EP1297208A2

EP1297208A2 - Device for conveying articles to be sewed

Info

Publication number: EP1297208A2
Application number: EP01953159A
Authority: EP
Inventors: Sevki Hosagasi
Original assignee: Quick-Rotan Elektromotoren GmbH
Current assignee: Quick-Rotan Elektromotoren GmbH
Priority date: 2000-05-25
Filing date: 2001-05-22
Publication date: 2003-04-02
Also published as: DE10025822A1; CZ20023559A3; DE10025822C5; US20030136320A1; CN1396970A; BR0107615A; WO2001090469A2; AU2001275673A1; MXPA02011601A; JP2003534076A; WO2001090469A3; KR20030007406A; DE10025822C2

Abstract

The invention relates to a device for conveying articles to be sewed, which is provided for a sewing device or sewing machine. Said device comprises at least one material advancing device for advancing the article to be sewed in the advancing direction of the material with an advancing speed defined by the speed of the machine and by the stitch length. The device also comprises at least one material conveying supplementary device which, in the form of a pressing means, subjects the upper material layer of the article to be sewed to a pressing force. The material conveying supplementary device rotates with a rotational speed, is arranged behind the material advancing device in the advancing direction of the material and can be proportionally driven with regard to the speed of the machine and to the stitch length. At least one device can increase the pressing force, which is exerted by the device onto the upper material layer of the article to be conveyed, with an increasing speed of the machine and/or in addition to the proportional increase with increasing speed of the machine, can further increase the rotational speed of the material conveying supplementary device.

Description

V O R R I C H T U N G Z U M T R A N S P O R T I E R E N V O N N Ä H G U T

The present invention relates to a device for transporting sewing material provided for a sewing device or sewing machine, comprising at least one fabric pusher device for advancing the sewing material in the fabric thrust direction with a feed speed determined by the machine speed and the stitch length and at least one in shape on the upper fabric layer of the fabric of a pressure medium acting with a pressure force and rotating at a rotational speed, an additional material transport device which is arranged in the material pushing direction behind the material pusher device and can be driven in proportion to the machine speed and the stitch length.

Here, the additional material transport device (cf. the relevant prior art, for example, the publication US Pat. No. 4,182,251) serves to offset the offset between the upper layer of fabric and the lower layer of fabric with the sewing device (hereinafter the term "sewing device" also includes sewing machines, whereby the present invention relates both to sewing devices and to sewing machines) to be processed. Experience has shown that this offset occurs when the lower layer of fabric is frictionally entrained by the teeth of the material pusher device, while the upper layer of fabric is only taken along by the friction between the upper layer of fabric and the lower layer of fabric.

In order to let this friction take effect, the sewing material is held down during the stitch formation and the sewing material transport with a so-called fabric presser device, so that the upper fabric layer and the lower fabric layer between the fabric presser device and the

The fabric pusher device is compressed and transported in the fabric pusher direction by means of the fabric pusher device.

During this transport phase, frictional forces occur between the upper fabric layer of the material to be transported and the presser device, which can cause an offset in the transport length between the upper fabric layer and the lower fabric layer. This extremely undesirable offset effect, which negatively influences the sewing results, occurs even at low speeds of the main shaft of the sewing device and therefore at low feed speeds; the higher the speed and the feed speed, the greater the offset effect.

The reason for this can be seen in the mode of operation of the fabric pusher device, which moves upwards at the beginning of the transport phase, that is to say in the direction of the fabric pusher device, so that the teeth the fabric pusher device can intervene in the lower fabric layer of the sewing material. During this time, the sewing material inevitably pushes the presser device upward, so that the pressure on the fabric layers increases due to the inertial mass of the presser device.

The fabric pusher device makes an approximately elliptical movement: As the fabric pusher device moves a little further up, the fabric pusher device begins to push the fabric layers in the fabric pusher direction. During this transport phase, the pressure of the presser device drops sharply until a spring force decelerates the upward movement of the presser device, ie away from the pushing device, and presses the presser device back onto the material.

In extreme cases, it can even happen that the fabric presser device loses contact with the material for a short time due to its vertical, upward movement, and the frictional connection between the upper fabric layer and the lower fabric layer is thereby eliminated. This known and extremely undesirable phenomenon becomes more apparent the higher the speeds of the main shaft of the sewing device and thus the feed speeds, so that the offset between the upper fabric layer and the lower fabric layer with the sewing speed, which is a measure of the feed speed, is getting bigger.

At the end of the transport phase, the fabric pusher device moves down, i.e. in Direction away from the presser device, so that the pressure of the presser device briefly decreases again. However, the latter phase has no significant influence on the offset between the upper fabric layer and the lower fabric layer.

In order to compensate for the offset effect, the additional material transport device attacks the upper fabric layer. Here, a mass transfer would only be carried out with the

Mass transport additional device cause a so-called "negative offset", that is, an advance of the upper layer of fabric over the lower layer of fabric.

With the correct setting of the rotational speed of the material transport additional device to the machine speed and the set stitch length, a seam section should be able to be produced without an offset.

For example, a fabric transport device for a sewing machine is known (cf. DE 29 36 697 C2), in which a pressure mechanism is assigned to the driven fabric transport roller, which serves on the one hand to set a gap between the fabric support surface and the fabric transport roller (roller) so that the The material transport roller cannot come into direct contact with the material support surface and, on the other hand, enables the setting of a pretensioning force with which the material transport roller presses the workpiece against the material support surface; however, this pre-tensioning force remains unchanged during the sewing end. Furthermore, a device for transporting sewing material is known (cf. DE 29 27 869 C2), in which the additional material transport device is intended to carry out a slightly larger transport amount (feed amount) than the material pusher device so that the sewing material is always kept under tension when feeding in the material feeding direction becomes. When sewing the upper fabric layer and the lower fabric layer, this is intended to prevent "slip-through wrinkles", that is to say in other words an offset formation; however, the set ratio between the transport amount of the fabric pusher device and the fabric transport roller of the fabric transport additional device remains constant during a sewing process, regardless of the respective machine speed of the sewing machine.

It has been found, however, that the offset between the upper fabric layer and the lower fabric layer is dependent on the speed of the main shaft of the sewing device, that is to say on the so-called machine speed, so that with this conventional device under changing conditions, such as at variable speed, the Main shaft of the sewing device and therefore with variable feed speed, no satisfactory and completely uniform sewing results can be achieved.

Based on the disadvantages and shortcomings set out above, the present invention is based on the object of a generic device for transporting sewing material train that even when changing as a result

Conditions (such as at variable speed of the

Main shaft of the sewing device and therefore at variable feed speed) varying offset between the upper layer of fabric and the lower

Fabrics always convincing, especially completely uniform sewing results can be achieved.

This object is achieved by a device for transporting sewing material according to the preamble of the main claim, in which, according to the teaching of the present invention, the pressing force exerted by the auxiliary material transport device on the upper fabric face of the sewing material to be transported can be increased with increasing machine speed and by means of at least one device / or the rotational speed of the

Mass transport additional device in addition to the proportional increase with increasing machine speed can be increased still further.

Thus, surprisingly, the fact is taken into account that the machine speed and / or the stitch length and therefore the feed speed influence the mode of operation and the function of the auxiliary material transport device. This is the pressure force that the

Additional material transport device exerts on the upper fabric layer of the material to be transported, can be enlarged by means of the at least one device with increasing machine speed. hereby can be taken into account the fact that the offset between the upper fabric layer and the lower fabric layer increases with increasing machine speed, so that the fabric transport additional device must develop an increasingly greater tensile stress in the upper fabric layer.

Alternatively or in addition to this, according to the teaching of the present invention, the rotational speed is

Additional mass transport device can be increased further in addition to the proportional increase with increasing machine speed. This also takes into account the fact that the offset between the upper layer of fabric and the lower layer of fabric increases with increasing machine speed, so that the auxiliary material transport device also has to develop an increasingly greater tension in the upper layer of fabric.

To the pressure force of the

Mass transport additional device and / or the

Orbital velocity of the

To be able to select additional material transport device as a function of the machine speed, the at least one device is provided, which can be designed, for example, as at least one actuator.

According to preferred embodiments, which can be carried out independently of one another or in connection with one another, it is provided that

the pressing force and / or the Circulation speed, preferably by means of the device, can also be adapted to the nature of the material to be transported; and or

the pressure force Fp is given by the formula

F _p = F ₀ + R • n,

where FQ is a constant force;

R is a coefficient of friction, the size of which is determined by the frictional relationships between the auxiliary material transport device and the upper fabric layer; and n is the engine speed; and or

the speed of the device is a measure of the rotational speed of the mass transport additional device or is equal to the rotational speed of the mass transport additional device; and or

the speed n _{p of} the device is given by the formula np = k • n ^■ L,

where k is an adjustment factor; n the engine speed; and

L is the stitch length; and or

the mass transfer device operates in low speed ranges (n _p <500 min " ¹ ) of the device in an intermittent mode; and / or

the on and off times of the facility are determined by the angular position of the main shaft of the sewing device or sewing machine; and or

the mass transfer device operates in high speed ranges (n _p > 500 min ^-1 ) of the device in a continuous mode; and or

the transport path of the mass transport additional device per stitch formation process is larger, in particular slightly. larger than the feed path of the material pusher device; and or

the pressing force of the mass transfer device and / or the speed of the device are electronically controllable; and or

at least one electronic control device is provided for controlling the pressing force of the mass transport additional device and / or the speed of the device; and or

the engine speed can be determined in the electronic control device; and or

the electronic control device receives the information about the stitch length by input using at least one control panel; and or

the electronic control device receives the information about the nature of the material to be transported by input using at least one control panel; and or

the device preferably at least one linear motor operated with direct current; and or

the linear motor has at least one stator element designed as a housing; and or

at least one rotor element designed as a drive rod is mounted in the stator element; and or

the stator element is arranged on the rear of the housing head of the sewing device or sewing machine; and or

the device has at least one drive motor, preferably operated with direct current, at least one transmission arranged between the drive motor and the mass transport additional device and at least one transmission element arranged between the transmission and the mass transport additional device for transmitting motion to the mass transport additional device; and or

the adaptation factor k is given by the formula k = k _x ^■ k ₂ ^• k ₃ ,

where ki is a parameter for the diameter of the

Additional material transport device, for the constant of the linear motor and for the reduction of the gear; k ₂ a measure of the functional Dependence of the offset between the upper layer of fabric and the lower layer of fabric on the machine speed; and k _{3 is} a parameter for the nature of the material to be transported; and or

the device has at least one carrier element which is connected to the rotor element and to which the drive motor, the transmission and the transmission element are attached; and or

the carrier element is mounted against rotation; and or

the carrier element is mounted against rotation by means of at least one guide rod; and or

the carrier element is prestressed by means of at least one resilient, low-mass coupling element; and or

the coupling element is at least one coil spring; and or

the mass transport additional device is designed as at least one rotating roller, in particular as at least one rotating take-off roller; and or

the device is designed as at least one actuator.

In particular, is among the preferred Embodiments, which can be provided independently of one another or in connection with one another, to explain the following:

According to an inventive development of the present device, the pressing force and / or the speed of rotation can also be adapted to the nature of the material to be transported, preferably by means of the device. This can take into account the fact that the offset between the upper layer of fabric and the lower layer of fabric not only by the machine speed, but also by the nature of the material to be transported and consequently in particular by the frictional relationships between the lower layer of fabric and the upper layer of fabric, and in particular is determined by the frictional relationships between the upper layer of fabric and the presser device.

The essence of the present invention is therefore to be seen in the fact that when the upper fabric layer and the lower fabric layer are sewn together, an offset caused by uneven presser forces and the resulting uneven feed conditions, that is to say the upper fabric layer remaining behind, can be compensated for, in addition to one per se conventional fabric pusher means an individually adaptable that acts on the upper fabric layer

Mass transport additional device is provided.

In this way, the upper layer of fabric is placed slightly under tension, the magnitude of the tension in a manner essential to the invention by the Amount of pressure force of the

Mass transport additional device can be influenced by a low pressure force in a preferred manner can cause the material transport additional device to slip at an early stage and thus a low tensile stress in the upper fabric layer; In a corresponding manner, a higher pressure force can cause the material transport additional device to slip later and thus a higher tensile stress in the upper fabric layer.

In this case, the tensile stress during the briefly occurring phases of low presser force causes the upper fabric layer to be slightly advanced over the lower fabric layer, thereby compensating for the otherwise occurring offset.

With regard to the mode of operation and the function of the present device for transporting material to be sewn, it must be taken into account that the offset between the upper layer of fabric and the lower layer of fabric occurs essentially at the beginning of each transport phase, because during this period the pressure of the presser device decreases the way of working and the function of the sliding gate device strongly. For this reason, the additional material transport device is of particular importance, because with the force that can be adjusted according to the teaching of the invention, with which the additional material transport device presses against the fabric layers, the stretch in the fabric layers is influenced:

So at the beginning of the transport phase, in the Due to the decreasing pressure of the presser device, the fabric offset between the upper fabric layer and the lower fabric layer occurs, this stretching of the upper fabric layer relative to the lower fabric layer in the fabric thrust direction and thereby compensates for the offset of the upper fabric surface, which is otherwise caused by the reduced pressure of the fabric presser device. This means - provided the parameters are set correctly - a longer seam can be achieved without any offset between the upper fabric layer and the lower fabric layer.

The magnitude Fp of the contact pressure can expediently be represented by the formula F _p = F _Q + R • n, where Fg is a constant force, R is a coefficient of friction, the size of which is determined by the frictional relationships between the

Mass transport additional device and the upper fabric layer is determined, and n is the machine speed.

From the formula F _p = F _Q + R • n it can thus be seen that the pressing force - in addition to a constant portion which is independent of the coefficient of friction and the machine speed - expediently essentially linearly with the coefficient of friction between the auxiliary material transport device and the upper fabric layer and / or can be increased substantially linearly with the machine speed.

Depending on the respective technical circumstances, the speed of the device can be a measure of the circulating speed of the auxiliary material transport device or - for example with direct translation or with direct Reduction - be equal to the speed of rotation of the mass transfer attachment.

Here, the speed np of the device can advantageously be given by the formula n _p = k ■ n ■ L, where k is an adaptation factor, n is the machine speed and L is the stitch length.

From the formula n _p = k • n • L it can thus be seen that the speed of the device and consequently the rotational speed of the

In addition to an adaptation factor specified below, the mass transport additional device can expediently be enlarged substantially linearly with the machine speed and / or essentially linearly with the stitch length.

The adaptation factor k is expediently given by the formula k = k] _ ■ k ₂ • k ₃ , where k] _ is a parameter for the diameter of the mass transfer device, for the constant of a linear motor (see below) and for the reduction of the Gear (see below), k _{2 is} a measure of the functional dependence of the offset between the upper layer of fabric and the lower layer of fabric on the machine speed, and k _{3 is} a parameter for the nature of the material to be transported.

From the formula k = k ^ • k ₂ ■ k _{3 it} can thus be seen that the speed of the device and consequently the rotational speed of the auxiliary material transport device depend on the technical conditions and requirements of the device and the auxiliary material transport device (-> factor k ^), depends on the function of the offset between the upper fabric layer and the lower fabric layer above the machine speed (-> factor k ₂ ) and on the nature of the material to be transported (-> factor k ₃ ).

According to an expedient embodiment of the present invention, the mass transfer device operates in low speed ranges np <500 min ^{-1 of} the device in an intermittent mode. In other words, this means that the drive motor of the device is switched on in the transport phase and switched off in the non-transport phase. The on and off times of the device are advantageously determined by the angular position of the main shaft of the sewing device or sewing machine.

According to a preferred embodiment of the present invention, a switch is made to a continuous drive above speeds n _p in the order of magnitude of approximately 500 min ⁻¹ , that is to say the mass transfer auxiliary device can operate in a continuous mode in high, speed ranges _p > 500 min ^{−1 of} the device , In this context, however, it should be taken into account that in speed ranges np above about 500 min ^-1 an intermittent movement due to inertia and the elastic behavior of the drive elements gradually merges into a quasi-continuous movement anyway.

In this context it is important that the stretching of the fabric layers depends on the friction conditions depends on the additional material transport device and the (nature of) the upper fabric layer. In this regard, too, the stretch in the material to be sewn can be influenced by the adjustable force with which the auxiliary material transport device is pressed against the material to be sewn.

In an expedient development of the present invention, the transport path of the additional material transport device per stitch formation process is larger, in particular slightly larger, than the feed path of the material pusher device. This technical measure also ensures that the sewing material is always kept under tension when it is fed in the direction of the fabric feed, which, when sewing the upper fabric layer and the lower fabric layer, prevents an offset from being formed.

The above-explained configurations, features and advantages of the additional material transport device come into play in a particularly concise manner if the additional material transport device is designed according to an expedient development of the present invention as at least one rotating roller, in particular as at least one rotating extraction roller.

According to a particularly inventive further development of the present device for transporting sewing material, the pressing force of the auxiliary material transport device and / or the speed of the device (-> the rotational speed of the auxiliary material transport device) can be controlled electronically. For this purpose, at least one electronic control device for controlling the pressure force of the Additional material transport device and / or the speed of the device (-> the rotational speed of the additional material transport device) may be provided.

Since the pressure force of the auxiliary material transport device and / or the speed of the device (-> the rotational speed of the auxiliary material transport device) can depend, among other things, on the machine speed, the machine speed can be determined in accordance with an expedient embodiment of the present invention in the electronic control device, so that at any time Adaptation of the pressure force of the auxiliary material transport device and / or the speed of the device (-> the rotational speed of the auxiliary material transport device) to the machine speed can take place.

Furthermore, the rotational speed of the auxiliary material transport device can be determined not only by the machine speed, but also, among other things, by the stitch length. Since this stitch length is generally set mechanically in a sewing device, the stitch length is generally not known to the electronic control device. Not least for this reason, the electronic control device can expediently obtain the information about the stitch length by input using at least one control panel. The setpoint for the speed of the drive motor of the device and thus its speed can then be determined by at least one computing algorithm in a manner essential to the invention. Furthermore, the pressing force of the auxiliary material transport device can be determined not only by the machine speed, but also, inter alia, by the frictional force acting between the auxiliary material transport device and the upper fabric layer of the material to be sewn. Since this frictional force in a sewing device generally depends on the nature of the material to be transported, the frictional force is generally not known to the electronic control device. Not least for this reason, the electronic control device can expediently receive the information about the nature of the material to be transported by input using at least one control panel. The setpoint value for the pressure force of the additional material transport device can then be determined by at least one computing algorithm in a manner essential to the invention.

If the device now advantageously has at least one linear motor, preferably operated with direct current, which practically has at least one stator element designed as a housing, in which at least one rotor element designed as a drive rod is expediently mounted, and / or if the device advantageously has at least one preferably having drive motor operated with direct current, then the pressing force of the mass transfer device and / or the speed of the device (-> the rotational speed of the

Mass transport additional device) are regulated by at least one (current) controller. Here, the invention makes use of the fact that, in the case of a linear motor, the contact pressure force imparted by the same and / or in the case of a drive motor, the speed or rotational speed conveyed by the same is, in any case essentially, directly proportional to the current supplied to the linear motor or the drive motor. For this reason, the linear motor current or the drive motor current is electronically controlled and consequently the desired pressure of the mass transfer device and / or the desired speed of the device (-> the desired rotational speed of the

Mass transport additional device) causes.

It can be of essential importance for the invention that the force of the linear motor does not have to be measured. The fabric transport additional device should expediently be designed such that it can be lifted off the upper fabric layer of the sewing material, for example in order to be able to remove the sewing material from the sewing device. This can also be accomplished by means of the linear motor, it being noted that the linear motor does not have to perform a positioning function in this context. With regard to the designs, the features and the advantages of the linear motor, reference is made here in full to the type of motor as described in German patent application DE 199 45 443.4 or in international patent application WO 00/18997.

In this context, according to a particularly inventive development of the present Device for transporting sewing material, both the initial value and the feed speed-dependent part of the pressing force are parameterized in a suitable manner and, for example, can be adapted to the respective sewing conditions via at least one control panel.

According to a particularly inventive further development of the present invention, the device has at least one stator element designed as a housing (see above), which can be (permanently) connected to at least one mounting plate and / or which can be arranged on the rear of the housing head of the sewing device, at least a rotor element designed as a drive rod (see above), at least one drive motor preferably operated with direct current (see above), at least one gear arranged between the drive motor and the auxiliary material transport device and at least one arranged between the gear and the auxiliary material transport device

Transmission element for transferring motion to the mass transport additional device.

The device can in this case have at least one support element that is connected to the rotor element and is preferably mounted such that it is secured against rotation, to which the drive motor, the transmission and the transmission element are attached (the support element can be secured against rotation by means of at least one guide rod, for example). Furthermore, an embodiment is recommended in which the carrier element is pretensioned by means of at least one resilient, low-mass coupling element, preferably by means of at least one helical spring. Also with regard to the designs, the features and the advantages of the coupling element, reference is made in full to the German patent application DE 199 45 443.4 or to the international patent application WO 00/18997, in particular with regard to the power-saving mode of operation associated with the coupling element.

Further refinements, features and advantages of the present invention are described below in the drawing with reference to FIGS. 1 to 5, by way of example an exemplary embodiment of the device for transporting sewing material according to the present invention is illustrated.

It shows :

Figure 1 shows an embodiment of a

Device for transporting sewing material according to the present invention, in a lateral sectional view;

FIG. 2 shows a diagram of the force F of the presser device as a function of the angle of rotation φ of the main shaft of the sewing device;

Figure 3 shows a first embodiment of the device from the device for Transporting the sewing material from FIG. 1, in a sectional view;

Figure 4 is a schematic representation of the

Interaction between the operating mechanism and the electronic control device of the sewing device; and

FIG. 5 shows a diagram of the pressure force F _{p of} the mass transport additional device as a function of the machine speed n.

Identical reference numerals refer to elements or features of the same or similar design in FIGS. 1 to 5.

The drawing shows a device for transporting sewing material provided for a sewing device 10 or sewing machine 10 (see FIG. 4), which has a fabric pusher device 1 (see FIG. 1) embedded in a needle plate 7 for advancing the sewing material in the fabric push direction D ( see Figure 1: arrow). Furthermore, the sewing device 10 (hereinafter the term "sewing device" also includes sewing machines, the present invention relating both to sewing devices and to sewing machines) has an action on the upper layer of fabric 8 of the sewing material with a pressing force Fp and with a rotational speed Up rotating

Fabric transport device 2, which is arranged in the fabric thrust direction D behind the fabric pusher device 1. In this case, the fabric transport additional device 2 serves to compensate for the offset between the upper fabric layer 8 and the lower fabric layer 9 of the sewing material to be processed with the sewing device 10. This offset occurs when the lower fabric layer 9 is non-positively entrained by the teeth of the fabric pusher device 1, while the upper fabric layer 8 is only carried along by the friction between the upper fabric layer 8 and the lower fabric layer 9.

In order to let this friction take effect, the sewing material is held down with the presser device 6 during stitch formation and the transport of the sewing material, so that the upper fabric layer 8 and the lower fabric layer 9 are pressed together between the presser device 6 and the pushing device 1 and by means of the pushing device 1 can be transported in fabric direction D.

During this transport phase (see FIG. 2), frictional forces now occur between the upper layer 8 of the material to be transported and the presser device 6, which can cause an offset in the transport length between the upper layer 8 and the lower layer 9. This offset effect already occurs at low machine speeds n of the main shaft of the sewing device 10 (cf. FIG. 4) and therefore at low feed speeds; the higher the machine speeds n and the feed speeds, the greater the offset effect. The reason for this can be seen in the mode of operation of the material pusher device 1, which at the beginning of the transport phase (see FIG. 2: angular position φ _a ) moves upward, that is in the direction of the material presser device 6, so that the teeth of the material pusher device 1 move into the lower one Fabric layer 9 of the sewing material can intervene. During this time, the sewing material pushes the presser device 6 upward - to a certain extent inevitably (see FIG. 1: arrow A), so that the pressure on the fabric layers 8, 9 increases due to the inertial mass of the presser device 6.

The fabric pusher device 1 makes an approximately elliptical movement: While the fabric pusher device 6 moves a little further upwards, the fabric pusher device 1 begins to push the fabric layers 8, 9 in the fabric pusher direction D. During this transport phase, the force F of the presser device 6 now decreases sharply (see FIG. 2: sharp drop in the force F exerted by the presser device 6 as a function of the angle of rotation φ of the main shaft of the sewing device 10) until a spring force moves upwards, that is to say of the fabric pusher device 1 directed movement of the fabric presser device 6 brakes and the push device 6 presses the material again.

In extreme cases, it can even happen that the presser device 6 loses contact with the material to be sewn for a short time due to its vertical, upward movement and thereby the frictional connection between the upper layer of fabric 8 and the lower fabric layer 9 is lifted. This phenomenon becomes all the more apparent the higher the machine speeds n of the main shaft of the sewing device 10 and thus the feed speeds, so that the offset between the upper fabric layer 8 and the lower fabric layer 9 with the sewing speed, which is a measure of the feed speed, is getting bigger.

At the end of the transport phase (cf. FIG. 2: angular position φ _e ), the fabric pusher device 1 moves downward, that is to say in the direction away from the fabric presser device 6, so that the pressure of the fabric presser device 6 briefly decreases again. However, the latter phase has no significant influence on the offset between the upper fabric layer 8 and the lower fabric layer 9.

In order to compensate for the offset effect, the additional material transport device 2 engages the upper fabric layer 8 (cf. FIG. 1). In this case, a material transport exclusively with the additional material transport device 2 would cause a so-called “negative offset”, that is to say that the upper layer of fabric 8 leads the lower layer 9 of material.

With the correct setting of the rotational speed Up (cf. FIG. 1) of the mass transport additional device 2 to the machine speed n (cf. FIGS. 4 and 5) and the set stitch length L, a seam section can be produced without an offset. Here, the device for transporting sewing material according to the embodiment of Figures 1 to 5 is like this trained that even with changing conditions (such as variable machine speed n of the main shaft of the sewing device 10 and thus at variable feed speed) varying offset between the upper layer 8 and the lower layer 9 always convincing, especially completely uniform sewing results can be achieved.

For this purpose, the pressure force Fp, which is designed in the form of a rotating take-off roller

Additional material transport device 2 exerts on the upper fabric layer 8 of the material to be transported, and / or the rotational speed Up can be adapted to the feed speed by means of a device 3 (cf. FIG. 3). Thus, in the exemplary embodiment shown in FIGS. 1 to 5, the pressing force Fp exerted by the auxiliary material transport device 2 on the upper fabric surface 8 of the material to be transported can be increased with increasing machine speed n and / or the rotational speed Up of the auxiliary material transport device 2 in addition to the proportional force Increase can be increased even further with increasing machine speed n.

This takes into account the fact that the machine speed n and / or the stitch length L and thus the feed speed influence the mode of operation and the function of the auxiliary material transport device 2. For this purpose, the pressing force Fp which the additional material transport device 2 exerts on the upper fabric layer 8 of the material to be transported is increased by means of the device 3 Machine speed n can be increased (see FIG. 5). In this way, the fact can be taken into account that the offset between the upper fabric layer 8 and the lower fabric layer 9 increases with increasing machine speed n, so that the fabric transport additional device 2 also has to develop an increasingly greater tensile stress in the upper fabric layer 8.

Alternatively or in addition to this, the rotational speed Up is the

Additional mass transport device 2 can be increased further in addition to the proportional increase with increasing machine speed n. This can also take into account the fact that the offset between the upper layer 8 and the lower layer 9 increases with increasing machine speed n, so that the mass transfer device 2 also has to develop an increasingly greater tensile stress in the upper layer 8.

In this case, the pressure force Fp of the mass transport additional device 2 and / or the rotational speed Up of

To be able to select auxiliary material transport device 2 as a function of machine speed n, device 3 is provided, which acts as an actuator in the exemplary illustration in FIG. 3.

In the exemplary embodiment explained, the pressing force Fp and / or the rotational speed Up can additionally be adapted to the nature of the material to be transported by means of the device 3. This can take account of the fact worn that the offset between the upper layer 8 and the lower layer 9 not only by the machine speed n, but also by the nature of the material to be transported and consequently in particular by the frictional relationships between the lower layer 9 and the upper layer 8 and in particular is determined by the frictional relationships between the upper layer of fabric 8 and the presser device 6.

The essence of the present invention is therefore to be seen in the fact that when sewing together the upper fabric layer 8 and the lower fabric layer 9, an offset caused by non-uniform presser forces F - as shown in FIG. 2 - and by the resulting non-uniform feed conditions, that is to say the upper ones are left behind The fabric layer 8 can be compensated by providing, in addition to a conventional fabric slide device 1, an individually adaptable fabric transport additional device 2 which acts on the upper fabric layer 8.

In this way, the upper layer of fabric 8 is placed slightly under tension (see FIG. 1), the magnitude of the tension being influenced by the amount of pressure force Fp of the mass transfer device 2 by a low pressure force Fp, a small tension in the top layer 8 and in connection with this causes the mass transport additional device 2 to slip through at an early stage; in a corresponding manner, a higher pressure force F _p causes a higher tensile stress in the upper layer of fabric 8 and in connection therewith later slipping through the

Additional mass transport device 2.

The tensile stress during the briefly occurring phases of low presser force F (see FIG. 2) causes the upper layer of fabric 8 to be slightly advanced over the lower layer of fabric 9 and the offset that otherwise occurs is compensated for.

With regard to the mode of operation and the function of the device for transporting sewing material exemplified with reference to FIGS. 1 to 5, it must be taken into account that the offset between the upper layer 8 and the lower layer 9 essentially at the beginning of each transport phase

(see FIG. 2: angular position φ _a ) arises because the pressure of the presser device 6 decreases sharply in this period due to the mode of operation and the function of the pushing device 1. For this reason, the mass transport additional device 2 is of particular importance, because with the adjustable force Fp

(cf. FIG. 5), with which the additional material transport device 2 presses against the layers of fabric 8, 9, the stretch in the layers of fabric 8, 9 is influenced:

Thus, at the beginning of the transport phase (see FIG. 2: angular position φ _a ), in which the fabric offset between the upper fabric layer 8 and the lower fabric layer 9 occurs due to the decreasing pressure of the fabric presser device 6, this stretch pulls the upper fabric layer 8 relative to the lower fabric layer 9 in the fabric thrust direction D (see FIG. 1) and is the same thereby the offset of the upper fabric layer 8 which is otherwise caused by the reduced pressure of the fabric presser device 6. In this way - provided the parameters are set correctly - a longer seam can be achieved without an offset between the upper layer 8 and the lower layer 9.

The mass transport additional device 2 operates in low speed ranges np <500 min " ^{1 of} the device 3 in an intermittent mode. In other words, this means that the drive motor 33 (cf. FIG. 3) of the device 3 in the transport phase (cf. FIG. 2: Angular positions φ _a <φ <φ _e ) are switched on and switched off in the non-transport phase (see FIG. 2: Angular positions 0 <φ <φ _a and angular positions φ _e <φ <2π) 3 determined by the angular position φ of the main shaft of the sewing device 10 (see FIG. 2).

Above speeds n _p in the order of magnitude of approximately 500 min ⁻¹ , a switch is made to a continuous drive, that is to say the mass transfer additional device 2 operates in a continuous mode in high speed ranges np> 500 min ^{−1 of} the device 3 into account that in speed ranges np above about 500 min ^"1 an intermittent motion by mass inertia and by the elastic behavior drive members gradually already looped to a quasi-continuous motion. In this connection, the stretching of the fabric layers 8, 9 depends on the frictional relationships between the auxiliary material transport device 2 and the (nature of) the upper fabric layer 8. In this regard, too, the stretch in the material to be sewn can be influenced with the adjustable force Fp with which the additional material transport device 2 is pressed against the material to be sewn.

The transport path of the fabric transport device 2 is slightly larger per stitch-forming process than the feed path of the fabric pusher device 1. This technical measure also ensures that the sewing material is always kept under tension when feeding in fabric direction D, which is when sewing the upper layer of fabric 8 and the lower one Layer 9 causes an offset formation to be avoided.

The pressure force Fp the

Mass transport additional device 2 and / or the speed n _{p of} the device 3 (-> the rotational speed Up the

Additional mass transport device 2) can be controlled electronically. For this purpose, there is an electronic control device 4a, 4b (cf. FIG. 4) for controlling the pressure force Fp of the mass transport additional device 2 and / or the speed _{p of} the device 3 (-> the rotational speed Up

Mass transport additional device 2) provided.

Since the pressure force F _p

Mass transport additional device 2 and / or the

Speed n _p of device 3 (-> die

Rotation speed Up the Additional material transport device 2) depend, among other things, on the machine speed n, the machine speed n can be determined in the electronic control device 4a, 4b (see FIG. 4), so that the pressing force Fp of the additional material transport device 2 and / or the speed np of the device 3 can be adjusted at any time (-> the rotational speed U _p the

Mass transport additional device 2) takes place at the machine speed n.

Furthermore, the rotational speed Up of the mass transport additional device 2 is determined not only by the machine speed n, but also by the stitch length L, among other things. Since this stitch length L is mechanically set in the sewing device 10, the stitch length L is generally not known to the electronic control device 4a, 4b. Not least for this reason, the electronic control device 4a receives the information about the stitch length L by input using a control panel 5 (cf. FIG. 4). The setpoint n _so n (see FIG. 4) for the speed nMotor ( ^v 9l • FIG. 4) of the drive motor 33 of the device 3 and thus its speed np is then determined by a computing algorithm RA I (see FIG. 4).

Since the device 3 now has a drive motor 33 operated with direct current (cf. FIGS. 3 and 4), the speed n _{p of} the device 3 (-> the rotational speed Up of the mass transport additional device 2) is controlled by the (current) controller 4a (cf. Figure 4) regulated. Here, the embodiment shown in Figures 1 to 5 takes advantage of the fact that when Drive motor 33, the speed np mediated by the same is directly proportional - in any case essentially - to the current supplied to drive motor 33. For this reason, the drive motor speed ⁿ motor (cf. FIG. 4) is electronically controlled and consequently the desired speed np of the device 3 (-> the desired circulation speed p of the mass transport additional device 2) is effected.

Furthermore, the pressing force Fp of the fabric transport additional device 2 is determined not only by the machine speed n, but also, among other things, by the frictional force acting between the fabric transport additional device 2 and the upper fabric layer 8 of the sewing material. Since this frictional force depends on the nature of the material to be transported, the electronic control device 4a, 4b generally does not know the frictional force. Not least for this reason, the electronic control device 4b receives the information about the nature of the material to be transported by input by means of a control panel 5 (cf. FIG. 4). The target value ^F target ("see FIG. 4) for the pressing force Fp of the mass transfer device 2 is then determined by the computing algorithm RA II (see FIG. 4).

Since the device 3 now has a linear motor 30 operated with direct current (cf. FIGS. 3 and 4), the pressing force Fp of the mass transport additional device 2 is regulated by the (current) controller 4b (cf. FIG. 4). Here, the embodiment shown in Figures 1 to 5 takes advantage of the fact that when Linear motor 30, which is at least essentially - directly proportional to the current supplied to the linear motor 30 (cf. FIG. 4: i otor) by the same contact pressure force Fp. For this reason, the linear motor current I motor is electronically controlled and consequently the desired pressure of the mass transport additional device 2 is effected ,

The force of the linear motor 30 does not have to be measured here. The fabric transport additional device 2 is designed such that it can be lifted off the upper fabric layer 8 of the sewing material, for example in order to be able to remove the sewing material from the sewing device 10. This can also be accomplished by means of the linear motor 30, it being noted that the linear motor 30 does not have to perform a positioning function in this connection. With regard to the designs, the features and the advantages of the linear motor 30, reference is made in full to the type of motor as described in German patent application DE 199 45 443.4 or in international patent application WO 00/18997.

In this context, both the initial value F _Q and the feed rate-dependent part Fp> F _{0 of} the pressing force Fp (see FIG. 5) can be parameterized in a suitable manner and, for example, adjusted to the respective sewing conditions using the control panel 5 (see FIG. 4):

The magnitude of the pressing force F _{p can be represented} by the formula Fp = F _Q + R ■ n (see FIG. 5), where F _{Q is} the constant initial value (see FIG. 5), R is a coefficient of friction shown in FIG as a slope the straight line shown appears and its size is determined by the frictional relationships between the additional material transport device 2 and the upper fabric layer 8, and n is the machine speed (see FIGS. 4 and 5).

It can thus be seen from the formula Fp = FQ + R • n graphically represented by FIG. 5 that the pressing force F _p - in addition to a constant portion FQ independent of the coefficient of friction R and the machine speed n - is essentially linear with the coefficient of friction R between the Additional material transport device 2 and the upper layer of fabric 8 and can be enlarged essentially linearly with the machine speed n.

As already explained above, in

Depending on the technical conditions

Speed np of the device 3 is equal to that

Rotation speed Up the

Mass transport additional device 2. Here is the

The speed np of the device 3 is given by the formula n _p = k • n • L, where k is an adaptation factor, n is the machine speed and L is the stitch length.

From the formula n _p = k • n • L it can thus be seen that the speed np of the device 3 and consequently the rotational speed Up of the mass transport additional device 2 - in addition to the adaptation factor k specified below - are essentially linear with the machine speed n and essentially linear can be enlarged with stitch length L.

The adaptation factor k is in turn given by the Formula k = k] _ • k ₂ • k ₃ , where ki is a parameter for the diameter of the mass transfer device 2, for the constant of the linear motor 30 and for the reduction of the gear 34, k is a measure of the functional dependence of the offset between the upper Layer 8 and the lower layer 9 of the machine speed n and k is a parameter for the nature of the material to be transported.

From the formula k = k ^ • k • k _{3 it} can thus be seen that the rotational speed np of the device 3 and consequently the rotational speed Up of the mass transfer device 2 from the technical conditions and requirements of the device 3 and the mass transfer device 2 (-> factor k _] _), on the function of the offset between the upper layer 8 and the lower layer 9 above the machine speed n (-> factor k) and on the nature of the material to be transported (-> factor k ₃ ).

It can be seen from the above explanations that the device 3 plays an essential role in the exemplary embodiment illustrated with reference to FIGS. 1 to 5. Here, their linear motor 30 has a stator element 31 designed as a housing, which is firmly connected to a mounting plate (not shown in FIGS. 1 to 5 for reasons of clarity) and which is arranged on the rear of the housing head of the sewing device 10. A rotor element 32 designed as a drive rod is mounted in the stator element 31.

The device 3 also has a direct current operated drive motor 33, one between the drive motor 33 and the

Additional material transport device 2 arranged gear 34 and a transmission element 35 arranged between the gear 34 and the additional material transport device 2 for transmitting motion to the additional material transport device 2.

The device 3 in this case has a carrier element 36, which is connected to the rotor element 32 and is secured against rotation, to which the drive motor 33, the gear 34 and the transmission element 35 are attached. The support element 36 is secured against rotation by means of a guide rod 37.

Furthermore, the carrier element 36 is prestressed by means of a resilient, low-mass coupling element 38 in the form of a helical spring. Also with regard to the designs, the features and the advantages of the coupling element 38, reference is made in full to the German patent application DE 199 45 443.4 or to the international patent application WO 00/18997, in particular with regard to the power-saving mode of operation associated with the coupling element 38.

Claims

To speech

1. A device for transporting sewing material provided for a sewing device (10) or sewing machine (10), comprising at least one cloth pusher device (1) for advancing the sewing material in the cloth pushing direction (D) with a through the machine speed (s) and the stitch length ( L) determined feed speed and at least one material transport additional device (2) acting on the upper fabric layer (8) of the sewing material in the form of a pressure medium with a pressure force (Fp) and rotating at a rotational speed (Up), which is in the material feed direction (D) behind the material pusher device ( 1) arranged and driven in proportion to the machine speed (n) and the stitch length (L),

characterized ,

that by means of at least one device (3) the pressure force (Fp) which the mass transfer additional device (2) exerts on the upper fabric layer (8) of the material to be transported can be increased with increasing machine speed (s) and / or the rotational speed (U _p ) of the additional material transport device (2) can be increased further in addition to the proportional increase with increasing machine speed (n).

2. Device according to claim 1, characterized in that the pressing force (Fp) and / or the rotational speed (U _p ), preferably by means of the device (3), can also be adapted to the nature of the material to be transported.

3. Device according to claim 1 or 2, characterized in that the pressing force (Fp) is given by the formula

F _p = F ₀ + R • n,

where FQ is a constant force;

R is a coefficient of friction, the size of which is determined by the frictional relationships between the additional material transport device (2) and the upper fabric layer (8); and n is the engine speed.

4. The device according to at least one of claims 1 to 3, characterized in that the speed (np) of the device (3) is a measure of the circulation speed (U _p ) of the mass transfer device (2) or equal to the circulation speed (Up) of the mass transport additional device (2), the speed (n _p ) of the device (3) preferably being given by the formula

where k is an adjustment factor; n the engine speed; and

L is the stitch length.

5. The device according to at least one of claims 1 to 4, characterized in that the mass transfer additional device (2) in low speed ranges (np <500 min " ¹ ) of the device

(3) works in an intermittent mode, the on and off times of the device (3) preferably by the angular position (φ) of the main shaft of the sewing device (10) or sewing machine

(10) are determined.

6. The device according to at least one of claims 1 to 5, characterized in that the mass transfer additional device (2) in high speed ranges (n _p > 500 min " ¹ ) of the device (3) operates in a continuous mode.

7. The device according to at least one of claims 1 to 6, characterized in that the transport path of the mass transport additional device (2) per stitch formation process larger, in particular slightly larger than the feed path of the Material slide device (1)

8. The device according to at least one of claims 1 to 7, characterized in that for controlling the pressing force (F _p ) of the mass transport additional device (2) and / or the speed (np) of the device (3) at least one electronic control device (4a or 4b) is provided, in which in particular the machine speed (s) can be determined and / or which in particular receives the information about the stitch length (L) by input using at least one control panel (5) or which in particular contains the information about the nature of the material to be transported Receives sewing material by input using at least one control panel (5).

9. The device according to at least one of claims 1 to 8, characterized in that the device (3) has at least one preferably operated with direct current linear motor (30), which preferably has at least one stator element (31) designed as a housing, in which preferably at least a rotor element (32) designed as a drive rod is mounted.

10. The device according to claim 4 and according to claim 9, characterized in that the adaptation factor (k) is given by the formula

k = i ^■ k ₂ ^■ k ₃ , where k is a parameter for the diameter of the

Mass transport additional device (2), for the constant of the linear motor (30) and for the reduction of the gear (34); k ₂ a measure of the functional

Dependence of the offset between the upper fabric layer (8) and the lower fabric layer (9) on the machine speed (n); and k _{3 is} a parameter for the nature of the material to be transported.

11. The device according to claim 9 and according to claim 10, characterized in that the device (3) has at least one with the rotor element (32) in connection with the support element (36) on which the drive motor (33), the gear (34) and the transmission element (35) is attached and / or which is preferably mounted such that it cannot rotate by means of at least one guide rod (37).

12. The apparatus according to claim 11, characterized in that the carrier element (36) by means of at least one resilient low-mass coupling element (38), in particular by means of at least one coil spring, is biased.