DEVICE AND METHOD FOR KNOTTING A STRING END

Abstract

The present invention relates to a device for knotting a thread end so that a loop is formed. The device 1 comprises a knotter assembly 3 for knotting two thread sections of the thread end, as well as a driver 5 for feeding the thread sections to the knotter assembly 3. It further comprises an orbital path 4 along which the driver and the knotter assembly 3 are guided. The orbital path has a knotting region and a turnover region and is designed to guide the driver at different speeds in the knotting region and turnover region. The present invention further relates to a method for knotting a thread end, and to a device for producing tampons having a proximal retrieval thread.

Claims

1. A device (1) for knotting a thread end so that a loop is formed, in particular a thread end of a retrieval thread for tampons, comprising: a. a knotter assembly (3) for knotting two thread sections of the thread end; b. a driver (5) for feeding the thread sections to the knotter assembly (3); c. an orbital path (4) along which the driver is guided around the knotter assembly (3), wherein the orbital path has a knotting region (V) in which the driver is movable at a first speed, and an envelope region (U) in which the driver is movable at a second speed.

2. The device of claim 1, further comprising a thread feed for continuously feeding a thread end to the driver.

3. The device of claim 1, further comprising a cutting element for severing the loop of the thread end.

4. The device of claim 1, wherein the orbital path is a substantially circular orbital path.

5. The device of claim 1, comprising a path inlet for passing a ribbon-shaped substrate through the effective region of the driver so that the thread end is laid around the ribbon-shaped substrate, in particular so that the thread end is laid around the ribbon-shaped substrate when the driver orbits on the orbital path.

6. The device of claim 1, further comprising a holding device, in particular a holding device designed as a latch, which is designed to exert a restoring force on a loop end of the thread end to be knotted.

7. The device of claim 5, further comprising a guide plate for guiding ribbon-shaped substrate through the active region of the driver.

8. The device of claim 1, further comprising a knot control for checking the knot of two thread sections tied by the knotter assembly (3).

9. The device of claim 1, wherein the orbital path is drivable, in particular comprises a toothing by which the orbital path is drivable by means of a toothed belt so as to be capable of performing an acceleratable rotation about an axis of rotation.

10. The device of claim 1, comprising a direct drive for driving the driver, in particular an electric direct drive.

11. The device of 10 claim 1, further comprising an orbital drive, in particular a continuously acceleratable orbital drive, for driving the driver on the orbital path.

12. The device of claim 1, wherein the knotter assembly comprises a knotting mandrel which is rotatably driven.

13. The device of claim 1, wherein the device is configured to guide the driver through a knotting region at a first speed, wherein the first speed is lower than a second speed at which the driver is guided through the envelope region, in particular wherein the first speed has a maximum speed that is lower than a maximum speed of the second speed by between two and nine times.

14. The device of claim 1, wherein the first speed is between 300 and 600°/s and the second speed is between 500 and 4000°/s.

15. The device of claim 14, wherein the device is configured to guide the driver at a first speed through a knotting region of between 50 and 150 rpm, particularly about 90 rpm, and to guide the driver at a second speed through an envelope region of between 200 rpm and 600 rpm, particularly about 500 rpm.

16. The device of claim 1, further comprising a drive control system for moving the driver in the knotting region at a first speed, and in an envelope region (U) at a second speed, in particular wherein the drive control system is adapted to guide the driver at a first speed through the knotting region so that this leaves the knotting region after the knotter assembly has performed between one and two, in particular substantially one and a half revolutions against the direction of the driver.

17. A method for knotting a thread end, in particular two thread sections of the thread end, so that a loop is formed which forms a retrieval thread for tampons, comprising the steps of: a. guiding a thread end of a thread by means of a driver movable on an orbital path along an orbital path around a knotter assembly and an envelope element, so that a loop of two thread sections of the thread end is formed between the knotter assembly and the envelope element; b. knotting the two thread sections by the knotter assembly and untying the loop at the envelope element, and wherein the orbital path has a knotting region (V) in which the driver is guided at a first speed, and has an envelope region (U) in which the driver is guided at a second speed.

18. The method of claim 15, wherein a. a feeding of a thread end from a thread on a bobbin on the driver movable over the orbital path occurs via a restoring force, and b. the releasing of the loop comprises cutting the thread end from the thread.

19. The method of claim 15, wherein the ratio of the first speed to the second speed is between 1:2 and 1:6.

20. The method of claim 16, wherein the knotting region (V) includes an angle of between 5 and 45 degrees of the orbital path, preferably including between 5 and 30 degrees, preferably including 15 degrees.

21. The method of any claim 15, wherein the untying of the loop on the envelope element provides for a releasing of a latch configured to exert a releasable restoring force in the direction of the driver and/or knotter assembly.

22. The method of claim 15, further comprising the steps of: a. providing a device (1) according to claim 1 for knotting a thread end so that a loop is formed; b. passing a ribbon-shaped substrate through an effective region of the driver so that the thread end is laid around the ribbon-shaped substrate, in particular so that the thread end is laid around the ribbon-shaped substrate when the driver orbits on the orbital path, wherein the passing of the ribbon-shaped substrate is arranged substantially normal to an orbital path of a driver.

23. A device for producing tampons having a proximal retrieval thread comprising two thread ends linked together, the device comprising: a. the device for knotting two thread ends according to claim 1, b. a conveying device for conveying ribbon-shaped substrate into an effective region of the device for knotting two thread ends, in particular wherein the conveying device is arranged substantially perpendicular to an orbital path of a driver for feeding the two threads to a knotter assembly, and wherein the conveying device for conveying the ribbon-shaped substrate conveys into the effective region of the device for knotting two thread ends in such a way that, during an orbital movement of a driver along an orbital path, the thread is laid around the ribbon-shaped substrate substantially transversely to the longitudinal axis thereof.

24. A device (1) for knotting a thread end so that a loop is formed around a ribbon-shaped substrate, in particular a thread end of a retrieval thread for tampons, comprising: a. a knotter assembly (3) for knotting two thread sections of the thread end; b. a driver (5) for feeding the thread sections to the knotter assembly (3), wherein the driver is rotatable along an orbital path (4) around a path inlet (8) for passing a ribbon-shaped substrate, in particular rotatable on a circular orbital path (4), so that a loop is formed, a pickup (15) arranged substantially normal to the path inlet (8) is provided to receive a thread section from the driver and deposit it onto the ribbon-shaped substrate.

25. The device of claim 24, wherein the pickup (15) is substantially metal.

26. The device of claim 24, comprising a pickup spring (15.3) which exerts a restoring force on the pickup (15).

Description

FIGURE DESCRIPTION

[0098] Examples of embodiments of the invention are described with reference to the following figures. Showing:

[0099] FIG. 1 schematically the structure of a device according to the invention;

[0100] FIG. 2 schematically an area breakdown of an orbital path;

[0101] FIG. 3 an example of a device according to the invention;

[0102] FIG. 4a schematically a latch as it can be used in a device according to the invention in a clamped position;

[0103] FIG. 4b the corresponding latch of FIG. 4a in a relaxed position;

[0104] FIG. 5a another example of a device according to the invention;

[0105] FIG. 5b alternative embodiment of the device according to FIG. 5a

[0106] FIG. 6 a schematic representation of a suitable knotter assembly;

[0107] FIG. 7a a view of a knotting mandrel without eyelet;

[0108] FIG. 7b a view of a knotting mandrel with eyelet, and

[0109] FIG. 8a an alternative example of a device according to the invention;

[0110] FIG. 8b a schematic section showing a detailed view of an unstressed pickup of embodiment 8a;

[0111] FIG. 8c a schematic section showing a detailed view of a tensioned pickup of embodiment 8a;

[0112] FIG. 8d a schematic section showing a detailed view of a knotter assembly of embodiment 8a, and

[0113] FIG. 9 schematically the structure of the embodiment according to FIG. 8a.

DESIGN OF THE INVENTION

[0114] FIG. 1 shows a schematic structure of a device 1 according to the invention for knotting a thread end. The aim of knotting is that two loose ends of a thread first form an eye, and the loose ends are knotted in such a way that together they form a tight loop. In the application method described, the loop is wrapped around a ribbon-shaped material so that both legs of the loop each come to rest on one side perpendicular to the longitudinal direction of the belt. When the ribbon-shaped material is rolled up, for example to form a tampon for feminine hygiene, the loop comes to rest inside the tampon. The knotted ends of the thread protrude from the tampon and the knot and the loop formed with the knot can serve as a retrieval thread, for example, to remove the tampon.

[0115] An orbital path 4 is initially provided for the device 1 for the purpose of wrapping around a web material and knotting the ends of the thread. In the present example, the orbital path is circular. Advantageous effects can be achieved by the circular design of the orbital path. Objects moving on a circular path can be moved at a constant radial speed. Bearings and/or drive means experience a substantially uniform load, and can be designed accordingly to avoid or at least minimize imbalance effects. In addition, the control of the individual elements (see later synchronization of the knotting mandrel with the thread driver) is simplified. Acceleration and deceleration of the elements can be carried out in coordination with angular segments, so that fine adjustments are also possible—such adjustments are particularly useful when a device according to the invention is adapted to a new thread material and/or web material. For this purpose, depending on the thread tension, elasticity and frictional resistance, the person skilled in the art can adjust the control to the movement of the elements as required.

[0116] In the present example, a driver 5 is moved along this orbital path 4 at different speeds in a direction of rotation R. For simplicity, this direction of rotation R corresponds to the clockwise direction and will be taken as a reference in the further course of the application to explain the direction of rotation of other components. Of course, a device according to the invention can also be designed as a mirror image, and the corresponding directions of rotation can be exactly opposite.

[0117] The driver 5 is used to carry a thread from a thread bobbin (not shown in FIG. 1) along the orbital path 4, thereby placing it around certain elements of the device 1.

[0118] On its way, the driver 5 wraps a thread in particular around a first pin 9.2, which in the present example serves as an envelope element. The pin 9.2 keeps one eye open during continuous movement around the orbital path. When moving along the orbital path 4, the driver 5 performs a complete circle as a whole and allows the thread, which may be arranged, for example, by a thread bobbin on the opposite edge of the first pin 9.2, to form a loop between the thread bobbin and a second pin 9.1. In the simplest embodiment, this second pin 9.1 is designed as a mandrel or sword which projects into the effective space of the driver 5 from a rear wall on which the elements of the device are placed and may also be drivable. In the present simplest case, the first pin 9.1 is also a mandrel, for example a mandrel tapering towards the viewer of FIG. 1, from which a knotted thread loop can easily slide off in the direction of the viewer, for example in which the thread loop is entrained by a belt conveyor running normally to the orbital path 4 of the device 1. In particular and particularly advantageous embodiments, the first pin 9.2 may be replaced by an actuated lever, or other powered holding device, such as a releasable latch.

[0119] In order to prevent that the thread end released from the first pin, which is formed as a mandrel, hits the ribbon-shaped substrate too hard with the loop, a deflection fin 7 is provided, which also extends into the effective region and into the interior of the loop, catches it when it is released from the mandrel and gently releases such a tapering end in the tape running direction onto the ribbon-shaped material.

[0120] Ribbon-like material enters the effective region of the driver 5 through a path inlet 8. In the simplest embodiment, the path inlet 8 is a recess in the rear wall of the device. A web guide plate 6 projects into the effective region of the device through the path inlet 8 and is arranged to guide a ribbon-shaped material into the device via a drive device, for example rollers (not shown). On this tape guide plate 6, ribbon-shaped material is conveyed into the active area of the driver 5. Once the driver has passed the second guide pin 9.1, the tape guide plate 6 and thus the ribbon-shaped substrate is located within an eye of a loop formed by two legs of the thread carried by the driver 5.

[0121] In the course of this movement, the driver 5 passes through a turnover region at a certain speed.

[0122] At the opposite end of the first pin 9.1 is arranged a knotter assembly 3, which is arranged within a knotter eyelet 2.

[0123] In the present example, the driver now travels through a knotting region at a speed that is different from the speed of the turnover region. This allows the driver 5 to travel down the turnover region at a speed between twice and five times the speed it travels in the knotting region. This knotting region begins where the action of the knotter assembly starts to act on the end of the thread, respectively where the knotter assembly links the two legs of the loop and forms a knot. In the present example, the knotting region begins approximately there after the driver 5 has passed the second pin 9.1 and has made a loop around the first pin 9.2, inside which the tape guide plate 6 is present. The corresponding knotting region and turnover region can be defined as the angle of the orbital path 4.

[0124] The speed of the driver 5 is variable and the driver 5 may be controlled and driven to accelerate and decelerate. If the driver 5 is in the knotting region, a knotting mandrel (not shown in FIG. 1) rotates in the knotter assembly 3 with a rotation, in particular one and a half times, in the opposite direction to the direction of rotation R1 of the driver 5. Finally, the driver 5 passes through the effective region of a cutting blade 14, which cuts off the end of the thread, thus enabling the knotted thread loop to be led away. The driver 5 picks up another thread end and continues the movement in rotation direction R.

[0125] In FIG. 2, the area breakdown according to FIG. 1 of the effective regions using angular openings of the orbital path 4 according to an arrangement as shown in FIG. 1 is explained again in more detail. FIG. 2 schematically shows again the orbital path 4 from FIG. 1. Also shown is a center M of the circular orbital path 4. The driver is guided on a radius of the orbital path 4. A process cycle begins when the driver 5 guides a loose thread end over an turnover region U. This turnover region U may include a first acceleration region B1. In the acceleration region B1, the driver accelerates to a second speed. This Second Speed can be more of 500 rpm (relative to the orbit) and in the present example is in the range of 510 rpm. In the acceleration region B1, an acceleration of between 200 and 950 rad/s.sup.2can take place.

[0126] The initial speed of the driver 5 at the beginning of the acceleration region B1 corresponds to a constant speed which the driver maintains during the entire passage through the knotting region V. The constant and comparatively lower speed in the knotting region V enables the knotter assembly 3 to knot the loop ends fed by the driver. In the present example, the speed of the driver is five to six times lower during the knotting region V than the maximum speed in the turnover region U is. Specifically, the driver 5 here leaves the knotting region V at a speed of between 50 and 15, in particular of about 90 rpm.

[0127] In order to ensure that, when the knotting region V is re-entered, the speed of the driver is decelerated to the constant speed, which is between half and six times lower than the maximum speed travelled by the driver in the turnover region U, the turnover region U comprises a second acceleration region B2, de facto a deceleration region B2, in which the speed around the driver is decelerated, for example with an acceleration between 200 and 950 wheel/s.sup.2.

[0128] In the present example, the knotting region may include an angle of substantially 15°. Thus, depending on the setting of the parameters by the person skilled in the art, there is a time interval in the knotting region of between 0.015 and 0.05 seconds for the formation of the knot. Overall, the speed of the driver in this specific exemplary embodiment is such that it performs a complete cycle within a period of between 0.08 and 0.18 seconds. In the present example, a time period of 0.028 seconds could be defined for the knotting region V, and a time period of 0.053 seconds for the turnover region U at an acceleration in the acceleration regions B1, B2 of +, respectively − approx. 940 rad/s.sup.2.

[0129] This has made it possible to provide a knotting device as described at the beginning of this article, which is capable of very high throughput speeds, and at the same time can run with low material wear and low maintenance.

[0130] FIG. 3 shows a possible embodiment of a device 1 according to the invention. In this example, a driver 5 is rigidly connected to an orbital path 4, which can be driven by means of toothing via a toothed belt (not shown). The orbital path 4 is arranged around a ring bearing. The driver 5 has a thread clamp 5.1 which grips a thread end 30. By its movement on the orbital path 4, the driver 5 unwinds thread from a (not shown) thread bobbin. In the present example, the uncoiling occurs via the movement of the driver 5 on the orbital path 4, and is thus continuous. Also conceivable, however, are intermediate deflection rollers or an unwinding roller which actively feeds the thread to the driver.

[0131] In the present example, the first pin 9.2 is replaced by a holding device 10, which has holding teeth 10.1, 10.2. These holding teeth 10.1, 10.2 hold open a loop end of the thread end 30 so that an eye is formed. In the actual operation of tampon manufacture, this forms the end face, i.e. the distal of a retrieval thread, which essentially comes to lie inside the tampon.

[0132] As the driver 5 moves along the orbital path 4, the legs are placed on the holding teeth 10.1, 10.2 in such a way that the loop is held up until knotting of the proximal loop ends, i.e. the thread ends facing away from the end face, has taken place. Inside the stopped loop is a web guide plate 6, on which a ribbon-shaped substrate is guided through the effective area of the device 1. A deflection fin 7 is provided to initially catch any loosening of the thread and to allow it to settle onto the ribbon-shaped substrate via a tapered end. The deflection fin 7 is initially designed so that it extends parallel to the conveying direction of the ribbon-shaped material into the effective area of the device and tapers on the end face to allow the loop to slide off smoothly. In particular embodiments, the deflection fin 7 can be installed in the device 1 in a replaceable and/or adjustable manner to facilitate fine adjustment of the operating parameters to the thread length, elasticity, etc. for the person skilled in the art.

[0133] The driver 5 guides the loop end in its movement around the holding teeth, around the tape guide plate 6 and around the deflection fin 7 to a knotter assembly 3. There, both loop ends are guided and knotted by a knot eye at a knotting mandrel.

[0134] Downstream of the knotter assembly, a blade may be provided to sever the end of the thread (not shown).

[0135] The entire device 1 is attached to a machine frame 11.

[0136] A holding device 10 which can be used for the device according to the invention as shown in FIG. 3 and which is designed as a latch is shown in FIGS. 4a and 4b. The holding device 10 has two holding teeth 10.1, 10.2. These serve to hold open a loop which is formed by the driver 5 during its radial movement on the orbital path around the holding teeth 10.1, 10.2. As a latch, the holding teeth 10.1, 10.2 are formed on a latch arm 1.6 and are rotatably mounted around a latch pin 10.3.

[0137] The holding device 10 is also designed with a locking screw and a locking plate 10.4 and can thus be mounted in the device in a displaceable manner. Once again, this makes it easier for the person skilled in the art to adjust the device to the properties of the thread material and a desired tape width, speed, thread section, etc. For this purpose, the locking plate 10.4 can also be arranged to be displaceable along a groove in an axis to the web feed via a screw. This displaceability guarantees in particular that different thread sections and desired loop sizes can be accommodated.

[0138] To ensure that the latch arm 10.6 returns to its original starting position after being released once, a restoring force or mechanism can be provided, such as a spring or pneumatic cylinder.

[0139] In the present example, the latch arm 10.10 is also spring-loaded with a restoring force via a damper 10.5 with a stop 10.9. Due to the suspension, it is possible that the thread does not break during the envelope. The spring acts directly on the thread end of the driver and ensures a certain play of the thread end (see also spring at the driver in FIG. 8). The thread is thus guided tightly and loosely at the same time, allows enough play for guiding and knotting without breaking.

[0140] In this particular embodiment, the holding device is configured to exert a force on the thread loop of between 5 and 25 N, preferably between 7.5 and 15 N, preferably substantially 10 N.

[0141] At FIG. 4b the holding device of FIG. 4a is shown, where the latch has been released, i.e. the latch arm is released. In this state, the loop previously held by the holding teeth 10.1, 1.2 is released and transferred to further process control. The spring 10.10 is released and the stop 10.9 is released. The release has taken place via a rotation of the latch lever 10.6 around the latch pin 10.3. In operation, the holding device 10 configured in this way would immediately return to the state shown in FIG. 4a to be ready to receive a new thread loop. In this example, a pneumatic cylinder can be used to return the latch lever to its original position. Depending on the settings of the spring strength and the desired force to be exerted on the thread loop of between 5 and 25 N, preferably of between 7.5 and 15 N, preferably of essentially 10 N, the stop 10.9 must also be pressed against the spring force of the relaxed spring 10.10.

[0142] FIG. 5 shows a further advantageous embodiment of a device 1 according to the invention. The device 1 comprises an orbital path 4, which can be driven by means of a toothing 4.1 via a toothed belt. A drive control is provided, which is designed in such a way that a speed of the orbital path 4, which is mounted on the machine frame 11 by means of a ring bearing, can be continuously adjusted.

[0143] In particular, said drive control is configured such that the orbital path is capable of traveling at a first speed in a first range and at a second speed in a second range. A driver 5 rigidly connected in the direction of rotation R (clockwise) of the orbital path is carried along.

[0144] A tape guide plate 6 extends through the device, through which a ribbon-shaped material enters the effective area of the driver 5 and a loop is formed around the ribbon-shaped substrate by the path of the driver 5 around a holding device 5 and the knotter assembly 3. In order to guide the loop ends to a knotter assembly 3 in a correct orientation, a knotter eyelet 2 is provided, which is radially beveled, and is designed to be aligned in the direction of rotation.

[0145] The device further comprises a knotter hook 12 driven by means of a drive wheel 13. The pin-shaped knotter hook 12 includes a hook end 12.1 and a drive end 12.2 connected to and supported by the drive wheel 13. In operation, the hook end 12.2 engages the loop and, next to the plane of rotation of the orbital path, opens it normally to it. For this purpose, the drive pulley 13 is arranged at right angles to the orbital path 4 and driven correspondingly normally to it.

[0146] In a particular embodiment, the knotter hook 12 can correctly feed the loop ends to the knotter assembly and/or facilitate the removal of the knotted loop by moving it, after the thread end has been cut, out of the effective region in the direction of rotation of the drive wheel 13 by means of the hook end 12. Lead out.

[0147] The drive wheel 13 of the knotter hook 12 is driven so that its movement and speed is synchronous with the driver 5. In other words, the drive wheel can be designed, for example, to complete one full revolution in the time it takes to move the driver once around the entire orbital path.

[0148] In a further additional or alternative embodiment, the knotter hook 12 can prevent the thread end from entering the effective region of the cutting element too early during knotting due to the pull of the driver. In this example, this can be facilitated by the knotter hook 12 by pulling on the loop, thus keeping the unfinished knotted loop end away from the cutting element. In this embodiment, the knotter hook 12 would preferably be synchronously clocked with the knotter assembly 3 via the drive wheel 13 so that it completes one revolution in the time it takes the knotter assembly 3 to form a knot, i.e. between 1 and 2 revolutions.

[0149] FIG. 5b shows a further advantageous embodiment of the device according to FIG. 5. In order to reduce the overall moving mass, it was surprisingly found that with a drive wheel 13′ with preferably three symmetrically arranged outriggers, a mass saving can be achieved with simultaneous high controllability and quietness of operation. Four- or multi-arm drive wheels would also be conceivable.

[0150] In FIG. 6, a detail is shown of a device as described in the figure descriptions above, which shows a suitable knotter assembly 3 and a driver 5.

[0151] The driver 5 shown is rigidly connected to an orbital path 4 and, for illustrative purposes, is located directly adjacent to a knotter assembly 3. The driver can be in this position, for example, at the start of entry into the knotting region. The loop ends of the thread end are not shown for the sake of simplicity.

[0152] The knotter assembly 3 is disposed within a knotter eyelet 2 and includes a knotting mandrel 3.1 configured to rotate counterclockwise within the knotter eyelet 2. In the process, the knotting mandrel 3.1 performs a dipping movement with a tip end running towards the thread loops and engages in loop ends held by the driver and holding device. The pressure of the loop ends, the rotation of the knotting mandrel and a guide over the knotter eyelet form a knot in a 1- to 2-fold, preferably one-and-a-half-fold rotation of the knotting mandrel.

[0153] The knotter eyelet 2 comprises a guide geometry 2.1 which is aligned towards the outside, i.e. in the radial direction. In operation, a loop end is initially guided to the guide geometry 2.1 and, as it continues along the path of the driver 5, is guided into the effective region of the knotting mandrel 3.1, which rotates in the opposite direction to the orbital path of the driver 5.

[0154] In the present example, the driver 5 has a driver gripper 5.1 provided with a restoring force, through which the loop is guided into the knot with sufficient play.

[0155] Finally, the second loop end enters the effective region of the knotting mandrel 3.1 and is knotted to the first loop end.

[0156] FIG. 7a shows a schematic side view of the knotter assembly of FIG. 6 without the knotter eyelet. The knotter assembly essentially comprises a replaceable knotting mandrel 3.1, which is detachably and rigidly connected to a rotatably mounted drive pulley 3.5 via a mandrel foot 3.3. Overall, the knotter assembly 3 shown has a multi-part design. The knotting mandrel 3.1 includes a first mandrel extension 3.1 and a parallel aligned second mandrel extension 3.2, as well as a thread guide aperture 3.4 also aligned parallel to the knotting mandrel extensions. In operation, the two-part mandrel shape and the thread guide aperture 3.4 ensure that the knotted thread loops can be discharged from the knotter assembly after knotting.

[0157] As can be seen in FIG. 7b, the laterally beveled and radially aligned knotter eyelet 2 has a corresponding recess.

[0158] Suitable for the device according to the invention is a driver rigidly connected to the orbital path in the direction of rotation. The driver can, for example, be detachably connected to the orbital path by means of a clamping screw or a plurality of clamping screws extending through the entire profile of the orbital path. For this purpose, pre-drilled recesses can be, for example, provided in the orbital path.

[0159] A first spring element may likewise be provided on the driver, spanning the entire profile thickness of the orbital path, and connecting a rear element of the driver to a front element of the driver. In the present example, the front element of the driver would be the element that guides the thread end into the effective region of the holding device and the knotting assembly. This allows the first spring element to create an effective connection between springs arranged on the rear side and a thread clamp provided on the front side. In operation, this would result in the thread clamp allowing some play for the thread end due to the spring action. Together, for example, with the spring-loaded holding device described above, this can facilitate knotting by the knotting assembly, prevent breaking of a thread end and enable higher process speeds.

[0160] FIG. 8a illustrates another aspect, respectively a particular embodiment, of the present invention. The device shown is suitable for placing a thread end around a ribbon-shaped substrate, for example a cotton tape for a tampon, and knotting two thread sections of this thread end so that a loop can be formed. When this cotton tape is rolled up, wound, and/or folded, these thread sections of the thread end can protrude from a resulting tampon and serve as a retrieval thread. Thus, when the end of the thread is knotted, a loop is formed around a ribbon-shaped substrate. The thread end (not shown) is unwound from a driver 5. The driver 5 is rigidly connected to a toothed rotating wheel 20. This rotating wheel 20 can be driven, for example, by a drive belt, or a drive wheel (not shown), and is preferably respectively acceleratable or deceleratable. The rotating wheel 20 is mounted on an orbital path 4 so that the driver 5 is able to perform a circular movement. In the process, the driver guides the thread end past various processing units.

[0161] During a complete rotation around the orbital path 4, the thread is wrapped once around a substrate tape, e.g. cotton tape, which is conveyed centrally into the effective region of the driver. The thread end is first placed around a pickup, which initially holds the thread end and the resulting loop open. A further thread section of the thread end is placed on a deflection fin.

[0162] The open thread end is then passed to a knotter assembly 3, where two thread sections of the thread end are knotted together. A guide geometry 2.1 formed on a knotter eyelet ensures that the free thread piece is correctly guided to the thread piece to be knotted. The loop created in this way is fed away in the normal to the image plane together with the cotton tape. The pickup 15 allows the loop created to slide down onto the substrate tape in a controlled manner by releasing the thread section held in a pickup hook 15.1 by lowering a pickup lever 15.4. For this purpose, the pickup lever 15.4 is pivotably mounted in a joint 15.2. A pickup spring 15.3 exerts a restoring force on the pickup hook 15.1. This is overcome by the knotting process of the knotter assembly 3 and corresponding traction on the thread end. When the pickup lever 15.4 is in its maximum lowered position, it releases the thread section, whereupon the restoring force returns it to its angled initial position.

[0163] After knotting, the end of the thread is moved past the cutting blade 14, which cuts off the loop. The driver 5 starts a new revolution on the orbital path 4 with a new thread end. The aforementioned elements are attached to a machine frame 11, through which centrally provided recesses allow a tape inlet for the substrate tape.

[0164] The substrate tape is guided horizontally by a tape guide plate 6. In addition to the tape guide plate, a stop plate 6.1 is formed parallel to it, which prevents the pickup hook from interfering with the belt conveyance of the ribbon-shaped substrate.

[0165] A deflection fin 7 guides the end of the thread from the opposite side close to the cotton tape and enables the loop created to slide on smoothly through its end tapering in the direction of conveyance of the cotton tape, i.e. towards the plane of the observer. In addition, the deflection fin exerts the necessary resistance for the knotter assembly to knot the thread ends by means of a notch. After the loop is finally knotted and a knotter hook (see FIG. 5a or 5b) guides the created loop away with the substrate tape, the deflection fin 7 guides the loop onto the ribbon-shaped substrate through its tapering shape. A bulbous shape following the notch also ensures the necessary pulling resistance to release the loop from the knotter eyelet 2

[0166] With the device shown and the resulting gentle deposition of the thread loop onto the cotton tape, a high process speed with high reliability can be achieved. This device is equally capable of driving a corresponding acceleration and variable speed of the driver 5, as described in the embodiment of FIGS. 1 to 7 above.

[0167] FIG. 8b shows a section of the pickup 15 at the upper end of the orbital path. The pickup 15 is positioned so that it makes an angle of not more than 95 and not less than 85° degrees with respect to the plane of the tape guide plate (not shown in this figure) and thus to the ribbon-shaped substrate. Here, the angle is viewed from the center of the end face of the pick-up hook 15.1. The pickup hook 15.1 is substantially hook-shaped at the end of a pickup lever 15.4 and is suitable for receiving a thread section of the thread end (not shown). The pickup lever 15.4 is pivoted about a joint 15.2 and is shown angled in FIG. 8b. A pickup spring is operatively connected between the pickup lever 15.4 and the machine frame 11 so that a restoring force acts on the pickup lever 15.4. The pickup 15 is bolted to the machine frame 11 by a flange 22 with a screw 21. An orbital path leads radially around the pickup 15. In FIG. 8b, grooves 23 and teeth 24 can be seen, which can be brought into operative connection with a drive belt or belt, for example, a caterpillar belt.

[0168] In FIG. 8c, the pickup lever 15.4 shown in FIG. 8b is shown in an angled position, where the pickup hook 15.1 releases the previously held thread section and allows it to slide onto a substrate tape. The pickup spring 15.3 is fully extended and exerts the full restoring force on the pickup lever. When the thread path has left the pickup hook, the pickup lever moves back to the angled position of FIG. 8b, ready to pick up a new piece of thread.

[0169] FIG. 8d shows another area of the embodiment of FIG. 8a in detail. Shown are a knotter assembly 3, a driver 5, and a cutting blade 14. The driver 5 is designed, in operation, to unwind a thread end, forming it into a loop as it travels along the orbital path of the device. Two thread sections are guided towards each other in the knotter assembly 3 in such a way that they can be knotted into a knot. The knotter assembly 3 is a complex component which is surrounded externally by a knotter eyelet 2. The knotter eyelet 2 has a guide geometry 2.1 on the side facing the direction of rotation, which serves to accommodate the free piece of thread. Above the knotter assembly 3, a cutting blade 14 is provided, which is firmly connected to the machine frame via a cutting blade holder 14.2, which in turn holds a replaceably designed blade 14.1 in the effective region of the driver, so that a loop is cut off from the thread end when the driver passes the cutting blade. The driver is rigidly connected to a rotating wheel, which can, for example, be driven by a belt as already described.

[0170] The operation of embodiment 8a-d is shown again schematically in FIG. 9.

[0171] The device 1 comprises an orbital path 4 around which a driver 5 is movably mounted. The driver 5 thus performs a circular movement around a path inlet 8 provided substantially centrally in the device 1, which serves to convey a ribbon-shaped substrate substantially perpendicular to the image plane into the effective region of the driver 5.

[0172] As it moves along its orbital path 4, the driver carries along a thread end whose thread sections interact with the individual elements of the device 1 arranged along the orbital path. First, a loop is formed around the path inlet 8 with the thread end. Two thread sections of the thread end are guided together in the knotter assembly 3 by a knotter eyelet 2 in such a way that a knotting mandrel (not shown) is able to knot them. In this case, a thread section is held by a pickup 15, which is arranged substantially at a right angle above the substrate tape. Subsequently, the thread path is gently lowered onto the substrate tape by the pickup 15 against a restoring force. A stop plate 6.1 may be provided above the ribbon-shaped substrate so that the pickup 15 does not touch it, and so could interfere with the running of the ribbon-shaped substrate. The ribbon-shaped substrate is guided at the path inlet 8 by a guide plate 6.

[0173] A cutting blade 14 fixed on the orbital path 4 cuts off the generated loop, which is discharged together with the substrate tape, in particular, for example, by a knotter hook 12 as shown in FIG. 5a or 5b. The loop formed is released from the knotter eyelet of the knotter assembly, and slides over a tapered deflection fin 7 onto the ribbon-shaped substrate at the end face. As the ribbon-shaped substrate is conveyed away, the loop is pulled along with it and can protrude as a retrieval thread in a tampon produced by means of winding, folding and/or pressing.

[0174] The present invention provides a device for knotting loose thread ends for the production of tampons with retrieval threads, which is safe in operation as well as easy to maintain and capable of providing continuous high volume tampon production.

LIST OF REFERENCE NUMBERS

[0175] 1 Device for knotting a thread end
2 Knotter eyelet
2.1 Guide geometry
3 Knotter assembly
3.1 Knotting mandrel
3.2 Second mandrel extension
3.4 Thread guide aperture
3.5 Rotatably mounted drive pulley
4 Orbital path

5 Driver

[0176] 5.1 Driver gripper
6 Guide plate
6.1 Stop plate

7 Deflection fin

[0177] 8 Path inlet

9.2 First pin

9.1 Second pin

[0178] 10 Holding device
10.1 First holding teeth
10.2 Second holding teeth

10.3 Latch pin

[0179] 10.4 Locking plate

10.5 Damper

10.6 Latch arm

10.9 Stop

10.10 Spring

[0180] 11 Machine frame
12 Knotter hook

12.1 Hook end

12.2 Drive end

[0181] 13 Drive wheel
14 Cutting blade

14.1 Blade

[0182] 14.2 Cutting blade holder

15 Pickup

[0183] 15.1 Pickup hook

15.2 Joint

[0184] 15.3 Pickup spring
15.4 Pickup levers
20 Rotating wheel

23 Groove

24 Tooth

30 Thread end

[0185] B1 Acceleration region
B2 Second acceleration region

M Center

[0186] V Knotting region
R Rotation direction
U Turnover region