GB2434115A

GB2434115A - Screwdriver with switchable magnetisation

Info

Publication number: GB2434115A
Application number: GB0625740A
Authority: GB
Inventors: Bettina Schneider; Marcus Schneider
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-12-30
Filing date: 2006-12-22
Publication date: 2007-07-18
Anticipated expiration: 2026-12-22
Also published as: GB2434115B; DE102005063187A1; GB0625740D0; CN1990187A

Abstract

A screwdriver 10 comprises a screwing tool 14 which, in its region of engagement with a screw 24, can be switchably magnetized to generate a magnetic force. The screwdriver 10 may be a mechanical manual screwdriver (as shown) or a cordless screwdriver (50, figure 3), in which any electrical power needed to produce the magnetism may be provided by a battery 16, (54, figure 3) in the handle 12. The magnetism may be provided by a permanent magnet (42, figure 2), an electromagnet 20 and/or electronic means. The magnetization may be selectively switched on and off, and/or made stronger or weaker.

Description

Screwdriver with switchable magnetisation

Prior art

Disclosure of the invention

The present invention relates to a screwing tool according to the pre-characterising clause of claim 1.

Magnetised screwing tools, such as screwdrivers or screwing inserts (for example "bits" for cordless screwdrivers) are already known in which a screw is secured against undesired detachment during the screwing process. In the process the screw generally remains reliably adhered to the magnetised screwing tool. However this has the following drawbacks: if a screw is to be screwed into an opening using a magnetised screwdriver bit, next to which opening magnetisable surroundings (for example a metal housing wall) are located, it is sometimes barely possible to guide the screw into the actual opening since it constantly adheres to the surroundings.

If an individual screw is to be retrieved from a container containing a large number of other screws using a magnetised screwdriver bit, many other screws, to a greater or lesser extent depending on the strength of the magnetisation, adhere. This makes manual intervention necessary and thus slows down the workf low.

If a screw is merely to be guided into an opening, provided therefor, of a workpiece and "deposited" there using a magnetised screwdriver bit, and is only to be screwed following final adjustment of the parts to be screwed (in order for example in the case of a plate that is to be fixed by a plurality of screws to prevent distortion of the parts), it is not possible to detach the screw from the screwdriver bit in a targeted manner because the screw adheres to the screwdriver bit more strongly than to the workpiece.

If a screw is to be unscrewed using a magnetised screwdriver bit and subsequently be deposited in a purposeful manner, then this is usually only possible with the aid of a suitable stripping edge or manually, whereby the workf low is slowed down.

If a screw is to be assembled, using a magnetised screwdriver bit, next to a component that is sensitive to magnetisation, the tool must be changed if it has previously been used for non-critical assembly. This change is sometimes forgotten, whereby damage may occur to the sensitive component.

Advantages of the invention The invention with the features of claim 1 relates to a screw driver or a screw insert, of which the magnetisation may be controlled/adjusted, for example by switching the magnetisation on/of f. The screwdriver may be adjusted and handled particularly safely, quickly and conveniently with one-handed operation. As a result screws may be secured in a purposeful manner and deposited in a targeted manner between other screws without using other means. Screws may moreover be safely introduced into an opening provided therefor and also be unscrewed without fixing the screwdriver tip and without using other means.

With magnetised surroundings the strength of the screwdriver tip magnetisation may be reduced to the extent that the screw is just still held, but the effect of the surroundings is negligible.

By reducing the magnetisation screwing work is also possible in magnetically sensitive surroundings without retooling.

Screws in amongst a quantity of other screws may be individually removed with the screwdriver tip by reducing the magnetisation and without using other means.

Drawings The invention is described in more detail hereinafter with reference to an embodiment with its associated description.

In the drawings: Fig. 1 shows a manual screwdriver with electromagnetic magnetisation, Fig. 2 shows a manual screwdriver with permanent magnetic rnagnetisation, and Fig. 3 shows a cordless screwdriver with electromagnetic magnetisation.

Description of the embodiment

Fig. 1 shows a mechanical screwdriver 10, comprising a blade 14 provided with a handle 12. The handle 12, preferably in the interior, receives a battery 16 and carries a switch 18. A magnetisation coil 20 integrated in the blade 14 may be activated by means of the switch 18 in that by closing the circuit 22, the inagnetisation coil 20 is provided with power and hence the electrical rnagnetisation may be switched. The battery 16 forms the power source. Inside the magnetisation coil 20 a magnetic field is created when there is a flow of current, by which a screw 24 is secured or attracted at least at the tip 26 of the blade 14. In an embodiment of the invention that is not illustrated the magnetisation is generated by electronic means.

Fig. 2 shows a screwdriver 30, comprising a blade 34, provided with a non-magnetisable handle 32, and mechanically switchable magnetisation, wherein magnetisation takes place by closing a gap 36 after actuation of the switch 38 at the handle end 40 between a permanent magnet 42 and a magnetisable rod 44 which also forms the blade 34 of the screwdriver 30. The rod 44 also becomes magnetic when the gap 36 is closed and therefore exerts, at least at the tip 36 of the blade 34, an attractive force on the screw. When the switch 38 is released the magnetisable rod 44 and the permanent magnet 42 are separated again, the gap 36 opens and the magnetising force on the tip 36 of the blade 34 returns to a minimum, or zero. In a further variant (not shown) the complete blade is magnetisable.

The screwdriver 30 according to Fig. 2 may be implemented using simple means, for example by a suitable cylindrical plastics material blank, in particular constructed as a turned part, for non-rotatable fastening to the blade 34, into which a guide with two different diameters is drilled over its entire length. A restoring spring 46 and the permanent magnet 42 are introduced from the handle end; a metal rod with a screwdriver tip is glued in from the blade side. An end cap with a push-button may be glued on.

Fig. 3 shows a cordless screwdriver 50, comprising a housing 52 which receives a rechargeable battery 54, a motor 56 with motor switch 58 and a gear 60 as well as a magnetisable chuck 62 for receiving a screw bit 64. The cordless screwdriver 50 is also provided with a hand-operable magnetising switch 66 comprising pressure spring 68, a magnetising coil 70 and a magnetisable rod 72.

The magnetisable rod 72 is pressed against the screw bit 64 in the chuck 62 by the pressure spring 68 and thus magnetises the screw bit 64 when the magnetisation switch 66 is activated and the battery 76 is connected to the magnetising coil 70. Consequently the screw bit 64 is likewise niagnetised and exerts an attraction on metal screws that are sensitive to magnets. By suitably coupling the power supply to the magnetising coil 70 (for example sliding contacts) magnetisation is also maintained in the case of motor operation following actuation of the motor switch 58 or may also be switched off if required. The magnetising device of the cordless screwdriver 50 is in the housing 52.

The magnetisation can be adjusted or switched in the case of the mechanical screwdriver 10, 30 according to Fig. 1 or Fig. 2 by means for example of a suitable device in the handle or blade. With an electrical screwing device 50 according to Fig. 3 the magnetisation may be arranged for example as a suitable device next to the switch 58 to start the turning process. One-handed operation is therefore possible in all cases. Magnetisation can take place electrically (for example Fig. 1) or mechanically (for example Fig. 2) in the process.

Claims

Claims 1. Screwdriver (10, 30, 50) comprising a screwing tool,

configured, in particular, as a blade (13, 34), or, preferably, as an exchangeable bit (64), for driving engagement in a screw, characterised in that the screwing tool, in its region of engagement associated with a screw that is to be screwed, can be switchably magnetised by corresponding means, such as a permanent and/or electromagnet (42, 20, 70) and/or electronic means, to generate a magnetic force.

2. Screwdriver according to claim 1, characterised in that the magnetisation of the means may be selectively switched on and/or off.

3. Screwdriver according to claim 1 or 2, characterised in that the magnetisation of the means can be set so as to be stronger or weaker.

4. A screwdriver substantially as herein described with reference to the accompanying drawings.