Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
2000-08-04
2001-07-17
Kramer, Dean J. (Department: 2167)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
C029S740000, C029S743000
Reexamination Certificate
active
06260898
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a mounting head for an electronic component-mounting apparatus that picks up electronic components by vacuum and mounts the electronic components on a circuit board.
2. Prior Art
Conventionally, a mounting head for an electronic component-mounting apparatus of this kind has been proposed in Japanese Laid-Open Patent Publication (Kokai) No. 5-226884, which includes a nozzle holder having a plurality of vacuum nozzles mounted thereon in a manner capable of projecting and retracting vertically, and a holder support member secured to a bracket mounted on a main unit of the electronic component-mounting apparatus, for rotatably supporting the nozzle holder via a pair of upper and lower bearings. The nozzle holder has a hook support member mounted at an upper portion thereof. The hook support member has a plurality of engaging hooks corresponding to the vacuum nozzles, respectively, and extending perpendicularly downward therefrom in a pivotally movable manner. Further, the hook support member has an upper end surface thereof formed with an engaging groove for engagement with an output end of a rotation drive mechanism arranged in the main unit. That is, the output end of the rotation drive mechanism engages with the engaging groove to drive the nozzle holder for rotation, whereby one of the vacuum nozzles selected for use is brought to a projecting position.
Each of the vacuum nozzles has a hook-catching member fixed to an upper portion thereof for engagement with a corresponding one of the engaging hooks. Retraction of the vacuum nozzles into the nozzle holder is effected by lowering the mounting head and causing the vacuum nozzles to strike against a nozzle stopper, while downward projection of a selected vacuum nozzle from the nozzle holder is effected by pivotally moving a corresponding one of the engaging hooks by a disengaging mechanism provided in the main unit, to disengage the engaging hook from a corresponding one of the hook-catching members. That is, in changing (switching) vacuum nozzles in use, the nozzle holder is rotated to bring a vacuum nozzle selected for use in a next mounting operation to a projecting position, then all the vacuum nozzles are struck against the nozzle stopper to be once retracted into the nozzle holder, and thereafter, only the selected vacuum nozzle is caused to project.
As described above, in the conventional mounting head, all the vacuum nozzles are required to be struck against the stopper before causing one of the vacuum nozzles to project for use. Since this operation is repeatedly carried out, the striking end of each vacuum nozzle is worn away or deformed, which inevitably shortens the service life of the vacuum nozzle.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a mounting head for an electronic component-mounting apparatus, which is capable of increasing the service life of vacuum nozzles, without causing any trouble in changing between them.
To attain the above object, the present invention provides a mounting head for an electronic component-mounting apparatus, including a nozzle holder having a plurality of vacuum nozzles arranged circumferentially about an axis thereof in a manner such that each vacuum nozzle is capable of projecting from the nozzle holder and retracting in the nozzle holder, a holder support member supporting the nozzle holder in a manner such that the nozzle holder can rotate about the axis thereof, and main rotation drive means for driving the nozzle holder about the axis thereof for rotation in normal and reverse directions, wherein the nozzle holder is rotated by the main rotation drive means to bring one of the vacuum nozzles selected for use to a projecting position, and the selected one is caused to project from a lower end face of the nozzle holder at the projecting position.
The mounting head according to the present invention is characterized by comprising a plurality of cam followers mounted at respective upper portions of the vacuum nozzles, an annular end cam with which the cam followers are in contact in a manner such that the cam followers can move on the annular end cam, the annular end cam being formed with a nozzle-projecting surface for causing the selected one of the vacuum nozzles to project from the lower end face of the nozzle holder when the selected one of the vacuum nozzles is at the projecting position, and auxiliary rotation drive means for driving the end cam for rotation about an axis of the end cam in normal and reverse directions.
According to this electronic component-mounting apparatus, the nozzle holder is driven for rotation by the main rotation drive means, whereby the vacuum nozzles arranged through the nozzle holder in a manner capable of projecting downward and retracting upward are moved about the axis of the nozzle holder. The movement of each of the vacuum nozzles causes a cam follower mounted at the upper portion of the vacuum nozzle to move on a cam surface of the annular end cam. During this process, any one of the vacuum nozzles which is brought to the nozzle-projecting surface of the end cam is caused to project from the lower end face of the nozzle holder by cam action between the cam follower and the end cam, while the other vacuum nozzles on part of the cam surface other than the nozzle-projecting surface are each held in a retracted state. On the other hand, the end cam is driven for rotation by the auxiliary rotation drive means so as to move the nozzle-projecting surface of the end cam to a desired projecting position, whereby it is possible to cause only one of the vacuum nozzles selected for use to project at the desired projecting position. Further, since the two rotation drive means can be each selectively rotated in a normal or reverse direction through the smaller rotational angle with respect to a predetermined rotational position, the nozzle holder and the end cam can be promptly rotated to respective predetermined positions.
Preferably, the main rotation drive means and the auxiliary rotation drive means are each formed by a stepping motor or a servomotor, the auxiliary rotation drive means being interposed between the holder support member and a lower portion of the end cam.
According to this preferred embodiment, since the main rotation drive means and the auxiliary rotation drive means are each formed by a stepping motor or a servomotor, the end cam is driven for rotation by the auxiliary rotation drive means so as to move the nozzle-projecting surface of the end cam to a desired projecting position in advance, and then, in a state of the nozzle-projecting surface being held at the position by the auxiliary rotation drive means maintained in its energized state, the nozzle holder is driven for rotation by the main rotation drive means so as to bring the selected vacuum nozzle (i.e. the cam follower thereof) to the position of the nozzle-projecting surface (i.e. the projecting position), whereby it is possible to cause the vacuum nozzle to project at the desired projecting position.
Preferably, the mounting head further comprises cam position-detecting means for detecting a rotational position of the nozzle-projecting surface of the end cam, nozzle position-detecting means for detecting a rotational position of each of the vacuum nozzles on the nozzle holder, and control means for controlling rotation of the main rotation drive means and rotation of the auxiliary rotation drive means, in response to respective detection signals from the cam position-detecting means and the nozzle position-detecting means.
According to this preferred embodiment, it is possible to always keep track of the rotational position of the nozzle-projecting surface and the rotational position of each of the vacuum nozzles with reference to results of detection by the cam position-detecting means and the nozzle position-detecting means, so that the two rotation drive means can be each rotated under control of the control means in the normal or reverse direction through the
Kano Yoshinori
Nagata Takahiro
Takemura Ikuo
Usui Yoshinao
Darby & Darby
Kramer Dean J.
Sanyo Electric Co,. Ltd.
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