GB2427577A

GB2427577A - Sanding platen for a hand-held sanding machine

Info

Publication number: GB2427577A
Application number: GB0612741A
Authority: GB
Inventors: Steffen Tiede; Joao Jorge Bergner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-06-29
Filing date: 2006-06-27
Publication date: 2007-01-03
Also published as: DE102005030215A1; GB0612741D0; CN1891404A

Abstract

A sanding platen for a hand-held sanding machine comprises a base body 10 and a flat bearing surface 13. Dust extraction holes 16 axially penetrate the base body 10 and the bearing surface 13 and means such as burr hooks are disposed on the bearing surface 13 for attachment of an abrasive sheet 14. Extraction channels 20 are formed in the bearing surface 13, which extend from extraction holes 16 to the outer edge of the bearing surface 13. Figure 1 shows four groups of extraction channels, each offset by 90{ from its adjacent groups, with the channels 20 from adjacent groups sharing an extraction hole 16. Alternatively the extraction channels 20 may extend radially, with each extending to its own extraction hole 6. The base body, bearing surface and attachment means may be manufactured in one piece for a plastics by injection moulding.

Description

ROBERT BOSCH GMBH, 70442 Stuttgart Sanding base for a hand-held sanding

machine

Background art

The invention proceeds from a sanding base for a hand-held sanding machine, in particular for an orbital sander, according to the preamble of claim 1.

A known sanding base (DE 103 57 144 Al) for an orbital sander comprises a base body, which IS manufactured from plastics material by a onecomponent injection moulding process and on which are formed a support structure, a flat plate resting against the Support structure and having a bearing surface for an abrasive sheet, and adherent means for establishing an adherent connection to the abrasive sheet. In the base body, extraction holes axially penetrating the support structure and the plate are formed for extracting sanding dust that collects under the abrasive sheet. The adherent means comprise burr hooks, which project from the bearing surface. The burr hooks have a foot exiting from the bearing surface as well as at least one hook bent in a defined direction on the free end of the foot. The burr hooks are disposed in groups of identical but, from group to group, differing orientation of their hooks in surface zones distributed over the bearing surface.

An electric hand tool machine in the form of an* orbital sander for driving the sanding base is described in US 5 018 314.

Advantages of the invention The sanding base according to the invention for a hand-held sanding machine having the features of claim 1 has the advantage of improved sanding dust removal from the working region of the abrasive sheet since not only the sanding dust that collects centrally under the sanding site is extracted through the extraction holes but also the sanding dust that is flung away laterally is extracted in the edge region of the abrasive sheet through the extraction channels and carried away through the extraction holes.

The extraction channels may be incorporated without difficulty in the injection moulding tool for the base body manufactured from plastics material by injection moulding and may therefore easily be simultaneously moulded into the base body during the injection moulding operation.

By virtue of the measures outlined in the further claims, advantageous developments and improvements of the sanding base indicated in claim 1 are possible.

According to an advantageous form of construction of the invention, the adherent means comprise burr hooks, which project from the bearing surface and are combined in mutually separate surface zones distributed over the bearing surface, and the extraction channels extend between the surface zones. The apportioning of the burr hooks to separate zones, segments or portions of the bearing surface, between which burr-hook-free strips extend, is advantageous in terms of tools for injection moulding and demoulding the burr hooks. In terms of injection moulding, the incorporation of the extraction channels into these surface strips is particularly simple to realize.

Drawings There now follows a detailed description of the invention with reference to an embodiment that is illustrated in the drawings. The drawings show: Fig. 1 an inverted plan view of a sanding base for an orbital sander, Fig. 2 a side view of the sanding base in Fig. 1 with attached abrasive sheet, Fig. 3 a section along the line 111-ill in Fig. 1.

Description of the embodiment

The sanding base, an inverted plan view, side view and sectional view of which is represented in the drawings, for an orbital sander as an embodiment of a hand-held sanding machine has a base body comprising a support structure 11, which is formed by ribs and on the underside of which a flat plate 12 is noulded. The underside of the plate 12 remote from the support structure 11 is designed as a flat bearing surface 13 for an abrasive sheet 14, which is shown in Fig. 2. The base body 10 is so designed that, whilst a minimum weight is achieved, the base body is able to withstand the forces that arise during no-load operation and during sanding. Formed in the base body 10 are through-holes 15 of stepped diameter, of which the larger- diameter hole portions penetrate the plate 12. In the embodiment, there are altogether eight stepped through- holes 15 arranged offset by identical angles at circumference relative to one another on an inner concentric divider circle. Four of the total of eight through-holes is are used for the passage of fastening screws, which are Screwed into threaded bores of a bearing flange of a drive unit of the orbital sander, wherein the screw heads of the fastening screws lie in the larger- diameter hole portions 151 of the through-holes 15. The remaining four through-holes are intended to receive centring pins. On an outer divider circle, which is concentric with the inner divider circle and has a larger diameter than the inner divider circle, extraction holes 16 are provided, which penetrate the plate 12 and the support structure ii and are used to extract sanding dust that collects under the abrasive sheet 14 during sanding. On the bearing surface 13 there are adherent means, which establish an adherent connection with the disk-shaped abrasive sheet 14. In the embodiment, the adherent means are burr hooks 17, which catch in a velour covering on the rear of the abrasive sheet 14. The burr hooks 16 may for example be designed in the manner described in the initially cited DE 103 57 144 Al, but may alternatively have other forms of hook. As adherent means, it is also possible to use double hooks, mushroom heads and the like.

The adherent means, which in Fig. 1 are indicated only diagrammatically as burr hooks 17, are combined in surface portions, surface segments or surface zones 18. The surface zones 18 are distributed separately from one another over the bearing surface 13, wherein between adjacent surface zones 18 there remain surface strips 19 that are free of adherent means, i.e. in the present case, free of burr hooks. Extending in these surface strips 19 are extraction channels 20, which open out in the extraction holes 20 and extend right to the edge of the bearing surface 13. The rectilinearly extending extraction channels 20 are realized by means of grooves 21, which are moulded into the plate 12 and are open towards the abrasive sheet 14. Because of the arrangement of the extraction channels 20 in the surface strips 19 between the surface zones 18, the extraction channels 20 form groups with in each case Parallel-running extraction channels 20, which are rotated through angles at circumference of 900 relative to one another. Mutually facing extraction channels 20 of adjacent groups open out in a common extraction hole 16.

In the embodiment of Fig. 1 having eight extraction holes 16, there are four groups of in each case three parallel- running extraction channels 20, wherein in four extraction holes 16 in each case two extraction channels 20 open out.

The described base body 10 comprising support structure ii, plate 12, bearing surface 13, extraction holes 16, and grooves 21 in the bearing surface 13 that form the extraction channels 20 as well as burr hooks 17 projecting from the bearing surface 13 is manufactured in one-piece from plastics material by injection moulding by means of an injection moulding tool. A one-component injection moulding method is preferred in this case. The arrangement of surface zones 18 of combined burr hooks 17 with surface strips 19 situated therebetween, which is described above and illustrated in Fig. 1, is in terms of injection moulding tools advantageous for demoulding the burr hooks 17.

The described embodiment of the sanding base may additionally be modified in various ways. For example, there may be any desired number of extraction channels 20 disposed such that they are distributed regularly or irregularly over the bearing surface. The extraction channels 20 may extend radially and open out in one extraction hole 16 each. Instead of a rectilinear course, the extraction channels 20 may alternatively follow a curved course. The grooves 21 forming the extraction channels 20 may be fashioned in any desired manner, for example in clear cross section they may be trough-shaped, arc-shaped, trapezoidal, ladder-shaped, stepped etc. , and their groove width may be constant or may progressively increase or decrease in size over the groove length.

Claims

ROBERT BOSCH GMBH, 70442 Stuttgart Claims 1. Sanding base for a hand-held

sanding machine, in particular for an orbital sander, having a base body (10), a flat bearing surface (13) for applying an abrasive sheet (14), having extraction holes (16) axially penetrating base body (10) and bearing surface (13) for extracting sanding dust, and having adherent means disposed on the bearing surface (13) for establishing an adherent connection with the abrasive sheet (14), characterized in that in the bearing surface (13) at least one extraction channel (20) is formed, which opens out in an extraction hole (16) and extends right to the outer edge of the bearing surface (13)
2. Sanding base according to claim 1, characterized in that the at least one extraction channel (20) has a clear cross section of any desired shape, e.g. rectangular, trapezoidal, ladder-shaped, which is constant or progressively diminishes or increases in size over the length of the extraction channel (20).
3. Sanding base according to claim 1, characterized in that the at least one extraction channel (20) is rectilinear.
4. Sanding base according to claim 3, characterized in that a plurality of extraction channels (20) form groups with parallel-running extraction channels (20), that the groups are offset by angles at circumference of 900 relative to one another and that the mutually facing extraction channels (20) of adjacent groups open out in a Common extraction hole (16)
5. Sanding base according to claim 4, characterized in that there are eight extraction holes (16) mutually offset by identical angles at circumference and each of the four groups of Parallel-running extraction channels (20) comprises three extraction channels (20)
6. Sanding base according to one of claims 1 to 3, characterized in that a plurality of extraction channels (20) extend radially and open out in one extraction hole (16) each.
7. Sanding base according to one of claims 1 to 6, characterized in that the adherent means project from the bearing surface (13) and are combined into surface zones (18), which are distributed over the bearing surface (13) and separated from one another by adherent-means-free surface strips (19), and that the extraction channels (20) extend in the surface strips (19) between the surface zones (18)
8. Sanding base according to claim 7, characterized in that the adherent means comprise burr hooks (17), double hooks, mushroom heads and the like.
9. Sanding base according to one of claims 1 to 8, characterized in that the base body (10) comprises a support structure (11) having formed thereon a flat plate (12), on the underside of which remote from the support structure (11) the bearing surface (13) is formed, and that the extraction channels (20) are formed by grooves (21) formed into the plate (12).
10. Sanding base according to claim 9, characterized in that the base body (10) comprising support structure (11), plate (12), bearing surface (13), extraction holes (16) and grooves (21) as well as adherent means is manufactured in one piece from plastics material by injection moulding, preferably by the one-component injection moulding method, by means of an injection moulding tool.
11. A sanding base for a hand-held sanding machine, substantially as herein described with reference to the accompanying drawings.