GB2364944A

GB2364944A - Hand tool machine with friction lining on tool support flange

Info

Publication number: GB2364944A
Application number: GB0114282A
Authority: GB
Inventors: Guenther Berger
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-06-14
Filing date: 2001-06-12
Publication date: 2002-02-13
Anticipated expiration: 2021-06-12
Also published as: GB2364944B; DE10029277A1; GB0114282D0; JP2002046063A

Abstract

A hand tool machine comprises a tool spindle 13 which has a free end onto which a disc-shaped tool 18 (e.g. a grinding disc or a circular saw) is clampable between a supporting flange 62 and a nut 20. The face of the flange 62 which abuts the tool 18 comprises a friction lining 53 made of an elastically compliant material such as rubber, PVC or PUR. When no force is applied to said face of the flange 62 the lining 53 projects beyond this face. The lining 53 may be captively retained in an annular groove 55 of rectangular or U-shaped cross-section. The lining 53 may be formed by introducing a compound into the groove 55 which has previously been provided with an adhesive primer, and then expanding and/or curing the compound in the groove 55.

Description

2364944 r 13 1 ROBERT BOSCH GMBH, 70442 Stuttgart Hand tool machine

Background art

The invention proceeds from a hand tool machine, e.g. in the form of a right angle grinder, circular hand saw or the like, according to the preamble of claim 1.

From DE 197 52 810.4 U1 a hand tool machine is known, in which the tool, e.g. a grinding wheel, is clampable firmly between a supporting flange and a clamping nut. The tool in said case lies against the end of the supporting flange. In order to increase the frictional force there, it is known to dispose at the end of the supporting flange an 0-ring, which in the unloaded state projects beyond the end of the supporting flange and during tightening of the clamping nut generates an initial tension and increased friction between the supporting flange and the tool. Such an 0-ring is very frequently lost during a tool change and is moreover subject to extremely high wear. Furthermore, only a relatively weak frictional coupling is achieved by said means.

2 Advantages of the invention In contrast, the hand tool machine according to the invention having the characterizing features of claim 1 has the advantage of a considerably improved frictional coupling on account of a much greater contact surface. A further advantage is a considerably increased stability under load, wherein moreover the preconditions exist for fixed, captive mounting of the friction lining, which is 10 consequently permanently available.

Advantageous developments and improvements of the hand tool machine indicated in claim 1 are possible by virtue of the measures outlined in the further claims. is Drawings There now follows a detailed description of an embodiment of the invention, which is illustrated in the drawings. 20 The drawings show:

Fig. la vertical section of part of a hand tool machine in the form of a right angle grinder, 25 Fig. 2 an enlarged inverted plan view of the supporting flange of the hand tool machine in Fig. 1, Fig. 3 a diagrammatic section along the line III-III in Fig. 2.

Description of the embodiment

Fig. 1 shows a hand tool machine in the form of construction of a right angle grinder 9. The latter comprises a housing 10, which accommodates an electric 3 drive motor 45 (not shown in further detail) with a drive shaft 11, a rightangle gear 12 and a workspindle 13. The right-angle gear 12 comprises a conical pinion 46, which is driven by the drive shaft 11 and is in mesh with a dish 5 wheel in the form of a bevel gear 47, which is nonrotatably connected to the workspindle 13. The workspindle 13 is rotatably supported in a bottom bearing 14 in the form of a ball bearing and a top bearing 15 in the form of a needle bearing. Both bearings 14, 15 are in particular designed as radial bearings. The bearing 15 is accommodated in the housing 10, while the bottom bearing 14 is accommodated by a special bearing flange 16, which forms in relation to the housing 10 an independent, hence firmly connected part made, for example, of plastics material.

The workspindle 13 projects with its free. in Fig. 1 bottom, end 131 axially beyond the bearing flange 16. Seated on said free end 131 is a clamping apparatus generally denoted by 17 for receiving and clamping a tool 18 in the form of e.g. a cutting-off wheel, grinding wheel or the like, which is drivable by means of the workspindle 13.

The clamping apparatus 17 comprises a clamping nut 20, which is screwable onto a threaded portion 21 of the free end 131 of the workspindle 13 and may act axially via an intermediate plain washer 24 from one direction upon the tool 18. A further constituent part of the clamping apparatus 17 is, for example, a non-threaded special nut assembled from three pieces into a single component in the form of a known SDS click nut, such as is known from EP 0 424 388 or DE 197 52 810. 4 U1, to which reference is hereby made in order to avoid unnecessary repetition. Said special nut comprises a rear supporting ring 63, which is connected in a non-rotatable but axially displaceable manner to the workspindle 13 and seated on the latter. The special nut further comprises a front supporting flange 62 4 with an axially projecting location gudgeon 23, against the axial end 52 of which the rear side of the tool 18 remote from the clamping nut 20 may rest, wherein depending on circumstances the tool 18 may be centred by means of a central centring hole 22 on the location gudgeon 23 of the supporting flange 62. The supporting flange 62 is supportable axially relative to the supporting ring 63 in order to take up the axial clamping pressure directed through the clamping nut 20 towards the tool 18. The supporting flange 62 is connected in a non-rotatable but axially displaceable manner to the supporting ring 63.

Thus, the supporting flange 62 and the supporting ring 63 are jointly displaceable axially in relation to the workspindle 13 but non-rotatably connected to the latter.

A further part of the special nut is an actuating ring 19, which is disposed axially between the supporting ring 63 and the supporting flange 62 and is rotationally adjustable in relation to both. During the rotational adjustment supporting bodies (not shown in detail here) are actuated so that through rotational adjustment of the actuating ring 19 the supporting flange 62 and the supporting ring 63 are moved axially towards one another, thereby allowing the axial clamping pressure relative to the clamped tool 18 to be reduced in such a way that the clamping nut 20 is easily detachable manually from the workspindle 13 and so no special tool is required for said detachment. Instead of said special nut, a supporting flange connected axially and non-rotatably to the workspindle 13 may be provided. Said supporting flange or the supporting flange 62 shown in Fig. 1 has, at its end 52 directed towards the tool 18, a friction lining 53. The latter is such that under an axial pressure load it is at least to a limited extent compliant, in particular substantially elastically compliant. The friction lining 53 is advantageously of a rubber-elastic design. It is made of rubber, PVC, PUR or similar materials behaving in a rubber-elastic manner. In the axially unloaded state according to Fig. 3, the friction lining 53 projects with its axial end face 54 axially beyond the end 52 of the supporting flange 62. The friction lining 53 is firmly connected in a captive manner to the supporting flange 62 and hence protected against loss. It is moreover wear-resistant and therefore guarantees a long service life. The friction lining 53 is contained in an annular groove 55 at the end 52 of the supporting flange 62. The annular groove 55 is rectangular in cross section and U-shaped and may axially directly adjoin the outer peripheral surface of the location gudgeon 23 of the supporting flange 62. In said case, the friction lining 53 is formed by introducing a compound of rubber, PVC, PUR or the like into the annular groove 55, which has previously been provided with adhesive primer, and then expanding and/or curing said compound in the annular groove 55. Because of the rectangular cross section of the annular groove 55, which is completely filled by the friction lining 53, the friction lining 53 has an effective, annular, axial end face 54 with a substantial radial extension. During introduction of the compound into the annular groove 55 the compound is quantitatively determined in such a way that in its expanded and/or cured state it projects with its axial end face 54 suitably beyond the end 52 of the supporting flange 62, as shown in Fig. 3.

When a new tool 18, e.g. a grinding wheel, is fitted onto the end of the workspindle 13, the rear end of the tool 18 is applied against the axial end face 54 of the friction lining 53 on the end 52 of the supporting flange 62. When the clamping nut 20 is then tightened, the tool 18 is pressed against the end face 54 of the friction lining 53.

In said case, the friction lining 53 gives at least slightly and via the tool 18 exerts an axial pressure upon the thread of the free end 131 and upon the clamping nut 20. Thus, in between an initial tension is generated.

Said initial tension prevents unintentional detachment of the clamping nut 20 and off-centre running of the tool 18 during no-load operation and slowing-down of the rightangle grinder 9. Because of the large surface contact between the tool 18 and the axial end face 54 of the friction lining 53 there is a highly effective frictional coupling between the supporting flange 62 and the tool 18. The friction lining 53 therefore in a simple, inexpensive manner eliminates the risk of the tool 18 working loose during no-load operation or slowing-down of the right- angl grinder 9 and enabling detachment of itself and the clamping nut 20. The friction lining 53 is highly stable under load and even after many changes of the tool 18 is not worn.

7 3 R.38312 17.4.2000 ROBERT BOSCH GMBH, 70442 Stuttgart

Claims

Claims

1. Hand tool machine for a wheel-shaped tool (18), having a housing (10) accommodating a workspindle (13), on the free end (131) of which the tool (18) is clampable between a supporting flange (62) and a clamping nut (20), characterized in that the supporting flange (62) at the end directed towards the tool (18) has a friction lining (53).

2. Hand tool machine according to claim 1, characterized in that the friction lining (53) i,s designed so a,,:--.o be compliant at least to a limited extent under axial pressure load.

Hand cool machine according to claim 1 or 2, characterized in that the friction lining (53) is designed so as to be substantially elastically compliant.

and tool machine according to one of claims 1 to 3, -iracterized in that the friction lining (53) is of a -)er-elastic design.

8 5. Hand tool machine according to one of claims 1 to 4, characterized in that the friction lining (53) in the axially unloaded state projects with its axial end face (54) axially beyond the end (52) of the supporting flange (62).

6. Hand tool machine according to one of claims 1 to 5, characterized in that the friction lining (53) is formed from rubber, PVC, PUR or a similar elastic material.

7. Hand tool machine according to one of claims 1 to 6, characterized in that the friction lining (53) is firmly connected in a captive manner to the supporting -;5 flange (62).

8. Hand tool machine according to one of claims 1. to 7, characterized in that the friction lining (53) is contained in an annular groove (55) of the end (52) of the supporting flange (62).

9. Hand tool machine according to one of claims 1 to 8, characterized in that the friction lining (53) has an effective, annular axial end face (54) of a substantial radial extension.

10. Hand tool machine according to claim 8 or 9, characterized in that the friction lining (53) is formed by introducing a compound into the annular groove (55), which has previously been provided with adhesive primer, and expanding and/or curing said compound in the annular groove (55).

11. Hand tool machine substantially as herein described with reference to the accompanying drawings.