GB2237294A

GB2237294A - A looper throw-out mechanism on a sewing machine

Info

Publication number: GB2237294A
Application number: GB9023391A
Authority: GB
Inventors: Hermann Gauch
Original assignee: Union Special GmbH
Current assignee: Union Special GmbH
Priority date: 1989-10-27
Filing date: 1990-10-26
Publication date: 1991-05-01
Also published as: DE3935779C1; IT9067823A1; IT9067823A0; IT1247767B; JPH03168179A; GB9023391D0; FR2653791A1

Abstract

A sewing machine has a looper shaft (37) which executes a pivoting and sliding movement, a flange (23) fastened on the looper shaft (37) and a looper holder (36) co-operating with the flange (23), there is also provided a looper throw-out mechanism using a looper (40) which can be pivoted out of a sewing position into a threading position. An intermediate transmission (28) is associated with the looper holder (36) and the flange (23) and is formed in such a way that its transmission movements are substantially parallel to the pivoting plane of the looper (40). The intermediate transmission has a lock-in position. <IMAGE>

Description

DESCRIPTION A LOOPER THROW-OUT MECRANISM ON A SEWING MACHINE

The invention relates to a looper throw-out mechanism on a sewing machine of the type having at least one looper and one needle, a looper shaft which executes a pivoting and sliding movement, a flange fastened on the looper shaft and a looper holder which co-operates with the flange and which can be pivoted out of a sewing position into a threading position.

Such a mechanism is known from US PS 4,671,195. This patent specification discloses a looper shaft which executes a pivoting and sliding movement, and a fork-shaped part which is fastened on a looper holder and cooperates with a disc (flange). which has stops and is fastened on the looper shaft, in such a way that the pivoting movement of the looper holder towards the threading position and towards the sewing position is limited. In order to secure the looper holder in one of the two positions, this mechanism has a manually operated lever with which the looper holder is clamped by means of a screw onto the looper shaft or detached from it. The pivoting movements of the lever take place in a plane which is parallel to the looper shaft. When this mechanism is operated properly, its function is completely fulfilled, although, if the lever ús not tightened properly,

1 -2there is a risk that the looper holder will become detached from the looper shaft. Following actuation of the sewing machine, this may lead to movement or even damage of the mechanism, since in such case the forkshaped part knocks in an uncontrolled manner against the stops of the disc.

It is an object of the present invention to provide a looper throw-out mechanism with operationally reliable engagement of the looper holder in the sewing position.

In accordance with the present invention, a looper throw-out mechanism comprises at least one looper and one needle, a looper shaft adapted to execute a pivoting and sliding movement, a flange fastened on the looper shaft, a looper holder which co-operates with the flange and which can be pivoted out of a sewing position into a threading position, and an intermediate transmission, having a lock-in position, and which is associated with the looper holder and the flange and is formed in such a way that its transmission movements are substantially parallel to the pivoting plane of the looper.

Using an intermediate transmission, which is associated with the looper holder and the flange and is formed in such a way that its movements are substantially parallel to the pivoting plane of the t, f.

-3-. looper, wherein the intermediate transmission has a lock-in position which corresponds to the sewing position of the looper holder and hence also of the looper, produces the great advantage that damage to the looper throw-out mechanism is avoided even when the looper is not engaged in its sewing position. Because of the mass inertia of the moving parts, the looper throw-out mechanism pushes the looper holder, following actuation of the sewing machine, into its sewing position due to the pivoting movement of the looper shaft.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:

Fig.1 is a front view of a part of a sewing machine having one embodiment of a looper throw-out mechanism in accordance with the present invention in the sewing position; Fig.2 is a front view of a part of a sewing machine wherein the looper throw-out mechanism of Fig.1 is in the threading position; Fig.3 is a side view of a part of a sewing machine having a looper throw- out mechanism in the sewing position; Fig.4 is a perspective view of a looper throw-out mechanism; Fig.5 is a front view of a part of a sewing machine having a further embodiment of a looper throwout mechanism in accordance with the present invention in the sewing position; and Fig.6 is a front view of a part of a sewing machine having the looper throw-out mechanism of Fig.5 in the threading position.

Fig.1 shows a part of a chain stitch sewing machine 10 having a looper throw-out mechanism. The sewing machine 10 has a lower part 12, a working surface 14 and a needle plate 15. At least one needle 16 is fastened by a screw 17 in a needle head 18, which is disposed at the end of a needle bar which moves up and down.

A cover plate 21, which is fastened to the lower part 12 by three screws 22, is disposed beyond a flange 23 which has a stop 24. An intermediate holder 25, which is adjustably secured on the flange 23, carries a catch 27, which is pivotable about a spigot 26 and is part of an intermediate transmission 28. The catch 27 is supported in a lock-in position 33 by a face 29 on a spigot 32 having a counter-face 31. A guide plate 34 is fastened on the intermediate holder 25 by a nut 35 and guides a looper holder 36, which is mounted so as to be pivotable about a screw 38 eccentrically to a looper shaft 37 on the flange 23.

C -5The flange 23 is clamped by a screw 39 onto the looper shaft 37. A looper 40 is fastened by a screw 411o the upper end of the looper holder 36; at.the lower end there is disposed the spigot 32 which brings about, together with the face 29 of the catch 27, the lock-in position 33 of the intermediate transmission 28, which corresponds to the sewing position of the looper 40. A dotted outline 42 shows the catch 27 in pivoted-out position, which permits the looper holder 36 to pivot into its threading position, which is shown in Fig.2.

In its threading position, the looper holder 36 is supported by a concave face 43 on the intermediate holder 25, which carries a spring 44, whose free end abuts resiliently against the catch 27. The catch 7 is supported in turnby a concave face 45 on the counter-face 31 of the spigot 32. The intermediate transmission 28 contains the intermediate holder 25, the spigot 26, the catch 27, the spigot 32 and the spring 44.

Fig.3 shows a known looper drive device 46 which imparts the sliding and pivoting movement to the looper shaft 37 and hence to the flange 23. The intermediate holder 25, in which the fastening to the flange 23 is eccentric to the spigot 26, is fastened by a nut 47 to the flange 43. The eccentricity on the -6intermediate holder 25 permits adjustment of the face 29 of the catch 27 towards the counter-face 31 of the spigot 32 (Fig.1). A stop 48 of the spigot 32 abuts against the flange 23 when the looper 40 is in the sewing position. The pivoting movement of the looper holder 36 takes place about a bushing 49, which is clamped by means of the screw 38 with the guide plate 34 against the flange 23. A known presser device 51 is disposed above the needle plate 15 and supports a workpiece 52 to be sewn.

The individual parts of the intermediate transmission 28 disposed between the flange 23 and the looper holder 36 are shown in Fig.4 in perspective.

By actuating the catch 27 in an anti-clockwise manner and simultaneously pivoting the looper holder 36 in a clockwise direction, the looper holder 36 is thrown or moved from its sewing position (Fig.1) into its threading position (Fig.2). The pivot travel of the looper holder 36 is in such case limited by the intermediate holder 25, and the pivot travel of the catch 27 is limited by the stop 24. Following release of the catch 27. it pivots as a result of the spring loading into the position shown in Fig.2.

The looper holder 36 is engaged in its sewing position by pivoting manually the looper holder 36 in an anti-clockwise direction until the counter-face 31 il -7of the spigot 32 comes into contact with the face 29 and the spigot 48 abuts against the flange 23. Pressing down the catch 27 further secures the intermediate transmission 28 in its lock-in position 33. since the face 29 prevents the looper lever 36 from pivoting back. The intermediate transmission 28 engages in its lock-in position 33 whether the sewing machine is actuated intentionally or unintentionally, such that damage to the looper throw-out mechanism is avoided.

Figs. 5 and 6 show a further embodiment incorporating the present invention. Parts which correspond to the above-described mechanism have been given the same reference numerals.

A flange 23A is clamped by the screw 39 onto the looper shaft 37 and carries an intermediate transmission 28A. The flange 23A has a hollow shaft 61, which is disposed concentrically to the looper shaft 37 and on which a looper holder 36A is mounted coaxially relative to the looper axis 37 on the flang 23A. A looper holder rod 62 is pivotally fastened by a screw 63 to the looper holder 36A and is connected in a form-locking mapner by way of a joint 64 to a flange rod 65, which is in turn articulated to a spigot 66 of the flange 23A. The intermediate transmission 28A contains the looper holder rod 62, -8the screw 63, the joint 64, the flange rod 65 and the pin 66. A stop 67, which is adjustably mounted on the flange 23A, limits the pivot travel of the looper holder 36A. The looper holder 36A may be sealed axially to the flange 23A by a split adjusting collar 68, which is clamped by a screw 69 onto the hollow shaft 61. The looper holder 36A carries two loopers 40 which co-operate with two needles 16.

The looper holder 36A is thrown out of its sewing position (Fig.5) into its threading position (Fig.6) by actuating the joint 64 in the clockwise direction. In the threading position, the looper holder 36A is supported on the joint 64. The looper holder 36A is engaged in its sewing position by pivoting the two rods 62 and 65 in the anti-clockwise direction into their extended position. In such case, the looper holder 36A pivots towards the stop 67. In this case too, the looper holder 36A can be engaged into its lock-in catch position 33A either manually or by operating the sewing machine. Due to the mass inertia of the parts, the intermediate transmission 28A is urged into its lock-in position 33A.

Claims

-gCLAIMS

1. A looper throw-out mechanism on a sewing machine, comprising at least one looper and one needle, a looper shaft adapted to execute a pivoting and sliding movement. a flange fastened on the looper shaft, a looper holder which co-operates with the flange and which can be pivoted out of a sewing position into a threading position, and an intermediate transmission, having a lock-in position, and which is associaed with the looper holder and the flange and is formed in such a way that its transmission movements are substantially parallel to the pivoting plane of the looper.

2. A looper throw-out mechanism as claimed in claim 1, wherein the looper holder is pivotally mounted eccentrically to the looper shaft on said flange, the flange carrying a catch which is supported, when the intermediate transmission is in the lock-in position, by the engagement of a first face on the catch with a counter-face carried by the looper holder, and which positions the looper in the sewing position.

3. A looper throw-out mechanism as claimed in claim 2, wherein a spring is associated with the catch.

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4. A looper throw-out mechanism as claimed in claim 2 or 3, wherein the looper holder has a stop which limits the pivoting movement of the looper holder towards the needle.

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5. A looper throw-out mechanism as claimed in claim 1, wherein the looper holder is pivotally mounted on the flange coaxially with the looper axis and wherein a looper holder rod and a flange rod form a transmission between the looper holder and the flange.

6. A looper throw-out mechanism as claimed in claim 5, wherein the flange has a stop which limits the pivoting movement of the looper holder.

7. A looper throw-out mechanism substantially as hereinbefore, described. with refeience to and as illustrated in the accompanying drawings.

Published 1991 at7be Patent Oflice.St2teHouse.66/71 High Holbom. LndonWCIR4fP- Further copies may be obtained from Sales Branch, Unit 6. Nine Mile point. Owmfelinfach, Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray. Kent.