| 摘要 |
721,975. Sewing-machines. PFAFF AKT.- GES., G. M. Aug. 11, 1952 [Aug. 9, 1951]. No. 20103/52. Class 112. Automatically exchanging loop-taker thread spools. A carrier having movement along and about an axis is arranged to grip the spool-case in the loop-taker and a replacement spool-case, to remove the former and discard it, and simultaneously to place the latter in the loop-taker. In the form shown in underneath view, the carrier comprises a bar 10 mounted to slide but not rotate on a spindle 4 parallel to the shaft of the loop-taker 30, each end of the bar being provided with a pivoted gripping device which includes a fork 25 to engage the bobbin latch hinge pin 28, a claw 23 to engage the end 29 of the latch, and a retaining spring 24. A plunger 21 is rigid with a member 15 slotted at 31 to slide transversely of the spindle 4 and formed with a cam surface 14 to move the carrier 10 along the spindle against a spring 13; a ratchet rack 20 pivoted to the plunger 21 is spring- pressed against a ratchet wheel 7 on the spindle, a detent being provided so that successive outward movements of the plunger cause successive half-revolutions of the spindle 4 with the carrier 10, the inward movements of the plunger producing axial movement of the bar 10 without rotation, which is prevented by engagement of one of a pair of holes 16 in the bar with a fixed pin 18. Two in-and-out operations of the plunger 21 are necessary to exchange the spools, the .first causing the carrier to engage and withdraw the spool-case in the loop-taker and a replacement spool-case in any suitable storage device, finally causing rotation of the carrier to place the new spool-case in line with the loop-taker, and the second to place the spool-case in the loop-taker and release it; the original spool-case is dropped into a collecting device during the first rotation. In a modification, suitable cam means may perform the necessary operations for a single actuation of the plunger. The plunger may be actuated by hand, foot, or knee, and hydraulic or electric power may be used. Any suitable means, such as an abutment to render the spring 24 inaffective, may be used to release the spoolcases from the carrier. |
