Patent GB-672098-A (GB)
Title: Improvements in overedge sewing machines
IPC: D05B85/06
Filed: 1950-05-31
Abstract: 672,098. Sewing-machines. UNION SPECIAL MACHINE CO. May 31, 1950'[Oct. 19, 1949], No. 13554/50. Class 112. An overedge sewing-machine has upper and lower loopers fixed to parallel shaft-like members which are reciprocated by connections from a main driving shaft, one of the members also being oscillated. All the mechanism is enclosed and lubricated by oil mist, except the feed-mechanism which is outside the main chamber and is lubricated by wicks. The presser - arm has adjustable spring - pressure means which can be put out of action to allow the arm to be swung aside. The machine has trimming mechanism, both blades being adjustable, and duplex feed mechanism with special covers. Stitch forming devices.-In the embodiment shown, the curved needle 30 is carried by an arm 32 on a rock-shaft 33 bearing in one wall 14 of the frame and actuated by a pitmar 37 from a crank on the mair shaft 24. The lower (threaded looper 40 is fixed to a rod 44 sliding parallel to the shaft 24 in bearings in the wall 14 and an intermediate wall 26 under the action of an arm 48 on a transverse rock-shaft 50 oscillated from a crank on the shaft 24 by a pitman 55. The upper looper 58 (also threaded) is fixed to a similar parallel rod 61 which is oscillated by a pitman 65 having universal connections with crank pins on the rod and the shaft 24 and which receives reciprocating motion from an arm 71, free on the shaft 50, actuated by a crank on the shaft 24 through a pitman 83 and toggle linkage 74, 73; the connections are such that the reciprocating movement is more rapid near one end of the stroke than the other. Either looper may be replaced by an unthreaded loop-spreader. A stitch-finger is carried by a member 132 laterally adjustable on the presser-foot. Presser - bars; work - supports.-The presserfoot 102 is pivoted on an arm 104 secured to a yoke 105 which is pivoted about a vertical axis to one end of a rock-shaft 110 carrying the usual presser-lifting lever 113 ; the lever 113 has a lug 115 engaging a screw 116 on the yoke 105 to lift the presser-arm. The presser-arm is normally forced against the work by a spring which is enclosed in a cup 127 screwed into a sleeve 120 and which bears on a plunger 119 having a forked end engaging the presser-arm 104; the sleeve 120 slides in a bearing 121 on the machine frame and has aT-slot engaging a pin 122 on the bearing, whereby the sleeve can be locked in the working position or' can be readily withdrawn to allow the presser-arm to be swung aside to provide access to the throat-plate and loopers. The work-supporting plate 16 is mounted on a pivot 19 at the rear of an extension 15 of the base of the machine frame, so that it can be swung aside to expose the mechanism under it. The throat-plate 23<SP>1</SP> is fixed to a pedestal 23 at the front of the frame extension 15. Trimming.-A fixed trimming blade 135 is adjustably clamped on a block 139 which is slidable in a transverse channel in the frame pedestal 23 under the action of a screw 143 and is clamped in adjusted position by a screw 141; the blade 135 is accommodated in a channel in the presserfoot member 132 carrying the stitch-finger. The moving blade 144, of L section, is clamped in an inclined position on a block 145 transversely adjustable on the end of an arm 148 fixed to a shaft 152 bearing in the frame wall 14 and oscillated by a pitman 158 connecting a crank on the shaft 24 to a downwardly-extending arm on the shaft 152. The end of the arm 148 is supported laterally by a bearing block. Feed by dogs.-Two feed dogs 86, 87 are provided, fixed to separate feed-bars each of which slides at its rear end on a block 88 (not shown) pivoted on a pin 90 and straddles at its forward end a square block 91 mounted on an eccentric part of the shaft 24 to provide the lifting motion of the feed-dogs. The feed-bars receive independent advance movements from pitmans 98, 92 respectively, actuated by separate eccentrics on the shaft 24, these eccentrics having bodies which may be readily replaced by others of different eccentricity for adjusting the feed. Lubricating; frames.-All the driving mechanism except that actuating the feed-bars is enclosed in an oil-tight chamber with a removable cover 12, and a disc 164 on the shaft 24 dips into a pool of oil in the bottom of the chamber to distribute it in the form of a mist to all the bearings and moving parts in the chamber; the cover may be formed with suitable downward projections to cause oil collecting on it to drip at appropriate places. The feed mechanism is lubricated by two wicks 168 which rest on members of the mechanism as shown in Fig. 5 and hang down inside the chamber; surplus oil from this mechanism collects in a sump from which it is returned to the chamber through a filter 169 and passage 171. The feed mechanism is mainly surrounded by a cover 20 pivoted on the same pin as the work support. An additional front cover 172 is fixed below and behind the trimming. blades.