The type of brush rings described above are being used to form brushes in most heterogeneous sweeping lorries and brushing machines. The brush rings being used today comprise usually a ring shaped frame part or in other words, that has been bent to a circumferential shape, when viewed in a perpendicular direction in respect to the longitudinal direction of the brushes, and that is usually made of thin sheet iron, the thickness of which is e.g. about 1 mm and in which the brushes have been attached e.g. by means of suitable

solidifying attachment mass. This type of brush rings are usually planar.

This type of brush rings, that are partly made of metal, tend to brake particularly because of cold, which is due to stiffening of the brushes. In such an occasion they open in certain places the frame sheet iron supporting the brush part of the brush ring, in which case bigger or smaller units of brush parts are released from the brush ring. In addition to that, such a problem is involved with the type of brush rings described above having metal frames and plastic brushes, that reuse of the same is impossible in practice, because removing of the frame sheet iron from the brushes is not economically justified in practice. That is why the type of brush rings are removed as a whole to the dumping area, that is naturally a significant waste problem. Furthermore when the type of brush rings described above are being used, very strongly built supporting structures must be used, also, such as space rings made of metal, fastening rings etc., which is why a brush being collected of this kind of brush rings becomes dispro- portionately expensive.

On the other hand from Finnish Patent No. 87977, a brush element is previously known, that is entirely made of plastic based material. When exploiting the method according to the patent in question, plastic paste existing essentially in a solid shape is being led on the melting existing at the top edge of the brush preform, that moves along in an essentially upright position, to work the brush ring to its final shape by means of a press mold assembly by forming the frame part and preferably the holding means from the said plastic paste. Arrangements explained in the patent in question to feed particularly the plastic paste on top of the melting edge of the brush preform

are insufficient when being carried out in practice, that leads to that, that the plastic paste gets eccentrically on the brush preform. This leads furt- hermore to that, that the result, when pressing the brush preform to bring out a final brush ring, is not adequately homogeneous. This results many significant disadvantages in practice, when the brush ring is being used in a brushing machine, wherein e.g. vibra- tion is caused due to unbalance and furthermore due to the above extra wearing of the brushing machine and discomfort for the use of the machine are caused as well. The brush elements being manufactured by the method described in the patent above are planar, that is why due to wearing of the brushes, the brushing of the brush formed of the brush rings becomes uncon- tinous in the longitudinal direction of the brush particularly in the jointing points of the brush rings, that is why the brush is not able to fulfill very far conventional demands, that are requested in certain purposes, because material to be brushed may go through the brush without touching the brushes, in which case the brush must be dismantled and the brush rings of the same replaced.

It is the aim of the method for manufacturing of a brush ring according to this invention to achieve a decisive improvement in the problems presented above and thus to raise essentially the level of knowledge in the field. To achieve this aim the method according to the invention is primarily characterized in, that the plastic paste is being led bent in a ready fi- nished shape, such as through a U-shaped extrusion groove or correspondingly, on the brush preform, preferably on top of a melting edge of the brush preform, that is being preheated in the same connecti- on.

As the most important advantages of the method, simplicity and the reliability of the same may be mentioned. Thanks to the invention it is first of all possible to produce brush rings, the manufacturing costs of which are significantly more profitable and that are more heterogeneous than present brush rings particularly due to that, that the plastic paste being bent in shape in advance improves significantly homogeneity of the brush rings, because the plastic paste forming the frame part is not able to get settled eccentrically. Thanks to the invention the brush rings being manufactured by this method are both very friendly for the user and longstanding parti- cularly due to homogeneity of the same. When exploi- ting advantageously preheating of the brush preform, the method according to the invention secures further- more that, that the contact between the solid melting paste and brush preform connecting the above to each other is achieved reliably and effectively already during the situation, when the plastic paste is being extruded on the brush preform. The preheating descri- bed above causes that, also, that roughness of the melting edge of the brush preform get balanced by influence of heating, which furthermore enables a touch as even as possible between the same and the plastic paste.

Advantageous embodiments of the method according to the invention are presented in the dependent claims directed to the method.

The invention relates to an apparatus functioning according to the principle of the method as well, that is being described in a greater detail in the preamble of the independent claim related to the same. The primary characteristics of the apparatus are represen- ted in the characterizing part of the corresponding claim.

As the most important advantages of the apparatus according to the invention may be mentioned simplicity and reliability of its construction and use, wherein by very simple arrangements, e.g. when advantageously preheating the brush preform during extrusion, it is possible to achieve a uniform and continuous contact between the melting edge of the brush preform and the plastic paste to be extruded on the same. The brush rings being manufactured by the apparatus are particu- larly homogeneous, thanks to that, that the extrusion groove, existing in the extrusion device belonging to the apparatus and the shape of which corresponds the shape of the brush preform, places the plastic paste in a ready formed shape on the brush preform, in which case it may not get settled e.g. eccentrically. The brush rings being manufactured by the apparatus according to the invention hold together particularly well thanks to that, that the contact between the plastic paste forming the frame part and the brush preform forming the brush part is sufficiently effi- cient already since extrusion thanks to preheating, thanks to which the brush rings being manufactured by the apparatus are in addition to homogeneity of the same also longstanding thanks to a strong structure of the same. It is advantageous to exploit the apparatus according to the invention particularly in connection with a brush ring, in which the touching point of the radially directed outer circle of the brush part of the brush ring has been arranged to change within the whole breadth of the brush ring, to achieve an essen- tially unbroken brush touch in the longitudinal direction of the brushing machine to the object being brushed continuously regardless of the lenght of the brushes, when the brush rings forming the brush keep rotating around the longitudinal axis. The brushing result of this type of brush ring stays optimal with a view to brushing effect despite wearing of the brushes significantly longer than with present planar

brushes, that means in principle till the end of the brushes.

Advantageous embodiments of the apparatus according to the invention are presented in the dependent claims directed to the apparatus.

In the following description, the invention is illu- strated in greater detail with reference to the appended drawings, in which Figs la and lb show sectional side views of a brush formed of conventional brush rings as slightly used (a) and as very used (b) Fig. 2 shows an advantageous brush ring as a pers- pective view, Fig. 3 shows manufacturing of a brush ring shown in fig. 2 viewed in the longitudinal direction, Figs 4a and 4b show an extrusion frame of an apparatus exploiting the method according to the inven- tion as a front view and a side view, and Figs 5a and 5b show some advantageous counterpart surface arrangements of an apparatus exploiting the method according to the invention.

The invention relates to a method for manufacturing of a brush ring, whereby the brush ring is intended to be used particularly with several corresponding brush rings as a brush, that rotates w around a longitudinal axis s, in a brushing machine. The brush ring consists of a brush part 1 and a ring shaped frame part 2, that

connects the radially directed r brushes la forming the brush part 1, which parts 1, 2 are formed as a uniform entirety preferably from plastic based mate- rial, and in which there has been arranged at least holding means 3 to prevent the brush ring from twis- ting, when the same has been assembled in place to the brush frame of the brushing machine. The brush ring is being manufactured from an essentially elongated brush preform 1', in which the brushes la are connected to each other by melting l's, wherein on the melting l's existing at the top edge of the brush preform 1', that moves along in an essentially upright position, plastic paste 2' is being led, that is in an essen- tially solid state, to work the brush ring to its final shape by means of a press mold assembly X by forming the frame part 2 and preferably the holding means 3 from the said plastic paste 2'. The plastic paste 2' is being led bent in a ready finished shape, such as through a U-shaped extrusion groove U or correspondingly, on top of the melting edge l's of the brush preform 1', that is as an advantageous embodi- ment being preheated in the same connection.

As a particularly advantageous embodiment, the ext- rusion device 4 feeding solid plastic paste 2', such as an extruder or like, comprises a heated and an essentially elongated extrusion frame 4a, inside of which the brush preform 1' is being led through a passage duct 4a' existing therewith, particularly for preheating of the melting edge l's of the brush preform 1' before extruding the plastic paste 2' on the same.

The principle described above may be noticed particu- larly from figures 4a and 4b, that show an extrusion frame of an extrusion device exploiting the method according to the invention as a front view and a side view. Furthermore in the advantageous brush rings

shown in figs 2 and 3 principles of the applicants previous patent application FI 963433, "Harjakiekko" have been adapted, in which case the frame part 2 of the brush ring, the cross section of which is arranged to stay essentially constant throughout and in which the brush part 1 has been attached centrically, has been arranged to project in at least two places x sidewards from the ground level o of the same, prefe- rably with a constant wave form. Furthermore as an advantageous embodiment, the frame part 2 has been arranged to project sidewards from the ground level o on one side sl of the same, only, by exploiting a so called three-dimensional press mold assembly X. In this case both of the press molds X1 of the press mold assembly X are arranged by the surfaces of the same existing adjacent to the frame part 2 and brush part 1 to project sidewards sl from the ground level o of the same advantageously in four places x.

When comparing a brush formed of brush rings according to the invention and functioning of the same particu- larly with an ordinary brush as shown in figs la and lb, it may be noticed, that the brush ring according to the invention may be used in principle as long as an adequate brushing effect may still be obtained with the brushes. When coupling ordinary brush rings, space collars are always needed in principle between the brush rings placed one after another, which points out furthermore unsatisfactory functioning of usual planar brush rings in such respect, that due to wearing of the brushes with reference particularly to fig. lb the contact surface brought out by the outer surface of the brush becomes very quickly uncontinuous. For example the brush shown in fig. lb would not be any more useable in most usual purposes and the brush as shown in fig. la as well already nearly unsatisfactory in certain demanding purposes.

Furthermore as an advantageous embodiment of the method the entire brush ring, that means the brushes la forming the brush part 1 of the same as well as plastic paste 2' forming the frame part of the same are manufactured from recycling and preferably essen- tially the same manufacturing material, such as from polypropylene or like.

Furthermore as an advantageous embodiment the shape of the plastic paste 2' extrusion is being adjusted to correspond the breadth of the brush preform 1' of each brush ring to be manufactured by exploiting extrusion frames 4a, that are connected e.g. removably to the extrusion device 4 and that have mutually differently shaped extrusion parts U and/or passage ducts 4a'.

The apparatus for manufacturing of the type of brush rings described above comprises thus at least an extrusion frame 4a to feed plastic paste 2', bent in a ready finished shape, such as through a U-shaped extrusion groove U or correspondingly, on the brush preform 1', that is preferably preheated in the same connection, whereafter the brush ring may be worked to its final shape between the press mold assembly X to form both the frame part 2 and advantageously the holding means 3 as well from the said plastic paste 2'.

As an advantageous embodiment the extrusion device 4 feeding solid plastic paste 2 comprises a heated and particularly with reference to fig. 4b an essentially elongated extrusion frame 4a, to lead the brush preform 1' inside the same through a passage duct 4a' or like existing therewith, particularly for pre- heating of the melting edge l's of the brush preform 1' before extruding the plastic paste 2 on the same.

As an advantageous embodiment the extrusion grooves U and/or passage ducts 4a' belonging to the extrusion

device 4 are connected removably to the extrusion frame 4a, to adjust e.g. the shape of the extrusion and/or the passage duct to correspond the breadth of the brush preform 1' of each brush ring to be manu- factured. Furthermore with reference particularly to fig. 4a the extrusion frame 4a comprises a passage duct 4a' existing at the bottom of the same, the breadth of which corresponds essentially the breadth of the brush preform 1', when viewed in a cross section. Furthermore with reference to fig. 4b at the extrusion end I of the extrusion frame 4a there has been arranged an extrusion groove U, that surrounds the passage duct 4a'.

Furthermore as an advantageous embodiment the brush ring has been worked to its final shape by means of the press mold assembly X, whereby the holding means 3 are formed in the same connection, when the frame part 2 is being pressed to the press mold assembly X by means of a counterpart surface arrangement 6 existing in the press mold assembly X, whereby the holding means 3 are being formed by means of material drifting from the frame part 2 thereto during pres- sing. The counterpart surface arrangement 6 has been arranged to the press mold assembly X as an entirety, that is connected separately to the same, particularly for preparing brush rings with differing holding means 3 by changing the counterpart surface arrangement 6 and exploiting otherwise essentially the same press mold assembly X.

Furthermore as an advantageous embodiment of the invention, the counterpart surface arrangement is intended particularly for manufacturing of a brush ring, that comprises an essentially circumferential frame part 2, when viewed in the longitudinal directi- on, in which case the holding means 3 comprise at least one shoulder arrangement 3a existing therewith

and, whereby the brush part 1 and the frame part 2 are entirely made of recycling and preferably essentially of the same manufacturing material, such as polypropy- lene or like. With reference to the embodiments shown particularly in figs 3, 5a and 5b, the counter part surface arrangement 6 has been attached removably preferably to the lower press mold X1 of the press mold assembly X, preferably by means of quick locking principle, such as by means of a form locking joint, screw joint 5 and/or correspondingly.

With reference particularly to the advantageous embodiment shown in fig. 3, the counterpart surface arrangement 6 has been arranged by an interchangeable counterpart piece 6a, that is placed essentially at the point of the holding means 3 in the press mold X1.

Furthermore as an advantageous embodiment, the coun- terpart surface arrangement 6 may be arranged by one uniform interchangeable counterpart surface existing in the press mold X1, that is e.g. continuously against the frame part 2 in the radial direction, whereby it is formed as shown in fig. 5a of a uniform circular ring 6a' and as shown in fig. 5b of e.g. an essentially uniform planar interchangeable counterpart plate 6a".

It is obvious, that the invention is not limited to the embodiments presented or described above, but it can be modified within the basic idea even to a great extent. In this case it is first of all possible to form the type of brush rings described above of a frame part, that is e.g. wider than presented and into which there has been attached e.g. one single spiral- shaped brushing or, that has been carried out by means of a two or multiple ended threading. It is also possible to exploit the principle described above on the other hand by using a solution like the one shown in the drawings, in which the frame part comprises a

structure, that has e.g. knees extending sidewards instead of a structure having a cross section, that extends constant. It is also possible to equip the brush rings according to the invention with auxiliary holding arrangements, functioning by means of e.g.

male-female-principle and that are placed at the axially directed side surfaces of the frame parts of the same in which case auxiliary counterpart surface arrangements for the same are naturally needed. It is naturally possible to produce a brush ring according to the invention from most heterogeneous materials, by exploiting most heterogeneous manufacturing methods, in which case use of polypropylene as the manufactu- ring material of the brush rings has been represented as one example, only, that is, however, a very suita- ble alternative in this connection.