CA2340896A1

CA2340896A1 - Method for quality inspection of bristles and use of said bristles

Info

Publication number: CA2340896A1
Application number: CA002340896A
Authority: CA
Inventors: Georg Weihrauch
Original assignee: Individual
Current assignee: Coronet Werke GmbH
Priority date: 1998-08-19
Filing date: 1999-07-28
Publication date: 2000-03-02
Also published as: KR20010072736A; HUP0103101A2; EG22580A; NO20010773D0; TR200100493T2; CZ2001591A3; JP2002523116A; ID28763A; CN1318988A; AR020214A1; PL346142A1; ZA200101261B; NO20010773L; DE19837676A1; TW398963B; EP1105022A1; AU5288999A; BR9913131A; WO2000010425A1

Abstract

The invention relates to a method for quality inspection of bristles, especially brush bristles, with formed useable ends that are rounded in a do me- like manner. According to said method, the adjacent ends (8) of a plurality of bristles (6) are photographed with an image analysis apparatus (15) and the degree of roundness of the bristles is detected through image evaluation. In order to obtain perfectly reproducible results, the bristles are aligned sid e by side with their casings parallel to each other and with their ends in an enveloping surface. Said bristle ends are superficially structured, before o r after said process, in such a way that a contrast is established between the ends and the casings. The bristle ends are then photographed by means of sai d image analysis apparatus (15). Quality inspection primarily comprises determining the quality of the shape given to bristle ends, but it can also concern the ratio of the end surface to the total surface of the bristle are a and the number of bristles per surface unit. For the purpose of implementing said method, coloured ends can be used on finished brushes to indicate brist le wear.

Description

._ 2 18349.3 Translation of PCT/EP99/05402 as amended on September 9, 2000 METHOD FOR THE QUALITY CONTROL OF BRISTLES
AND THE USE OF SUCH BRISTLES
The invention relates to a method for the quality control or inspection of bristles intended for brushware, particularly brushes, which are shaped at their use-side ends, particularly rounded to a spherical tip, in that the juxtaposed ends of a plurality of bristles are recorded with an image identification or recognition device and conclusions are drawn regarding the degree of shaping of the bristle ends as a result of image evaluation. The invention also relates to the use of bristles inspected in this way for brushware, as well as to brushware with characteristics reflecting visualization of the quality of the shaping of the bristles.
Nowadays plastic bristles are produced by cutting to the desired length from continuous monofilaments or monofilament strands. During the cutting process a planar or flat surface of cut is not always obtained, which is perpendicular or inclined to the bristle axis and instead burrs are formed on the cut edges. It is already known in connection with natural bristles (US 74,560), that for brushes for treating or working sensitive surfaces, the ends of the bristles should have a spherical tip. This applies to an even greater extent for the generally harder plastic bristles. Therefore, for the latter, numerous methods have been proposed for rounding the bristle ends, rounding being obtained by mechanical grinding (DE 4425 231, DE 19526 933, EP 736270, EP 740916), by producing frictional heat at the bristle ends (DE 296 14 118) or by chemical treatment. In all cases said working takes place on the finished brush, to which the bristles are fixed in bundles, the bristles within the bundle and the complete bristle area optionally having different lengths. These known methods do not make it possible to obtain a completely satisfactory dome-shaped rounding of the ends of a uniform nature for all the bristles. This more particularly applies with different bristle lengths within the bundle.
According to another known method (EP 444436), prior to their fixing to the brush body, the ends of the bristles undergo a working operation. For this purpose the bristles are brought into a parallel position, pounded flat at their ends and subsequently the ends are rounded by grinding. In this method each individual bristle within the union is uniformly subject to grinding forces, so that a uniform, good rounding is obtained on all the bristles. Such uniformly rounded bristles can then be so positioned by an axial relative mutual displacement that their ends have arbitrary curved or stepped envelopes (EP 346646).
Hitherto effective methods for the inspection of bristle ends to establish whether their working has taken place or to what extent they have been shaped, particularly rounded have not existed. The knowledge of the quality of she shaping of the bristle ends is of decisive importance for brushes for the treatment or working of sensitive surfaces, particularly tooth-brushes, but also textile brushes, polishing brushes, etc., so that in the mass production brushes whose bristles do not comply with the necessary quality level can be discarded.
According to a known proposal (DE 3741 616) individual bundles on a finished brush undergo spot checks. For this purpose use is made of a conventional camera, whose optical axis is inclined by a steep angle to the bristles. In order to adequately illuminate the very small inspection or control field of the bristle ends and avoid optical interference by reflection and the like, the bundle must be illuminated with a vertically oriented light guide. The aforementioned document leaves open how it is possible to obtain with such an optical configuration a close to reality image of the end of each individual bristle within the bundle. A valid result cannot be expected with such an inspection, because it is not possible to record the entire worked surface at the ends of the bristles and also the ends within the bundle assume different positions with respect to the optical axis of the camera and consequently also produce different images.
In a similar procedure (EP 0 189 067 A2), bristles which are to be cut, which protrude upwardly beyond the bristle stock as well as bristles which have spread sidewardly beyond the bristle stock are illuminated from the side and electro-optically recorded for subsequent manual removal.

Alternatively, the entire brush is rejected. This method is not capable of checking the finished quality of the bristle ends.
The problem of the invention is to propose a method with which a valid, reproducible quality control of the use-side ends of bristles following the working thereof is possible.
On the basis of the above-described, known method, this problem is solved in that the bristles are oriented with their jacket in the parallel juxtaposed form and with their ends in a planar envelope, beforehand or subsequently their ends undergo surface structuring or coloring for contrasting thereof compared with the bristle jacket and subsequently the structures or surface pattern formed by the ends in the envelope are recorded with the image recognition device, wherein the bristle ends, following this contrasting, can be inspected. This can e.g. take place with an opto-electronic camera, whose optical axis is oriented perpendicular to the envelope and parallel to the bristles.
In the method according to the invention it is firstly ensured that the bristles are in the same relative position to one another and the worked bristle ends are in a single, common plane. In plan view, all the bristle ends form individual, small surfaces in a uniform surface grid or raster. These individual, small surfaces contrast as a result of their structure or color with the very smooth bristle jacket. In the case of a corresponding orientation of the image recognition device with respect to the planar envelope or to the axis of the bristle, this grid field of small surfaces is imaged by means of the opto-electronics. Completely satisfactorily shaped ends with an ideal hemispherical, semi-elliptical or conically rounded contour have the same reflection behavior and consequently give a uniform grid field as the image. By image comparison with a master image, which reproduces the desired state, it is possible to bring about a qualitative and quantitative comparison of the shaping quality of the tested bristles. Instead of an image comparison, it is also possible to use any other electronic transformation and evaluation. The quality is simultaneously visualized in the case of colored or dyed bristle ends.
Bristles, whose ends diverge from the ideal contour or which are not completely within the decisive plane, appear as defective surfaces in the grid image. Tolerances can be defined for the number of defective surfaces and when exceeded the bristles or the complete brush is discarded.
By means of the method according to the invention and within the framework of the quality control, it is also possible to establish the surface proportion of the bristles satisfying the quality requirements and the number of bristles per unit area and to this extent also check the maintaining of the tolerances.
This quality control preferably takes place prior to the manufacture of the brushware, in that the bristles, following the cutting to length of the continuous monofilament or from a mufti-element monofilament strand, are positioned in parallel and their ends are pounded into a common, planar envelope. The bristle ends are then mechanically shaped, particularly rounded, e.g. by grinding or the like. The quality control can then take place in the same position, but optionally also after shifting into another plane.
The method according to the invention can also be implemented on the finished brush, provided that all the bristle ends are in one plane. The bristles can be combined into bundles or can be fixed in individual standing manner to the brush body.
Opto-electronic methods which can be used in conjunction with the invention are already known. Reference is made in exemplified manner to DE 19724 421, which describes a method for the opto-electronic measurement of plaque on teeth.
For contrasting the ends of the bristles with the remaining bristle, the bristle ends can be colored in contrasting manner prior to inspection. For example, to the ends of the bristles can be applied a contrasting dye or color by application or dipping.
According to another variant of the method, the shaped ends of the bristles, following dyeing and prior to quality control, can be finely ground or polished.

If contrasting takes place by structuring, advantageously the ends of the bristles are pre-shaped by mechanical grinding and undergo surface structuring, followed by inspection. In this case the structured ends are only finely ground or polished following image evaluation.
Instead of this, it is also possible to produce the bristles from a plastics material filled with optionally reversible color-reactive pigments and only the ends of the bristles are treated before and/or during inspection in order to bring about the color change. It is in particular possible to use those pigments, which react to thermal or radiant energy by a color change. If the color reactivity of the pigments is reversible, the individual bristle has the same appearance before and after quality control. However, in the case of permanent coloring, it remains on the bristle and therefore on the finished brush and can initially provide a guarantee to the customer that the bristles or brush have been quality controlled.
According to a further variant, use is made of bristles with a dye located in their interior and on shaping the ends said dye is distributed over the rounded surface. Bristle ends dyed or colored in this way can also be opto-electronically inspected in the aforementioned manner.
If the dye or color is applied following the shaping of the ends, it is e.g. possible to proceed in such a way that the unworked bristles, which are parallel to one another and whose ends are in a planar envelope are pre-shaped and structured by means of a grinding surface acting an their ends and which is parallel to the envelope, so that they can subsequently undergo inspection. Instead of this and whilst maintaining the positioning of the bristles, the ends of the bristles can be subject to the action of a disk parallel to the envelope and by means of which the dye is transferred.
This method ensures that dyeing takes place under identical geometrical and kinematic conditions to the shaping of the bristle ends. This method can also be integrated without difficulty into corresponding manufacturing sequences.
The structured bristles can be finely ground or polished after the inspection and the dyed bristles before the inspection with a disk parallel to the envelope.
The method according to the invention can also be modified in such a way that when using bristles with color-reactive pigments, thermal or radiant energy is made to act OT1 the ends located in the planar envelope.
Another preferred method variant is characterized in that, following inspection, the bristles are axially displaced relative to one another, so as to bring their ends into a predetermined, contoured envelope and subsequently are processed whilst maintaining their relative position to the brushware.

Thus, even if the bristles following the production of the brushware have their ends in a contoured surface, which can be curved or stepped, a quality control can still take place and which subsequently with differently long bristles still provides clear information concerning the shaping quality, the surface proportions and the number of bristles.
The advantage of this method is particularly noteworthy if, during the displacement the bristles are deflected in a predetermined angle, in order to fix the bristles to the finished brushware in a more or less spread apart position.
Also in this case all the bristles have a uniform coloring of their ends.
If, in accordance with the method of the invention, the bristle ends undergo a permanent surface coloring or a coloring by incorporated, color-reactive pigments, the colored ends are retained after quality control. They do not interfere with proper use of the brush. The invention even offers the possibility of visualizing the degree of abrasion or wear to the bristles. When used correctly, the br=istles mainly become worn at their end-near jacket as a result of material removal and in conically pointed manner. The removal of the jacket is accompanied by the removal of the color. The particular shade in which the entire bristle surface appears, can be used to indicate wear.
The invention also relates to brushware, particularly toothbrushes, with bristles having shaped ends, particularly l rounded ends and which are characterized in that the shaped bristle ends are colored in contrasting manner compared with the bristle jacket for visualizing the shaping quality.
In the case of a good quality, uniform shaping of the bristle ends, the bristle field with the contrasting, colored bristles appears optically as a uniform grid or raster surface, so that the quality of the shaping is shown to the user.
According to an embodiment, a dye is uniformly applied to the surface of the bristle ends. Instead of this it is also possible for the bristles to contain color-reactive pigments, which react to the thermal or radiant energy with a color change and for the bristle ends to be treated with thermal or radiant energy up to the color change.
The invention is described in greater detail hereinafter relative to the attached drawings, wherein show:
Fig. 1 A schematic representation of a device for rounding bristles.
Fig. 2 A schematic representation of a device for applying dye to the rounded bristle ends.
Fig. 3 A schematic plan view of the disk with drive used in the devices of figs. 1 and 2.

Fig. 4 A testing or inspection device operating according to the inventive method.
Fig. 5 A longitudinal section through several bristles prepared for inspection with different end constructions.
Fig. 6 A plan view of the bristles according to fig. 5.
Fig. 7 A longitudinal section and plan view of another embodiment of a bristle.
Fig. 8 A longitudinal section through a bristle with rounded end in the unused and worn state.
Fig. 9 A plan view of the ends of the bristles of fig. 8.
Fig. 1 shows a device for working, particularly rounding the ends of bristles. It has a disk 1 with an. abrasive coating 2, which is driven by means of a cam 3 and is mounted with two cams 4, 5 (cf. fig. 3), the movement direction being indicated by arrows.
The individual bristles 6 are combined in a tight parallel arrangement so as to form bundles 7. The ends 8 of the bristles 6 of the bundles 7 are in a planar envelope or enveloping surface. By means of a support. 9, which ensures the positioning of the bristles 6, said bristles are so oriented that the envelope of the bristle ends is parallel to the abrasive coating 2. The support 9 can also be the brush body, to which the bristles 6 or bundles 7 are fixed. By a relative displacement according to the directional arrow 10, the abrasive coating 2 comes into contact with the bristle ends and the ends 8 of the same are uniformly rounded through the movement of the disk 1.
Following working, the support 9 with the bundles 7 is brought into the station according to fig. 2, where once again is provided a disk 11 with the same drive as the disk 1 according to fig. 1. The disk 11 has a support layer 12 for receiving a dye coating 13. The disk 11 and support 9 are moved relative to one another according to the directional arrow 14 until the dye coating 13 is in contact with the bristle ends 8 and the dye is transferred to said bristle ends.
The support 9 with the bundles 7 then arrives in the inspection station according to fig. 4, where the bristles 6 or bundles 7 are oriented parallel to the optical axis of the opto-electronic device 15. The light striking in the bristle direction, as indicated by the directional arrows, is reflected on the shaped bristle ends 8. UIllformly shaped and in particular rounded bristles produce in the image evaluating means 16 a uniform grid or raster field which, following alignment in the reference device 17, care be evaluated by means of the screen 18 or printer 19.

Fig. 5 shows two bristles 20, which have a complete satisfactory rounding of their ends. The dye application 22 obtained with the device according to fig. 2 or by dipping is uniformly distributed over the rounded end 21. The image of the ends 21 of the two bristles 20 recorded with the device according to fig. 4 is reproduced at 23 in fig. 6. It shows a uniform, circular surface with optionally graduated gray tones. Fig. 5 also shows a bristle 24, which has remained unworked and which e.g. has the sloping cut face 25 with a burr 26 resulting from cutting to length. This unworked bristle is also dyed using the device according to fig. 2. Its surface image 27 (fig. 6) is deformed and enlarged compared with the circular shape. The same applies for the bristle 28 in fig. 5. whose end 29 has assumed a conical shape during grinding, so that the color or dye application 30 is correspondingly represented. Such a bristle end gives the image 31 according to fig. 6. Fig. 5 finally shows an unworked bristle 32 with a sloping cut face 33, which is only provided in the depth application area with a dye coating. Its photographic image 34 is reproduced in fig. 6.
During quality control the raster surfaces 23 according to fig. 6 meet the requisite quality standard, whereas all the other surfaces 27, 31 and 34 fall outside the same and appear as defective surfaces in the opto-electronic evaluation. By laying down corresponding tolerances, it= is possible to create a sorting criterion, which is decisive for the discarding of bristles or the brush.

It is also possible to establish the surface proportions of adequate quality ends or also the number of bristles.
In place of dyeing in accordance with fig. 2. the bristle ends 8 can also be coarsely ground in the station according to fig.
1, so that although they acquire their final shape, they have a very pronounced surface structure, which has a widely differing reflection behavior as compared with the bristle jacket and which can be used for photo-optical evaluation.
Following the quality control according to fig. 3 the ends of the bristles are finely ground or polished.
Fig. 7 shows a bristle 35 with a differently finished end. The bristle 35 is conically ground over a partial length 36 and rounded at its end 37 to a tip. As described herein before, the rounded end 37 is dyed and the color or dye coating is designated 38. Beforehand the complete conical area 36 can be given a different dye coloring or structuring. Photo-electronic evaluation provides a surface image 39. Bristles of this type are used in toothbrushes, particularly for cleaning fissures on the tooth surface.
Bristles dyed in accordance with the invention offer a further possibility when using a brush equipped therewith. Figs. 8 and 9 show a bristle 40 with an end 41 rounded in a completely satisfactory manner. On its rounded end the bristle 40 has the dye application 42, which in this case is in a firmly adhering form. When using a brush equipped with such bristles, wear takes place from the bristle jacket to the bristle ends, so that the dye application 42 is gradually worn away and finally a sharp end 43 is formed. This creates a use or wear indication, which indicates to the user the state of use of the brush or leads to the brush being replaced.

Claims

16

1. Method for the quality control of bristles intended for brushware, particularly brushes, which are shaped at their use-side ends and in particular rounded to a spherical tip, in that the juxtaposed ends of a plurality of bristles are recorded with an image recognition device and by image evaluation the degree of shaping of the bristle ends can be established, characterized in that the bristles (6) with their jacket are oriented in parallel juxtaposed manner and have their ends (8) in a planar envelope, beforehand or subsequently their ends undergo surface structuring or dyeing for contrasting them with the bristle jacket and subsequently the structure or surface pattern formed by the ends (8) in the envelope are recorded with the image recognition device, wherein the bristle ends, following this contrasting are inspected.

2. Method according to claim 1, characterized in that the ends (8) of the bristles (6) are recorded with an opto-electronic camera (15), oriented with its optical axis perpendicular to the envelope and parallel to the bristles (6).

3. Method according to claim 1 or 2, characterized in that the bristles (6) are inspected prior to processing to brushware.

4. Method according to one of the claims 1 to 3, characterized in that a contrasting dye is applied by application or dipping to the shaped ends (8) of the bristles (6).

5. Method according to one of the claims 1 to 4, characterized in that, after dyeing, the shaped ends (8) of the bristles (6) are finely ground or polished.

6. Method according to one of the claims 1 to 3, characterized in that the ends (8) of the bristles (6) are pre-shaped by mechanical grinding, undergo surface structuring and are then inspected.

7. Method according to claim 6, characterized in that, after inspection, the shaped and structured ends (8) of the bristles (6) are finely ground or polished.

8. Method according to one of the claims 1 to 3, characterized in that the bristles (6) are produced from a plastics material filled with optionally reversible, color-reactive pigments and only the ends (8) of the bristles are treated before and/or during inspection for obtaining a contrasting color change.

9. Method according to claim 8, characterized in that the bristles (6) are filled with pigments reacting to thermal or radiant energy with a color change.

10. Method according to one of the claims 1 to 3, characterized in that use is made of bristles (6) with a dye located in the interior thereof and on shaping the ends (8) the dye is distributed over the shaped surface.

11. Method according to one of the claims 1 to 10, characterized in that the unworked bristles (6), which are parallel to one another and whose ends (8) are in a planar envelope are pre-shaped and structured by means of a grinding surface, which is parallel to the envelope and acts on the ends.

12. Method according to one of the claims 1 to 10, characterized in that the unworked bristles (6), which are parallel to one another and whose ends (8) are in a planar envelope, are shaped by means of a grinding surface parallel to the envelope and acting on the ends (8) thereof and subsequently the ends are dyed in contrasting manner, whilst maintaining the positioning of the bristles (6).

13. Method according to claim 12, characterized in that the shaped ends (8) are subject to the action of a disk (11) parallel to the envelope and by means of which dye is transferred to the ends (8) of the bristles (6).

14. Method according to claim 12, characterized in that when using bristles (6) with color-reactive pigments thermal or radiant energy is made to act on the ends located in the planar envelope.

15. Method according to one of the claims 11 to 14, characterized in that the ends (8) of the bristles (6) are treated with a fine grinding or polishing disk parallel to the envelope thereof.

16. Method according to one of the claims 1 to 15, characterized in that, following quality control, the bristles (6) are axially displaced relative to one another in order to bring their ends into a predetermined, contoured envelope and subsequently are processed to brushware, whilst maintaining their relative position.

17. Method according to claim 16, characterized in that, during axial displacement, the bristles (6) are deflected from the parallel position at predetermined angles.

18. Use of bristles which have undergone a quality control according to the method of one of the claims 1 to 17, for the manufacture of brushware, in which at least the ends (8) of the bristles (6) are subject to wear, characterized in that during the use of the brushware use is made of the removal of the durably applied or incorporated dye (22) accompanying the wear to the (8) ends of the bristles (6) for wear indication purposes.

19. Brushware with bristles having rounded ends, characterized in that the rounded ends (8) of the bristles (6) are dyed in contrasting manner compared with the bristle jacket for visualizing the rounding quality.

20. Brushware according to claim 19, characterized in that a dye (22) is applied to the surface of the ends (8) of the bristles (6).

21. Brushware according to claim 19, characterized in that the bristles (6) contain color-reactive pigments, which react to radiant or thermal energy with a color change and that the ends (8) of the bristles (6) are treated with thermal or radiant energy up to the color change.