Sewing – Special machines – Buttonhole
Reexamination Certificate
2000-03-16
2001-10-09
Izaguirre, Ismael (Department: 3741)
Sewing
Special machines
Buttonhole
Reexamination Certificate
active
06298798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a buttonhole forming apparatus that is provided on a buttonhole sewing machine and forms a buttonhole on a work cloth by stitching a buttonhole and cutting a slit.
2. Description of Related Art
A conventional buttonhole sewing machine comprises a sewing device where buttonhole stitches are made on a work cloth, a cutter that makes a cut between buttonhole stitches made by the sewing device, a cutter driving mechanism that drives the cutter to move vertically, and a supporting device that supports the work cloth thereon having a cutter hole where the top of the cutter is inserted. A buttonhole forming apparatus is thought to be included in such a buttonhole sewing machine.
On this kind of buttonhole forming apparatus, a work cloth is held on the top of the supporting device, in which buttonhole stitches are made, the cutter vertically driven by the cutter driving mechanism is inserted through the work cloth into the cutter hole and then pulled out therefrom. Thus, a cut is made between the buttonhole stitches made by the sewing device, and finally a buttonhole is formed.
So far, a cutter driving mechanism has been arranged in most cases that a driving force of the machine motor is mechanically transmitted to the cutter via a link system, and the cutter cuts the work cloth.
However, application of such a mechanical cutter driving mechanism to a machine provides the cutter with the necessary driving force, but the operation of the cutter is slow, therefore the reduction of the cycle time of the machine is longer than desired.
In addition, currently being developed by the assignee of the instant application, is an air cylinder that can be used to drive the cutter driving mechanism. In this case, the operational speed of the cutter is increased, but the cutting performance of the cutting device cannot be fully assured. Moreover, in another ongoing development, the cutter driving mechanism is driven by a solenoid, the operational speed of the cutter would be expected to be faster, but the cutter may not return to its original position, as it may be kept inserted into the work cloth.
For example, as shown in
FIG. 11
, the needle plate
151
having a cutter hole
167
with the same width as the thickness of the cutter is disposed on the bed of the buttonhole sewing machine as the supporting device. A buttonhole is formed on a work cloth placed on the top
151
a
of the needle plate
151
. In this case, the sewing device, such as a needle (not shown), forms buttonhole stitches in ranges indicated by A on both sides, a top of the cutter
13
is inserted into the cutter hole
167
to cut the work cloth, and a buttonhole is defined. However, as is obvious from
FIG. 11
, the work cloth W may be caught between the cutter hole
167
and the edge of the cutter
13
, and the cutter
13
may not be returned to its original position only by the action of an air cylinder or a restoring spring of the solenoid (not shown).
This problem of catching of the work cloth is thought of as the use of an air cylinder or solenoid cannot secure the required cutting performance. Therefore, if the cutter driving mechanism is arranged using the air cylinder or the solenoid, the cycle time can be reduced but buttonholes can not be correctly formed on a thicker material.
SUMMARY OF THE INVENTION
The invention was made in consideration of the above circumstances. It is an object of the invention to provide a buttonhole forming apparatus for a sewing machine that can form buttonholes correctly and smoothly on a thick and heavy cloth and fully realize a cycle time reduction in the buttonhole forming process.
The buttonhole forming apparatus, which has been designed so as to accomplish the object, comprises a cutter that cuts a buttonhole slit on a work cloth, a cutter driving mechanism that drives the cutter, a supporting plate that supports the work cloth thereon, and a guide that guides the cutter, the guide being disposed on the supporting plate and defining a hole formed therethrough into which an edge of the cutter is inserted, at least a part of the guide being made of an elastic member. The elastic member is disposed around the hole on the supporting plate that supports the work cloth thereon. The elastic member allows the hole to gradually enlarge as the edge of the cutter goes into the hole. Therefore, the width of the hole can be originally set as small as possible so as not to clog a work cloth in the hole. When a buttonhole slit is made in the work cloth, the cutter goes into the hole and the hole is gradually enlarged. Therefore, the work cloth is not retained in the hole. Buttonhole slits can be made on a thick and heavy cloth correctly without any interruption from the work cloth being retained in the hole. In addition, the load placed on the cutter driving mechanism can be reduced, therefore, a solenoid can be used in the cutter driving mechanism. As a result, the invention provides appropriate buttonholes on a thick and heavy cloth, and realizes the cycle time reduction fully.
In a preferred aspect of the invention, a hard material is used for a peripheral edge portion around the hole of the guide. The hard material that defines the hole is movably disposed in a direction of the cutter width. The elastic member moves the hard material outward in the width direction as the edge of the cutter is inserted into the hole. In other words, when the edge of the cutter or a part of the work cloth, which is to be cut, makes contact with the elastic member, the elastic member is deformed, causing the hard material to move outward and the width of the hole to be enlarged. Because of this, the hole can be enlarged with stability even if the cutter becomes dull. Furthermore, the hole is hardly deformed due to abrasion even if it is repeatedly used. Therefore, the stable cutting performance and prevention of the work cloth from clogging in the hole can be obtained for a long time.
In another preferred aspect of the invention, the elastic member of the buttonhole forming apparatus is made of rubber. Because the rubber serves as a tight seal, dust of thread scraps, which is generated normally after the cutter cuts a buttonhole slit on the work cloth, is little clogged in the hole. Therefore, the function of the elastic member that enlarges the hole can be obtained for a long time with greater stability. This also ensures stable cutting performance and prevents the work cloth from remaining clogged in the hole for a long time. The arrangement and assembling operation for attaching the rubber around the hole, and maintenance including cleaning can be extremely simplified, comparing with the case where the other member, such as a spring, is used. As a result, the cost of manufacturing can be reduced.
In a further preferred aspect of the invention, the rubber defines a hollow at a bottom surface thereof. The rubber as the elastic member has a plurality of hollows that improve its flexibility. This can ensure the stable cutting performance and prevention of the work cloth from remaining clogged in the hole for a long time. Therefore, the load placed on the cutter driving mechanism can be reduced, bringing a further cycle time reduction. Because the hollows are not open through the top of the supporting plate, dust of thread scraps will not fall from the supporting plate to the hollows.
In another preferred aspect of the invention, the cutter driving mechanism includes a solenoid that drives the cutter. Therefore, the operational speed of the cutter can be speeded up. As a result, the cycle time reduction can be fully realized.
In a further preferred aspect of the invention, the buttonhole forming apparatus further comprises a fixing member that maintains the guide in fixed position with respect to the supporting plate. This prevents the elastic member and hard material from rising from the supporting plate after the cutter makes a buttonhole slit on a cloth. Therefore, dust of threads can be kept from going under the elastic member or hard mater
Funahashi Akihiro
Gamano Jun
Kondo Takashi
Nomura Etsuzo
Shibata Itaru
Brother Kogyo Kabushiki Kaisha
Izaguirre Ismael
Oliff & Berridg,e PLC
LandOfFree
Buttonhole forming apparatus for sewing machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Buttonhole forming apparatus for sewing machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Buttonhole forming apparatus for sewing machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2577744