Sewing – Method of sewing – Workpiece manipulation other than straight line feeding
Reexamination Certificate
1999-07-22
2001-02-13
Izaguirre, Ismael (Department: 3741)
Sewing
Method of sewing
Workpiece manipulation other than straight line feeding
C112S141000
Reexamination Certificate
active
06186084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an apparatus for folding margins of flexible materials and, more particularly, to an air enhanced hem former to be used with a sewing machine.
2. Description of the Prior Art
Materials used in the manufacture of clothing, such as cotton, polyester, rayon and other cloth materials invariably have an end, or margin. The margin is typically folded and sewn to form a hem. The hem provides strength to the clothing, prevents fraying, evens the length of the margin, and allows for subsequent length adjustments. Hems are formed in a variety of ways.
One common method of forming a hem is to manually fold the margin back onto the material and then hand or machine stitch the margin to the material. However, this method is very time consuming and requires skilled operators. Another common method of forming a hem uses a thin plate to fold the margin around and then back onto the material. Once the margin is so positioned, an operator can hand or machine stitch the margin to the material. However, it is often difficult, if not impossible, for an operator to quickly and accurately fold the margin around the plate and into position for stitching.
To overcome the problems relating to quickly and accurately folding the margin into a proper stitching position, streams of compressed air have been used. One such design is illustrated by U.S. Pat. No. 3,631,826 issued to Morgan. Morgan apparently discloses a hem former in which the path traveled by the margin during sewing uses an airflow outlet formed below the margin and below a support plate, with the airflow perpendicular thereto. A deflector
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,
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perpendicularly deflects the airflow toward the margin so that the margin is carried by the airstream toward the sewing needle whereas other airstreams guide the margin through multiple folds for stitching parallel to the margin. However, this airstream design causes the margin to flutter when in the airstream and inefficiently directs the margin toward the stitching needle because of the 90° angle change which the airstream undergoes. Further, margin positioning is not maintained during stitching.
Another air enhanced hem former design is illustrated by U.S. Pat. No. 5,441,004 issued to Bottoms. Bottoms apparently discloses an airflow outlet that is angularly formed toward the rear bottom portion of a support plate
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. The margin is manually urged across the plate, then vertically downward below the plate, and only then does the margin
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enter the airstream. Thus, an operator must manually urge the material across the plate and then vertically downward over the edge of the pate before the margin enters the airstream
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. Only after this manual urging can the airstream fold and direct the margin into position for stitching. However, manual urging of the margin can cause the margin to snag, bunch, or misalign before entering into the airstream.
Additionally, the prior art does not address the problem of maintaining the margin in a proper position after being directed by the airstream. Thus, after the airstream folds and directs the margin but before the stitching process is completed, the margin can become mispositioned. This results in improperly stitched margins.
There is thus a need for a hem former which urges the material toward the needle, directs the material to a proper sewing position and maintains this proper sewing position until the needle has stitched the hem.
SUMMARY OF THE INVENTION
The present invention provides a hem former which uses at least one stream of pressurized air to urge a margin of a material toward a needle, direct the margin to a proper stitching position, and maintain this proper stitching position until the needle has stitched the hem.
One aspect of the invention involves an air-enhanced hem former for folding a margin of a foldable material to be stitched. The hem former has a first, generally U-shaped cavity having first and second legs and a bottom joining the legs. The cavity is sized to allow air to carry the margin through the cavity. At least one outlet opens into the first leg and is directed toward the bottom to introduce an airstream into the cavity. The outlet may be located along the first leg and before the bottom.
The hem former described above may further comprise a second, generally U-shaped cavity having first and second legs and a bottom joining the legs. The second cavity is also sized to allow the airstream to carry the margin through the second cavity. At least one outlet opens into the first leg of the second cavity and is directed toward the bottom of the second cavity to introduce an airstream into the second cavity. The outlet may be located along the first leg and before the bottom of the second cavity. If two such hem formers are used, they are aligned so a margin can be inserted through each hem former, and are spaced apart a distance sufficient to allow a needle to sew the margin between the hem formers.
Another aspect of the present invention includes an air-assisted sewing apparatus comprising a first cavity having a U-shaped portion formed by a first and second generally parallel legs joined by a curved bottom. The first leg has an end opposite the bottom that forms an opening into which the margin is introduced to the cavity. An outlet is in fluid communication with an air source and orientated to introduce an airstream into the first leg directed toward the bottom. The size of the first cavity and the airstream cooperate to move the margin through the cavity to an end of the second leg. Also, a second apparatus having a second cavity constructed as the first cavity, may be used. If used, the second cavity is generally parallel to and separated from the first cavity a distance sufficient to allow a needle to stitch the margin between the cavities.
Yet another aspect of the invention involves a sewing apparatus which has a first passageway with a U-shaped portion formed by a first and second generally parallel legs joined by a curved bottom. The first leg of the U-shaped portion has an end opposite the bottom that forms an opening into which the margin is introduced to the passageway. A first airflow means is in fluid communication with the first leg for moving the margin through the passageway to an end of the second leg. Optionally, the sewing apparatus may further include a second passageway having a U-shaped portion formed by first and second generally parallel legs joined by a curved bottom. If used, the first leg of the second passageway has an end opposite the bottom that forms an opening into which the margin is introduced to the second passageway. A second airflow means in fluid communication with the first leg of the second passageway moves the margin through the second passageway to an end of the second leg of the second passageway. The second passageway may be aligned with the first passageway and separated from the first passageway a distance sufficient to allow a needle to stitch the margin between the passageways.
The present invention also includes a method for folding a margin of a foldable material to be stitched. The method comprises the steps of introducing the margin into a first, generally U-shaped cavity having first and second legs and a bottom joining the legs. Sizing the cavity to allow air to carry the margin through the cavity. Passing air through at least one outlet opening into the first leg and directed toward the bottom to form an airstream in the cavity. Locating the outlet along the first leg and before the bottom, with the airstream moving the margin through the cavity to an end of the second leg opposite the bottom to form the folded margin. Further optional steps may include introducing the margin into a second, generally U-shaped cavity having first and second legs and a bottom joining the legs. Sizing the second cavity to allow air to carry the margin through the second cavity. Passing air through at least one outlet opening into the first leg of the second cavity and directed toward the bott
Izaguirre Ismael
Knobbe Martens Olson & Bear LLP
Orange County Industrial Sewing Machine Co., Inc.
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