Patent FR-2826897-A1 (FR)
Title: Mechanism for loading and unloading of boxes containing microelectronic wafers for transferring from equipment to trolley and vice versa
Inventor: ROCHET ANDRE
IPC: B25J18/04
Filed: 2001-07-04
Abstract: The mechanism used for loading and unloading of a box (12) containing microelectronic wafers, comprises a gripping head (17) mechanically coupled to a kinematic manipulator device (18) for a multidirectional transfer of the box to a predetermined position on one of the loading posts (A,B) of the equipment (14) or to a trolley (16). The kinematic device (18) comprises a pair of carrier arms (26,28) with pivotal mounting composed by use of joints (32,38,40) between the gripping head (17) and a footed support (30). The joints (32,38,40) are equipped with position indexers (68,70) for controlling the angular displacements of the carrier arms (26,28). The control means include an actuator controlled by a selector of rising and lowering motions of the gripping head (17), wherein the selector is joined with the gripping head and has interrupters for rising and lowering motions controlled in alternation by a small-motion vertical displacement of the gripping head so to trigger the actuator setting a relay in the same direction of vertical displacement.  The first joint (32) provides a rotary link between the carrier arm (26) and the vertical axis of the gripping head (17). The two carrier arms (26,28) constitute a knee whose bending axis is given by the second joint (38). The third joint (40) links the carrier arm (28) to the upper end of an axle coupled to the actuator mounted inside the lowre part of the support (30). The vertical displacement of the axle is limited by contacts for the end-of-rising and the end-of-lowering motions. The actuator is constituted of an electromotor-reductor associated with a screw-lift device. Each position indexer (68,70) is equipped with a set of rings each with possibility of angular adjustment on a disc, and a dent on periphery cooperating with a sensor carried by a plate spring. A semi-circular screw-lift is inserted between the plate springs and the respective rings, and the screw-lift is rotatable between two positions, for activating and deactivating the indexing function. The gripping head (17) comprises a sub-carrier with an intermediate plate joined to the vertical axis and constrained by support parts, a mobile sub-carrier with an upper plate where a control handle, a selector cover, and motion limiters are fastened, and a lower plate joined to the upper plate. the two sub-carriers are held in a stationary position by compensation springs mounted in openings of the support parts for compensating the weight of the mobile sub-carrier, and pin springs mounted on the upper plate around the control handle. The upper part of the box (12) is equipped with a holding palte projecting in a rectangular form and having a centring opening, and the lower plate has a rectangular opening of a slightly larger dimensions; a triangular limiting plate is associated with the control handle to stop the lowering motion when the holding plate is anchored. The centring of the gripping head is facilitated by a telescopic part forced downwards by a compression spring laid on the limiting plate. The anchoring of the box is in centred position by turning the gripping head by a 90 deg. angle when the holding plate is in the limit position against the side of the support parts.