Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Reexamination Certificate
2000-12-18
2003-11-04
Lillis, Eileen D. (Department: 3652)
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
C074S025000, C074S049000, C074S053000, C074S490010, C074S490050, C074S490080, C414S729000, C414S749100
Reexamination Certificate
active
06640660
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pick-up and placement apparatus, and more particularly to a structure of a preferable transfer mechanism for picking up precious components, etc., and moving the same to other places.
BACKGROUND OF THE INVENTION
Generally speaking, a pick-up and placement apparatus is used for picking up workpieces at a certain place, transferring the same and placing the same at places distant therefrom, and is used to feed various types of components to places where processing and machining are carried out, and remove the same from the processing and machining places. A pick-up and placement apparatus is generally composed of an arm provided with a grasping mechanism, etc., to grasp workpieces and a drive mechanism for reciprocating the arm. The arm is usually driven and reciprocated along an inverted U-shaped motion locus by the drive mechanism. Therefore, the drive mechanism is provided with a drive source such as a drive motor, etc., which actuates the arm portion, and a motion converting portion which transmits power from the drive source to the arm and simultaneously provides the arm with a desired motion.
Apparatuses described in Japanese Patent Publication No. 57240 of 1982 and Japanese Utility Model Publication No. 126522 of 1991 have been brought about as a pick-up and placement apparatus having this type of structure. The abovementioned motion converting portion described in these publications is provided with, for example, a swiveling member which can normally and reversely be turned by a drive motor, a driven member (cam follower) slidably attached to the tip end of the swiveling member in the radial direction, an inverted U-shaped cam groove which guides the corresponding driven member, and a transmitting member such as a transmission lever, gear, etc., which is connected between the driven member and the abovementioned arm as necessary. When the swiveling member swivels, the driven member slides and reciprocates along the cam groove, and the arm is operated in response to a sliding locus of the driven member.
However, in the prior art pick-up and placement apparatus, in order to achieve the abovementioned motions of the arm, the driven member attached to the swiveling member is devised so as to be guided by, for example, an inverted U-shaped cam groove. Therefore, large and excessive loads are given to the drive source due to the sliding resistance and vibration of the swiveling member, driven member and cam groove, and there is a problem when an attempt is made to accelerate the reciprocation speed of the arm.
In particular, since a general cam is composed of, for example, a horizontal portion linearly extending in the left and right direction, an elevating portion linearly extending in the vertical direction, which is disposed at both sides of the moving extent, and a curved portion having a small curvature radius and arcuately extending between the horizontal portion and the elevating portion, a large stress is applied from the cam groove to the swiveling member and driven member at the curved portion provided with a small curvature radius, and thereby causes such a problem that a load applied to the drive source and a drive loss are increased. The drive load and the degree of drive loss are remarkably increased in proportion to a square or a cube of the moving speed of the driven member, which increases in line with an increase in the arm speed.
Also, since the arm is moved in compliance with the driven member that reciprocates along the cam groove as described above, it is necessary to change the shape of the cam groove in order to alter the motion locus of the arm. Therefore, there is another problem in that it is difficult to change the motion locus of the arm.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a pick-up and placement apparatus equipped with a novel structure, in which stress is hardly generated when the apparatus operates, and loads applied to the drive source thereof can be reduced.
Further, it is another object of the invention to provide a pick-up and placement apparatus which can increase the speed of motion in the arm.
It is still another object of the invention to provide a pick-up placement apparatus in which the motion locus of the arm portion can be easily changed.
A pick-up and placement apparatus according to the invention has an arm that executes pick-up and placement motions and a drive mechanism that drives the corresponding arm. The corresponding drive mechanism comprises a rotating member that is normally or reversely driven and rotated in an appointed range of rotation, for example by a drive source, a swiveling member that is slidably attached to the corresponding rotating member in the radial direction and normally or reversely swivels in an appointed range of rotation by normal and reverse rotations of the corresponding rotating member, and is provided with a connection portion directly or indirectly linked with the corresponding arm, a retaining means that applies a retaining force to retain the corresponding swiveling member at an appointed position in the radial direction with respect to the corresponding rotating member while slidably retaining the corresponding swiveling member, and a means for regulating and guiding the corresponding connection portion to linearly move the same by directly or indirectly regulating the corresponding swiveling member in the vicinity of both ends in the corresponding range of rotation. The corresponding connection portion is constructed so as to reciprocate on a motion locus consisting of an arcuate locus portion, which is composed by the swiveling of the corresponding swiveling member without being substantially regulated, and a linear locus portion connected to both ends of the corresponding arcuate locus portion and composed by being regulated by the corresponding regulating and guiding means. The corresponding arm carries out motions substantially corresponding to the motion locus of the connection portion.
Since the swiveling member slidably attached to the rotating member swivels while it is retained by the retaining means at an appointed position in the radial direction in a state where it is not substantially regulated, the connection portion moves in a circular arc (that is, along the arcuate locus portion), and when the swiveling member is regulated by the regulating and guiding means in the vicinity of both ends of the range of rotation, the connection portion linearly moves (that is, along the linear locus portion). Resultantly, since the connection portion will reciprocate along an inverted U-shaped locus of movement, the arm will also reciprocate like an inverted U-shape. Therefore, the swiveling member is not substantially regulated other than being restricted by the regulating and guiding means in the vicinity of both ends of the range of rotation, and can freely swivel while maintaining a swiveling radius by the retaining means, wherein there is no case where the swiveling member is always regulated by a cam groove, etc., as in the prior arts. Therefore, the drive load and vibration resulting from regulation of the locus can be reduced. Resultantly, it becomes possible to operate the arm at a high speed. Further, since the locus of movement of the connection portion is composed by connecting the arcuate locus portion and linear locus portion to each other, the connection angle at the corresponding portion can be slackened, and it is possible to suppress or prevent the swiveling member from receiving an impact or generating vibration at the regulation commencing position by the regulating and guiding means. Further, there is no need to constitute an integrated regulating and guide member like a cam groove, and the inverted U-shaped motion locus of the arm are enabled by only providing a regulating and guiding means at both ends of the range of rotation. Therefore, it is possible to simply change the motions of the arm in a wider range by only changing the regulating and guiding position by the re
Cook Alex McFarron Manzo Cummings & Mehler, Ltd.
Lillis Eileen D.
Lowe Michael
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