NZ617988B2 - Grinding head - Google Patents

Abstract

Disclosed is a grinding head (1') adapted to rotate about a central axis, having a surface (2') selected between a plane surface and a cylindrical surface, and which is provided with retainer grooves for edge profile parts (14) of a number of abrasive paper members (3) with associated support brushes (4), wherein the abrasive paper members (3) are mounted at an angle of 20-40°, preferably about 30°, directed obliquely forward in the direction of rotation of the plane surface (2') and the tangential plane of the cylindrical surface, respectively, wherein the retainer grooves (12) for the edge profile parts (14) of the abrasive paper members (3) extends obliquely rearwards in the direction of rotation of the plane surface (2') at an angle (8) of 3-10° relative to a radial extension, or wherein the retainer grooves (12) of the edge profile parts (14) of the abrasive paper members (3) extend obliquely rearwards in the direction of rotation of the cylindrical surface (13) at an angle of 3-10° relative to an axially parallel generatrix of the cylindrical surface (13). In a simple way is hereby readily achieved a more optimal abrading of particularly outer side edges and edge areas of plate-shaped items. s (4), wherein the abrasive paper members (3) are mounted at an angle of 20-40°, preferably about 30°, directed obliquely forward in the direction of rotation of the plane surface (2') and the tangential plane of the cylindrical surface, respectively, wherein the retainer grooves (12) for the edge profile parts (14) of the abrasive paper members (3) extends obliquely rearwards in the direction of rotation of the plane surface (2') at an angle (8) of 3-10° relative to a radial extension, or wherein the retainer grooves (12) of the edge profile parts (14) of the abrasive paper members (3) extend obliquely rearwards in the direction of rotation of the cylindrical surface (13) at an angle of 3-10° relative to an axially parallel generatrix of the cylindrical surface (13). In a simple way is hereby readily achieved a more optimal abrading of particularly outer side edges and edge areas of plate-shaped items.

Description

Grinding Head Field of the Invention The present invention relates to a grinding head adapted to rotate about a central axis, having a surface which is selected between a plane surface and a cylindrical surface, and which is provided with retainer grooves for edge profile parts of a number of abrasive paper members with associated support brushes.

Background of the Invention EP 1633530 B1 describes a grinding head or an abrading disc of the kind indicated in the preamble of claim 1, intended for being rotated about a central axis. The abrading disc has a surface with radial retainer grooves for end parts of abrasive paper mem- bers with associated support brushes with a radial extension over the greater part of radius of the surface which has increasing height inwardly from the periphery.

The abrading disc is designed such that the surface has increasing height inwardly from a periphery of the surface, and so that the abrasive paper members have ap- proximately radial extension across the greater part of radius of the surface. Hereby is ensured a stable and uniform grinding which is suited for grinding concave, con- vex and plane surfaces and recesses/countersinks.

In order to achieve a more stable and good grinding of a surface, the abrasive paper members are distributed diametrically and evenly on the surface of the grinding disc such that the abrasive paper members here cover the greater part of the radius of the surface, entailing that the greater part of the grinding disc surface can be used for counter grinding.

That the surface has increasing height inwards from the periphery of the surface causes the grinding wheel to be felt very stable as it is the centre part of the grinding disc which strikes the surface to be ground first. Around the centre part of the grind- ing wheel there will be no large lateral forces pulling the grinding disc across the surface, and therefore it will be easy to hold the grinding disc against the surface. 5925979_2 An embodiment of the invention seeks to provide a further improved grinding head which makes it easier to achieve a more optimal grinding particularly of side edges and edge areas of plate-shaped items, e.g. blockboard and furniture doors, or corre- sponding plate-shaped items.

Alternatively or additionally, an embodiment of the invention seeks to at least pro- vide the public with a useful choice.

Description of the Invention The present invention provides a grinding head adapted to rotate about a central axis, having a surface which is selected between a plane surface and a cylindrical surface, and which is provided with retainer grooves for edge profile parts of a number of abrasive paper members with associated support brushes, wherein the abrasive paper members are mounted at an angle of 20-40º, directed obliquely forward in the direc- tion of rotation of the plane surface and the tangential plane of the cylindrical sur- face, respectively.

The abrasive paper members may be mounted at an angle of 30º, for example, di- rected obliquely forward in the direction of rotation of the plane surface and the tan- gential plane of the cylindrical surface, respectively.

In a simple way is hereby readily achieved a more optimal abrading of particularly side edges and edge areas of plate-shaped items.

For example, it is to be emphasised that grinding of outer edges of laser-cut items of metal sheeting can be optimised by the oblique angle directed forward in the direc- tion of rotation, further facilitating the making of a slight chamfer or rounding of outer top side edges of laser-cut items of metal sheeting.

The grinding head according to an embodiment of the invention is designed such that the retainer grooves for the edge profile parts of the abrasive paper members extend obliquely rearwards in the direction of rotation of the plane surface at an angle of 3- 10º relative to a radial extension. 5925979_2 Alternatively, the grinding head according to an embodiment of the invention is de- signed such that the retainer grooves for the edge profile parts of the abrasive paper members extend obliquely rearwards in direction of rotation of the cylindrical sur- face at an angle of 3-10º relative to an axially parallel generatrix of the cylindrical surface.

The grinding head according to an embodiment of the invention may advantageously be designed such that the plane surface between the retainer grooves for the edge profile parts of the abrasive paper members is designed with radial suction apertures, and that the grinding head includes an enclosing housing which is provided along its periphery with an annular lip seal.

The grinding head according to an embodiment of the invention may further suitably be designed such that the lip seal is constituted by brushes made of an electrically conducting material, e.g. carbon fibre brushes.

The grinding head according to an embodiment of the invention can be designed such that side edges of the radial suction apertures have an inclined course down- wards in the direction of rotation such that rotation of the plane surface can cause a sucking effect by itself.

Suitably, the grinding head according to an embodiment of the invention is designed so that the support brushes consist of relatively soft brushes of pig’s bristles.

Alternatively, the grinding head according to an embodiment of the invention can be designed so that the support brushes consist of soft horsehair brushes.

Or the grinding head according to an embodiment of the invention can be designed so that the support brushes consist of stiff brushes of Tampico fibres.

For optimisation for specific tasks, the support brushes may consist of a suitable mix- ture of pig’s bristles, horsehair and Tampico fibres.

Description of the Drawing The invention is explained more closely in the following, by way of non-limiting example only, with reference to the accompanying drawings, in which: 5925979_2 Fig. 1 shows a plan view of a prior art abrading disc; and Fig. 2 shows a plan view in section of the prior art abrasive disc according to Fig. 1; Fig. 3 shows a plan view of an embodiment of a grinding head according to the invention, as shown during grinding of a plate item; Fig. 4 shows a perspective view of the grinding head according to the invention shown in Fig. 3 for illustrating an oblique angular position of the abrasive paper members; Fig. 5 shows a perspective view of the grinding head according to the invention shown in Fig. 3 for illustrating an angular displacement relative to radial of the abrasive paper members; Fig. 6 shows a plan view of a prior art cylindrical grinding head with longitudinal retainer grooves for radial abrasive paper members; Fig. 7 shows a plan view in detail of the grinding head shown in Fig. 6; Fig. 8 shows a perspective view of an embodiment of a cylindrical grinding head according to the invention where the abrasive paper members are angled forward in the direction of rotation relative to a tangent plane of cylindrical surface of the grinding head; Fig. 9 shows a perspective view in detail of the grinding head shown in Fig. 8; Fig. 10 shows a perspective view of a modified embodiment of a grinding head ac- cording to the invention where the plane grinding head includes an enclos- ing housing which is provided along its periphery with an annular lip seal; Fig. 11 shows a perspective view of the grinding head shown in Fig. 10, as seen from its outer side. 5925979_2 Detailed Description of Embodiments of the Invention Fig. 1 shows a prior art grinding head 1 e.g. as in EP 1 633 530 B1, having a surface 2 to which a number of abrasive paper members 3 are fastened, and having a radial extension across the greater part of the surface 2. Behind each abrasive paper mem- ber 3, the grinding disc 1 is provided with a row of support brushes 4.

The number of abrasive paper members 3 and support brushes 4 can be arbitrary. In the shown prior art embodiment of a grinding head 1, there are eight radial abrasive paper members with associated single rows of support brushes 4.

Fig. 2 shows the prior art grinding head 1 with two abrasive paper members 3 which are slit such that the abrasive paper members 3 are divided into a number of abrading strips 5. The abrasive paper members 3 are fastened in a surface of the grinding head 1. The surface 2 has increasing height inwards from its periphery 6. Behind the abra- sive paper members 3, support brushes 4 are provided, with uniform height such that the polishing pressure becomes uniform in height.

Figs. 3-5 show a preferred embodiment of a grinding head 1’ according to the inven- tion where the grinding head 1’ in Fig. 3 during rotation is moved towards the right side of the drawing, along an outer side edge 9 of a plate-shaped item 10 to be abraded.

Fig. 4 illustrates that the abrasive paper members 3 with associated support brushes 4 are mounted in retainer grooves 12 in the grinding head 1’ at an oblique angle 7 of -40º, preferably about 30º, directed forward in the direction of rotation of a plane surface 2’. It is to be mentioned that the oblique angle 7 is measured in relation to a generatrix 11 standing perpendicularly to the periphery of the grinding head 1’.

Fig. 5 illustrates that that the retainer grooves 12 for the edge profile parts 14 of the abrasive paper members 3 extend obliquely rearwards in the direction of rotation of the plane surface 2’ at an angle 8 of 3-10º relative to a radial extension, i.e. the abra- sive paper members 3 are angularly displaced relative to a central axis.

Fig. 6 shows a prior art cylindrical grinding head 19 e.g. as in EP 1 509 365 B1, hav- ing longitudinal retainer grooves 20 for receiving edge profile parts 21 of abrasive 5925979_2 paper members 3 with associated support brushes 4, whereas Fig. 7 shows a detail view of retainer grooves 20 and edge profile parts 21, respectively, for reception in retainer grooves 20.

Fig. 8 shows a modified embodiment of a grinding head 1’ with a large number of retainer grooves 12 for edge profile parts 14, where the retainer grooves 12 have an inclined orientation of 20-40º, preferably about 30º, forward in the direction of rota- tion as well as the retainer grooves 12 for the edge profile parts 14 of the abrasive paper members 3 extend obliquely rearwards in the direction of rotation of the cylin- drical surface 13 at an angle of 3-10º relative to the tangent plane of the cylindrical surface 13.

Figs. 10 and 11 show a grinding head 1’’ with a plane surface 2’ which between the retainer grooves 12 for the abrasive paper members 3 and the support brushes 4, re- spectively, is designed with radial suction apertures 15, and which includes an en- closing housing 16 which is provided along its periphery with an annular lip seal 17 and an external suction branch 22. This is intended for connection with a hose for a suction cleaner or a central suction system.

The lip seal 7 is constituted by brushes that are made of an electrically conducting material, e.g. carbon fibre brushes 18, such that static electricity can be earthed thereby via the carbon fibre brushes 17, of course on the condition that the grinding head 1’’ with the carbon fibre brushes 17 as such is provided with a potential equali- sation connection (earth connection).

Side edges 19 of the radial suction apertures 15 have an inclined course downwards against lower sharp edges in the direction of rotation such that rotation of the plane surface 2’ only can cause a substantial sucking effect by itself. 5925979_2

Claims (14)

1. Grinding head adapted to rotate about a central axis, having a surface which is selected between a plane surface and a cylindrical surface, and which is provided with retainer grooves for edge profile parts of a number of abrasive paper members 5 with associated support brushes, wherein the abrasive paper members are mounted at an angle of 20-40º, directed obliquely forward in the direction of rotation of the plane surface and the tangential plane of the cylindrical surface, respectively.

2. Grinding head according to claim 1, wherein the retainer grooves for the edge pro- 10 file parts of the abrasive paper members extend obliquely rearwards in the direction of rotation of the plane surface at an angle of 3-10º relative to a radial extension.

3. Grinding head according to claim 1, wherein the retainer grooves of the edge pro- file parts of the abrasive paper members extend obliquely rearwards in the direction 15 of rotation of the cylindrical surface at an angle of about 3-10º relative to an axially parallel generatrix of the cylindrical surface.

4. Grinding head according to claim 1 or claim 2, wherein the plane surface between the retainer grooves for the edge profile parts of the abrasive paper members includes 20 radial suction apertures, and wherein the grinding head includes an enclosing hous- ing which is provided along its periphery with an annular lip seal.

5. Grinding head according to claim 4, wherein the lip seal is constituted by brushes made of an electrically conducting material.

6. Grinding head according to claim 4, wherein side edges of the radial suction aper- tures have an inclined course downwards in the direction of rotation.

7. Grinding head according to any preceding claim, wherein the support brushes con- 30 sist of brushes of pig’s bristles.

8. Grinding head according to any preceding claim, wherein the support brushes con- sist of horsehair brushes. 5925979_2

9. Grinding head according to any preceding claim, wherein the support brushes con- sist of brushes of Tampico fibres.

10. Grinding head according to any preceding claim, wherein the support brushes 5 consist of a mixture of pig’s bristles, horsehair and Tampico fibres.

11. Grinding head according to any preceding claim, wherein the abrasive paper members are mounted at an angle of 30º, directed obliquely forward in the direction of rotation of the plane surface and the tangential plane of the cylindrical surface, 10 respectively.

12. Grinding head according to claim 5, wherein the lip seal is constituted by carbon fibre brushes. 15

13. Grinding head according to claim 1, being substantially as herein described with reference to any embodiment disclosed.

14. Grinding head being substantially as herein described with reference to any em- bodiment shown in