Sewing – Elements – Frames
Patent
1993-04-12
1995-01-10
Nerbun, Peter
Sewing
Elements
Frames
1122622, 112 63, 11212114, D05B 300
Patent
active
053797086
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of forming three-dimensional envelopes from blanks.
Usually, sewn three-dimensional envelopes are manufactured by laying flat the blanks to be sewn together in a sewing machine and by passing them under the sewing foot of the sewing machine. The edges of the blanks are provided with marks which have to be placed matchingly one upon the other. This kind of sewing requires a high degree of skill. Nevertheless, it cannot be avoided that the blanks are displaced relative to each other during sewing which results in wave formations and gatherings in the envelope during manufacture.
The performance facilities of the sewing machine are not utilized owing to the relatively slow manual control.
From DE 33 38 405 A1, a method for manufacturing three-dimensional envelopes of articles provided with sewn seams is known, wherein blanks are fastened to a three-dimensional carrier body and a sewing machine fastened to a manipulator arm is moved along the intended seam line. The edges of the blanks are laid flat, one upon the other, on the carrier body, and the needle of the sewing machine is pierced through the edges into the carrier body. This requires the introduction of a rotating gripper into the interior of the carrier body for producing the seam.
In another method known from EP 0 344 400 A1 for sewing an arm sleeve into a jacket, the sleeve is inserted into the reversed jacket such that the edge of the sleeve opening is laid from the inside against the edge of the jacket opening (armhole). For sewing, a sewing machine is led around the edges lying together, the needle plate with the rotating gripper arranged beneath being introduced into the opening. A problem that arises is that the outer edge and the inner edge which is enclosed by the outer one have different diameters during the sewing process so that these edges, one lying within the other, are subject to forces.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a method of and a device for forming three-dimensional envelopes, which, independently of the accuracy of the blanks to be sewn together, permit a manufacture of the envelope with a correct shape and size.
In German Patent Application P 41 02 840 (not prepublished), a method is described in which the seam is produced along the root line formed by the kink line of the edges.
In the method according to the present invention, the two blanks are laid on the carrier body such-that their edge portions abut face to face and form a double flange portion. The blanks which are positioned on the carrier body in this way are sewn together with at least one sewing machine along their edge portions lying together and projecting obliquely from the carrier body, which sewing machine makes the seam along the root line. Thus, not only a fast and exact positioning of the blanks to be sewn together is possible but also a proper creating of the seam without any creases or drawing.
The edges project obliquely from the two support surfaces, i.e. they form an angle with each one of these support surfaces, which is larger than 0.degree. and smaller than 90.degree., preferably 45.degree.. The intended seam line along which the needle of the sewing machine is guided extends exactly along the root line of the double flange portion formed by the abutting edge portions of the blanks, i.e. along the kink lines of the edge portions of the blanks. Subsequently, the work piece can be reversed so that the abutting edge portions of the blanks forming the double flange portion lie in the interior of the work piece. When manufacturing three-dimensional envelopes of plane blanks, this results in different lengths for the seam lines at the outer and the inner blank in the seam region. In the method according to the invention, both blanks are opposed in a form so that this length difference is created without any force. Any inaccuracies which might arise when manufacturing the blanks, or subsequent changes in their dimensions, do not have any influence on the
REFERENCES:
patent: 4756261 (1988-07-01), Gershoni
patent: 4862815 (1989-09-01), Thurner et al.
patent: 4905615 (1990-03-01), Pofferi
patent: 5163376 (1992-11-01), Frye
Behrens Hans
Moll Philipp
Moll Automatische Naehsysteme GmbH i.g.
Nerbun Peter
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