A METHOD OF MANUFACTURING A PLASTIC-FRAMED BRUSH ELEMENT

Abstract: A manufacturing method for the manufacturing of a plastic-framed brush element. In present brush elements metal backing strips to which the brush fibres are attached are used. They are, howerver, heavy in construction, unbalanced, and sometimes open in use so that the fibres detache themselves from the backing part. In the manufacturing method in accordance with the invention the frame section is formed of plastic in such a way that a molten plastic strip (3) is sprayed on top of the ribbon of joined fibres and a predetermined length of the preform thus formed is pressed between forms (4 and 5), when a very dimensionally exact, light, and durably constructed brush plate (6) of solid plastic is formed.

Description: A Method of Manufacturing a Plastic-framed Brush Element This invention concerns a method of manufacturing a plastic-framed brush element. Previously brush elements have been manufactured in such a way that the bristle fibres have been melted or glued together at one end to form in this way a 0,5-1,5cm thick comb-like ribbon. There are in existence various different recognized manufacturing methods for joining the fibres together. The fibre ribbon that is manufactured by joining together is then pressed into a metal backing part, when a finished product is formed in which the points of the fibres point straight outwards from the metal backing strip. Brushes are usually straight strips or round cylinder-like brush disks in model. This present method, however, includes very many work stages in the manufacture of the metal backing strip, so that the manufacturing time of the product has become unnecessarily great. Also when the brushes are in use the metal backing strips sometimes open and the fibres become detached from it. In cylinder-like models the metal backing strip has shown itself to be unbalanced in construction, so that during brushing even very strong vibration has sometimes appeared in the brushing machine itself. Previous experiments have also been made to manufacture the brush element entirely from plastic, but the parts corresponding to the bristle fibres in a brush made by the spray moulding technique have not withstood brushing, due to the fact that the fibres of the brush element must be absolutely orientated fibres in order to withstand hard wear and orientation cannot be achieved in the fibres by the spray moulding technique. It is the intention of this invention to present a method of attaching the brush fibres to a plastic backing strip, when with the aid of the method it is possible to produce brush elements more economically, and in which the fibres will definitely remain attached to the backing strip, and which at the same time are also more balanced in construction also in cylinder-like models. By this method it is also possible to achieve backing strips that are dimensionally very exact compared to the corresponding metal ones and the weight of the brush part of a brushing machine lightened by 15 - 30 in which case the transmission eqipment of the brushing machine is subject to smaller stress. It is characteristic of the invention that a molten plastic mass is first sprayed on top of the joined brush fibres and that the preform thus created is placed in an open form in such a way that when the forms are closed the molten plastic mass is squeezed into the shape of the form and at the same time fills the gaps between the fibres in the backing strip. TheSspraying of the plastic mass into a closed form carried out by spray moulding technique does not succeed in this case, because the molten plastic mass extrudes between the fibres before the form-shaped cover part is completly filled with the plastic mass. In what follows the invention is described in detail with the aid of an example by refering to the accompanying drawings in which, Figure 1 shows the spraying of the plastic mass on top of the bristle fibre ribbon in accordance with the invention Figure 2 shows a cross-section of pre-sprayed:form with the molten plastic mass prior to the form being closed. The example is from the manufacture of a cylinder-like brush component Figure 3 shows a cross-section when the halves of the form are closed, when the plastic mass distributes itself in accordance with the form forming the solid backing part of a plastic brush sheet. Figure 4 shows a finished brush element. In Figure 1 shows the spraying of the plastic mass on top of the brush fibres. From the one end the fibre ribbon 1 manufactured from fibres melted or glued together is transported for example between two turning conveyor belts under nozzle 2, which simultaneously squeezes the ribbon-like molten plastic mass 3 on top of the fibre ribbon in such a way that the plastic mass is bent by about 20 - 30 mm on either side of the fibre ribbon. The thickness of the molten plastic strip is 2 - 15 mn depending on the volume of the backing part of the brush component. A length of the preform thus formed is cut as required and bent around the lower part 4 of the form shown in Figure 2. The upper form 5 is pressed against the lower form 3 in accordance with Figure 3, when the plastic mass is squeezed into the shape of the form at the same time filling the gaps between the fibres in the backing strip and thus the solid plastic backing strip 6 is formed. If required e.g. metal reinforcing pieces or securing pieces can be placed in the preform to be squeezed before the halves of the form are pressed together. It is clear to a tradesman acquainted with the field that the size and form of the brush elements manufactured by the method according to the invention can be varied within extremely large limits, which concerns fibre materials or their dimensions. Other products too, e.g. plastic ski-slope elements, street brooms, etc. can be manufactured by the same method. The construction of the equipment and forms in accordance with the invention can also be varied correspondingly within the framework of the invention in many ways. In a finished brush element the fibres (8) are firmly fixed inside the backing strip (6), figure 4. When attaching the brush element to an axle a tooth (7) is formed in it. This can be formed either directly in the form or as above by a reinforcing component added to the preform.

Claims: Patent Claims l. A method of manufacturing a plastic-framed brush element, in which the brush element consists of a backing part (6) formed of plastic mass and brush fibres (8') or bristles placed inside this from one end, characterized in that on top of the ribbon (l) formed of brush fibres joined together at one end molten or plastic plastic mass (3) is sprayed or squeezed and that the preform thus formed is placed into an open form, most advantageously into the lower form (4) after which the form is closed, most advantageously by means of the upper form (5), when the plastic mass (3) when squeezed forms the backing part (6), in which the plastic mass (3) substantially fills the gaps between the fibres (8). 2. A manufacturing method in accordance with Claim 1, c ha r a c terized in that a reinforcing or securing part is added to the preform made of the fibre ribben (l) and the plastic mass (3) before the form is pressed together. 3. A manufacturing method in accordance with Claims 1 or 2, c ha ra ct er iz ed in that the preform is placed to form a ring with the aid of a ring form (4,5) suitable for this, in which case the finished brush element forms a ring.

Inventors: KIRKKALA MAUNO, KIRKKALA, MAUNO
Applicants: KIRKKALA MAUNO, KIRKKALA, MAUNO
Application year: 1986
Main classification: A46B3
IPC codes: A46B3, A46D3