Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
2000-03-13
2001-10-30
Young, Lee (Department: 3723)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S743000, C029S840000, C029S834000, C029SDIG004, C294S064200
Reexamination Certificate
active
06308403
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a part mounting apparatus, and more particularly, to a head assembly for a part mounting apparatus having a plurality of spindle units, and a part mounting apparatus adopting the same.
2. Description of the Related Art
Part mounting apparatuses having a fast and accurate mounting function have been developed in response to the needs of high integration, high functions and being small and light weight of various electronic devices. The performance of the part mounting apparatus is determined by various factors, in particular, by how a head where an absorbing nozzle is installed for absorbing parts can be rapidly and accurately moved and located at a predetermined position. To rapidly and accurately position the head at a desired position, the size and weight of the head needs to be decreased. Also, to accurately grab a part, many methods and apparatuses have been developed.
Typically, a head performs a vertical elevation movement and a rotation movement. For these two movements, a timing belt, gear or ball screw is used as a power transfer mechanism. That is, in a conventional part mounting apparatus, a spindle installed at a head is elevated up and down and rotated to mount parts on a printed circuit board. Here, the power of a motor is transferred to the spindle through a power transfer means such as a timing belt, gear or ball screw so that parts are mounted.
However, in a typical part mounting apparatus having the above power transfer mechanism, the power generated from a driving shaft of a motor is not accurately transferred to a spindle due to sagging of the timing belt or backlash of the gear. Thus, accuracy of part mounting cannot be expected. In particular, the tension of the timing belt changes according to changes in temperature so that the rotation force of the motor cannot be accurately transferred to the spindle performing elevating and rotation movements. Also, thermal and mechanical durability of the belt itself cannot be guaranteed. Also, the structure of the head becomes complicated and the weight thereof increases so that fast and accurate position selection of the head is difficult and also repair and maintenance of the apparatus is difficult.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a head assembly for a part mounting apparatus in which a spindle can accurately perform an elevation movement and a rotation movement.
It is another object of the present invention to provide a head assembly for a part mounting apparatus in which a plurality of absorbing nozzles and spindles are installed inside a housing so that many parts can be simultaneously gripped and mounted.
It is yet another objective of the present invention to provide a head assembly for a part mounting apparatus which has a simple structure and is small and light weight and simultaneously a part mounting operation of a high efficiency is possible.
It is yet further another objective of the present invention to provide a part mounting apparatus adopting the above head assembly so that a highly efficient work can be done.
Accordingly, to achieve the above objectives, there is provided a head assembly for a part mounting apparatus comprising a housing, a plurality of rod housings installed to be capable of elevating with respect to the housing, a plurality of voice coil motors fixed to the housing to be capable of elevating the respective rod housings, a plurality of spindle motors, each having a part picking device at an end portion thereof, installed to be capable of rotating with respect to the respective rod housings and elevating together according to the elevation of the rod housings, and a plurality of linear position transformers installed at the respective voice coil motors for detecting and controlling the position of elevation of each of the rod housings.
It is preferred in the present invention that the head assembly further comprises a first gear installed at the outer circumferential surface of each of the spindle units for rotating each spindle unit, a rack gear engaged with the first gear and linearly reciprocating with respect to the housing, and a driving means installed at one side of the housing for driving the rack gear to linearly reciprocate.
It is also preferred in the present invention that the driving means is a motor installed at one side of the housing and a second gear installed at a rotation shaft of the motor is engaged with the rack gear.
It is also preferred in the present invention that the driving motor is a linear motor which is installed to make the rack gear perform a linear movement.
It is also preferred in the present invention that the housing comprises an upper portion where an insertion hole for inserting the linear position transformer is formed and a body portion where an insertion hole for inserting the spindle motor is formed, and a rack gear guide installation surface where the rack gear is installed is formed between the upper portion and the body portion.
It is also preferred in the present invention that each of the rod housings comprises a pair of first rod housing and a second rod housing, a coupling surface coupled to an moving portion of the voice coil motor and an insertion hole for inserting the spindle unit are formed at the upper portion of each of the rod housings, and the insertion holes formed in the first and second rod housings are linearly arranged while the coupling surfaces are arranged to be separated far apart from one another.
It is also preferred in the present invention that the head assembly further comprises first and second pinion gears fixed to the outer circumferential surface of the spindle unit and the driving motor, respectively, wherein each of the pinion gears has first and second gears having at least one pair of a protrusion and a groove and a spring elastically and rotatably supported between the first and second gears.
It is also preferred in the present invention that a hollow portion is formed in the voice coil motor, the linear position transformer is inserted in the hollow portion, and one side of the linear position transformer is connected to the moving portion of the voice coil motor so that the position of the moving portion of the voice coil motor is detected and controlled.
It is also preferred in the present invention that the linear position transformer is operated to change the descending speed of the voice coil motor when the absorbing nozzle arrives at a set position above the surface of a part or a printed circuit board.
To achieve the above objectives, there is provided a part mounting apparatus adopting a head assembly comprises a housing, a plurality of rod housings installed to be capable of elevating with respect to the housing, a plurality of voice coil motors fixed to the housing to be capable of elevating the respective rod housings, a plurality of spindle motors, each having a part picking device at an end portion thereof, installed to be capable of rotating with respect to the respective rod housings and elevating together according to the elevation of the rod housings, and a plurality of linear position transformers installed at the respective voice coil motors for detecting and controlling the position of elevation of each of the rod housings.
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patent: 4451976 (1984-06-01), Fujita et al.
patent: 4498023 (1985-02-01), Stout
patent: 5070598 (1991-12-01), Itagaki et al.
patent: 5397423 (1995-03-01), Bantz et al.
patent: 5588195 (1996-12-01), Asai et al.
patent: 5850683 (1998-12-01), Okazaki et al.
patent: 10-163686 (1998-06-01), None
patent: 11-68389 (1999-03-01), None
patent: 11-198079 (1999-07-01), None
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Samsung Aerospace Industries Ltd.
Trinh Minh
Young Lee
LandOfFree
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