| 摘要 |
The mechanism to operate the thread guide lever (1), at a multi-head embroidery machine, has a shaft (9) with a cam disk (8) to operate levers (4,6) acting on the thread guide lever (1). A cam follower (7), to transmit the cam movements to the guide lever through the drive levers, can be moved away from the cam groove (8a) over a total or part angular range. A setting unit swings and/or holds the cam follower (7) in an inactive position. The cam follower (7) is under a movement pressure towards the cam disk (8) so that, when released from the inactive position, it is moved towards the cam disk (8) and engages the cam groove (8a) immediately on or after shaft (9) rotation. The deflection angle of the linkage levers (4,6) into the rest position is at least equal to the deflection angle of the levers (4,6) through the cam disk (8). The cam follower (7) is a bolt or shaped projection or rotating roller, on a rotating axis parallel to the cam disk (8) axis. The setting unit is a spring and a limit (8b), where the displaced cam follower (7) is held against the limit (8b). The limit (8b) is a shaped tube or sleeve projection at the cam disk (8), as an inactive curve for the follower (7). The inner radius of the limit (8b) equals the max. radial gap between the rotary axis and the outer groove wall of the cam disk (8), and the setting spring presses the cam follower (7) against the inner wall of the projection (8b). An additional holder is fitted at the side of the linkage levers (4,6) away from the cam disk (8), as a projection or bolt and especially a rotating body, to be held against the limit by the setting spring. The limit can also be a projection fitted to the shaft, where the spring holds the cam follower against its inner wall. The inner radius of the limit projection is set so that the cam follower has a simple axial sliding movement back to the cam disk and/or is moved into the cam groove by the shaft rotation. The cam follower (7) and the holder are on the same axis, as a bolt through the lever. An additional cam disk can be fitted to the shaft (9), with the lever linkage (4,6) between them to engage either the cam groove (8a) of the first disk (8) or the cam groove of the second disk. Both cam disks have projections as limits. The end of the lever has a U-shape, with followers at the inner sides of the legs for selective engagement with the cam disk or sliding block on the shaft (9). A limit projection is at one of the two flat sides of the sliding block. The shapes of the cam grooves, or guide surfaces, give different movement profiles to the thread guide lever (1). The assembly has a drive, to move the linkage levers (4,6) or cam follower with its holder in an axial direction to and from the shaft (9). The movement is through an eccentric, lifting magnet or an electromagnetic drive. The cam groove can be replaced by a sliding block with a number of overlaid guide surfaces.
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