US1773271A - Sewing machine - Google Patents

Description

Aug. 19', 1930.

o. 1.. LAWSON SEWING uAcHn'm Filed Jan. 5; 1926 2 Sheets-Sheet 1 Aug. 19, 1930. L. LAWSON SEWING MACHINE Patented Aug. 19, 1930 UNITED STATES PATENT OFFICE J OSCAR I4. LAWSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO UNITED SHOE MACHINERY CORPORATION, OF PATERSON, NEW JERSEY, A CORPORATION OFNEW JERSEY SEWING MACHINE Application filed. January 5, 1926. Serial No. 79,453.

The present invention relates to sewing machines and more particularly to a presser foot lifting mechanism adapted for use in a lockstitch horn sewing machine.

The object of the invention is to proyide a presser foot lifting mechanism of new and improved construction which will operate in an accurate and reliable manner to lift the presser foot a uniform distance during each cycle of operations of the machine irrespective of the thickness of the work.

A further object of the invention is to provide a mechanism of this character in which the parts are so constructed and arranged as co-prevent all possibility of lost motion or slipping.

lVith these objects in view the invention consists of the devices, combinations and arrangement of parts hereinafter described and 23 claimed. While the invention is particu larly adapted for use in a lockstitch horn sewing machine it is also capable of use in other types of sewing machines.

The several features of the present inven- 33 tion and the advantages attained thereby will be readily understood by those skilled in the art from the following description taken in connection with the accompanying drawings which illustrate the features of the invention 37 as embodied in a lockstitch horn sewing machine, so much only of the machine being indicated as is necessary to show the connection of the invention therewith.

In the drawings Figure 1 is a left eleva- 53 tion of the presser foot lifting mechanism, Fig. 2 is a front elevation of the same, Fig. 3 is a detailed rear elevation of part of the presser foot lifting mechanism including the bell crank lever and its cam, Fig. 4 is a de- 47 tailed side elevation, and Fig. 5 is a detailed rear elevation of the wedge adjusting mech-,

. has a corresponding groove 42 :for the-lower anlsm.

The lockstitch horn sewing machine therein illustrated includes a straight hook needle indicated at 6, a presser foot 8, a shuttle with its bracket 10, and a horn which serves as a work support as indicated at 12.

The needle is fast to the lower end of the needle bar 14 which is connected through 50 link 16 with one end of the lever 18, the other the lever which engages a cam groove 26 in the cam disk 28.

The presser foot lifting mechanism, which embodies the subj cot-matter of this invention,

comprises a lifting lever, pivoted directly in front of the presser foot bar on the machine frame, a block secured to thepresser footbar and a cam-actuated bellcrank lever to operate the lifting lever. A wedge inserted between the lifting lever and the block provides a means automatically to adjust the lifting mechanism to raise the presser foot a uniform distance irrespective of the thickness of the work. A bell crank lever is mounted on the presser foot bar with'its lower arm connected to the wedge and its horizontal arm arranged to engage an abutment on the machine frame. During the downward stroke of the presser foot the lever is turned about its pivot to withdraw the Wedge a greater or less distance depending on the fall of the presser foot. During the lifting operation the wedge thus positioned with relation to the thickness of the work is held in adjust!- ment by means of a pinch dog mounted on the rear end of the lifting lever. The lifting movement of the cam-actuated bell crank lever first causes the pinch dog to clamp the wedge and then turns the lifting lever about its pivot to raise the presser foot.

Describing this presser foot lifting mechanism somewhat more specifically with reference to the drawings, the presser foot bar 30 has fastened thereto a block 32 which has on its under side a groove 34 adapted to receive the upper edge of a wedge 36. A lifting lever 38 mounted on the machine frame at 40 directly in front of 'thepresser foot bar edge of the wedge. To hold the vwedgein position during the lifting operation a pinch dog 44 is mounted on the rear end-of the lifting lever. The wedge is-adjusted in accordance with the thickness of the work to allow the lifting lever always to raise the presser foot a uniform, distance by means of a bell crank lever 46 pivoted onthe presser foot bar at 48. On the lower arm of this lever is a pin which runs in a vertical slot 52 formed in the wed The horizontal arm carries a pin 54 whic projects over a ledge or abutment 56 adjustably mounted on the machine frame by means of screws 57 projectingtthrough vertical slots 58 in the frame. A s rmg 59 acting on the pin tends to force the liorizontal arm of the lever downwardly.

As P Q er falls, the lever is turned aboutits pivot by'the engagement of the pin with the abutment to slide the wedge to the right. Durin the upward stroke of the presser foot, t e wedge is held in position by the pinch dog and the pin 54 is lifted off its abutment against-the pressure of the spring 59. A set screw 62 is provided to adjust the position of the ledge or abutment and thus determine the distance the presser foot is to be raised above the work. A bell crank lever 64 voted at 66 on'the machine frame carries omits vertical arm a roll 68 adapted to run on the cam surface 70. The other arm is adapted to engage the pinch dog pivoted on the litting lever. The lever 64 engages the pinch dog, first locking the wedge and then twt'hing the lifting lever about its pivot to raise the prssser feet. In "order to permit an adjustment of the effective throw of the bell crank lever in its lifting movement the two arms are pivoted indzpendently at 66 and are held in the desired r atiorn to each other by means of set screws 72.

The nature and object of the invention having been indicated and a machine embodying the several features of the invention having beendeacribed, what is claimed is INA sewing machine having, in combination, a work support, a presse/r foot, a presser foot bar, an abutment on the bar, a lift ng member, a w interposed between the liftingiiie'mber an the abutment, means for acmating the lifting member to the presser and means for positioning the wedge with relation to the lifting member in aceel-dame the thickness of the work to raise the resser foot a uniform distance from the work to permit the feeding of the Wm. I i n I I 2. A sewing machine having, in combination, I work support, a preaserfoot, a presser feet bar, a 1i member, an abutment on the resser foot alga wedge, a bell crank lever for ositiening the wedge pivoted on the ot her and having one end eonwith the wedge, and an abutment on time to engage the other end of at one end a pin and slot connection with the wedge, and an abutment on the machine frame to engage the other end of the bell crank.

4. A sewing machine having, in combination, a work support, a presser foot, a presser foot bar, means comprising an adjustable wedge and a lifting member to raise the presser foot a uniform distance irrespective of the thickness ofthe work, means for positioning the wedge in accordance with the thickness of the work and a pinch dog to lock the wedge in position during the lifting operation.

5. A sewing machine having, in combination, a work support, a presser foot, a presser foot bar, an abutment on the presser foot bar, a lifting lever, an adjustable Wedge supported on the lifting lever and arranged to come in contact with the abutment, a pinch dog pivoted on the lifting lever to lock the wedge in position, and means operating on the pinch dog to lock the wedge in position and thereafter actuate the lifting lever to raise the presser foot.

6. A sewing machine having, in combination, a work support, a presser foot, a presser foot bar, a block fixed to the bar, a lifting lever, 21 wedge arranged to cooperate with the lifting lever and the block to lift the presscr foot, means for positioning the wedge to raise the presser foot a uniform distance regardless of the thickness of the work, a pinch dog to lock the wedge in position during the lifting operation, and means to operate the pinch dog to lock the wedge and thereafter actuate the lifting lever to raise the presser foot.

7. A sewing machine having, in combination, a work support, a pressei' foot, a pressei' foot bar, means comprising an adjustable wedge and a lifting member to raise the presser foot a uniform distance irrespective of the thickness of the work, a pinch dog to lock the wedge in position during the lifting operation, a cam, and a lever actuated by the cam to operate the pinch dog to clamp the wedge in position and thereafter to actuate the lifting member to raise the presser foot.

8. A sewing machine having, in combination, a Work support, a prcsser foot, a presser foot bar, a block fixed to the bar, a lifting lever, an adjustable wedge supported on the lifting lever and arranged to come in contact with the block, a pinch dog pivoted on the lifting lever to lock the wedge in position, a cam and a bell crank lever actuated by the cam to operate the pinch dog to clamp the wedge in position and thereafter to actuate the lifting member to raise the presser foot.

In testimony whereof I have signedmy name to this specification.

OSCAR Lawson.-

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