with which, when the mounting head is in operation, only after the shaft driving means is activated are the first levers opened via the second lever by driving the release pin in the driving direction, and at the end of the operation, the driving of the release pin by the second lever is released, so that the shaft is vertically supported by the first levers. In this case, since the second lever is not forced by the spring in the direction opposite to the driving direction, the speed of response when the second lever is driven in the release pin driving direction is increased, i.e., the response of actions in both directions is enhanced, by which a high-speed mounting operation is realized. By employing a double-acting air cylinder device as the reciprocating moving means, high-speed operation of the second lever is possible by a simple construction with an air source and a solenoid valve.
In the case where the
Kabeshita Akira
Kitamura Naoyuki
Okuda Osamu
Yoshida Yoshihiro
Matsushita Electric - Industrial Co., Ltd.
Price and Gess
Tugbang A. Dexter
Young Lee
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