Sewing – Special machines – Buttonhole
Reexamination Certificate
1998-12-22
2001-01-30
Izaguirre, Ismael (Department: 3741)
Sewing
Special machines
Buttonhole
C112S291000
Reexamination Certificate
active
06178902
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thread-cutting device for an eyelet buttonhole sewing machine according to the preamble of claim
1
.
An eyelet buttonhole sewing machine of the generic type became known as Exhibit 30 at the IMB Fair of 1997 in Cologne as D{umlaut over (u)}rkopp Adler Class 578-113221 E831 (recently designated as Cl. 578-113221 E1831), with which a stitch row is produced which is designed in the shape of a zig-zag and in alternating fashion as a single chain and double chain stitch seam. The eyelet buttonhole sewing machine includes rotatable sewing tools, including a rotatable looper support arranged below the support for the material to be sewn. It is possible to rotate the sewing tools and the looper support about an axis extending parallel to the longitudinal axis of the sewing needle. A thread cutter is arranged on the rotary looper support and is constructed with one thread-cutting tool for the needle thread and with another thread-cutting tool for the looper thread. Each thread-cutting tool can be moved independently of the other and may be operated via separate drives. Required movements for the thread-cutting tools are initiated by producing the drive connection from the thread-cutting tools to the drives arranged in a stationary fashion on the sewing machine frame in a defined rotary position of the looper support. Consequently, the thread-cutting device and/or the individual thread-cutting tools can be driven only subsequently, thus lengthening the machine cycle.
In principle, movement is initiated for a thread cutter of an eyelet buttonhole sewing machine as disclosed in DE-C 631 138.
Furthermore, disadvantages relating to application or use are entailed by the design described. Thus, even when laying out a seam, it is necessary for its end to always be aligned and/or arranged such that the looper support assumes the rotary position which permits thread cutting. In specific applications this leads to limitations which impair the appearance of a buttonhole produced. Furthermore, specific seam shapes, for example, a lacing hole, can cause limitations with regard to the position of the lacing hole relative to the actual part of the material to be sewn, and thus cause a reduction in quality.
There is further difficulty when it is intended to use the main cam plate for the thread-cutting device, as that plate rotates by only a few angular degrees. The eyelet buttonhole sewing machine may not receive the required drive movement at the end of the sewing operation.
The number of components which are required for the drive linkage to operate the thread-cutting device is also disadvantageous, including the required couplings for producing the drive connection in the defined position of the looper support relative to the machine housing and to the drives mounted thereon.
SUMMARY OF THE INVENTION
It is an object of the present invention to develop a thread-cutting device of the type useful for an eyelet buttonhole sewing machine such that its thread-cutting tools can be driven in any rotary position of the looper support.
This object is achieved with a thread cutting device for an eyelet buttonhole sewing machine. The machine includes a looper support that is rotatable about an axis and that is for receiving a looper thread that is fed to the support. A needle also extends essentially on the axis and is for receiving a needle thread. There is a first thread cutting tool for the needle thread, and a second thread cutting tool for the looper thread which are both mounted on the looper support and which are both moveable with respect to the looper support. There is a first drive for the first thread cutting tool, a second drive for the second thread cutting tool and both of the drives are on the looper support. An energy supply device supplies the first and second drives with energy.
The invention is distinguished by the following advantages:
the thread cutter can operate irrespective of the looper support,
the machine cycle period can be shortened by overlapping operations of the looper support rotation and the thread cutter drive,
enhancement of the stitch pattern quality by removing any restrictions in the structural design of a stitch pattern to be produced, as well as its arrangement in the part of the material to be sewn,
a low number of components required, lowering production costs and enhancing reliability,
the thread-cutting device is a perfect component of the looper support, making the looper support a cost-effective unit which can be preassembled.
A sewing unit from KSL GmbH Keilmann discloses an arrangement of a drive device on the looper support, which can be rotated about a spindle, for operating a thread cutter. A sewing unit in which a rotatable sewing head is always aligned tangential to the course of the seam is disclosed in a brochure KL 110 CNC Sewing Unit with rotating sewing head, Impressum j/11Obrief, Nov. 5, 1996, and the associated description pages 2 and 3 of the CNC sewing unit from KSL GmbH Keilmann. As is further described and as is known from public presentations of such machines at fairs, the sewing head can be configured with a double lock stitch or double chain stitch design and with a thread cutter arranged on the rotary looper support. In this case, a pneumatic cylinder arranged on the looper support operates a single thread-pulling and thread-cutting tool gripping the needle thread and looper thread. This prior art does not suggest using separate drive devices to drive the thread-cutting tools required for the needle thread and the looper thread in the case of an eyelet buttonhole sewing machine.
The invention permits the supply of energy from a stationary energy source via at least one line. An energy supply which can be subjected to high loads is achieved with a hollow shaft that extends around the axis and through which the at least one line extends. Providing at least one of the drive devices with a pneumatic cylinder for drive purposes leads to a simple and operationally reliable drive device by means of which it is possible to achieve relatively high forces with respect to its required overall volume. When that pneumatic cylinder is constructed as a double action pneumatic cylinder, this leads to a drive for a thread cutter which can be subjected to greater loads. Having one of the drive devices as a single action pneumatic cylinder and the other as a double action pneumatic cylinder yields the advantage of a simple and yet separate control of the individual pneumatic cylinders. Mounting the pneumatic cylinders on the looper support so that their axis or axes extend parallel to the main axis leads to a space-saving design. The looper support has a flange which extends radially relative to the axis and the pneumatic cylinder is fastened on the flange. This has design advantages for arranging the drive devices. Constructing the lines as elastic hoses leads to a cost-effective and reliable operating solution for connecting the drive devices to a stationary compressed air source. Providing a rotary bushing for delivery of compressed air from the stationary energy source to the drive devices permits complete freedom of movement with regard to the rotary position of the looper support with the thread-cutting tools arranged thereon. This has the advantage that it is possible to achieve desired rotary positions of the looper support in a minimum time.
It is known from DE 34 11 178 C2 (corresponding to U.S. Pat. No. 4,594,954) to feed compressed air from a stationary compressed air source to a rotary housing via a rotary bushing.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 1373227 (1921-03-01), Fifield
patent: 1705044 (1929-03-01), Carlson
patent: 1991627 (1935-02-01), Reece
patent: 2020779 (1935-11-01), Grip
patent: 2499335 (1950-02-01), Spaine
patent: 2707927 (1955-05-01), Artzt et al.
patent: 4404921 (1983-09-01), Kastrup et al.
patent: 4594954 (1985-02
Kastrup Eberhard
Noltge Thomas
D{umlaut over (u)}rkopp Adler Aktiengesellschaft
Izaguirre Ismael
Ostrolenk Faber Gerb & Soffen, LLP
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