GB2408709A

GB2408709A - Hand-held machine tool having a threaded clamping means

Info

Publication number: GB2408709A
Application number: GB0426271A
Authority: GB
Inventors: Adolf Zaiser; Joerg Albrecht
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2003-12-01
Filing date: 2004-11-30
Publication date: 2005-06-08
Also published as: DE10356051A1; GB0426271D0; CN1623726A

Abstract

Hand-held machine tool 10 with a housing 12 and a tool carrier 18, which carries a movable tool 19 which can be clamped by means of threaded clamping means 34 such as threaded bolts or threaded nuts. The clamping means 34 is supported on a mating thread carrier 30 with a suitable mating thread 32, and is more secure because the mating thread carrier 30 is designed as a specific clamping part. This clamping part can, in particular, be operated by hand, which carries a thread 33 counter to the mating thread 32 which is a male thread if the mating thread is a female thread or which is a female thread if the mating thread is a male thread and which rotably engages in a second, suitable mating thread 28 of a second mating thread carrier 26. Accordingly, the thread assemblies 28, 33; 32, 36 have the same direction of rotation, being in particular coarse screw threads.

Description

Hand-held Machine Tool

Prior Art

The present invention is based on a hand-held machine tool according to the preamble of claim 1 and on threaded clamping means according to the preamble of claims 5 and 6.

Until now, only hand-held machine tools were known with threaded clamping means for clamping an insert tool which can be screwed into a mating thread via a single coarse or fine screw thread with a more or less large pitch and in their clamped position secure the insert tool free of rotation to a tool carrier.

The known threaded clamping means with an inexpensive, robust coarse screw thread can only be sufficiently securely clamped with a specific tool, such as a spanner or screwdriver, whilst threaded clamping means for fastening, in particular for releasing, without the use of tools are more costly and expensive.

Advantages of the Invention The invention with the features of claim 1 has the advantage that the clamping means for fixing the insert tool are very inexpensive and can produce a clamping force simply by hand which is threefold higher than previous comparable clamping means with coarse screw threads. As a result, it is not necessary to carry specific tools such as spanners or screwdrivers to operate the threaded clamping means. The insert tool is thus held on the tool holder with a clamping force which until now could not be produced by a coarse screw thread but only by a fine screw thread, whose sensitivity and liability to breakdown is thereby avoided, high safety requirements being fulfilled.

As the first mating thread has a smaller pitch relative to the second, in particular by a third, the clamping stroke of the coarse screw thread is geared down during the clamping process, so that a markedly higher clamping force can be produced manually than was previously possible with coarse screw threads. The gearing down can also be selected to be even smaller, the clamping path then increasing, ie the number of revolutions of the screwing means which are necessary for clamping.

As the invention is used for an oscillating tool which is penetrated centrally by threaded clamping means and is secured, the manual clamping force is so great that a release of the oscillating tool in the counter oscillating stroke which impinges on the threaded clamping means in the direction of release, is reliably excluded.

As the threaded clamping means is provided with a manual operating surface, it is possible to clamp the tool particularly easily.

The invention with the features of claim 5 has the advantage that a threaded clamping means with a coarse screw thread is produced which is suitable for all kinds of clamping purposes and which allows a manual clamping force which is as high as with fine screw threads but which is more robust and less liable to break down.

The invention with the features of claims 5 and 6 has the advantage that the threaded clamping means and its clamping partner can be manufactured inexpensively and with coarse tolerance in the conventional manner as coarse screw threaded parts.

As the clamping part with the thread and counter thread is the clamping part to be operated actively by hand, a simple manageable clamping system with a coarse screw thread is produced with a previously unachieved high clamping force.

As the clamping part carries out a reduced clamping stroke when operated and rotated relative to the threaded clamping means, a particularly high clamping force is produced.

As the two threads of the clamping part are either right hand or lefthand threads, the manufacturing costs of the clamping part are particularly favourable.

As the second mating thread for the clamping part belongs to a second clamping partner, this clamping partner can be particularly easily and inexpensively manufactured independently from the first.

As the second clamping partner can be positioned fixed in terms of rotation relative to the first, it is ensured that the threaded clamping means is positioned fixed in terms of rotation and the clamping part can be simply tightened manually by rotating its handle.

Drawings The invention will be described hereinafter with reference to an embodiment with accompanying drawings, in which: Fig. 1 is a hand-held machine tool with the clamping device according to the invention, Fig. 2 is a further embodiment of the clamping device.

Description of the Embodiment

A hand-held machine tool 10 shown diagrammatically in longitudinal section in Fig. 1 has an elongate housing 12, of which the rear region is shown in section to the right on the drawing.

In the interior of the housing 12 a motor 14 is arranged with a motor shaft 16 which transfers the motor speed to an output spindle 18 arranged perpendicular thereto. Between the motor shaft 16 and the output spindle 18 a bevel gear system 20 is arranged which converts the rotational movement of the motor shaft 16 into a rotating swivelling movement of the output spindle 18, moving to and fro.

The output spindle 18 carries on its lower free end an insert tool 19 which is designed as a saw blade and which, by means of its rotational movement to and fro, saws effectively with a low risk of injury if contact is made with the saw blade, as is already known from medical saws.

The output spindle 18 is mounted above and below in a respective solid housing spindle bearing 22, 24. The output spindle 18 is hollow inside and terminates on the side of the tool in a clamping flange 26, on the front face of which the insert tool 19 to be clamped is supported. The insert tool 19 is clamped in its support position on the clamping flange 26 by screwing in a threaded clamping means 34 which is designed as a threaded bolt. In the process, the threaded clamping means 34 engages with its clamping thread 36, designed as a male thread, in a mating thread 32, designed as a female thread, of a specific clamping part 30 which additionally carries a counter male thread 33 with which it engages in the flange thread 28 of the clamping flange 26.

The two thread assemblies 28, 33 and 32, 36 have the same direction of rotation with differing pitches.

Clamping the insert tool 19 takes place in the following steps: the threaded clamping means 34 is inserted with its threaded bolt 37 through a central aperture, not shown in more detail, of the insert tool 19, so that it rests on the flange head 35. Then the threaded clamping means 34 is screwed in manually after inserting the threaded bolt 37 into the mating thread 32 of the clamping part 30. As soon as the flange head 35 supports itself with relatively low support force flat on the insert tool 19 and on the front face of the clamping flange 26 - after opening a cover retracted into the housing contour and not shown in more detail - the handle 40 of the clamping part 30 is moved in the rotational direction of clamping. The clamping stroke between the threaded clamping means 34 and the clamping part 30 is relatively long. However, the absolute clamping stroke between the threaded clamping means 34 and the clamping flange 26 is markedly shorter as the clamping part - together with the threaded clamping means 34 - carries out a counter stroke relative to the clamping flange 26 in an axial direction, at the same time as the clamping stroke between the clamping part 30 and the threaded clamping means 34. Thus a large number of turns of the screw on the handle 40 produces a relatively short total clamping stroke, so that a clamping force can be achieved as with a manually screwed-in fine thread bolt. Also, by using coarse screw threads a considerably higher load bearing capacity is achieved than with a fine screw thread. Inadvertent release of a clamping device which is easily manufactured and highly reducing is thereby excluded with a connection which is highly robust and is very secure. The end condition for effective clamping is that before operating the handle 40 the friction between the flange head 35, the tool 19 and the clamping flange 26 is great enough to prevent rotation of the threaded clamping means 34 when the clamping part 30 rotates and to allow relative rotation between the clamping part 30 and the threaded clamping means 34.

In this case, means could optionally be provided which secure the threaded clamping means 34 positively relative to the clamping flange 26 and the tool 19, even when screwing by hand, so that with the clamping part 30 an effective clamping stroke can be transferred to the threaded clamping means 34.

Fig. 2 shows a further variant of the clamping means 54, 58, 66 according to the invention which allows a clamping object 52, for example the pivot guide arm of a circular saw, to be manually clamped relative to a base object 50, for example the base plate of the circular saw, with high clamping force and with a high load bearing capacity of the threaded parts.

In addition a threaded clamping means 54 designed as a coach bolt is inserted through a bore not shown in more detail, for example an elongate hole through the base- and the clamping object 50, 52, so that it sits fixed in terms of rotation with its polygonal edge 70 in the elongate hole not shown in more detail. A clamping part 58 designed as a wing nut is screwed with its mating thread 60 via the clamping thread 56 designed as a male thread of the threaded clamping means 54. The clamping part 58 carries a counter thread 62 externally, via which a clamping partner 66 is screwed with a suitable flange thread 68. The operating levers of the handle 64 of the wing nuts can be designed asymmetrically, ie with differing lengths or as a single lever arm.

To clamp the clamping object 52 to the base object 50 the clamping partner 66 designed as a female thread sleeve is then manually rotated, such that it is supported on the clamping object 52 with a low axial force, such that minimal friction between the clamping partner 66 and the clamping object 52 prevents a rotation of the clamping object 52 when the clamping part 58 is rotationally actuated. Furthermore, the clamping part 58 can be gripped at the handle 64 and rotated in the screwing direction of clamping, moving through the first coarse screw thread assembly 56, 60 with a relatively long first clamping stroke relative to the threaded clamping means 54. As at the same time a specific shorter counter stroke is produced synchronously to the first clamping stroke via the second coarse screw thread assembly 62, 68, the resulting or absolute clamping stroke with which the clamping partner 66 is clamped against the base- and clamping object 50, 52, is reduced to a value which can be achieved with a fine screw thread.

Such a high clamping force can simply be applied manually by means of this reduced total clamping stroke, that the base- and clamping object 50, 52 are supported securely and fixed in rotation against one another against inadvertent release, an auxiliary tool, such as for example a screwdriver for clamping and releasing, being unnecessary.

The reverse procedure is for releasing the connection.

Claims

Claims 1. Hand-held machine tool (10) with a housing (12) and a tool

carrier (18, 26) which carries a movable tool (19) which can be clamped by means of threaded clamping means (34) such as threaded bolts or threaded nuts or the like, supported on a mating thread carrier (30) with a suitable mating thread (32), characterized in that the mating thread carrier (30) is designed as a specific clamping part which can in particular be operated by hand, which carries a thread (33) counter to the mating thread (32) which is a male thread if the mating thread is a female thread or which is a female thread if the mating thread is a male thread and which rotatably engages in a second, suitable mating thread (28) of a second mating thread carrier (26), the thread assemblies (28, 33; 32, 36) having the same direction of rotation, and being in particular coarse screw threads.
2. Hand-held machine tool according to claim 1, characterized in that between the first (32) relative to the second mating thread (28) there is a difference in pitch, in particular 1/3.
3. Hand-held machine tool according to claim 1 or 2, characterized in that the tool (19) is a rotary tool located preferably centrally on a work spindle (18) which is penetrated, preferably centrally, by a threaded bolt (34) and can be tightened on a work spindle ( 26) .
4. Hand-held machine tool according to claim 3, characterized in that the threaded clamping means (34) and the clamping part ( 30) can be operated manually without the use of tools, in particular by means of a handle (40) . (Knurling)
5. Threaded clamping means (34) for fixing a clamping object (19) relative to a base object (26), a clamping stroke being transferred to the threaded clamping means (34) by rotating in a mating thread (32), characterized in that simultaneously a counter stroke can be produced, overlapping the clamping stroke and reducing it, with the threaded clamping means (34) and a further clamping partner (26).
6. Threaded clamping means (54) which via a first thread assembly corresponds to a first clamping partner (58) designed as a clamping part, which by rotating its mating thread (60) relative to the thread (56) of the threaded clamping means ( 54) undergoes a clamping stroke or releasing stroke for fixing a clamping object (52), characterized in that the clamping part (58) corresponds to a further clamping partner (66) via a further thread assembly (62, 68) each comprising a thread and a mating thread, which when rotating the clamping part ( 58) causes a further corresponding clamping or releasing stroke and between which the clamping object can be fixed.
7. Threaded clamping means according to claim 2, characterized in that the clamping part (58) carries a thread (62) counter to the first thread (60), ie if the first is a male thread, the second is a female thread, preferably a threaded nut, and if the first is a female thread, the second is a male thread, preferably a threaded bolt, a corresponding second mating thread (68) being associated with the counter thread (62), relative to which the clamping part (58) can be rotated.
8. Threaded clamping means according to claim 6 or 7, characterized in that the threaded clamping means (34, 54) and the further clamping partner (26, 66) can be positioned fixed in rotation before the final clamping.
9. Threaded clamping means according to any of the preceding claims, characterized in that the two thread assemblies (56, 60; 62, 68) are both either right-hand or left-hand coarse screw threads.
10. Threaded clamping means according to any of claims 5 to 9, characterized in that the second mating thread (68) belongs to a second clamping partner (66).
11. Threaded clamping means according to any of claims 5 to 10, characterized in that the second clamping partner (66) can be positioned fixed in terms of rotation relative to the threaded clamping means (54) and can be rotated relative to the first clamping partner (58).
12. A hand-held machine tool substantially as herein described with reference to the accompanying drawings.
13. A threaded clamping device substantially as herein described with reference to the accompanying drawings.