EP1913190B1 - Method and apparatus for operating a thread-processing machine having a thread-cutting device - Google Patents

Abstract

The present invention relates to a method and an apparatus for operating a thread-processing machine having a thread-cutting device. In order to provide a method and a corresponding apparatus for operating a thread-processing machine having a thread-cutting device, which achieves improved results with increased operational reliability in comparison with known apparatuses and methods, it is proposed that the processed product (3) is covered with an articulated or flexible protective element to protect the surface of the sewn product in a region around a thread (2) which is to be severed only after the thread-processing operation is ended, and the thread-cutting device (4) is moved onto a cutting point and is positioned for cutting relative to the protective element.

Description

The present invention relates to a method and apparatus for operating a yarn processing machine having a thread cutting device.

The term thread processing machine in the context of the present invention in addition to sewing machines and knitting and weaving machines or other machines understood. Various approaches are known in the art, e.g. in the case of sewing machines in industrial use, to provide an independently operating additional device for cutting upper and / or lower threads after completion of a respective sewing operation. As a rule, during a machine revolution, which is additionally slowed down by a positioning motor, at least one thread to be cut is caught with special gripping and holding fingers. After reaching standstill of the machine in an upper dead center dead center, the thread is cut by a knife, a pair of scissors, a punch or similar instrument.

In the following, the invention will be illustrated without limiting its field of application using the example of industrial sewing machines or short sewing machines. Robust and heavy industrial sewing machines are particularly used as short seam sewing machines but also in various forms of load or seat belts use when sewing garniture, when sewing buckle caps, loops, suitcases, tarpaulins, backpacks, backpacks or similar at least partially made of heavy fabric, plastic materials or leather articles. Furthermore, highly safety-relevant elements such as gas bags of airbags, which have a variety of seams, are manufactured with sewing machines. In sewing machines of this type, sewing threads made of synthetic material have been used regularly for years and must be separated again frequently and even after very short sewing distances. The products listed above by way of example regularly have a material upper edge on the processed product or the material to be sewn, which also simultaneously constitutes an outer visible edge. It is therefore desirable that when using automatic thread cutting devices remaining after the removal of the thread remaining thread is as short as possible or not visible.

According to the state of the art, in addition to manual reworking, special machines for reworking seams are known, which in a separate operation trap the cut threads and also shorten them. Such a method is too complicated from an apparative point of view and in terms of time factor to still perform it as standard in today's productions.

US 5,887,537 A discloses a cutting-clamping device which severes a needle thread at one end of a seam very short over the fabric and at the same time holds a needle thread starting piece at least the production of initial stitches. For this purpose, a device is disclosed in which a rigid bracket along two rigid axes or rods is pressed perpendicular to the fabric.

US 3,094,031 A discloses a fork rigidly connected to a knife at the end of a rod, the entire apparatus itself also being rigidly connected to a sewing machine.

With the focus on creating a cutting / clamping device while minimizing the risk of so-called nesting caused by too long initial thread sections.

The DE 36 24 933 A1 discloses a cutting device for a sewing machine having a cutting device associated with a cutting device with a blade movable to the cutting point. With the stated aim of creating a device that can not lead to injury even if a finger of the seamstress is in the trajectory of the knife guard this publication discloses a protective device surrounding a knife, from a rest position at a distance from the cutting point until the cutting point has movable blade protection. According to this teaching, therefore, the separating element is covered protective, first the knife guard placed in a protective finger of the seamstress position before the cutting point and then the actual cutting movement of the knife is triggered.

It is therefore the object of the present invention to provide a method and a corresponding device for operating a yarn processing machine with a thread cutting device, which achieves improved results with increased operational reliability compared to known devices and methods.

This object is solved by the features of the independent claims. Accordingly, a method according to the invention for operating a thread processing machine with a thread cutting device is characterized in that only at the end of the Fadenverarbeitungs- or sewing operation, the processed product at least in an area around the thread to be separated with a hinged or flexible protective element to protect the surface of Material is covered and the thread cutting device moves to an interface and is positioned relative to the protective element for cutting. This is the first time a protection of the processed product is realized, which can very effectively prevent any type of damage to the machined product, especially on its surface during thread trimming. In addition, by the positioning of the thread cutting device relative to the protective element so accurate positioning of the thread cutting device can be realized that very short thread remnants can remain after the separation of the thread on the processed product.

Any change in a surface of the sewing material must be excluded in a thread separation process even in the immediate vicinity of the residual thread. Otherwise, at least one overall visual impression would be impaired or even safety-relevant mechanical properties of the material would be changed unfavorably. In both cases, the fabric would thus Committee. These requirements are met according to the invention by the protective element, so that, by a method according to the invention, workpieces with very short residual thread lengths and unchanged high surface quality are also processed reliably in the area of the residual thread.

Since the positioning of the thread cutting device takes place relative to the protective element and thus is independent of a thickness of a respective processed product, has an inventive Method and a corresponding device also has the advantage of an automatic height adjustment. Thus, in embodiments of the invention, a length of a thread remnant with, for example, a melt bead to almost 0 mm to about 2 mm regardless of the thickness of a particular processed product safely and reproducibly adjustable.

In an alternative field of application of a method according to the invention and a corresponding device, too long protruding thread residues are shortened defined. For this purpose, devices known per se for catching such thread remnants are used, whereby e.g. drawing a thread residue into a tube opening using vacuum air suction. In a subsequent step, a method according to the invention is used to also process material with very short residual thread lengths and unchanged high surface quality in the area of the residual thread with high reliability.

As indicated above, a method according to the invention can therefore be completely decoupled from an actual sewing process. In addition, however, a method according to the invention can also be used in the working direction, counter to a working direction, or in all other angular positions relative to a working direction of a thread-processing machine. The steps of a method according to the invention, ie placing a protection and cutting, can be carried out from the same or different directions.

In an advantageous development of the invention, an apron is used as a protective element in a device according to the invention. In one embodiment of the invention, the protective element encompasses the puncture site of the thread to be severed or cut on the processed product symmetrically and substantially U- or V-shaped. Preferably the protective element is formed on one side with an edge for forming an abutment for the separating device during the cutting operation of the thread. Thus, according to a further embodiment of the invention, the protective element in an area of a puncture site in one embodiment of the invention is asymmetrical and preferably L- or J-shaped.

The protective element is pressed according to the invention at an angle between about 25 ° and up to 50 °, but preferably of about 30 ° by a drive relative to the surface normal of the sewing material on the processed product by being connected to a corresponding positioning and pressing device. By pressing a compression of the sewing material and / or pressing on the throat plate in the area around the thread to be cut is effected, so that a thread separation in a range is possible, which is in a normal state below a surface of the fabric. So that also residual thread lengths of almost 0 mm can be realized. This device comprises in a preferred embodiment at least one drive, which is preferably operated electrically or pneumatically. The drive is formed in embodiments of the invention as a linear or rotary cylinder or as a stepper or stepper motor, etc.

In alternative embodiments of the invention, an inclined protective element and / or a separating device is swiveled in from the side into a working position on the needle of the sewing machine using a rotary cylinder. As a result, accessibility of the needle is increased outside of a respective separation process.

In a further embodiment of the invention, the separating device moves at least partially along the protective element to reach its predetermined position. The protective element is preferably articulated in such a way and / or flexibly formed that it is pressed onto the processed product only in contact with the separating device. This contact preferably takes place only immediately before the actual separation process.

In a particularly preferred embodiment of the invention, the protective element and the separating device are coupled together and are moved together by only one drive. Preferably, such a thread cutting device is tiltably attached to a respective sewing machine against a resilient restoring force, so that a feed movement of the protective element in superficial contact with the fabric under a tilting of the thread cutting device and dissipating a contact force in a cutting motion can pass. In one embodiment, the protective element is employed during the feed movement to facilitate the tilting movement at least in a free end region at an angle relative to the surface of the sewing material. Preferably, the protective element is formed several times angled.

In a preferred embodiment of the invention, an electric firing device is used as the thread cutting device. Various such devices are known which heat a heating wire by controlled current flow for separating an adjacent thread. Further, as a burners ultra-sound, arc, laser or similar devices can be used. Due to the increased mechanical demands on modern sewing machines as well as the needle threads used for sewing synthetic twines are used, especially in heavy duty sewing machines, which consists of several individual yarns are composed. A use of knives, etc. for purely mechanical separation of a thread can be susceptible to errors in such threads and / or lead to unsatisfactory cutting results. By means of a combustion device, sufficient heat can be generated by selectively supplying electrical energy in a heating wire or the like in order to thermally sever such synthetic threads such that the cut ends join together during the separation process by a type of welding or form a melt ball at the end , Advantageously, the use of such a thread cutting device further reduces the length of the remaining thread remaining on the processed product as a result of the melting of an end region of the thread. By virtue of the protective element provided according to the invention, however, the processed product is at the same time very effectively protected against any undesired thermal influence on its surface, which could occur during the separation process by the electrical combustion device. This ensures that even a visible surface by the thread cutting process undergoes no impairment in terms of their optical and mechanical quality.

When using a heating wire in the separating device is preferably used instead of a wire approximately U-shaped bent sheet having a strong taper in the throat of the U. This defines a thermal cutting edge with the highest temperature.

In a preferred embodiment, a method according to the invention and a corresponding device for the separation of upper threads on Riegler or Tacker automatic sewing machines is used. An adaptation of a device according to the invention for a transection of the lower thread is, for example by using a second device constructed according to the invention, which is arranged below the sewing table and adapted to the limited space available there. In the case of the use of a stitch stitching, depending on the requirement, cutting only above, only below or else above and below the sewing table is necessary and can be carried out with a device according to the invention. It is also possible to adapt to a sealing cut off of overlock threads above the sewing table using a method according to the invention.

Figur 1:

eine schematische Darstellung eines laufenden Nähvor- gangs mit einer Ausführungsform einer erfindungsgemä- ßen Fadenschneideinrichtung an einer Nähmaschine in einer Ruheposition;

Figur 2:

die Vorrichtung gemäß Figur 1 bei abgesenktem Schutz- blech während der Positionierung der Abtrenneinrich- tung;

Figur 3:

eine Vorrichtung gemäß Figur 2 während des Faden- Trennvorganges bei Anwendung an einem vergleichsweise dünneren Nähgut als bearbeitetem Produkt;

Figur 4:

eine Draufsicht auf einen Teil der Anordnung gemäß Abbildung von Figur 3;

Figur 5:

ein weiteres Ausführungsbeispiel einer Fadenschneid- einrichtung analog der Darstellung von Figur 1;

Figuren 6a und 6b:

Ausschnittvergrößerungen von Figur 5 zur Darstellung der Vorgänge kurz vor dem Aufsetzen des Schutzele- ments und beim Durchschneiden des Fadens und

Figur 7:

eine Draufsicht auf eine Einheit aus Heiß- Schneideelements und Schutzblech des zweiten Ausfüh- rungsbeispiels.

The invention with reference to an embodiment with reference to figures of the drawing to illustrate further features and advantages will be explained in more detail. In the drawing show:

FIG. 1:

a schematic representation of a running sewing process with an embodiment of a thread cutting device according to the invention on a sewing machine in a rest position;

FIG. 2:

the device according to FIG. 1 with the protective sheet lowered while positioning the separation device;

FIG. 3:

a device according to FIG. 2 during the thread separation process when used on a comparatively thinner material than processed product;

FIG. 4:

a plan view of a portion of the arrangement as shown in FIG FIG. 3 ;

FIG. 5:

a further embodiment of a thread cutting device analogous to the representation of FIG. 1 ;

FIGS. 6a and 6b:

Detail enlargements of FIG. 5 to illustrate the events shortly before the protection element is put on and when the thread is cut and

FIG. 7:

a top view of a unit of hot cutting element and fender of the second embodiment.

Throughout the various illustrations, the same reference numerals are always used for the same elements. Without limiting the invention, only a treatment of a top thread on a thread processing machine in the form of a sewing machine will be shown and described below.

FIG. 1 shows a schematic representation of a running sewing process. Of the sewing machine, only a portion of a needle bar with a needle 1, a thread 2, a sewing table with a processed product 3, here a fabric 3, and an embodiment of a thread cutting device 4 according to the invention are shown. The thread cutting device 4 is constructed very compact and can therefore in principle be arranged in any Winkelrich direction around the needle 1, here it is rigidly aligned. For this reason and to increase the clarity of the drawing, no further orientation marks of the sewing machine have been drawn. Practically, there are restrictions on the freedom of positioning from a particular application and use on a particular machine.

In the present embodiment, the thread cutting device 4 is fixed in a manner not shown on the sewing machine. The thread trimmer 4 is in the snapshot of FIG. 1 in a rest position, since there is still a sewing process and the needle 1 has not yet come to rest in a top dead center position accordingly.

The thread cutting device 4 comprises a security element in the form of a protective plate 5, which is connected via a rod 6 with a linear cylinder 7, via which the protective plate 5 can be moved. In the region of the rod 6, a separating device 8 is fixed in a adjustable manner around a pivot point 9 in its angular position, depending on the application. The severing device 8 can also be moved via a linear cylinder 10 by means of an electronic program control (not shown).

In the presentation of FIG. 2 the needle 1 has reached a top dead center with completion of the sewing process. The thread-cutting device 4 therefore now comes into action with a first step: The protective plate with the separating device 5 has thus been lowered onto a surface 0 of the sewing material 3. As a result, an essential prerequisite for a precise positioning of the separating device 8 is met, so that automatically the position to be cut of the thread 2 of a respective thickness d of the sewing material 3 is correspondingly positioned. Thus, in particular, a manual readjustment of the thread cutting device 4 is not required. By placing and pressing the mudguard 5 on the surface 0 of the material 3, the severing device 8 itself is already precisely positioned, because the severing device 8 is moved only relative to the mudguard 5.

FIG. 3 time a device according to the figure of FIG. 2 during the thread-separating process when used on a comparatively thinner fabric. Here, the second linear cylinder 10 has moved the electrical cutting unit of the separating device 8 to the cutting position, a heating wire 11 is heated by regulated current flow and cuts or welds the sewing thread 2 at the exact position. This position is always achieved independently of the material thickness d according to a default setting of the thread cutting device 4 due to the position of the protective sheet 5.

FIG. 4 Finally, FIG. 1 shows a top view of a part of the arrangement according to the illustration of FIG FIG. 3 in the section plane AA. In this plan view, the U-shaped configuration of the mudguard 5 can be clearly seen through a recess 12. The recess 12 in the fender 5, which justifies this particular U-shape, now advantageously offers the possibilities to cut the thread 2 over the fender 5, in the plane of the surface of the fender 5 or below the plane of the surface of the fender 5. In one embodiment of the invention can thus be cut in the recess 12 of the mudguard 5, that is much deeper and thus closer to the surface of the material to be sewn, as would be possible in the prior art. Depending on the application, a selection must be made by means of a corresponding presetting.

The fender 5 is closer to the severed thread 2 around, as this would be the case, for example, by a likewise not shown here further Nähfuß. In industrial heavy-duty sewing machines, a sewing foot frames sewing fields of up to approx. 600 mm * 3000 mm rectangular extent, in which the needle 1 executes sewing tasks under given sewing patterns under the effect of an xy positioning. This can especially in the Special case that a presser foot substantially corresponds to the shape of the mudguard 5, the actual presser foot in favor of the mudguard 5 accounts. For the operation of the mudguard 5 then an already existing automatic presser foot, a presser foot, sewing frame or the like can be used. In these cases, then the linear cylinder 7 or a similar drive element for a separate drive of the mudguard 5 could be saved.

In the presentation of FIG. 4 It is also clear that in the present embodiment of the invention, the axes of movement of the independent linear cylinder 7, 10 in this embodiment lie in a plane, but are opposite the surface normal of the material 3 at different angles, and in particular an angle γ> 10 ° include , The abovementioned angles .alpha., .Beta.,. Gamma. Are all freely adjustable within wide ranges and can thus be adjusted correspondingly to the respective space requirements, ie in particular also as equal-sized angles .alpha., Ie .gamma. = 0.degree.

In an exemplary embodiment of the invention which is not illustrated here, the protective sheet 5 and the separating device 8 are arranged in a telescopic mechanism at substantially the same angular position relative to the surface normal of the material 3. Thus, a feed movement a and cutting movement c occur substantially under the same spatial direction. In this case, these elements are driven together in the above-described sequential steps via only a stepper or stepper motor. However, to adapt to an application, the angular positions of the two elements and the associated method steps can also be designed differently.

FIG. 5 shows a further embodiment of a thread cutting device 4 analogous to the representation of FIG. 1 , Here, a protective element 13 and the separating device 8 are rigidly coupled together. They are moved together by only one drive in the form of the linear cylinder 7, as already indicated above. With respect to the sewing material 3, the protective element 13 of the separating device 8 is arranged in an anticipatory manner. The thread cutting device 4 is here at a pivot point 14 movable against a resilient restoring force tilted on the drawing in FIG. 5 only indicated sewing machine attached and preset. A feed movement a of the protective element 13 into a superficial contact with the sewing material 3 takes place substantially linearly and then passes under a tilting b of the entire thread cutting device 4 and finally transferring a pressing force p into a cutting movement c. Seen in this embodiment, delivery and cutting movement despite rigid coupling of protective element 13 and separating device 8 is not carried out under the same spatial direction in this embodiment. The feed movement a runs at the angle α with respect to the surface normal, while the cutting movement c runs essentially parallel to the surface 0 of the sewing material 3.

The contact pressure can be adjusted via the spring characteristic of a spring element not shown in the region of the pivot point 14, but in this example it is adjusted by the preset maximum displacement of the cylinder 7 and a preset end stop for limiting the tilting movement b. A preset end stop also defines the direction of the infeed movement a.

The pictures of the Figures 6a and 6b clarify as a detail enlargements of FIG. 5 the events just before the

Placing the protective element 13, so the feed movement a with subsequent tilting b and the actual cutting movement c. FIG. 6b shows enlarged the situation when cutting the thread 2. Here, the severing device 8 has been placed around a last insertion point of the thread to be separated around 2 and pressed. Under the action of a pressing force p, the sewing material 3 has been compressed by an amount Δ. This can subsequently also be thermally cut in the region of the level of the surface 0 without the surface of the material 3 being damaged: there is still a sufficient distance between the surface of the material 3 and an actual cutting element, with surrounding areas passing through Protective element to be covered safely.

The protective element 13 is set in a free end region 15 at an angle δ relative to the surface of the sewing material 3. At the end of the feed movement a, contact of the free end region of the protective element 13 with the surface 0 of the sewing material 3 is achieved. To facilitate the tilting movement b then the configuration of the free end portion 15 is used at the angle δ. In the present example, the protective element 13 is designed as a piece of sheet bent several times in order to achieve an angle of approximately 130 ° in these steps or bending points 16, 17 and to allow a sliding of the device to the thread section.

FIG. 7 shows another peculiarity in the structure of the protective element 13 and a vote of a hot-cutting element 18 to this application. A plan view of a unit of hot cutting element 18 and the protective plate of the protective element 13 of this second embodiment shows that the protective element 13 at its free end 15 an L-shaped and thus asymmetrically to a central axis M recess 12 has. When rounding the inner edge, the recess 12 may also be J-shaped. An approximately U-shaped bent taper 19 of the hot cutting element 18 extends to the recess 12, which is fed via the free end 15 of the protective element 13 in the course of each cutting movement c to a thread 2 to be separated in the region of a puncture site. The hot-cutting element 18 is held in an electrical insulation block 20, which also carries not shown terminals for power supply lines.

In summary, therefore, a method and a corresponding device have been described, which provides an effective surface protection for the tissue, or a seam and / or a processed product during a thread-separating process, and a residual thread without superficial injury or other mechanical impairment of the material definite short cuts , In addition, this advantageous property is ensured without mechanical adjustment by an automatic, flexible height adjustment. The height adjustment can be controlled by additional monitoring mechanisms and also electronically checked and / or logged. However, such measures are not required in principle.

A device according to the invention of the type exemplified above is advantageously also used in conjunction with multi-needle sewing machines. In the case of highly safety-relevant sewing products, such as the airbag gas bags, double seams are finished with two parallel needles at a distance of, for example, 6 to 8 mm. Up to 70 such double seams are located on an airbag gas bag, which must each have at their beginning and end defined short residual threads. At a narrow needle spacing, such a double-needle sewing machine can be provided with a device according to the invention, wherein a respective protective element and a or two hot cutters must be adapted to the geometry. It can also be used in parallel two running device according to the invention, as they claim only work space for thread cutting under the sewing machine and build very slim.

A starting thread can also be processed with adapted use of a device according to the invention by a thread catcher, for example, with a primer catches a respective starting thread, mechanically clamped and positioned so that it can be cut by a preferably be provided separately inventive device. With appropriate guidance of the process, this process can also take place on a sewing table outside the actual area of a sewing machine.

LIST OF REFERENCE NUMBERS

1

needle

2

thread

3

processed product / sewing material

4

Thread cutter

5

mudguard

6

pole

7

linear cylinder

8th

separating

9

Pivot point .

10

linear cylinder

11

heating wire

12

Recess of the mudguard 5 / protection element 13

13

protection element

14

pivot point

15

free end region of protective element 13

16

bend

17

bend

18

Hot-cutting element

19

rejuvenation

20

electrical insulation block

a

infeed

b

tilt

c

cutting motion

d

Thickness of the processed product or the sewing material 2

p

pressing force

α

Angle of the feed axis

β

Angle of the cutting axis

γ

Angle between the directions a and c

δ

Angle of the free end region 15

Δ

Indentation depth of protective element 13 in sewing material 3

M

central axis

N

surface normal

0

Surface of the sewing material 3

Claims (14)

1. Method for operating a thread processing machine with a thread cutting unit, wherein the processed product (3) is covered only on completion of the thread processing sequence with an articulated or flexible protective element for protecting the surface of the sewing material in a region around a thread (2) to be separated, characterised in that
   the protective element is lowered under an angle (α) with 25° ≤ α ≤ 50° relative to the surface normal (N) onto the processed product (3), and
   subsequently the thread cutting unit (4) is moved towards a cutting point under an angle (β) and is positioned relative to the protective element for cutting.
2. Method according to claim 1, characterised in that a separating unit (8) is driven by a drive (7, 10) under an angle (β) into a cutting position and the thread (2) is separated.
3. Method according to any one of the preceding claims, characterised in that a protective element inclined under an angle (α) and/or a separating unit (8) at an inclination of an angle (β) are swung in from the side using a rotating cylinder.
4. Method according to any one of the preceding claims, characterised in that the separating unit (8), in order to reach its predetermined position, runs at least partly along the protective element and/or slides with the protective element over the fabric layers.
5. Method according to one of the preceding claims, characterised in that the thread is thermally (2) separated.
6. Method according to any one of the preceding claims, characterised in that the protective element and the separating unit (8) are mechanically rigidly coupled with one another and are moved by a common drive (7).
7. Method according to any one of the preceding claims, characterised in that the protective element and the separating unit (8) are guided in different directions of motion (a, c) that are at an angle (γ) to one another.
8. Method according to the preceding claim, characterised in that a feed motion (a) runs off into a cutting motion (c) after a tilt (b) about an angle (δ).
9. Device for operating a thread cutting machine with a thread cutting unit, characterised in that the device for executing the method according to one or more of the preceding claims is configured such that a thread cutting unit (4) is provided that has a protective element configured such that it can lowered as surface protection onto the processed product (3) under an angle (α) of approximately 25°≤ α ≤ 50°, the protective element covers the processed product (3) in an articulated or flexible manner in a region around a thread (2) to be separated, and a separating unit (8) is provided for engaging in the area of the protective element.
10. Device according to the preceding claim, characterised in that the protective element and the separating unit (8) are configured such that they can be swivelled in and/or be retracted, aligned oriented in the working direction of the machine.
11. Device according to any one of the preceding claims 9 - 10, characterised in that the protective element is configured so as to surround, substantially in a symmetrical U-shape or V-shape, the penetration point of the thread (2) to be separated or cut on the surface product (3), wherein a recess (12) of the protective element is configured and positioned in such a way that an edge for forming a one-sided support is formed, particularly for guiding the thread (2).
12. Device according to any one of the preceding claims 9 - 11, characterised in that the protective element, for pressing under an angle (α) of α ≈ 30° relative to a surface normal (N) onto the processed product (3), is connected to a positioning and pressing unit which includes, in particular, a linear or rotating cylinder or a step or stepper motor.
13. Device according to any one of the preceding claims 9 - 12, characterised in that a protective element (13) and a separating unit (8) that are rigidly coupled to one another are jointly moved by only one drive in the form of a linear cylinder (7), wherein, relative to the sewing material (3), the protective element (13) is arranged so as to precede the separating unit (8).
14. Device according to the preceding claim, characterised in that the thread cutting unit (4) is fixed at a pivot point (14) in a pre-settable manner on a working machine so as to be movable and, in particular tiltable, against a resilient restoring force.

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