Disengagement of Needle Thread from Rotating Hook, Effects of Its Timing on Tightening Tension, Industrial Single-Needle Lokstitch Sewing Machine

Abstract

This paper aims to investigate experimentally the disengagement of needle thread from rotating hook in an industrial single-needle lockstitch sewing machine with respect to tightening tension.For this purpose, the disengagement of the thread from rotating hook was photographically observed, and the resultant changes in needle thread tension were recorded simultaneously. A rotating hook, manufactured by Hirose Manufacturing Co., Ltd., model HSL-B was used, which was provided with a rotating hook section jib. Sewing speed was 2,250 spm, and the sewing threads used were cotton, and filament threads of polyester and nylon.The experimental investigation above revealed that the timing of the disengagement of needle thread from rotating hook is affected by the elongation properties of the sewing threads.If the cotton thread low in elongation was used, the needle thread first slips out of the jib and thereafter slips out of the `rotating hook bobbin case holder position bracket'. This is because when the needle thread becomes tight the rotating hook is beyond the correct angular position. The needle thread behavior therefore is abnormal. In this case, it is estimated that if the shortage of needle thread slack can not be compensated by the thread take-up spring or by thread elongation, the thread is frequently drawn out of the tension disc to result in an insufficient tightening tension.When polyester or nylon threads higher in elongation than cotton are used disengagement of needle thread from the rotating hook is normal since the needle thread first slips out of the bracket and thereafter slips out of the jib. When the disengagement occurs in this order the timing of disengagement has no effect on the tightening tension.

A Study of the Consumption of Sewing Threads for Women's Underwear: Bras and Panties

“…For each sewing machine used (see Figure 4) to sew women's underwear bras and panties, a relationship between the consumed amount of thread and tensions generated was derived and discussed. By comparing between overall evolutions of the consumption behaviors, it may be concluded that the amount of the sewing thread consumed has a good correlation when tension of threads increases [9,[15][16][17].…”

“…To provide a better quality of sewing thread and high appearance of seaming fabrics, some researchers used different techniques [6,29]. According to obtained coeffi cient of determination (R = 0.937), a good relationship between the consumption behavior and the tensions of looper and needle threads is found [7,15]. Therefore, it may be concluded that the predicted values on consumed sewing thread are signifi cant, in the experimental set-up.…”

Influence of Needle Heat during Sewing Process on Tensile Properties of Sewing Thread

“…e damage is mostly concentrated at the interlocking portion of the needle thread in the stitch, where maximum tension, bending and thread-thread abrasion take place [5,8]. A number of researchers also studied the thread tensions during the sewing process and it is well known that the highest thread tension force occurs at the moment of stitch tightening [13][14][15][16]. Nevertheless, earlier studies are based on the e ect of mechanical abrasion [17] as a cause of the thread tensile loss.…”

Studies on the Changes in Tensile Properties of Sewing Thread at Different Sewing Stages

“…The damage is mostly concentrated at the interlocking portion of the needle thread in the stitch, where maximum tension, bending, and thread-thread abrasion take place [4,7]. A number of researchers also studied the thread tensions during the sewing process and it is well known that the highest thread tension force occurs at the moment of stitch tightening [11][12][13][14]. The mechanical properties of the threads become altered during high-speed sewing; and therefore predictability of performance characteristics of thread become dif-ficult.…”