US3232258A

US3232258A - Rotating sewing machine hook

Info

Publication number: US3232258A
Application number: US246043A
Authority: US
Inventors: Jr Fritz Gegauf
Original assignee: Fritz Gegauf AG
Current assignee: Fritz Gegauf AG
Priority date: 1962-01-10
Filing date: 1962-12-20
Publication date: 1966-02-01
Anticipated expiration: 1983-02-01
Also published as: DE1201666B; AT241253B; GB1025239A; CH390035A

Description

Feb. I, 1966 F. GEGAUF, JR

ROTATING SEWING MACHINE HOOK Filed Deo. 20, 1962 2 r fl A ,ww/

Ma fm United States Patent Oiitice Patented Feb. l, i966 3,232,258 RUE'ATENG SEWENG MACHHNE HGK Fritz Gegauf, fr., Steckleorn, Thurgau, Switzerland, asf

signor to Fritz Gegauf Ahtieugesellschaft Bernina- Nahniaschinenfabrik, Steckhorn, Thurgau, Switzerland lFiled Dec. 20, 19.62, Ser. No. 246,043 Claims priority, application Switzerland, ian. 10, 1962, 249/62 4 Claims. (Cl. 112--228) The prime object ofthe present invent-ion is to realize a rotating sewing machine hook that cannot jam the thread and consequently block the sewing machine.

There are sewing machine hooks known in the art that have on4 three sides guiding paths rotating about the counter path of the bobbin case support which is stationary during the sewing operation. The play between the guiding surfaces of the hook and of the bobbin support is smaller in axial direction than it is in radial direction in order to ascertain for a safe taking-over of the loop at the needle. In both directions this play always is smaller than the thickness of the threads to be sewn. Such guiding paths have the great disadvantage that upon a wrong thread supply which does not correspond to the actual need the upper thread is drawn into the hook path. Such faulty thread supply appears particularly at the beginning of the sewing due to an incorrect attendance. As a result of such wrong thread supply, the upper thread drawn into the path of the hook is jammed in the guiding path of the bobbin support and blocks the whole machine.

This blocking is the stronger the thicker the upper thread is. In most of such cases of jamming, it is necessary to disassemble the hook in order to remove thread rests. This operation is very complicated and may be eifected only by an operator to whom such operation has been taught. In order to prevent such blocking, it has already been proposed to provide the guiding path of the bobbin support with thread cutting grooves. Such cutting grooves were intended to sever the jammed thread so as to enable upon further sewing the thread rests to be removed from the guiding path. However, this step has not been successful in practice. Also reduction of the supporting portion of the running surfaces was unsuccessful since even reduced guiding surfaces proved to be able to jam the thread and to block the machine. In order to remove these latter drawbacks it has also been proposed to make the axial guiding paths fof the hook resilient. Such hooks are constructed in such manner that the guiding cover enclosing the hook shells is made resilient and easy to disassemble. Radially extending longitudinal slots are provided on the cylinder shell at the points where the guiding cover is secured. These slots are intended to make possible for this cylinder shell to give way in axial direction. Now the resiliency of a cylindrical body provided with several radial slots is very small and further this system may not be applied in many hooks so that even with such hooks blocking of the machine may not be safely prevented. As well for the manufacturer as also for the retailer and buyer `of sewing machines with hooks of the above type, time losses and costs are involved for teaching the operator the correct attendance of the machine.

In the sewing machine according to the present invention such blocking is effectively prevented owing to the fact that an axial guiding surface of the guiding may give way to such an extent that the hook may entrain any thread that has penetrated into the path through the whole guiding. Thus the costly teaching of the retailer and buyer may be dispensed with, which obviously is a substantial technical progress.

This progress is realized according to the invention in a rotating sewing machine hook having a support for the lower thread bobbin and a guiding path therefor, by forming at least one axial guiding of the hook as a radially resilient split tension ring adapted to move axially to prevent blocking of the hook at the thread insert.

Other features and advantages of the invention will become apparent from the description now to follow of a preferred embodiment thereof, given by way of example only, and in which reference will be made to the accompanying drawing, in which:

FIGURE 1 is a front View of a rotating, sewing machine hook.

FIGURE 2 is a longitudinal section throughv the hook taken along the line lI-II in FIGURE l;

FIGURE 3 is a partial section through the tension ring of the hook, and

FIGURE 4 is a perspective view of a disassembled hook.

The drawings illustrate the invention as incorporated in a rotating sewing machine hook such as used in known sewing machines designed for making straight, zig-zag, or ornamental stitches. For example, the particular conventional sewing machine parts illustrated are parts of the universally known BERNINA sewing machine, but are likewise representative, essentially, of corresponding constructions used in other conventional sewing machines.

ln the drawing, reference numeral 1 designates the hook shaft projecting from the base plate of the sewing machine (not shown). On this shaft is secured the hook 2 with its hub 3 by means of a screw 4. The hook tip 5 takes the upper thread from the needle (not shown). On the side of the hub 3 there is secured a hook disk 6 by means of a screw 7. The hook 2 is formed with an axially extending annular surface 8 and a radially extending annular surface 9 as well as a proled tension ring 11 the plane surface l@ of which forms a second radially extending annular surface. This guiding 8, 9, 10 receives a bobbin case support 12 having a threesided guiding crown 13 and a holding member 14. The split tension ring 11 is lodged in the conical groove formed between a bevelled or conical bearing surface 15 and a horizontal surface 16. At the end of the tension ring 1l. there is arranged a cranked tap i7 engaging a groove 1S in the hook 2 in order to stop the hook, i.e. to prevent the ring l1 from rotating relative to the hook 2. To the hook 2, there is further secured by means of two screws Ztl a member i9 destined to deflect the loop. The deector 21 of the member projects beyond the hook tip in order to ascertain a safe loop formation. The stem or tap 22 of the bobbin case support 12 carries the bobbin case 23 having a locking means 24. The hollow space of the bobbin case 23 receives the lower thread bobbin 25.

When the machine is used to sew, the described hook 2 operates in a manner known per se by running about the bobbin case support l2 locked at the holding member 14 and cooperating with the stitch formation elements of the sewing machine (not shown) and more particularly with the needle. The hook tip 5 takes the upper thread from the needle in form lof a loop, widens this loop and guides the thread about the bobbin case 23 whereby the tensioned lower thread is passed through the loop as is well known. The hook disk or washer 6 serves as a support for the upper thread loop. The loop deiiecting member i9 prevents the lower thread from being seized by the hook tip 5. Finally the upper thread is lifted by the take-up lever (not represented) so as to terminate the stitch. This cycle is repeated at each stitch.

If now the upper thread for example due to a wrong operation of the machine at the beginning of the sewing is drawn into the guiding

paths

8, 9, 10 of the hook 2 the actual guiding surface 10 -of the tension ring 1l may give way in accordance with the pressure produced and depending on the strength of the thread. The tension ring 11 climbs along the annular bevel surface 15 thereby reducing its diameter and affording for suicient play to permit the jammed thread to be entrained by the hook 2 and to be evacuated at the open point. Thereby the jamming of the upper thread between the guiding

paths

8, 9, 10 of the hook 2 and the guiding 13 of the bobbin case support 12 leading in machines having rigid guidings to a blocking thereof, is effectively prevented. The tension ring 11 gives way in response to the strength of the used thread. As soon as the thread rests have been removed the proled tension ring 11 comes again to rest with its plane surface 10 on the horizontal surface 16 of the hook 2 since the ring 11 is always and automatically pressed into this base position by the bevelled surface 15.

I claim:

1. In a freely rotating sewing machine hook, a hook body; a lower thread bobbin-case carrier having an annular peripheral bearing rib; an annular track for said bearing rib formed by an internal annular shoulder in said hook body and a guard ring in said hook body cooperable with said shoulder and axially spaced therefrom; said ring forming the axially outer part of said track and being adapted to yield resiliently for axially outward displacement relative to the hook body; said guard ring comprising a split ring mounted axially inwardly of and engaging a conical inner bearing surface in said hook body, said conical bearing surface converging in a direction axially outwardly of said hook body.

2. In a freely rotating sewing machine hook as claimed in claim 1, said split ring having a cross sectional shape such as to provide a line Contact with said conical inner bearing surface of said hook body.

3. In a freely rotating sewing machine hook as claimed in claim 1, said hook body being formed with a radially extending plane bearing surface intersecting said conical inner bearing surface, and said ring having a plane surface engaging said radial plane surface whereby to determine the Width of said track.

4. In a freely rotating sewing machine hook, as claimed in claim 1, said hook body being formed with a radial recess; a free end of said split ring being bent for engagement into said radial recess for restraining relative rotation of said hook body and said split ring.

References Cited by the Examiner UNITED STATES PATENTS 2,065,349 12/1936 Southam et al 112-228 2,452,167 10/1948 Wainwright 112-228 2,743,689 5/1956 Ruemmler 112-228 2,773,464 12/1956 Rabezzana 112-228 2,857,869 12/1958 Odermann 112-228 3,097,619 7/1963 Cerliani 112-228 JORDAN FRANKLIN, Primary Examiner. DAVID I. WILLIAMOWSKY, Examiner.

Claims

1. IN A FREELY ROTATING SEWING MACHINE HOOK, A HOOK BODY; A LOWER THREAD BOBBIN-CASE CARRIER HAVING AN ANNULAR PERIPHERAL BEARING RIB; AN ANNULAR TRACK FOR SAID BEARING RIB FORMED BY AN INTERNAL ANNULAR SHOULDER IN SAID HOOK BODY AND A GUARD RING IN SAID HOOK BODY COOPERABLE WITH SAID SHOULDER AND AXIALLY SPACED THEREFROM; SAID RING FORMING THE AXIALLY OUTER PARTLY OF SAID TRACK AND BEING ADAPTED TO YIELD RESILIENTLY FOR AXIALLY OUTWARD DISPLACEMENT RELATIVE TO THE HOOK BODY; SAID GUARD RING COMPRISING A SPLIT RING MOUNTED AXIALLY INWARDLY OF AND ENGAGING A CONICAL INNER BEARING SURFACE IN SAID HOOK BODY, SAID CONICAL BEARING SURFACE CONVERGING IN A DIRECTION AXIALLY OUTWARDLY OF SAID HOOK BODY.