US2491022A - Loop-taker for sewing machines - Google Patents

Description

Dec. 13, 1949 w. M. ABRESKY 2,491,022

LOOP-TAKER FOR SEWING MACHINES Filed Jan. 4, 1945 INVENTOR Patented Dec. 13, 1949 LOOP-TAKER FOR SEWING MACHINES William M. Abresky, Stratford, Conn.

Application January 4, 1945, Serial No. 571,232

1 Claim.

This invention relates to sewing machines, and more particularly to loop-takers of sewing machines, wherein a loop-seizing beak 0r hook periodically engages the thread of the machine during the sewing operations.

The invention is shown by way of example in connection with rotary loop-takers of the type used in multiple-needle lock-stitch and zigzagstitch machines.

Many of the conventional machines of this type operate at high speeds, in the order of five thousand or more stitches :per minute. At these speeds, and in regular production work, many miles of stitches are sewn and the rotary looptakers, generally rotating at a speed double the number of stitches per minute, are subject to wear so that replacement of the entire looptaker assembly is required at not infrequent intervals.

Part of the wear, to which the rotary looptaker is subjected, is bearing wear and means are provided usually for minimizing this, to reduce the frequency of replacement Of the loop-taker assembly. As a result, the useful life of the looptakers has been extended to some degree by this method, and now they are replaced mostly because of the wear on the thread-engaging surfaces of the loop-seizing beak. When the beak of a new loop-taker has worn to the extent that it interferes with the sewing operations, I have found that it is customary in sewing shops to advance the loop-taker in a make-shift and inconvenient way by hammering or otherwise forcing the driving gear mechanism so that the press-fitted gears are shifted on their shafts. This expedient increases the useful life of the loop-taker to an extent, but it is an undesirable method of doing this, and at times may result in breakage or other damage to the mechanism, requiring the installation of new parts. No adjustment means as such is provided for conveniently advancing the loop-taker to compensate for the wear.

Moreover, at best the extension of life of the loop-taker is not considerable, and therefore eventually the entire loop-taker assembly has to be replaced with a new one, involving delay and expense. Over a period of time the number of replacements of the loop-taker assemblies becomes considerable, so that the overall expense becomes significant. Also, at the time of installing a new loop-taker assembly, the forced gears of the driving mechanism must be reset, thereby adding to the dificulty and expense of the replacement.

The above difficulties and disadvantages are obviated in a simple, novel and effective manner by the present invention, which provides for forming the initial thread-engaging portion of the loop-taker, which is usually the tip of the hook or beak, of an exceedingly hard, wear-resistant material such as cemented carbide, this being applied preferably as a slug being secured to the loop-taker by brazing or other suitable means in place of the usual tip.

I have found that the cemented carbides, which are commonly employed for cutting tools, are suitable and desirable for use on the beak of a loop-taker as stated above to minimize to a considerable extent the wear caused by the thread during high-speed sewing operations.

Heretofore the reduction of wear at the beak of a loop-taker was accomplished by overall hardening of the material of the loop-taker, beak, body and all. I have discovered, however, that the useful life Of a loop-taker may be extended considerably by incorporating a cemented carbide tip at the beak, and this may be done even though the beak is slender and elongate, as in the case of loop-takers used in sewing zigzag stitches.

For the latter type of loop-takers, the entire beak may be formed of carbide, whereas in the case of loop-takers having comparatively short stocky beaks, the thread-engaging tips only may be formed. a

My invention may be applied to loop-takers at the time of their manufacture, or it may be applied as a replacement part in reconditioning a loop-taker after it has become worn, so that it may be used over again and may have a' life considerably extended beyond the original.

Other features and advantages will hereinafter appear in connection with the following description, claim and accompanying drawings, in which:

Figure 1 is a side elevation of a loop-taker embodying the invention, having a shape similar to those used for two and three needle sewing.

Fig. 2 is a face View of the loop-taker of Fig. 1.

Fig. 3 illustrates a modification of the invention, showing in side elevation a loop-taker adapted for sewing zigzag, and

Fig. 4 is a face view of the loop-taker of Fig. 3.

The rotary loop-taker of the present invention, as shown in Figs. 1 and 2, comprises a. shank l0 adapted to be secured to an actuating spindle (not shown) of a sewing machine in the usual manner, At one end of the shank In, a cupshaped body II is provided, comprising a circular rim or gib 12 carried by a plate [3 which at its center is secured to the shank Ill. The body II has a flange portion l4 integral with a hook or beak I5 having a shape adapted to seize the needle thread loop of the machine. The shank l0, body II and flange portion [4 may be formed of hardened steel, all parts integral with each other, as is common practice.

According to the present invention the beak l5 of the loop-taker is provided with a tip or threadengaging portion it which is formed of cemented carbide securely attached to the rest of the beak for the purpose of minimizing wear resulting from continual periodic engagement at high speeds with the sewing thread.

The beak l 5 may be formed in various ways according to the invention. It the rotary looptaker is an old one that has been discarded from a machine because the beak has become worn beyond further use, the loop-taker may be reconditioned to give it a considerably extended life by cutting oil the worn tip of the beak, as along the line l'l' shown in the figures. A slug of carbide, which may be of the type known as Carboloy or Kennametal may be formed to have a shape closely approximating the original shape of the beak before it became worn. This slug may then be secured to the remaining portion of the beak in any suitable manner, that at present preferred being by brazing. If the slug is to be secured to the beak by brazing, I have found it desirable to form the slug approximately .010" oversize on each surface, to allow for finish grinding. The surfaces tobe joined are made clean, and the brazing may be done by use of a thin shim of brazing material such as Easy Flow. N0. 3, inserted between the two parts. Before applying heat, the joint may be covered with flux, and then a torch used to heat the parts and melt the brazing material.

If desired the brazing may be donewith the help of a fixture to hold the loop-taker and the slug in correct position. After the brazing, has been completed, the surfaces of the carbide slug are finish-ground so that they merge with, and become coextensive with the surfaces of the remainder of the beak.

I have found that the tip of a Worn beak may be removed for a distance of one-quarter inch,

so that a similar length of carbide material may be brazed in place, to produce a loop-taker of long useful life.

The present invention is also applicable to the initial manufacture of rotary loop-takers. During such manufacture the body ll of the loop-' taker may be formed with the beak I5 shortened- 4 to the extent that carbide material is to be added at the tip. The slug of carbide may then be brazed in place or fastened in any other suitable manner, and the surfaces finish-ground to the desired shape.

A modification of the invention is illustrated in Figs. 3 and 4 wherein a. loop-taker adapted for use in sewing zigzag stitches is provided with an entire beak of cemented carbide. As shown in the figures, the loop-taker comprises a shank Hla and cup-shaped body Ha with rim or gib l2a all of which may be integrally formed of steel. The body Ila has a flange portion Ma from which extends a. beak l5a which is comparatively elongate and slender. The beak I511 in its entirety may comprise cemented carbide material, this material being joined to the flange portion l4a along the line ITa as indicated. I have found that. a practical and extremely wear-resistant loop-taker may thus be formed, with the entire beak 15a comprising carbide material, and that sufiicient strength is provided to enable the looptaken to operate satisfactorily for the purpose intended.

By the present invention there is thus provided a loop-taker for sewing machines which is extremely resistant to Wear at the points where it engages the thread during th sewing operation, so that the loop-taker need not be readjusted by makeshift or other methods, or eventually replaced due to failure of the beak to properly handle the thread.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim:

A metal. wear-resisting loop taker for sewing machines, including a loop-seizing beak having a tip of hard wear-resisting carbide brazed thereto with the thread-engaging surfaces thereof ground to provide smooth continuations of the thread-engaging. surfaces of the beak.

WJLLIAM M. ABRESKY.

REFERENCES CITED The following references are of record in the file. of this patent:

UNITED STATES PATENTS Number Name Date 620,729 Bertrand Mar. 7, 1899. 1,431,380 Dickson Oct. 10, 1922 2,206,760 Turner Jan. '7, 1936 2,148,925 Bochy Feb. 28, 1939 2,219,308 Haas Oct. 29, 1940

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