EP1260319A2 - Screw driving device for screwdriver bits - Google Patents

Abstract

The screwdriver to turn a screw (4) through a drive shaft (2), of a power tool, has an inner sleeve (1) fitted to the drive shaft to take a screwdriver attachment (3) with an outer sleeve (6) around it with a restricted axial movement. It has a permanent magnet (7) at its leading side, with a passage opening (7a) through it extending from a profile tip (3a) of the attachment. A screw placed on the profile tip is held in place by the permanent magnet and, at the same time, the screw head (4a) is secured with the full extent of the profile tip into the inner screw head profile, and the outer sleeve is moved by the permanent magnet to bring the end surface (7b) against the surface of the screw head.

Description

The invention relates to a screw device in the preamble of claim 1 specified genus.

A known screwing device of this type (e.g. US Pat. No. 5,724,873) has a Drive shaft, which at one end in a receiving chuck or a plug device Power wrench, e.g. B. an electric screwdriver, is used at the other end with a Provide receptacle, interchangeably inserted in the screwdriver bits become. The drive shaft and the end sections of the bits usually have Hexagon external cross-sections and the corresponding inner profiles.

In order to ensure that the screws to be screwed in with such a screwing device automatically held on the profile tips of the screwdriver bits is in one middle region of the receiving sleeve is a rod-shaped or disk-shaped first Permanent magnet and on the front of the receiving sleeve an annular, of which Profile tip of the insert penetrated second permanent magnet. Here is the Arrangement made so that the first permanent magnet the screwdriver insert securely and holds axially firmly in the receiving sleeve and that when inserting the profile tip into the Internal profile of a screw head jointly ensure both permanent magnets that the end faces of the screw heads against the contact surface one with the second Permanent magnet connected, magnetically conductive disc are pulled.

In this construction, the screw is magnetic against the large magnetic force conductive disc pulled, but there is a full contact of the profile tip of the Screwdriver insert in the inner profile of the screw head only if the depth of the Receiving opening in the receiving sleeve, the length of the screwdriver bit and the Thickness of the magnetically conductive disc are adjusted so that the length of the Washer excellent profile tip exactly the depth of the inner profile of the screw head equivalent. However, there are screws with the same inner profile, for example cross recess Phillips (PH) 2, whose heads are different in height with different screw sizes, accordingly the cross recess inner profile is of different depths. It also points out However, the internal profile of the screws varies in depth due to manufacturing tolerances and widths, and also the length of the screwdriver bits and the tip profiles are subject to certain manufacturing tolerances. In the device, however, is the axial position of the screwdriver insert to the contact surface of the disc cannot be changed, accordingly the length of the protruding profile tip. As a result, in many cases the Screw head rests on the face of the magnetically conductive disc, but that The tip profile does not lie completely over the inner profile of the screw. This will make it The tip profile is particularly stressed at its edges, which leads to a relatively fast Wear of the profile leads and the entire screwdriver insert are replaced got to. In the opposite case, the entire top profile lies in the inner profile of the Screw on, but there is no gap-free contact of the screw heads on the front of the magnetically conductive disc reached. The magnetic field acting on the screw and thus the tightening force is therefore weaker. In addition, is not achieved by a Place the screw heads on the face of the magnetically conductive disc are aligned coaxially with the axis of the screwdriver bit. This applies in particular to Flat head screws, the most commonly used type of screw.

To avoid these disadvantages, a further screwing device is the one mentioned at the beginning Genre known (DE 199 07 837 A1), in which the second, annular Permanent magnet is attached to the front end of an outer sleeve that has an internal thread has and on a corresponding external thread section of the receiving or Twisted inner sleeve and thus axially adjusted relative to the screwdriver insert can be. This is to ensure that both the profile of the profile tip full-surface contact with the inner profile of the screw head as well as the end surface of the screw head for gap-free contact with the ring-shaped permanent magnet formed contact surface can be brought. Such settings are, however for practical applications, e.g. B. when screwing in one after the other Many screws, too time consuming and therefore hardly usable. But when you get out of it assumes that the setting for a certain screw type only at the beginning of the screwing activity If tolerances occur, the screws have a similar disadvantage from, as is the case with the screw device described above. It is also unfavorable that the outer sleeve is perfect for replacing the screwdriver bit must be unscrewed and that with certain tolerance positions the screw head on the Magnets exert pressure, which can lead to breakage.

From DE-DM 1 784 695 a holder for insert tools of screwing devices with against Spring pressure sliding guide sleeves known. This holder is essentially like this constructed that the screw to be screwed with the screw head inside the guide sleeve to be led. A ring magnet is embedded in the face of the guide sleeve. When the screw is screwed in, the guide sleeve is included in the final phase of the process its front face on the surface into which the screw is screwed. The guide sleeve is then pushed back against a compression spring until the Screw head sits on the surface and the screwing process is complete. in the In the initial state, the compression spring pushes the guide sleeve forward until it is Shoulder rests on a ring which is arranged inside the holder and with the Intermediate piece is connected. Will a screw with the screw head on the face of the ring magnet, the screw is not at the profile tip of the screwdriver insert centered because this stands back from the end face of the ring magnet and the guide sleeve with the ring magnet is only pushed back when the end face the guide sleeve on the surface into which the screw is screwed. The Before starting the screwing process, the screw must be put by hand into the head Guide sleeve inserted and attached to the profile tip of the screwdriver bit become. An additional alignment of the screw head to the profile tip only takes place if the diameter of the screw head exactly the diameter of the hole in the guide sleeve equivalent. Even then, an alignment of the screw is concentric with the axis of the Screwdriver insert only given for cylinder head screws where the cylindrical Sidewall of the screw head offers a longer contact surface.

Another screwing device with magnet is known from EP 1 027 959 A2. This Screwing device shows a screwdriver insert with a larger shaft Diameter and a reduced diameter tip on which a spacer sleeve is attached, which is provided on both ends with ring magnets. The shaft goes over one step up into the top. The length of the spacer sleeve, along with the ring magnets is dimensioned such that the profile of the screwdriver tip is in contact with the back of the step on a length such that when the screw is placed between the screw head and the front end of the spacer sleeve remains a gap (g). The screw head is pulled by the ring magnet against the profile tip of the screwdriver bit, however, there is an additional axial alignment of the screw to the axis of the screwdriver insert when attaching the screw not because the screw head with its Head surface is not in contact with the end face of the ring magnet. This can lead to the The screw is at an angle to the axis of the screwdriver bit. In a variant of the spacer sleeve two rubber rings are installed inside, the dimensions of which are so the diameter of the shaft of the tip is matched by the rubber rings Tension between the circumference of the shaft of the tip and the jacket of the spacer sleeve is effected. Through this bracing, the spacer sleeve is preselected axial position held on the shaft of the tip. Ideally, this situation should be such that on the one hand the head of the screw rests on the face of the front ring magnet, on the other hand with the inner profile on the profile of the tip of the screwdriver bit. A such a preselected position would correspond to the position as with the "screwing tool magnetic bearing surface "is set according to DE 199 07 837 A1 automatic compensation between tolerances in the inner profile and outer profile of the Screwdriver tip is not possible. The friction caused by the rubber rings on the Shank is greater than the attraction of the ring magnets on the screw head. If at corresponding tolerance between the profile tip and the inner profile of the screw both do not rest on the full surface, the screw can not by the force of the ring magnets Profile tip can be used until the profiles are completely in place.

US 3,707,894 describes a device in which concentric sleeves are attached and this by radially arranged screws in a preselected position to the tip of the Screwdriver insert can be fixed. There is at least one between the sleeves sleeve-like magnet arranged. In one version, the screw head dips into one spherical recess on the end face of the inner sleeve and lies on the surface of the Formation. At the same time, the tip of the bit engages in the inner profile of the screw head on. The sleeves are fixed on the screwdriver insert in a preselected position so that the profile of the tip of the screwdriver bit to the inside profile of the screw head assumes a fixed position, but does not automatically compensate for tolerances is possible. The function of this device thus corresponds essentially to that Device according to DE 199 07 837 A1.

From US-PS 3, 392, 767 known as "Magnetic Tools" devices are known in which essentially a plate-shaped magnetic material is rolled into a cylindrical sleeve and is arranged concentrically between an inner sleeve and an outer sleeve made of steel. In the case of a device, the outer sleeve has an inner profile at its front opening for receiving a hexagon screw - or nut -, the inner sleeve and the magnetic intermediate layer are set back with respect to the front edge of the outer sleeve. A screw or nut immersed in the inner profile is held there by the magnetic field. This device is placed on a drive device, for example a handle for socket heads.
In a second embodiment according to FIGS. 5 to 7, the device is plugged onto a screwdriver insert. The front edges of the outer and inner sleeves are in one plane, the magnetic material arranged between them is set back slightly from the edges. The head surface of a screw should rest on the edges of the two sleeves and be held by the magnetic field. Inner sleeve, magnetic interlayer and outer sleeve form a solid unit. The device is held on the shaft of the screwdriver insert by two spring washers which grip around the shaft of the screwdriver insert or snap into a groove in the shaft. On the outer circumference, they engage in an annular recess which is formed between the inner sleeve, which is shortened at the rear end, and a rear wall of the outer sleeve which is drawn radially inward at the rear end, with an opening for plugging onto the shaft of the screwdriver bit. The recess is larger in the longitudinal direction than the width of the snap rings, so that a limited axial mobility of the device on the shaft of the screwdriver insert is possible. This mobility is intended to compensate for tolerances in the inner profile of the screw, as well as wear of the screwdriver bit, while at the same time ensuring direct contact between the screw head and the front edges of the inner and outer sleeves. A disadvantage of this embodiment, also in the device according to US Pat. No. 3,707,894, is that the elastic magnetic material provided develops a relatively weak magnetic force, in particular if the length of the magnetic intermediate layer is as short as it should be when the device is open a standard short screwdriver insert with a length of 25 mm is to be attached. It therefore appears questionable whether the desired function is achieved that the device is automatically brought into a position by axial displacement in which both the profile tip is fully immersed in the inner profile of the screw and the head surface rests on the edges of the inner and outer sleeve , Achieving the function described also appears questionable because when the screw head is placed on the profile tip of the screwdriver insert, the magnetic field is closed at the poles, which are formed by the front edges of the inner sleeve and outer sleeve on the front of the device. In the rear area of the device, the magnetic field is closed via the radially inward base ring and the inner sleeve abutting it. As a result, the attraction only acts on its front side, but not in the direction of the rear shaft part of the screwdriver bit. In practice, this means that the screw head only rests with its inner profile on the profile tip of the screwdriver insert and at the same time the head surface on the pole edges if the device rests with the bottom edge on the spring ring clamped onto the shaft of the screwdriver insert and the resulting distance between the pole edges and the head surface corresponds exactly to the depth of immersion of the profile tip in the inner profile of the screw head. In all other positions, either the head surface lies against the pole edges and the profile tip of the screwdriver insert does not dip into the inner profile of the screwdriver insert until it is in full contact, or there is the opposite position, between the pole edges and the head surface an air gap remains. An automatic setting for the simultaneous creation of the profiles and the head surface does not appear possible. The mode of operation therefore essentially corresponds to the device according to DE 199 07 837 A1. The required short overall length also results in a very short guidance of the device on the hexagonal shaft of the screwdriver insert through the remaining piece of the inner sleeve, especially since commercially available screwdriver inserts only have the hexagonal shaft in the clamping area, but are turned towards the profile tip to a round cross-section. Fig. 5 shows the proportions on a scale of 1: 1. However, good guidance is a prerequisite for the device to be coaxial with the axis of the screwdriver insert and to move, and for the screw to be aligned coaxially. Even longer screwdriver bits, the next largest length customary on the market is 50 mm, are turned towards the profile tip over a long distance with a round cross-section, and to different diameters, depending on the size of the profile tip. If a device according to the principle described is used, a suitable device would have to be offered for each diameter. Furthermore, it appears very uncertain whether the device can be held in the selected axial position on the shaft of the screwdriver bit by the clamping action of the spring washers when the bit is used in electrical screws because stronger shocks act on the bit. This weakness also indicates that the later patent 3, 707, 894 by the same applicant provides for the attachment of such a device by means of radially arranged screws. If, however, 3, 392, 767 is to be securely fastened by snapping the spring washers into a groove in the shaft of the screwdriver insert, then inserts with a special design must be offered and commercially available inserts cannot be used. Another disadvantage is that, due to the short shaft, the device can be carelessly clamped into a drive device, for example the receiving chuck of an electric screwdriver, up to the stop on the rear floor. Then, however, an adjustment, for example by moving the device on the shaft of the screwdriver insert to the rear, is not possible, the clamping must be released and the device pulled out further.

In a further device according to the cited patent, the inner sleeve is seated, Magnetic sleeve and outer sleeve as a unit on the shaft of a long screwdriver bit. A coil spring inside the device is supported on the one hand Spring washer, which is embedded in a groove in the screwdriver shaft, on the other hand on one Ring that is mounted at the rear end of the inner sleeve. The device is made by the between the rings biased spring in a certain position to the profile tip of the Brought screwdriver insert. The screw is in an opening on the front of the Device used and lies on the edge of the inner sleeve. In the starting position the profile tip of the screwdriver stands back from the head surface of the screw, shift only when the device is axially loaded when the screw is attached the sleeves with the screw so far that the profile tip with the inner profile of the screw comes to the intervention. Since the screwdriver insert is often already there when the screw is attached turns - for finding the engagement position of the profile tip in the inner profile in the screw head If turning is necessary anyway - the profile tip and / or inner profile in the Screw head damaged.

A disadvantage of the known devices is that the end components continue to expand turn when the device with the screw adhering to the end face on a Touches the surface and damages it by turning the front components further becomes.

The task is to develop a screwing device, the following Requirements fulfilled and the disadvantages of the devices avoided: normal, commercially available screwdriver bits can be used immediately when attaching the Screw on the device is supposed to work automatically due to the action of the permanent magnet both a full-surface contact of the profile of the profile tip in the inner profile of the Screw head can be reached, even if the profiles have tolerances and the Head heights are different and there is supposed to be an attachment to the end face of the screw head on the front of the device and thereby strong adhesion of the screw to the Profile tip of the screwdriver insert be guaranteed, it should be achieved that the screw adhering to the device coaxial to the axis of the screwdriver insert is aimed when countersinking screw heads in a resilient surface the outer sleeve with the permanent magnet opposite the profile tip of the screwdriver with the attached screw, move back and move easily, with the same surface The outer sleeve with the permanent magnet should screw in countersunk screws do not continue to turn if the end face of the permanent magnet touches the surface - this should prevent damage to the surface; Screwdriver bits can be easily removed from the device.

The invention has the advantage that a precise adjustment of the outer sleeve on the No inner sleeve by means of a screw thread or radially arranged screws is required. Due to the essentially free axial displacement of the outer sleeve the inner sleeve and a corresponding arrangement and dimensioning of the different Rather, parts is achieved that the desired settings when approaching the Obtain screw heads to the front of the screw device by itself.

Further advantageous features of the invention emerge from the subclaims.

Fig. 1 und 2 je einen Längsschnitt durch ein erstes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung in zwei unterschiedlichen Stellungen;

Fig. 3 und 4 den Fig. 1 und 2 entsprechende Schnitte durch ein zweites Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung;

Fig. 5 und 6 den Fig. 1 und 2 entsprechende Schnitte durch ein drittes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung;

Fig. 7 und 8 den Fig. 1 und 2 entsprechende Schnitte durch ein viertes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung;

Fig. 9 eine Seitenansicht der Schraubvorrichtung nach Fig. 7 und 8;

Fig. 10 einen Teilschnitt mit einer gegenüber Fig. 8 veränderten Einzelheit; und

Fig. 11 und 12 der Fig. 1 entsprechende Schnitte durch ein fünftes und sechstes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung.

Fig. 13 bis 15 ein siebentes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung in zwei den Fig. 1 und 2 entsprechenden Ansichten und einer dritten, das Auswechseln eines Einsatzes erleichternden Stellung, wobei außerdem in Fig. 13a eine vergrößerte Einzelheit der Fig. 13 zu sehen ist.

Fig. 16 bis 18 ein achtes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung in den Fig. 13 bis 15 entsprechenden Ansichten.

Fig. 19 und 20 ein neuntes Ausführungsbeispiel der erfindungsgemäßen Schraubvorrichtung im wesentlichen entsprechend Fig. 13 bis 15, jedoch mit einer anderen Vorrichtung zur Aufnahme des Einsatzes.

The invention is explained below in connection with the accompanying drawings of exemplary embodiments. Show it:

Figures 1 and 2 each a longitudinal section through a first embodiment of the screwing device according to the invention in two different positions.

3 and 4 the sections corresponding to FIGS. 1 and 2 through a second embodiment of the screwing device according to the invention;

5 and 6 the sections corresponding to FIGS. 1 and 2 through a third embodiment of the screwing device according to the invention;

7 and 8 the sections corresponding to FIGS. 1 and 2 through a fourth embodiment of the screwing device according to the invention;

9 shows a side view of the screwing device according to FIGS. 7 and 8;

FIG. 10 shows a partial section with a detail changed compared to FIG. 8; and

11 and 12 of FIG. 1 corresponding sections through a fifth and sixth embodiment of the screwing device according to the invention.

13 to 15 a seventh exemplary embodiment of the screwing device according to the invention in two views corresponding to FIGS. 1 and 2 and a third position which facilitates the replacement of an insert, wherein an enlarged detail of FIG. 13 can also be seen in FIG. 13a.

16 to 18 an eighth embodiment of the screwing device according to the invention in FIGS. 13 to 15 corresponding views.

19 and 20 a ninth embodiment of the screwing device according to the invention essentially corresponding to FIGS. 13 to 15, but with a different device for receiving the insert.

1 and 2, a screwing device according to the invention does not contain one from one Receiving or inner sleeve 1 made of ferromagnetic material with a hexagonal inner cross section. In the rear part there is one end with one corresponding hexagon outer cross section provided drive shaft 2, which also is axially fixed in the inner sleeve 1. The front part of the inner sleeve 1 is used for Image of a screwdriver bit made of a ferromagnetic material 3, the rear portion of which is positively in the direction of rotation in the inner sleeve 1 matching hexagon outer cross section and on the front with one Profile tip 3a is provided. This has a profile designed here as a cross recess profile on, which can be inserted into a corresponding Phillips inner profile, which in the Heads 4a conventional Phillips screws 4 is formed. Alternatively, it could of course also around profile tips with Torx or other known profiles for Torx or act other screws. The insert 3 is axially z. B. with a snap ring 5 in the Secured inner sleeve 1, which engages in corresponding annular grooves of both parts. When turning the screwing device by means of one engaging at the free end of the drive section 2 Power wrench or the like. The torque exerted on the drive shaft 2 is via the Transfer the inner sleeve 1 to the insert 3 and from there to the screw 4.

On the inner sleeve 1 is made of a non-ferromagnetic material Outer sleeve 6 axially slidably guided, the one on the inner sleeve 1 axially outstanding front side with an opening 7a inserted into it having permanent magnets 7 (ring magnets) projecting axially beyond the inner sleeve 1 is provided. The permanent magnet 7 is preferably in the front end of the outer sleeve 6 used that he with an end face 7b slightly over the front protrudes, and by gluing or otherwise firmly connected to the outer sleeve 6. The The internal cross section of the opening 7a is preferably somewhat smaller than that External cross section of the inner sleeve 1.

Both the interaction of the outer sleeve 6, the inner sleeve 1 with the inserted screwdriver insert 3 and the permanent magnet 7 in the situation before the screw 4 was placed on the profile tip 3a was surprising, as was the reaction immediately when the screw was put on: the outer sleeve 6 becomes a first embodiment, preferably held by the force of the permanent magnet 7 in a preselected axial position according to FIG. 1 or set in this position. In this position, the opening 7a of the permanent magnet 7 is arranged approximately in a central region of the profile tip 3a of the insert 3 and preferably in such a way that the permanent magnet 7 abuts at the front end of the inner sleeve 1 or at the front end of the spacer sleeve 8 abutting against it. This position is achieved because the magnetic force field of the permanent magnet 7 attracts the solid part of the insert 3, which has the hexagonal cross section, more strongly than the profile tip 3 a, which has a considerably smaller cross section and is surrounded by an air gap. However, since the insert 3 is fixed in the inner sleeve 1, the freely movable outer sleeve 6 is automatically moved in the direction of the drive shaft 2 until the permanent magnet 7 strikes the front end of the inner sleeve 1 or the spacer sleeve 8. By suitable axial dimensioning of the inner sleeve 1 and the permanent magnet 7, the axial length of which is preferably less than that of the profile tip 3a, it is also achieved that the profile tip 3a protrudes forward in this preselected position by as much as the prescribed surface 7b Immersion depth in the associated inner profile of the screws 4 plus a preselected tolerance dimension s in Fig. 1 corresponds. This tolerance dimension s is chosen so that - as long as the outer sleeve 6 assumes the preselected position shown in FIG. 1 - on the one hand the profile tip 3a, taking into account the different head heights of the screws provided for processing with the device, always up to the positive contact in the inner profile of the screw heads 4a can penetrate, on the other hand, after reaching this prescribed immersion depth between the end faces 4b of the screw heads 4a and the contact surface 7b, a small air gap remains. In fact, due to the preferably very smooth axial displaceability of the outer sleeve 6, the arrangement according to the invention has the result that it is automatically transferred from the position shown in FIG. 1 to the position shown in FIG. 2 as soon as the profile tip 3a is in the inner profile of a screw head 4a entry. This position is preferred for magnetic reasons, because the magnetic field tends to shorten the length of the field lines. When the screw head enters the magnetic field, a stronger magnetic force now acts in the direction of the profile tip 3a than in the starting position, the outer sleeve 6 moves somewhat in the direction of the profile tip with the screw seated until the contact surface 7b of the permanent magnet 7 on the end face 4b of the screw head rests and holds the screw tight. It is of course assumed that the screw heads 4a or screws 4 consist of a ferromagnetic material, which is assumed for the purposes of the invention. Since in the position according to FIG. 2 the attraction force of the permanent magnet 7 continues to act more strongly on the solid shaft section of the insert 3 lying in full contact in the inner sleeve 1 than on the profile tip 3a with the seated screw, that is to say a contractive force between the permanent magnet 7 and the Behind section of the insert 3 acts, the result is that the outer sleeve 6 with the permanent magnet 7 and the adhering screw head 4a until the immersion and stop of the profile tip 3a of the screwdriver insert 3 is used in the inner profile of the screw head 4a. The attractive force of the magnetic field continues to act strongly in the direction of the shaft section, so that the screw 4 is held firmly on the profile tip 3a.

The axial mobility of the outer sleeve 6 in the opposite direction, i. H. axial away from the drive shaft 2 is in itself arbitrary. However, you should by the attack of the Approach 6a to the rear end of the inner sleeve 1 are limited so that the outer sleeve 6th even from the most advanced position by magnetic force alone the preselected position according to FIG. 1 can be traced back. This is indicated in Fig. 2 after which in the fully immersed position of the profile tip 3a and at the same time the End surface 4b on the contact surface 7b only a comparatively small axial distance between the back of the inner sleeve 1 and the approach 6a.

3 and 4 are the same parts with the same reference numerals Mistake. The only difference to FIGS. 1 and 2 is that the insert 3 does not pass through the snap ring 5, but by a rod-shaped or disk-shaped second permanent magnet 9 is held in the inner sleeve 1. The permanent magnet 9 is, for. B. on the Insert facing end face of the drive shaft 2 arranged by gluing or otherwise connected to this and provided with an outer cross section that the External cross section of the drive shaft 2 corresponds. In this case the power is second Permanent magnets 9 to be selected so that the insert 3 is securely in the inner sleeve 1 is held, but this does not significantly impair the use of FIGS. 1 and 2 described function occurs.

5 and 6, in which again the same parts with the same 1 and 2 is a two-part instead of a one-part Outer sleeve 10 is provided. The outer sleeve 10 contains a permanent magnet 7 load-bearing front section 10a and a rear section 10b with a radially inward projecting approach 10c is provided, which protrudes through a middle, from the drive shaft 2 Breakthrough with an inner cross section that is smaller than the outer cross section of the Inner sleeve 1 is d. H. the approach 10c corresponds to the approach 6a in FIGS. 1 to 4. The front section 10a and the rear section 10b are also used to produce an axial Connection certain locking means 11 and 12, 14 provided. In the embodiment there is the latching means 11 from an annular groove formed in the outer jacket of the front section 10a, while the locking means 12, 14 at least one axially forward from the rear portion 10b extended, resilient tongue 12 and one attached to the front end, radially inward protruding and intended to enter the annular groove 11 cam 14. Are there 5 and 6 on the circumference of the rear section 10b preferably several, in Spaces arranged and formed as a whole elastic tongues 12 available. It is also clear that the locking means 11 also on the rear section 10b and the locking means 12, 14 could be attached to the front portion 10a. After all, other than that locking means or snap connection elements are provided, and instead the locking means 11 or 12, 14 could of course also have other fastening elements his.

5 to 10 further show, the insert 3 and the inner sleeve 1 by a Clamping connection axially interconnected, the at least one ball 15 and one on Includes circumference of the inner sleeve 1 adjacent band ring spring 16. The ball 15 is in one arranged radial recess of the inner sleeve 1 and under the elastic biasing force the radially outer band ring spring 16 limited, but so far radially inward movable so that it in a on the outer circumference of the hexagonal portion of the insert 3rd trained notch enter and can therefore fix it axially in the inner sleeve 1. Alternatively, a sufficient clamping effect can be achieved even without a notch be achieved. The use of such clamp connections can be like one Snap ring 5 (Fig. 1) compared to the use of a second permanent or Holding magnet 9 (Fig. 3) may be advantageous, as this will have the effect of the first permanent magnet 7 can not be affected and therefore no adjustment of the two Permanent magnets 7 and 9 to each other is required.

Finally, in the embodiment according to FIGS. 5 and 6 it is provided that in the preselected axial position not the permanent magnet 7, but one on the front section 10a attached radially inwardly projecting shoulder 10d to the front end of the inner sleeve 1 strikes, as Fig. 5 shows.

Otherwise, the design and arrangement of the various parts are analogous to those 1 to 4.

The two-part variant of the outer sleeve 10 according to FIGS. 5 and 6 has the advantage that the Front portion 10a is easily replaceable. This allows the front section 10a can be exchanged for a front section, if necessary, for another Diameter or another shape or size of the profile tip 3a is designed and z. B. also another permanent magnet 7 with a larger or smaller contact surface 7b can have. This is particularly advantageous because screws are the same Inner profile, e.g. B. a Pozidriv profile of size 2, depending on the thread diameter different Have head diameter. For screws with smaller head diameters expediently selected an annular permanent magnet 7, the smaller one Breakthrough has so that the largest possible contact surface 7b for the screw head 4a given is. Finally, the two-part variant makes it easier to replace the inserts 3, since their profile tips 3a after removing the front portion 10a easily by hand detected and then they can be pulled out of the inner sleeve 1.

The embodiment of FIGS. 7 to 9, in which the same parts with the same reference numerals as used in the above-described embodiments, the Preselected axial position of the outer sleeve 10 formed according to FIGS. 5 and 6 with the help a spring 17 shown here as a helical compression spring. The spring 17 is on the Drive shaft 2 mounted and between the rear end of the inner sleeve 1 and Front end of the rear portion 10 b of the outer sleeve 10 supported. This will make the Outer sleeve 10 axially positioned so far in the direction of the drive shaft 2 that it and in the front end used permanent magnet 7, the preselected axial position relative to the Profile tip 3a of the screwdriver insert.

7 to 9 also show a variant in which the preselected axial position of the outer sleeve 10 on the inner sleeve 1 is adjustable without the screwing device having to be dismantled and, if necessary, provided with a different spacer sleeve 8 (FIG. 1). For this purpose, the drive shaft 2 is provided in an area protruding from the extension 10c or the rear section 10b with an external thread section onto which an adjusting nut 18 provided with a corresponding internal thread is screwed, against which the rear section 17b can engage under the action of the spring 17 , In this case, the axial movement of the outer sleeve 10 is limited in one direction by the rear section 10b abutting the adjusting nut 18 and in the opposite direction by the rear section 10b abutting the compressed spring 17. As a result, the adjusting nut 18 can be set once when the screwing device is started up so that the profile tip 3a used in the individual case protrudes forward from the permanent magnet 7 just as much from the permanent magnet 7 as the sum of the prescribed penetration depth and when the outer sleeve 10 stops against the adjusting nut 18 corresponds to the tolerance dimension s described with reference to FIGS. 1 and 2. This position can then be fixed with a lock nut 19 which is also screwed onto the drive shaft 2.

When using the spring 17, the function according to the invention can be carried out in the same way can be achieved, as described above with reference to FIGS. 1 and 2. It is only for this required to choose the force (here the compressive force) of the spring 17 so that on the one hand not used screwing device, the outer sleeve 10 always in the visible from Fig. 7 withdraws the selected starting position, but on the other hand when a screw head approaches 4a is weaker than the tensile force of the permanent magnets 7 corresponds. This will the outer sleeve 10 as in the case of FIGS. 1 to 6 when a screw head 4a is approached below the influence of the permanent magnet 7 always automatically shifted so that the one hand End surface 4b of the screw head 4a abuts the stop or adhesive surface 7b, on the other hand the profile tip 3a up to the positive contact in the inner profile of the screw head 4a immersed.

Otherwise, the exemplary embodiment according to FIGS. 7 to 9 already corresponds to the above described embodiments.

10 shows a variant of the exemplary embodiment according to FIGS. 7 to 9. The outer sleeve 10 is here provided with a permanent magnet 20, in which a front contact surface 20a a conical or dome-shaped depression is provided. This embodiment is therefore suitable especially for screws 21 with lens heads 21a, the end faces in Contrary to the essentially flat end faces 4b of normal countersunk screws 4 (e.g. Fig. 1) are rounded. The better the contact surface 20a with its depression on the Rounding of the screw heads 21a is adjusted, the better the adhesion achieved of screws 21 on the screwing device.

10 corresponds to that according to FIGS. 7 to 9.

5 to 10 finally show a variant in which the screwing device held and guided with fingers during a screwing process if necessary can. For this purpose, a third sleeve 22 is attached to the outer sleeve 10, which is between a Heel in the front section 10a and a shoulder at the front end of the locking means 11 of the Rear section 10b is easily rotatably mounted.

11 and 12 is the spacer sleeve shown in FIGS. 1 to 4 8 made in one piece with the outer sleeve 6 and as one at the front end integrally formed, radially inwardly projecting, annular projection 6b formed like the The spacer sleeve 8 is at least partially penetrated by the profile tip 3a. So that one Assembly of the screwing device by pushing the outer sleeve 6 onto the inner sleeve 1 is possible, the approach 6a is missing at the rear end of the outer sleeve. Instead, the 11 shows a pot-like, on the rear end of the outer sleeve 6th Pressable end piece 23 is provided. The end piece 23 has a passage for the Drive shaft 2 and can be firmly connected to the outer sleeve 6 after this has been mounted on the inner sleeve 1. Alternatively, as the embodiment of the 12 shows a sleeve 24 which can be pressed into the rear end of the outer sleeve 6 be provided with a passage for the drive shaft 2 analogous to the end piece 23 and is mountable. Otherwise, the two exemplary embodiments according to FIG. 11 and 12 that of FIGS. 1 and 2, which is why the same parts with the same reference numerals are provided.

13 to 15, in which in turn the same parts the same reference numerals as in Fig. 1 and 2, the spacer sleeve 8 is by a Spacer in the form of a spring 25, here a helical compression spring replaced. This is supported with a rear end on a formed at the front end of the inner sleeve 1 Shoulder off, while its front end to rest on a rear contact surface 7c des Permanent magnet 7 is determined. In addition, the inner sleeve 1 is at the front end expedient compared to Fig. 1 and 2 shortened so much that the hexagonal shaft of Screwdriver insert 3 protrudes further from the inner sleeve than on the one hand Constructions according to FIGS. 1 to 12, but on the other hand however deep into the inner sleeve 1 immersed as required to transmit the desired torque. alternative the spring 25 could e.g. also between the inner sleeve 1 and the shoulder 10d Outer sleeve 10 (Fig. 5, 6) or the extension 6b of the outer sleeve 6 (Fig. 11, 12) is arranged his.

The axially acting force of the spring 25 is thus on the magnetic force of the permanent magnet 7 matched that in the apparent from Fig. 13 equilibrium to the front end the coil spring 25 abutting permanent magnet 7 and thus also the outer sleeve 6 Assume preselected axial positions described above with reference to FIGS. 1 and 2. there the spring 25 is preferably in a substantially relaxed state, so that its front end as in Fig. 1, the front end of the spacer 8 essentially only as Stop for the permanent magnet 7 is used. Therefore, the profile tip 3a of the insert 3 analogous to Fig. 2 inserted into the inner profile of the screw head 4a (Fig. 14), then causes Magnetic force automatically an axial displacement of the outer sleeve 6 in such a way that on the one hand the profile tip 3a penetrates fully into the inner profile of the screw head 4a and on the other hand the screw head 4a on the front contact surface 7b of the permanent magnet 7 invests. The rear contact surface 7c of the permanent magnet can, as shown in FIG. 14 shows, axially from the front end of the helical compression spring 25, which is inoperative is.

A major advantage of the spring 25 is that the outer sleeve 6 with the fingers and further compressing the spring 25 axially from the position shown in FIG. 13 backwards, i.e. can be moved in the direction of the drive shaft 2, as in FIG. 15 can be seen. As a result, the front end of the outer sleeve 6 is axially relatively far behind Profile tip 3a of the insert 3 pushed back that the profile tip 3a practically completely free lies or at least protrudes so far forward over the permanent magnet 7 that it can easily be gripped with the fingers and pulled out of the device. That would not possible if the outer sleeve 6, as in the exemplary embodiments according to FIGS. 1 to 12 could only be moved back so much that the profile tip 3a just so much much protrudes from the screwing device, as Fig. 1 shows. If the pressure on the spring 25 Removed again, this automatically leads the outer sleeve 6 into the position according to FIG. 13 back.

As a further improvement is provided in the embodiment of FIGS. 13 to 15, such as 13a in particular shows that the axial positions of one formed in the inner sleeve 1 Ring groove 5a with the snap ring inserted and formed in the hexagonal shaft of the insert 3 Notches 5b are selected so that the resilient snap ring 5 at as far as it will go insert 3 inserted into the inner sleeve 1 does not fully engage in the notches 5b, but is partially against an inclined surface of the annular groove 5b. This will make the axial Pulling out the insert 3 forward with your fingers facilitated without the use of pliers or Like. Must be taken to help. This applies even if the wire ends of the Snap rings or spring washers 5 are small burrs due to production. Still remains in this arrangement, the clamping force caused by the snap ring 5 is sufficiently large to to hold the insert 3 securely in the inner sleeve 1 when working.

In addition, a third sleeve 22 can preferably be rotatably mounted on the outer sleeve 6 be, which corresponds to the sleeve 22 in FIGS. 4 to 10, or the outer sleeve a jacket 26 Have plastic.

The exemplary embodiment according to FIGS. 16 to 18 corresponds to the exemplary embodiment according to FIG. 13 to 15 with the difference that the helical compression spring 25 is missing. In this case they are Force of the permanent magnet 7 and the dimensions of the inner sleeve 1 and outer sleeve 6 so designed that the described with reference to the above embodiments Function then results when the outer sleeve 6 is approximately one from FIG. 16 in the unused state apparent intermediate position. This intermediate position is but not by a stroke limiting means for the permanent magnet 7 or the outer sleeve 6 fixed, stable position, which is when the device is not in use automatically sets, but a largely unstable situation. Between this Intermediate position and a fully retracted position by the stop of the Permanent magnet 7 is given on the inner sleeve 1 (FIG. 18) and as in the case of FIG. 13 to 15 facilitates the removal of the insert 3 from the inner sleeve 1, are practically all axial positions possible. This could result in the permanent magnet 7 not automatically in the approach of the device to the screw head 4a Position changes to Fig. 17. This position can easily be obtained by the fact that the outer sleeve 6 when using the device with the fingers from the position shown in FIG. 18 is advanced axially in the direction of the position according to FIG. 16 until the magnetic action is analogous 13 to 15 and then in the further course the one based on FIGS. 1 to 12 described mode of action automatically results.

In the exemplary embodiments described so far, the hexagonal shaft 3 of the insert in the inner sleeve 1 either by a snap ring 5, a permanent magnet 9 or by the ball 15, biased by the ring spring 16, held. Another 19 and 20, the hexagonal shaft of the insert 3 by a Ball 27 held in a radial bore in the front region of the extension 1a becomes. The ball is radially inward by an axially displaceable further sleeve 29 moves until it in the on the outer periphery of the hex section of the insert 3 trained notch snaps into place. The radial movement is effected by a cone 30, which in the front region of the axial bore of the sleeve 29 is incorporated and in Contact position with the ball 27, the axial force acting on the sleeve 29 by a spring 28 translates into a radial force. Instead of the ball, another one can be designed Clamping element are provided, which are machined radially into the extension 1a Slit moved essentially radially.

If the axial movement of the sleeve 29 is not due to bracing with the clamping element is limited, so if there is no insert in the receptacle, the axial movement limited to the front by the locking ring 31. The spring 28 is supported with the from the rear end on a shoulder, which is formed where the inner sleeve 1 in the Extension 1a merges. The outer sleeve 6 is essentially axial on the inner sleeve 1 slidably guided, the outer surface of the sleeve 29 can be provided as an additional guide become. On the end face of the sleeve 29, the spring 25 is supported, which the outer sleeve 1 with the ring magnet 7 in the preselected position to the tip 3a of the insert.

In connection with the screw device according to the invention, the pushing back of the Sleeve 29 causes the outer sleeve 6 to be pushed back until the spring 25 so is stretched far or completely compressed that that acting on the sleeve 29 from the front Force is greater than the force of the spring 28 and the sleeve 29 are pushed back so far can that the ball 27 or another clamping element deflect radially outwards and the clamping of the hexagon section of the insert 3 is released.

The dimensions of the extension 1a, the distance from its front to Ring magnets 7, the lengths of the springs 25 and 28 in the compressed state and the Length of the sleeve 29 are adjusted so that when pressed to the stop Springs 25 and 28 of the outer sleeve 6 pushed back using the screwdriver insert 3 its front part protrudes far from the screwing device, gripped well with the fingers and can be pulled out of the screwing device.

FIG. 21 shows a device according to the invention, which essentially corresponds to the embodiment according to FIG. 13. In contrast to the embodiment according to FIG. 13, the embodiment according to FIG. 21 has a stop sleeve 32 in the rear region of the device, which is pressed or pushed onto the shaft 2 and secured with the spring ring 35 and with the front end 33 to the Abuts the rear end of the inner sleeve 1, extends through the enlarged opening in the extension 6a of the outer sleeve 6, 10 and forms a stop with the rear end 34, which prevents the shaft 2 of the device from being too far into the receptacle, for example a three-jaw chuck Electric screwdriver is inserted and about the end of the three-jaw chuck comes to rest on the back of the outer sleeve 6, 10, so that an axial movement of the outer sleeve to the rear is no longer possible. Instead of the sleeve, the shaft 2 could have a collar as a stop at this point. The stop sleeve 32 and a collar preferably have a circular peripheral contour so that the outer sleeve 6, 10 can rotate on the inner sleeve 1 and the stop sleeve 32. In a very simple embodiment, the stop is formed by a spring ring which is embedded in a groove in the shaft 2 at a corresponding point and whose circumferential diameter is larger than the diameter of the shaft.
Of course, all of the design variants shown in the figures can also be provided with a stop sleeve or collar.

On the one hand, all of the exemplary embodiments described have the desired function in common, namely that the screw 4, 21 is held securely and in a coaxial position with the screwdriver insert 3 at the front end of the screwing device and, at the same time, the profile tip 3a up to full contact with the inner profile in the screw heads 4a, 21a dips. The coaxial position of the screw 4 is achieved in that the outer sleeve 6 has a precise and relatively long guide on the inner sleeve 1, so that the end face 7b of the permanent magnet 7 is always at right angles to the axis of the screwdriver bit 3 and the screw is not is pulled into an oblique position by an abutment surface 7b which is not approximately at right angles to the axis and thus remains standing, there is no longer any coaxial centering of the screw by the inner profile in the screw head 4a on the profile tip 3a. In all of the exemplary embodiments, the later behavior of the outer sleeve 6, 10 when a screw 4, 21 is screwed in is largely insignificant. When screwing in the screw 4, 21, the axial forces exerted by the power screwdriver or the like via the screwdriver insert 3 and its profile tip 3a act directly on the screw heads 4a, 21a, so that the axial position which then arises Outer sleeve 6, 10 is not essential.
However, it is advantageous in all the exemplary embodiments that the axial load when screwing in a screw acts only on the tip of the insert 3, but not also on the permanent magnet 7, because the latter is in contact with the screw head, but can move axially with the outer sleeve 6, 10. This avoids the risk that the permanent magnet 7, designed as a ring magnet, generally consisting of a brittle material, will break over time due to excessive stress. Furthermore, as required in the task, the axial deflection or retraction of the outer sleeve 6, 10 enables screws to be countersunk.
Since the outer sleeve 6, 10 can rotate on the inner sleeve, the rotation of the outer sleeve 6, 10 is stopped as soon as the front contact surface 7b of the permanent magnet 7 touches the surface into which the screw is screwed, and friction on the contact surface 7b acts. This largely prevents damage to the surface. At this moment there is a relative rotary movement of the end face 4b of the screw head 4a, but only in relation to the contact face 7b on the permanently degreased until the screw is slightly countersunk.

The main design features of the device in the different Design variants are that the outer sleeve 6, 10 with the inserted in its end face Permanent magnet 7 on the inner sleeve 1 in two directions axially easily displaceable and is rotatably guided that the dimensions and shapes of the inner sleeve 1 and the outer sleeve 6, 10 and the magnetic force are selected so that under the influence of the magnetic force and / or the elements influencing the positioning of the sleeves, such as the spring, Spacer sleeve, the outer sleeve occupies a position in an initial position relative to the inner sleeve, in which the standard screwdriver insert 3 inserted into the inner sleeve 1 with its Profile tip 3a from the opening of the permanent magnet comprising the profile tip protrudes so far that the outstanding length is larger than the tolerance dimension s greatest occurring depth of the inner profile in one of the profile tip 3a assigned Screw Type.

The invention is not restricted to the exemplary embodiments described, which are based on can be modified in many ways. This initially applies to the type of used Screwdriver bits, especially their profile tips, as well as the associated ones Screws. Instead of screws with Phillips internal profiles, Torx, Pozidriv and other screws and associated inserts can be provided. That is further Invention is not limited to the design of the inner and outer sleeves described. If the benefits of the rotatable outer sleeve can be neglected, it could not rotatable on the inner sleeve even with a cross-section other than cylindrical his. Furthermore, the contact surfaces for the screw heads do not necessarily need to be on the Permanent magnets 7, 20 themselves be formed. Rather, it would also be possible to front end faces of the permanent magnets 7, 21 and the outer sleeves 6, 10 in one plane to arrange and the screw heads at least partially with the front faces to bring the outer sleeves into contact. Constructions are also conceivable in which the contact surfaces through the front faces of one on the permanent magnet overlying pole plate are formed. The outer and inner sleeves do not have to go further necessarily consist of non-ferromagnetic materials, even if materials such. B. stainless steel, brass or aluminum or the like are preferred for them. Finally it is understood that the various features also in other than those shown and described combinations and design variants can be used. The Screwing device according to the invention can according to the in variants described construction principle of course manufactured in different sizes become. The most common screwdriver bits on the market are included Shaft cross section made of 4 mm, 6.35 mm (1/4 ") and 8 mm hexagon of the screwdriver shafts certain parts of the device must of course be adapted to different dimensions, including the width of the opening in the Permanent magnets, while other parts may remain the same. But it appears expedient, the screw device overall the dimensions of the different sizes of Adjust screwdriver bits. For special purposes, for example Assembly lines, screwing devices according to the invention Construction principle also as a special version on special versions of Screwdriver bits can be adapted, for example to those with a round Cross-section of the shaft and a driving surface.

Claims (23)

Screwing device for tightening screws (4, 21) made of ferromagnetic material, which have screw heads (4a, 21a) provided with internal profiles, consisting of an inner sleeve (1) for non-rotatable and axially secured mounting of a commercially available screwdriver insert (3), the one for insertion into the inner profiles of the screw heads (4a, 21a), which has a profile tip (3a) protruding from the front of the inner sleeve (1), a drive shaft (2) connected to the inner sleeve and an outer sleeve (at least partially surrounding the inner sleeve (1)) 6, 10), in the front of which an annular permanent magnet (7, 20) is installed, which is provided with an opening (7a) penetrated by the profile tip (3a) of the screwdriver insert (3), and one for contacting the screw heads ( 4a, 21a) has certain, magnetically effective contact surface (7b, 20a), characterized in that the outer sleeve (6, 10) can be slid axially back and forth the inner sleeve (1) is supported and guided and, when the screwdriver insert (3) is inserted, can be brought into a preselected axial position such that when a screw (4) is placed on the profile tip (3a) by the magnetic force of the permanent magnet (7, 20) At the same time, both the screw head (4a) on the profile tip (3a) until the profile tip is in full contact in the inner profile of the screw head (4a) and the outer sleeve (6, 10) with the permanent magnet (7, 20) on the screw head (4a) to be used to abut the end face (7b) of the permanent magnet on the end face (4b) of the screw head. Screwing device according to claim 1, characterized in that between the permanent magnet (7, 20) and the inner sleeve (1) there is arranged a spacer (8) coaxial therewith and made of a non-ferromagnetic material. Screwing device according to claim 2, characterized in that the spacer is a spacer sleeve (8) arranged in the front end of the outer sleeve (6). Screwing device according to claim 2, characterized in that the spacer (8) is an extension (6b) made in one piece with the outer sleeve (6). Screwing device according to claims 1 to 4, characterized in that the shaft (2) has a stop which either consists of a stop sleeve (32) which is pressed onto the shaft (2) or pushed on with a sliding fit and axially through the spring ring (35) is secured and the front end (33) abuts the rear end of the inner sleeve (1) or the shaft (2) has a collar in one piece, which projects beyond the diameter of the hexagon profile and corresponds in length and cross section to the stop sleeve or the stop alone a spring ring inserted into a groove in the shaft (2) and projecting beyond the shaft profile. Screwing device according to claim 5, characterized in that the outer sleeve (6) is formed in one piece and the extension (6a) is part of the outer sleeve (6). Screwing device according to claims 1 to 5, characterized in that the outer sleeve (10) is formed in two parts and the extension (10c) is part of a rear section (10b) detachably connectable to a front section (10a) of the outer sleeve (10) and the front section (10a ) and the rear section (10b) are provided with locking means (11; 12, 14) intended for establishing an axial connection. Screwing device according to claim 7, characterized in that the latching means contain an annular groove (11) on one section (10a) and resilient tongues (12) with cams (14) on the other section (10b) intended for snapping into the annular groove (11). Screwing device according to one of claims 1 to 8, characterized in that the insert (3) and the inner sleeve (1) are provided with latching means (15, 16, 27, 28, 29, 30) intended to produce an axial connection. Screwing device according to one of claims 1 to 9, characterized in that the arrangement and coordination of the components is such that the outer sleeve (6, 10) by the magnetic force of the permanent magnet (7, 20) and optionally a second permanent magnet (9) in a preselected position on the inner sleeve (1) is set. Screwing device according to one of claims 1 to 10, characterized in that the outer sleeve (10) is at least partially supported by a helical spring (17), which is mounted on the drive shaft (2) and is supported between the rear of the inner sleeve (1) and the shoulder (10c) the preselected axial position is positioned. Screwing device according to Claims 1 to 11, characterized in that the preselected position can be adjusted in that the drive shaft (2) has an external thread section in an area projecting axially from the extension (10c), onto which a portion bearing on the extension (10c) is attached an internally threaded adjusting nut (18) is unscrewed. Screwing device according to one of claims 10 to 12, characterized in that the preselected axial position is set such that the profile tip (3a) in this position of the outer sleeve (6, 10) plus the maximum depth of penetration into the inner profile in the screw head (4a) a tolerance dimension (s) protrudes forward over the contact surface (7a), but the outer sleeve (6, 10) is still axially displaceable. Screwing device according to one of claims 1 to 13, characterized in that when the insert (3) is fully inserted into the inner sleeve (1), the outer sleeve (6) is axially displaceable in the direction of the drive shaft (2) beyond the preselected position that the profile tip (3a) protrudes more forward over the contact surface (7b) of the permanent magnet (7) than the maximum penetration depth plus a tolerance measure ( s ). Screwing device according to claim 14, characterized in that the spacer is a spring (25) arranged in front of the end face of the inner sleeve (1). Screwing device according to claim 15, characterized in that the length and / or the force of the spring is selected such that the outer sleeve (6) assumes the preselected position in an essentially relaxed state of the spring (25). Screwing device according to one of claims 1 to 16, characterized in that the contact surface (7b, 20a) is formed by a front end face of the permanent magnet (7, 20) and is flat or adapted to the shape of the end faces of the screw heads (21a) and, for example is correspondingly concave. Screwing device according to one of claims 1 to 17, characterized in that the outer sleeve (6) has a casing (26) made of plastic. Screwing device according to one of claims 1 to 18, characterized in that the position of the snap ring (5) in the inner sleeve (1) axially as far as the position of the notches (5b) in the hexagonal shaft (3) is on the end face of the drive shaft (2 ) the screwdriver insert is offset so that the snap ring (5) only partially engages in the notches (5b). Screwing device according to one of claims 1 to 19, characterized in that the position of the outer sleeve (6) relative to the inner sleeve (1) on the back of the device through an extension (6a) or a ring (24) and on the front of the device the permanent magnet (7) or an extension (6b) shortened in its axial extension compared to the representation in FIGS. 11 and 12 (FIGS. 16 to 18). Screwing device according to claims 1, 2, 5, 6, 18 to 25 and 27, characterized in that the hexagonal shaft (3) of the insert is received in an extension (1a) of the inner sleeve (1), on the extension (1a) a sleeve ( 29) axially displaceable and at least one clamping element (30) is mounted in a radial bore or a radial incision in the extension (1a) and by a cone (30) incorporated in the front area of the sleeve (29) under the action of a 29) axially acting force of a spring (28) is pressed radially against the hexagonal shaft (3), a spring (25) is arranged in the space between the end face of the sleeve (29) and the permanent magnet (7), the dimensions and / or force on the one hand are dimensioned such that in the substantially relaxed state of the spring (25) the outer sleeve (1) with the permanent magnet (7) assumes the preselected position relative to the profile tip (3a), and on the other hand in the compressed state the spring (25) rests Lse (29) pushes back so far that the enlarged part of the cone (30) machined into the bore of the sleeve comes to rest on the ball (27). Screwing device according to claims 1, 2, 5, 6, 18 to 25, 27 and 28, characterized in that the dimensions of the extension (1a), the distance from its front to the ring magnet (7), the lengths of the springs (25) and (28) in the compressed state and the length of the sleeve (29) are adjusted so that the outer sleeve (6) can be pushed back so far that the screwdriver insert (3) protrudes far out of the screwing device with its front part so that it is good can be gripped with the fingers and pulled out of the screwing device. Screwing device according to claims 1 to 22, characterized in that the outer sleeve (6, 10) is rotatably mounted on the inner sleeve (1).

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