Bobbin changer apparatus for sewing machine

Abstract

Transfer mechanism (20) is provided for reciprocally transferring a bobbin grasping device (10), grasping a bobbin case (B) at the distal end of a chuck section (11), between a rotary hook (6) of a sewing machine and a bobbin stock section (8). First cam plate (31) is provided adjacent to one end for orienting the chuck section (11) toward the rotary hook (6) during the transfer, while a second cam plate (41) is provided adjacent to the other end for orienting the chuck section (11) toward the bobbin stock section (8) during the transfer. The cam plates (31, 41) are detachable from the transfer mechanism (20), and, in transportation of the machine, one of the cam plates is transported as an attachment to a main sewing table, while the other plate is transported as an attachment to an extension sewing table. The bobbin grasping device (10) includes a moving body section (13), chuck section (11), and a spring member (19) for normally biasing the chuck section toward a predetermined neutral position.

Description

TECHNICAL FIELD [0001] The present invention relates to a bobbin changer apparatus for automatically replacing a bobbin case having accommodated therein a lower thread bobbin to be mounted in a rotary hook of a sewing machine. BACKGROUND ART [0002] Lower thread change devices are arranged to, when a bobbin, contained in a bobbin case mounted in a rotary hook supported on a rotary hook base, has run out of a lower thread, automatically replace the empty bobbin case with a new bobbin case containing a bobbin with a sufficient lower thread wound thereon, and such lower thread change devices have been known as bobbin changers. In Japanese Patent Application Laid-open Publication No. 2000-157774, there is disclosed a multi-head sewing machine equipped with a plurality of machine heads, where a bobbin changer is provided for each of the machine heads (i.e., for each of the rotary hook bases) and drive mechanisms of the individual bobbin changers are drivable via a same or common drive sou...

AI Technical Summary

Benefits of technology

[0008] In view of the foregoing, it is an object of the present invention to provide a bobbin changer apparatus of a novel construction with various improvements over the conventional counterparts. It is another object of the present invention to provide an easy-to-use bobbin changer apparatus which can readily deal with a difference in traveling distance of a bobbin grasping device. It is still another object of the present invention to provide a bobbin changer apparatus which can be detached and reattached without cumbersome operation even where it is applied to a dividable sewing table.

[0010] Because the first and second orientation change mechanisms, provided on a traveling path of the transfer mechanism, are detachable from the transfer mechanism, the first and second orientation change mechanisms of the same construction can be used even where the transfer mechanism is constructed to be able to deal with any desired reciprocal traveling distances. Thus, even where the traveling distance of the bobbin grasping device differs depending on the depth (dimension in the front-rear direction) of the sewing table, the present invention can appropriately deal with a difference in traveling distance of the bobbin grasping device, without requiring large amounts of time and labor in making of component parts, at relatively low cost, thereby achieving an easy-to-use bobbin changer apparatus with a general versatility. Further, in the present invention, the first and second orientation change mechanisms and the transfer mechanism between the orientation change mechanisms are detachable from each other, and thus, in detachment operation to be performed in the case where the bobbin changer apparatus is applied to a sewing table of a type dividable into a front section and a main section, the first and second orientation change mechanisms can be left mounted to the main and front sections, respectively, of the sewing table with only the transfer mechanism detached. Thus, with the present invention, the detachment operation does not require a great amount of time and labor, and, in reassembly of the machine, there is no need at all for cumbersome position adjustment of the orientation change mechanisms (because the orientation change mechanisms need not be detached in the detachment operation).

[0011] According to another aspect of the present invention, there is provided a bobbin changer apparatus for replacing a lower thread bobbin to be mounted in a rotary hook of a sewing machine, which comprises: a bobbin grasping device for grasping a bobbin case at a distal end of a chuck section; a transfer mechanism for reciprocally transferring the bobbin grasping device between the rotary hook of the sewing machine and a bobbin stock section; a first orientation change mechanism for orienting the chuck section of the bobbin grasping device toward the rotary hook of the sewing machine during transfer, by the transfer mechanism, of the bobbin grasping device toward the rotary hook; and a second orientation change mechanism for orienting the chuck section of the bobbin grasping device toward the bobbin stock section during transfer, by the transfer mechanism, of the bobbin grasping device toward the bobbin stock section, and in which the bobbin grasping device includes a moving body section linearly movable by the transfer mechanism, the chuck section pivotally supported on the moving body section, and a spring member for normally biasing the chuck section toward a predetermined neutral position. Further, in the bobbin changer apparatus of the present invention, the first orientation change mechanism orients the distal end of the chuck section toward the rotary hook against a biasing force of the spring member, and the second orientation change mechanism orients the distal end of the chuck section toward the bobbin stock section against the biasing force of the spring member. The bobbin changer apparatus thus arranged can achieve the superior benefit that it is possible to perform orientation control, i.e. posture control, of the chuck section with a simple construction.

[0012] As an example, the transfer mechanism may include a guide section for guiding the bobbin grasping device through transfer between the rotary hook and the bobbin stock section, and a drive section for reciprocally transferring the bobbin grasping device along the guide section. Thus, the transfer mechanism can be simplified in construction. Each of the first and second orientation change mechanisms has a slanted cam surface, and the bobbin grasping device includes a cam follower in relation to the chuck section. The chuck section may be caused to pivot to appropriately change the orientation of the distal end by the cam follower moving along the cam surface. Thus, the orientation change mechanisms in the present invention can be simplified in construction.

[0013] According to still another aspect of the present invention, there is provided a bobbin changer apparatus for replacing a lower thread bobbin to be mounted in a rotary hook of a sewing machine, which comprises: a bobbin grasping device for grasping a bobbin case at a distal end of a chuck section; and a transfer mechanism for reciprocally transferring the bobbin grasping device between the rotary hook of the sewing machine and a bobbin stock section, and in which the bobbin grasping device comprises: an arm-grasping claw for pulling out a bobbin case arm; a drive section for causing the arm-grasping claw to pivot so as to pull out the bobbin case arm; and an arm-engaging protrusion for engaging with the bobbin case arm having been pulled out by the arm-grasping claw. Thus, the bobbin case grasping structure of the bobbin grasping device can be simplified while still ensuring reliable grasping of the bobbin case.

Problems solved by technology

Where such a bobbin changer is not used, the human operator has to get into under the sewing table and manually change bobbin cases in the rotary hook on the hook base, which is very cumbersome.

With the aforementioned conventional technique, where the guide plate has integrally incorporated therein the mechanisms for changing the orientation of the chuck section at the opposite ends of the transfer stroke, it is necessary to separately make guide plates, having integrally incorporated therein the mechanisms for changing the orientation of the chuck section at the opposite ends of the transfer stroke, in various sizes and constructions suited for various types of sewing machines, which tends to take a lot of time and labor in manufacturing of component parts and therefore result in high cost.

Such operation tends to take a lot of time and labor.

Particularly, because positioning of the bobbin grasping device relative to the rotary hook and bobbin stock section depends on the positions of the orientation-changing mechanisms in the opposite end portions of the guide plate, position adjustment of the guide plate tends to be very time-consuming.

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