EP1262121B1 - Method and device for manufacturing a brush - Google Patents

Description

The present invention relates to a method for manufacturing a brush, in particular a toothbrush, in which a strand of a single filament or a bundle of bristles is unwound from a bobbin and passed past a cutting device in which a predetermined length of the strand is cut off from the latter and in which Length piece is connected to a bristle carrier. Such a method is known, for example, from US Pat. No. 2,643,158.

In the previously known method, a plurality of strands of filament bundles are simultaneously unwound from coils and fed to a so-called perforated field plate, which is later incorporated to complete an injection mold in them. The removal of each strand from the coil and the insertion of the strand into the perforated field plate is done by mechanically clamping each strand. A feed device has a stationary clamping device and a movable clamping device for each strand. The movable clamping device is moved towards the stationary clamping device. In this case, the stationary clamping device is effective, i. the strand is held. Thereafter, the stationary clamping is released and the movable clamping switched. The movable clamping device is moved away from the stationary clamping device in the conveying direction. In this case, both further strand material is unwound from the coil and the front free end of the strand is introduced into the perforated field plate.

A similar device, which likewise contacts the supplied strands, is known, for example, from US Pat. No. 3,408,112. From DE-OS 25 52 213 and for example DE-OS 28 49 510 it is known to guide the strands between two driven propulsion rollers and advance. Here, compared to the former solution, there is the problem of slippage between the strand and the drive rollers. The desired feed of the strand is not reliably achieved.

In both of the above methods, the strand is gripped behind its front, free end and moved forward by this clamping, so that special care in threading the strand is required to buckling the To prevent single filaments or individual filaments of a filament bundle. Such a buckling of the filaments leads to impairment of the process. In particular, at the usual high processing speeds today, there is a high rejection and sometimes to stop the entire manufacturing process.

In addition, the known from the prior art conveyors for unwinding and forwarding of the strand for later connection of the same with a bristle carrier have a design-related inertia. This limits the maximum possible processing speed. The mechanical parts are also elaborately constructed and maintenance-intensive.

The present invention is based on the problem to provide a method for producing a brush of the type mentioned, which allows a higher productivity. In addition, the present invention is based on the problem to provide a device suitable for carrying out the method, which is simpler than the previously known devices.

To solve the procedural problem with the present invention, the above-mentioned method is further developed such that the unwound from the coil strand and / or the length piece is driven after cutting to length by an air flow in the conveying direction.

In the method according to the invention, the strand is first separated from the continuous material wound on the coil. Only then does the conveying of the length piece take place. In this case, no conveyor acts directly on the peripheral surface of the strand. Rather, the length piece is conveyed without contact by a force acting on the peripheral surface of the strand air flow, which flows in the conveying direction. With the air flow much higher speeds can be achieved during transport of the length piece, especially since this is no longer connected to the spool product during transport. In addition, the air flow through valves can be brought to effect very quickly. The known from the prior art constructive inertia of the conveyor is eliminated. Furthermore, kinking of individual filaments is prevented in the method according to the invention. Since there is no clamping of the filaments, the filaments become not forced against a resistance. Furthermore, it has been shown that the filaments first stick to a possible resistance, but then find their way together with the air flow.

In combination with this procedure or alternatively, to achieve the v.g. Advantages are also promoted the endless strand via a force in the conveying direction, which is generated by an air flow. The speed of this alternative proposal according to the invention can be further increased by the fact that the spool is driven rotated to provide a partial length of the strand, which can be supplied by the air flow towards the cutting device, without that by the air flow to rotate the Coil required force must be applied.

In a preferred embodiment of the method according to the invention, the length piece is guided in a guide channel to a holding channels having plate, preferably a mold cavity of an injection mold covering hole field plate and introduced by the air flow in one of the holding channels. Following this, the length pieces introduced into the perforated field plate are moved exclusively together with the perforated field plate. In other words, the conveyance of the length is in its critical phase, i. before recording in a retaining channel of the perforated field plate exclusively by the air flow. It has been shown that the guide channel and the retaining channel can have a significant angular offset, without a kinking or entanglement to be feared during insertion of the length piece in the respective retaining channel. The brush prepared in this way can have bristle bundles of different inclinations, sometimes having bristle bundles crossing over one another.

In a further preferred embodiment of the method according to the invention for cutting the length of the strand is struck with its front end face against a stop surface and then cut the length to length. This ensures that, in particular in a bundle strand all filaments of the strand are cut off with the same length.

This development of the method can then be carried out particularly effectively when the abutment surface is moved substantially transverse to its longitudinal axis after cutting the length piece and a passage opening arranged adjacent to the abutment surface is arranged in alignment with the length piece, the length piece being passed through the passage opening for attachment to the bristle carrier. This process allows a high output with reliable compliance with the desired length of the length.

In a further preferred embodiment of the present invention, the use-side ends of the individual filaments of a filament bundle are arranged in a simple manner in a surface deviating from a flat surface. In this development, the length piece is axially displaced by the passage opening and the filament bundle in the longitudinal direction before reaching an end position in which the rear end of the length piece projects beyond the passage opening, contoured by axial displacement of the filaments against each other.

In known manner, the preparation of the thus cut to length and forwarded filaments preferably takes place in that the rear end of the length piece, which projects beyond the passage opening, is melted after reaching the end position, optionally after prior cutting. As a result, the single filament or all filaments of a strand for later attachment to a bristle carrier is prepared by encapsulation with a plastic component.

According to a further preferred embodiment of the present invention, the front ends of the endless material wound on the bobbin are brought into a defined position in that the strand fed by the bobbin is pressed against the cutting device during conveyance of the length piece. As a result, defined initial conditions are generated before the strand is advanced, cut to form a defined length and finally cut from the continuous material.

The method according to the invention can be further accelerated and simplified in that, for unwinding the strand from the bobbin, an air flow is guided past the strand in a circumferential manner. After that, not only to feed the Continuous material to the cutting device or for passing the cut length piece, but also for unwinding of the continuous material from the coil an air flow used.

In order to achieve the above object with the present invention, the present invention proposes a device known per se from the prior art for producing a brush, in particular a toothbrush having at least one coil containing a wound strand of a bristle filament or a filament bundle, a first guide device with an unwinding guide channel to each strand, one of the first guide means downstream second guide means having a aligned with the unwinding channel guide channel, a feed strand on the length of cutting blade and pulling on the strand conveyor for unwinding the strand of the spool to the effect that a pressure source or is provided, which communicates with the unwinding channel and / or the guide channel and which in the unwinding channel or the guide channel in the conveying direction of the St ranges acting air flow generated. In the embodiment of the device according to the invention can be completely or partially dispensed with the strand circumferentially clamping mechanical devices which grip and promote the bristles for attachment to the brush body. The device according to the invention for producing a brush, in particular a toothbrush, is thus considerably simplified and less susceptible to interference than the devices mentioned in the introduction.

The second guide device preferably has a clamping device acting on the outer peripheral surface of the strand, so that the strand guided through the second guide device can be clamped according to any feed path and fixed in the guide device. Hereby, lengths of deviating length can be easily adjusted.

Alternatively or in combination with such a clamping direction may preferably be provided cooperating with the front end of the strand stop surface, which downstream of the second guide means and in a length of a cut length piece corresponding distance to the blade is arranged. Such a stop is preferable if all or almost all lengths of the bristles to be formed on the brush have an identical length.

Alternatively, a stop can be provided which is variable with respect to the longitudinal axis of the lengths. As a result, the length of each individual piece of length can be adjusted individually.

Particularly simple device of the invention is preferably formed by the fact that the abovementioned stop surface is formed on a mold cavity of an injection mold covering the perforated field plate. Instead of a perforated field plate, the stop may also be provided on an intermediate plate, which has at least one bore for receiving the cut length piece. This intermediate plate has at least one, preferably a plurality of bores for receiving the length piece. These holes are designed such that the lengths can be easier to incorporate in these holes. From the holes, the lengths produced are transferred to the hole field plate. For this purpose, the intermediate plate is preferably brought to a transfer station, where the perforated field plate is located. In a further preferred embodiment of the device according to the invention, the perforated field plate or the intermediate plate are movable in a direction substantially perpendicular to the longitudinal extent of the strand. Between the cutting of individual lengths so that the perforated field plate or the intermediate plate can be changed in their distance from the cutting device. Length pieces of different lengths are produced. Alternatively it can be provided on the side facing away from the guide device side of the perforated field plate or the intermediate plate a solid, but in particular movable stop. In this development, the length piece is cut off after insertion into the perforated field plate or intermediate plate and striking the movable stop of the endless strand.

Further details, advantages and features of the present invention will become apparent from the following description of an embodiment in conjunction with the drawings. In the drawing, a schematic representation of an embodiment of a device for producing a toothbrush is shown.

The exemplary embodiment shown in the drawing serves to cut and feed a strand 4 of a filament bundle stored on a schematically indicated coil 2. From this coil 2, the strand 4 is introduced into a perforated field plate 6 after prior cutting. The device has a first guide device 8, which has an unwind guide channel 10. In this unwinding channel 10 of the endless strand 4 is introduced. In the conveying direction behind the first guide device 8, a movable blade 12 is arranged. This is located downstream of a second guide device 14, which has a aligned with the unwinding guide channel 10 guide channel 16. About perpendicular to the guide channel 16 is movable a clamping punch 18, which extends to a reciprocating piston of a double-acting pneumatic pressure cylinder 20. This impression cylinder 20 is connected to the second guide device 14. Adjacent to the front end side of the second guide device 14, the perforated field plate 6 is held. This has a plurality of holding channels 22 for receiving bristle bundles and can be moved in a direction perpendicular to the longitudinal extent of the second guide means.

The unwinding channel 10 communicates via a pressure line 24 with a pressure source, not shown. In the same way, the pressure source is connected via a pressure line 26 to the guide channel 16. The two pressure lines 24 and 26 open into an annular channel surrounding the channels 10, 16, which aligns the air flow substantially parallel to the longitudinal extent of the channels 10, 16 and in the conveying direction of the strand 4. In the embodiment shown, a directed air flow is thus generated in the channels 10, 16 by overpressure.

The strand 4 is first conveyed via this directed air flow in the first guide device 8 in the direction of the perforated field plate 6. The strand 4 enters the second guide device 14 with its front free end. There, too, an air flow acts at least peripherally on the strand and promotes it further in the direction of the perforated field plate 6. This perforated field plate 6 is initially arranged such that none of the adjacent to the second guide means arranged inlet openings of the holding channels 22 is aligned with the guide channel 16. The front end of the strand 4 therefore abuts initially against a stop surface formed on the perforated field plate 6 28. This adjusts the desired length of a piece of length. Thereafter, the blade 12 separates by advancing perpendicular to the longitudinal direction of the strand of a held in the second guide means length piece 30 from the endless strand 4 from. In this separation process, at least the pressure line 24 is preferably separated from the pressure source by a controllable valve.

Now the perforated field plate 6 is displaced relative to the second guide means 14 and an inlet opening of the holding channel 22 is arranged in alignment with the guide channel 16. At the same time, the pressure source of the first guide means 8 can be switched to press the supplied endless strand 4 with all its filaments against the surface of the blade 12. The perforated field plate 6 is again displaced relative to the second guide means 14 to locate the abutment surface 28 or another abutment surface formed adjacent to an inlet opening of another holding channel 22 in alignment with the guide channel 16. The blade 12 is returned to its original position shown in Figure 1, to release the passage from the first guide means 8 to the second guide means 14. The endless strand 4 shoots again against the stop surface. The method described above is repeated, only with the difference that now another retaining channel is arranged with its inlet opening in alignment with the guide channel and equipped with a different length.

If a length piece is to be produced with a shorter length, the clamping punch 18 can circumferentially clamp the introduced into the guide means strand. Alternatively, different, the guide channel 16 completely penetrating slide can be provided, against which the front end of the endless strand abuts. In this case, a contact surface is formed by one of the rails above.

In an alternative embodiment, the abutment surface may be provided behind the perforated plate 6. Preferably, such a stop surface in the longitudinal direction of the fed endless strand 4 is displaceable. In this case, the endless strand is first pushed through the retaining channel 22 of the perforated field plate until the front end abuts against the stop. Thereafter, the cutting of the length piece 30 is carried out. The perforated field plate is displaced in order to align a further holding channel again in alignment with the fed endless strand 4. Before further feeding of the endless strand, the distance of the stop to the perforated field plate is possibly changed in order to change the length of the now to be cut length compared to the previously produced length.

Alternatively to the embodiment shown in the figure, instead of a perforated field plate, an intermediate plate may be provided which has at least one, preferably a plurality of bores for receiving the lengths. These holes are filled in one piece with lengths. Thereafter, the intermediate plate is brought to a transfer station, where the formed on the intermediate plate bores are brought to cover with the respective holding channels of a perforated field plate. The lengths are then pushed out into the holding channels. The holes of the intermediate plate are preferably larger than the holes of the retaining channels. As a result, the bristle bundles can be more easily transferred from the guide device to the intermediate plate.

In the embodiment shown, the endless strand 4 is unwound in the circumferential direction of the coil 2. In view of a twist of the endless strand in its front, deducted area, which favors easier handling of the strand, it may be preferable to unwind the endless strand 4 tangentially over the head of the coil 2. The withdrawal of the endless strand 4 from the spool 2 in this case takes place essentially in the direction of the central longitudinal axis of the spool 2.

LIST OF REFERENCE NUMBERS

2

Kitchen sink

4

continuous strand

6

Hole field plate

8th

first guide device

10

Abwickelführungskanal

12

blade

14

second guide device

16

guide channel

18

terminal temple

20

double-acting impression cylinder

22

retaining channel

24

pressure line

26

pressure line

28

stop surface

30

length piece

Claims (14)

1. A method of producing a brush, especially a tooth brush, comprising the steps of unwinding a strand of a single filament or of a filament bundle from a spool and moving it past a cutting means in which a predetermined length piece of the strand is cut off, and connecting said length piece to a bristle carrier,
   characterized in that,
   the strand which has been unwound from the spool and/or the length piece is/are advanced in the direction of transport by an airflow.
2. A method according to claim 1, characterized in that the length piece is guided in a guide channel towards a plate provided with at least one retaining channel, preferably a perforated field plate covering a die cavity of an injection mould, and is introduced by means of the airflow into the retaining channel formed on the plate.
3. A method according to claim 1, characterized in that the length piece is deflected when it is being introduced in the perforated field plate.
4. A method according to one of the preceding claims, characterized in that, for cutting the length piece to length, the front end face of the strand is caused to knock against a stop surface and that the length piece is then cut to length.
5. A method according to claim 4, characterized in that, when the length piece has been cut off, the stop surface is moved essentially transversely to the longitudinal axis of said length piece, and that a passage opening arranged in the vicinity of the stop surface is arranged in alignment with the length piece and the length piece is advanced through said passage opening so as to fasten it to the bristle carrier.
6. A method according to claim 4 or 5, characterized in that the length piece is axially displaced through the passage opening and that the filament bundle of the length piece is contoured by axially displacing the filaments relative to one another before it has reached a final position at which the rear end of the length piece projects beyond the passage opening.
7. A method according to claim 6, characterized in that the rear end of the length piece is partially melted, if necessary after previous cutting to size, when it has reached said final position.
8. A method according to one of the preceding claims, characterized in that the strand supplied from the spool is pressed against the cutting means before a length piece is cut off.
9. An apparatus for producing a brush, especially a tooth brush, comprising at least one spool (2) keeping a wound-up strand of a bristle filament or of a filament bundle ready for use, a first guide means (8) with a take-off guide channel (10) for each strand, a second guide means (14) following said first guide means (8) and provided with a guide channel (16) which is in alignment with said take-off guide channel (10), a blade (12) cutting the supplied strand (4) to length, and a conveying means (24) drawing on the strand (4) and used for unwinding said strand (4) from the spool (2),
   characterized by
   a pressure source or a vacuum source communicating with the take-off guide channel (10) and the guide channel (16) and producing in said take-off guide channel (10) and said guide channel (16) an airflow which is effective in the direction of transport of the strand (4).
10. An apparatus according to claim 9, characterized in that at least the second guide means (14) comprises a clamping means (18, 20) which acts on the outer circumferential surface of the strand (4).
11. An apparatus according to claim 9 or 10, characterized by a stop surface (28) cooperating with the front end of the strand (4), said stop surface (28) being arranged after the second guide means (14) and positioned at a distance from the blade (12) which corresponds to the length of a cut-off length piece (30).
12. An apparatus according to one of the claims 9 to 11, characterized in that the stop surface for adjusting the length of the cut-off length piece is movable in the longitudinal direction of the bristle filaments.
13. An apparatus according to one of the claims 9 to 12, characterized in that the stop surface (28) is formed on a perforated field plate (6) covering a die cavity of an injection mould or on an intermediate plate having at least one reception hole for receiving the length piece cut to length, said intermediate plate being adapted to be moved from a filling station where the hole is in alignment with the guide channel (16) to a transfer station where the hole is in alignment with a hole of the perforated field plate.
14. An apparatus according to claim 12, characterized in that the perforated field plate (6) is movable in a direction which is essentially perpendicular to the longitudinal dimensions of the strand (4).

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