GB2390316A

GB2390316A - Backing pad for an abrasive disc

Info

Publication number: GB2390316A
Application number: GB0315621A
Authority: GB
Inventors: Albrecht Hofmann; Harald Krondorfer; Markus Heckmann; Thomas Schomisch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-07-05
Filing date: 2003-07-03
Publication date: 2004-01-07
Anticipated expiration: 2023-07-03
Also published as: GB2390316B; DE10230308B4; CN100586658C; JP5064645B2; GB0315621D0; CN1468684A; DE10230308A1; JP2004090212A

Abstract

A backing pad for supporting an abrasive disc 28 comprises a support plate 10 and coupling means 14. The coupling means 14 has at least one means 16 and 18 mounted eccentrically relative to centre of the support plate 10, for example a recess for receiving a bolt, for attachment to a hand tool. The support plate 10 may be extrusion coated over at least a part of the coupling means 14, in which case the support plate 10 is also extrusion coated around a form fit element 22 punched onto the coupling means 14. Alternatively the coupling means 14 and support plate 10 may be connected by welding, gluing or soldering. The coupling means 14 terminates flush with the support plate 10 in at least one area on the side of the pad which in use faces the tool. One part of a hook and loop type fastening is fixed to the support plate 10, for attachment to an abrasive disc 28 which bears the other part.

Description

23903 1 6

Insert Tool with a Support Plat_ The invention is based on an insert tool with support plate according to the preamble of claim 1.

DE-OS 1577 422 discloses a generic insert tool with a support plate which has a support chuck and an elastically deformable, flexible outer area. In the support plate is attached a bush in which can be inserted a cylindrical 10 stopper with a separate guide ring. The stopper is held in the bush by means of a threaded connector which is arranged on the side of the stopper facing the machine and is screwed into a threaded opening of a base part of the bush facing the machine. In the bush is mounted a locking pin 15 adjustable in the axial direction via a knurled nut.

On a face of the bush turned away from the machine is attached a plate by means of a fixing bolt. On its side facing away from the machine the plate has lugs serving as 20 couplings which can be inserted in undercut openings of an abrasive body or abrasive disc in order to attach this to the insert tool.

The invention is based on an insert tool with a support 25 plate, in particular with an elastically flexible outer area and with a coupling means which has at least one eccentrically arranged fixing means for fixing to a machine tool, in particular a hand-held angle grinder.

30 It is proposed that the coupling means and the support plate be connected with material addition. A simple design of insert tool can be achieved with a few extra components and low installation cost, with which also simple, rapid

and comfortable assembly of an abrasive disc can be achieved. The term "material addition connection" in this context 5 means a connection which - as well as the processes generally regarded as material addition such as welding, gluing and soldering - is achieved by extrusion-coating of the coupling means by the support plate. If the coupling means is extrusion-coated at least partly by the support 10 plate, a particularly economic production process of the insert tool can be achieved as in particular no additional adhesion or welding processes are required with the production stations required for these.

15 In a further embodiment of the invention it is proposed that the fixing means be formed by a locking lug whereby the insert tool can be attached particularly quickly, simply and without tools to a machine, in particular an angle grinding machine.

If the fixing means is formed by an eccentrically arranged locking recess which serves to hold a function element of a fast clamping device formed in particular by a bolt mounted displaceably against a spring element, compatibility with a 25 fast clamping device with an advantageous torque transfer can be achieved. The bolt can have various cross section forms deemed suitable by an expert e.g. circular, elliptical, triangular, square or polygonal etc. It is also proposed that the fixing means have a pot-like 30 recess area extending in the axial direction. Advantageous protection of the function element can be achieved on unintentional collision with a workplace to be machined, where the axial extension of the holding area is preferably

larger than a projection of the function element or bolt beyond the coupling means. Via the holding area also a large contact surface is achieved for the function element, advantageously preventing the coupling means from cutting 5 into the function element. Wear on the function element under the influence of abrasive dust, such as in particular corundum dust, can be reduced as the holding area arranged on the coupling means largely covers the function element.

The coupling means can safely be removed from the function 10 element at any time and premature wear of the function element due to cutting in can be avoided and service intervals extended. Furthermore with a holding area extending in the axial direction a laterally reversed assembly of the insert tool in the tool holder can 15 advantageously be avoided.

The holding area can be designed as one piece or in several pieces with the coupling means. If the holding area is designed in several pieces with the coupling means, 20 different materials can be used for the coupling means and the holding area e.g. metal for the coupling means and plastic for the holding area etc. Particularly advantageously however the holding area is designed as one piece with the coupling means. This ensures a particularly 25 stable holding with a particularly advantageous protection of the function element against mechanical damage. The holding area here can be moulded on the coupling means particularly easily and economically in a deep drawing process. If the coupling means comprise a centrally arranged centring recess, an advantageous centring of the insert tool in a tool holder of a machine tool can be achieved.

the centring recess is formed by a through opening, advantageously compatibility can be achieved with common clamping systems each with a centrally arranged clamping nut. In a further embodiment of the invention it is proposed that the support plate and coupling means be connected in the peripheral direction by at least one form-fit element, advantageously supporting the material addition connection 10 on torque transfer and, despite high torque figures, always achieving a secure connection between the coupling means and the support plate.

Here the form-fit element is advantageously formed by a 15 projection moulded onto the coupling means and pointing in the axial direction, which can be moulded thereon economically and easily directly on production of the coupling means, such as in particular in a punching process. Furthermore it is proposed that the coupling means terminate flush with the support plate at least in one area on the side facing the machine. This achieves an advantageous support surface and avoids dirty edges.

25 Furthermore on a side facing the working direction, an advantageously deep pot-like area is created to protect the function element of a clamping system.

If the support plate is formed annularly, in the centre 30 area advantageously a recess can be created for fitting and removal of the insert tool on the machine tool, allowing access to the coupling means or in particular to an unlocking element of a fast clamping system.

If a Velcro-like attachment for securing an abrasive disc is fastened to the support plate, in particular a rapid and comfortable fitting and removal of the abrasive disc on the 5 insert tool can be achieved. In principle however other fixing means which the expert considers suitable can also be used.

Furthermore it is proposed that the Velaro-like attachment be designed in annular fashion, thus for a large surface achieving an advantageous clear space in the centre area in order to attach the insert tool to and remove it from a machine tool.

15 If the abrasive disc is likewise designed in annular manner, advantageously access can be achieved to a central function element, in particular an unlocking element of a fast clamping device, without the need to remove the abrasive disc from the insert tool. Furthermore a high 20 efficiency can be achieved. With a full surface abrasive disc, because of the low peripheral speed a central area makes practically no contribution to the grinding result and rather promotes deposits. With an annular abrasive disc the recess in the centre area can prevent deposits and also 25 saves energy, whereby such abrasive discs are particularly suitable for machine tools in which the energy available is limited and the performance rather low, such as in particular with battery-operated angle grinders.

30 Further advantages arise from the description of the

drawing below. The drawing shows an embodiment example of the invention. The drawing, description and claims contain

numerous features in combination. The expert will suitably

also consider the features individually and combine these into sensible further combinations.

The drawings show: Fig. 1 an insert tool according to the invention with an abrasive disc attached, opposite the machining direction, and Fig. 2 a section along line II-II in fig. 1 in enlarged 10 view. Figure 1 shows an insert tool with an annular support plate 10 of rubber which has an elastically flexible outer area 12, and with a cup-like coupling means 14 formed by a 15 metal part which in the radial inner area of the support plate 10 has a centrally arranged centring recess 20 and six fixing means 16a, 16b, 16c, 18a, lab, 18c arranged eccentrically and distributed evenly about the periphery for fixing to a hand-held angle grinder not shown in 20 detail.

The support plate 10 has a greater material thickness in the radial inner area than the radial outer area, and the material thickness of the support plate 10 diminishes 25 continuously starting from its inner diameter 32 up to around half the ring surface diameter 34, and remains constant starting from half the ring surface diameter 34 up to the outer diameter 36 (fig. 2).

30 The cup-like coupling means 14 is extrusion-coated on its outer periphery by the support plate 10, so that a first part 38 of the coupling means 14 extending in the axial direction 44 and a second part 40 connected to the first

part 38 and extending radially outwards are surrounded by the support plate 10. On a side facing the machine, the coupling means 14 terminates flush with the support plate 10 in the radial inner area 24 thereof.

In the second part 40 of the coupling means 14 extending radially outwards, spaced evenly over the periphery and extending in the axial direction 52 are moulded form-fit elements 22 formed by bearers' via which the support 10 plate 10 and the coupling means 14 are connected together in form-fit manner in the peripheral direction. The form-

fit elements 22 are moulded onto the coupling means 14 in a punching process in which the latter is punched out of a metal plate. Furthermore in the punching process the 15 centring recess 20 and the fixing means 16, 18 are moulded onto the coupling means 14. The coupling means 14 is of identical construction with a coupling means to which a grinding means is attached directly, for example to form a cutting disc, abrasive disc, sanding disc etc. The fixing means 18a, lab, 18c arranged between the support plate 10 and the centring recess 20 are formed by recesses which are arranged distributed evenly in the peripheral direction, and have a narrow first area extending in the 25 peripheral direction and next to this against the direction of rotation 42 a second broad area extending in the peripheral direction.

If the insert tool is mounted on the angle grinding 30 machine, three retainers of a fast clamping device of the angle grinder reach through the fixing means 18a, 18b, 18c in the axial direction 44 and fix the insert tool in the axial direction to a tool holder. The centring recess 20

made in the centre area of the coupling means 14 here serves to centre the insert tool on a collar of the tool holder of the angle grinder.

5 Between the fixing means 18a, 18b, 18c are fitted the three fixing means 16a, 16b, 16c evenly distributed in the peripheral direction in the coupling means 14 and formed by locking recesses, these means each serve to hold a function element of the fast clamping device formed by a bolt and 10 for this each have a pot-like holding area extending in the axial direction 44. The insert tool can be connected for drive with the angle grinder via the fast clamping device bolts, not shown in detail and each mounted moveably against a spring element, which in an operating position of 15 the insert tool engage in the holding areas and fix the insert tool in form-fit manner in the peripheral direction.

The holding areas which have a round cross-section are made of one piece with the coupling means 14 and each have a 20 closed side wall. On their faces turned away from the machine and pointing in the axial direction 44, the holding areas each have a through opening 46, 48, 50. The holding areas project beyond the three retainers of the fast clamping device in the axial direction 44. On rotating 25 drive in direction of rotation 42, the three retainers of the fast clamping device therefore lie in a wind shadow of the holding areas and are protected by these.

On a side of the support plate 10 facing in the machining 30 direction 44 is glued an annular Velaro-like attachment 26 with counter hooks for fixing an abrasive disc 28, substantially covering the entire side of support plate 10 facing in the machining direction 44.

The abrasive disc 28 allocated to the insert tool is also designed in annular fashion corresponding to the support plate 10 and glued on this on a side facing the insert tool 5 is an annular Velcro-like attachment 30 formed by a fleece.

The grinding plate 28 is attached via the Velcro-like attachment 30 to the Velcro-like attachment 26 of the insert tool.

References 10 Support plate 12 Outer area 5 14 Coupling means 16 Fixing means 18 Fixing means 20 Centring recess 22 Form-fit element 10 24 Area 26 Velcro-like attachment 28 Abrasive disc 30 Velcro-like attachment 32 Inner diameter 15 34 Ring surface diameter 36 Outer diameter 38 Part 40 Part 42 Direction of rotation 20 44 Machining direction 46 Through opening 48 Through opening 50 Through opening 52 Direction

Claims

l Claims

1. Insert tool with a support plate (10) in particular with an elastically flexible outer area (12) and with 5 a coupling means (14) which has at least one eccentrically arranged fixing means (16, 18) for fixing to a machine tool, in particular to a hand held angle grinding machine, characterized in that the coupling means (14) and the support plate (10) are 10 connected together with material addition.

2. Insert tool according to claim 1, characterized in that the coupling means (14) are extrusion-coated at least partly by the support plate (10).

3. Insert tool according to claim 1 or 2, characterized in that the fixing means (16) are formed by a locking means. 20

4. Insert tool according to claim 3, characterized in that the fixing means (16) are formed by an eccentrically arranged locking recess which serves to hold a function element, formed by a bolt, of a fast clamping device.

5. Insert tool according to claim 4, characterized in that the fixing means (16) have a pot-like holding area extending in the axial direction (44).

30

6. Insert tool according to any of the previous claims, characterized in that the coupling means (14) have a centrally arranged centring recess (20).

7. Insert tool according to any of the previous claims, characterised in that the support plate (10) and the coupling means (14) are connected in the peripheral direction by at least one form-fit element (22).

8. Insert tool according to claim 7, characterised in that the form-fit element (22) is formed by a projection moulded onto the coupling means (14) and pointing in the axial direction (52).

9. Insert tool according to any of the previous claims, characterised in that the coupling means (14) on a side facing the machine terminate flush with the support plate (10) in at least one area (24).

10. Insert tool according to any of the previous claims, characterised in that the support plate (10) is designed in annular manner.

20

11. Insert tool according to any of the previous claims, characterised in that fixed to the support plate (10) is a Velcro-like attachment (26) for securing an abrasive disc (28).

25

12. Insert tool according to claim 11, characterised in that the Velcro-like attachment (26) is designed in annular manner.

13. Abrasive disc for an insert tool according to any of 30 the previous claims, characterised by an annular design.

14. Abrasive disc according to claim 13, characterized by at least one Velaro-like attachment (30).

15. An insert tool substantially as described herein with 5 reference to the accompanying drawings.

16. An abrasive disc substantially as described herein with reference to the accompanying drawings.