EP0487957B1 - Device for holding screws during tightening - Google Patents

Abstract

A device for holding screws (2) during tightening can be fixed to the housing of a drive unit (4). A screw nut, which can be connected to the drive, serves to receive at least a part section of the drive end of a screw. Also provided are two support jaws (9, 10) which are pivotable transversely to the screwing-in axis (14) and in their rest position leave free a passage opening for the shaft (20) of the screw (2). In their rest position, which at the same time also represents the use position, the two support jaws (9, 10) are freely projecting from their rotary bearing (15, 16) to the screwing-in axis (14), aligned approximately transversely to the screwing-in axis (14). In the direction counter to the screwing-in direction (E), the support jaws (9, 10) are spring-loaded and pivotable in the screwing-in direction (14). The screws are thus held in two places arranged at a distance from one another, and more specifically on the one hand by the screw nut on the screw head and on the other hand by the support jaws (9, 10) on the screw shaft, so that even relatively long screws can be held safely, until the penetrating tip of the screws has bored into the workpiece. <IMAGE>

Description

The invention relates to a device for holding screws, in particular self-tapping and self-tapping screws, when screwing in, consisting of a component which can be fixed on the housing of a drive unit, a screw nut which can be coupled to the drive and which is designed to receive at least a portion of the drive end, and at least Two support jaws pivotable about pivot bearings oriented transversely to the screw-in axis, in their rest position leaving a passage opening for the shaft of a screw, the support jaws in their rest position being approximately transverse to the screw-in axis and projecting freely from their pivot bearing in the direction of the screw-in axis.

A device for holding screws when screwing in, which is known from DD 228 769 A1, has support jaws combined into a three-jaw holding chuck, which are held together by a cord spring. The ends of these support jaws which grip the screw shank are offset by a substantial amount in the direction of the screw-in axis with respect to their rotary bearing. If a lateral load is exerted on the screw tip, the support jaws are pivoted outwards and the screw is no longer held and securely supported. A secure mounting and support of long screws is not possible with this known device. Furthermore, the screws can only be inserted from the back of the three-jaw chuck in the screw-in direction. This is also the reason why in this known device the use of screws is only possible up to a certain length and usually only of short screws.

A device known from DE 25 49 601 A1 for holding screws when screwing in has a similar structure. In this device, a lock is provided which only allows the support jaws to be pivoted out when the fastening process of the fastener is already in a corresponding stage. Relatively complicated locking elements which are displaceable in the screwing-in direction and which can be withdrawn again are therefore required, which only release the support jaws for a pivoting operation at a specific time. In this known device, too, the screws can only be inserted from the back of the support jaws in the screw-in direction. For this purpose, the device is provided with a filling tube protruding at an acute angle. In this device too, therefore, only screws up to a certain length and generally only short screws can be used.

In a device of the type mentioned at the beginning (FR-A-1 573 990), two pivot bearings which can be pivoted about transverse to the screw-in axis are In its rest position, a passage opening for the shank of a screw is provided, which, in its rest position, projects approximately freely transversely to the screw-in axis from its pivot bearing in the direction of the screw-in axis. From this rest position, the support jaws can be pivoted in the screwing direction.

These support jaws are held in their position by a spring-loaded sleeve and swivel downwards when the head of the screw to be screwed hits.

Especially when screwing in relatively long screws, and here in particular self-drilling and self-tapping screws, it is a basic requirement that the screws have an exact holder in alignment with the screw-in axis. At least until the screw tip is finally drilled, this exact alignment must be given, since otherwise a screw cannot be screwed in at the intended location or just falls out of the mounting device several times during screw-in attempts.

The object of the invention is to design a device of the type mentioned in the introduction in such a way that simple and secure support and mounting of long screws is also possible.

To achieve this object, it is proposed according to the invention that the support jaws of the above-mentioned device rest against a stop in a spring-loaded manner in the rest position in the direction opposite to the screw-in direction, are designed to be pivotable from the rest position in the screw-in direction and include an acute angle with the screw-in axis in their rest position facing the screw-in axis , are slightly inclined towards the screw nut.

Such an arrangement of the support jaws enables a screw, in particular a relatively long screw, to be held securely, since the screw can be inserted into the screw nut with its drive end on the one hand and can be held in the region of the shaft at a corresponding distance from the screw nut from the support jaws becomes. An approximately rigid alignment of the shaft of the screw is therefore possible exactly in the screw-in axis.

This inventive design of the device has created the possibility of preventing the support jaws from swiveling out to the side even without additional locking elements which can be actuated as a function of the axial displacement of any parts in the screwing direction. It has namely been recognized that when the support jaws in their rest position are oriented approximately transversely to the screw-in axis and project freely from their pivot bearing in the direction of the screw-in axis, lateral loads on the screw used have no effect on the support jaws, as a result of the practically perpendicular to the Forces acting on the pivot bearing no torque is exerted on the support jaws. The support jaws remain in position and provide proper support and support even long screws without the need for additional locking elements. Only when the screw head, a large sealing washer located under the screw head, or the screw nut hits the support jaws in the screwing direction, do they pivot downwards, whereby the screw has already drilled the workpiece in question at this stage or has been partially screwed into it .

Since the support jaws bear against a stop in a spring-loaded manner in the direction opposite to the screw-in direction and are designed to be pivotable in the screw-in direction, they are pivoted back again and again spring-loaded into the same position after being pivoted out, this position being defined by corresponding stops.

A very safe lock against unwanted pivoting of the support jaws is achieved in that the support jaws form an acute angle with the screw-in axis in their rest position directed towards the screw-in axis, that is to say are slightly inclined towards the screw-nut. This also means that the conical indentation by lever action cannot unintentionally cause the support jaws to pivot. The support jaws only pivot downwards when a load is exerted on them in the screwing direction.

So that the rest of the support jaws firmly resting against each other at their two ends can always pivot well against one another, the support jaws have inclined end faces, so that the end faces include an open angle towards the screw nut and / or away from it, with the screw-in axis.

Of particular advantage is a constructive measure according to which at least one of the two side surfaces of the support jaws merges into the oblique end surfaces thereof with an acute-angled bevel or a rounding. This measure enables the screws to be simply inserted before a screwing-in process. The screws can be inserted with the screw head into the screw nut from obliquely outside the area enclosed by the support jaws and then cause the support jaws to open by a pivoting movement toward the screw-in axis. Because of the acute-angled bevels or due to a rounding on the side surfaces, a corresponding load is exerted on the support jaws in the screwing-in direction, so that the support jaws swing downward against the load of a spring. The screw shaft can thus be pivoted into the corresponding position, whereupon the support jaws are then returned to their rest position. It is therefore very easy to insert, in particular long screws, into the device.

It is further proposed that a yoke-like supporting part is provided for the storage and mounting of the support jaws, the legs of which protrude freely parallel to one another at a distance have the pivot bearings and stops for the support jaws. The support jaws are thus in two mutually opposite sides from freely accessible areas, so that just long screws can be used by hand in a very simple manner.

So that even screws with relatively large heads, corresponding flanges under the head or fitted with a sealing washer can be inserted and screwed in, it is particularly advantageous if the support jaws are held pivotable by an angle of approximately 90 ° and completely against the force of a spring are pivotable into the legs of the supporting part. As a result, the entire area between the two legs of the supporting part is cleared, so that a relatively large washer or sealing washer can also sit on the screw shaft.

In order to achieve a further advantageous function for these bars at the same time, it is proposed that the free ends of the legs of the yoke-like supporting part be designed as supports and for support on the workpiece to be screwed.

Fig. 1

eine Seitenansicht einer Vorrichtung zur Halterung von Schrauben, teilweise aufgeschnitten dargestellt;

Fig. 2

einen Längsschnitt durch die Vorrichtung nach Fig. 1;

Fig. 3

einen Schnitt nach der Linie III-III in Fig. 2;

Fig. 4

eine Seitenansicht eines Stützbacken aufnehmenden Tragteils;

Fig. 5

einen Schnitt nach der Linie IV-IV in Fig. 4;

Fig. 6

einen Schnitt nach der Linie VI-VI in Fig. 4;

Fig. 7

eine Ansicht eines Stützbackens von unten;

Fig. 8

eine Ansicht des Stützbackens von vorne;

Fig. 9

eine Seitenansicht des Stützbackens;

Fig. 10 und 11

Längsschnitte durch den Tragteil der Vorrichtung, wobei die beiden Endstellungen eines Stützbackens ersichtlich sind.

An embodiment of the invention is explained in more detail in the following description with reference to the drawings. Show it:

Fig. 1

a side view of a device for holding screws, shown partially cut away;

Fig. 2

a longitudinal section through the device of FIG. 1;

Fig. 3

a section along the line III-III in Fig. 2;

Fig. 4

a side view of a support member receiving support jaw;

Fig. 5

a section along the line IV-IV in Fig. 4;

Fig. 6

a section along the line VI-VI in Fig. 4;

Fig. 7

a view of a support jaw from below;

Fig. 8

a view of the support jaw from the front;

Fig. 9

a side view of the support jaw;

10 and 11

Longitudinal sections through the supporting part of the device, the two end positions of a support jaw being visible.

The device 1 for holding screws 2 when screwing in essentially consists of a component 5 which can be fixed on the housing 3 of a drive unit 4, a screw nut 6 which is designed to receive at least a portion of the drive end 7 of a screw 2, and a support part 8, in which at least two support jaws 9, 10 are held. The nut 6 can be coupled to a drive 11. To guide the screw nut 6 within the component 5, two spaced-apart guide disks 12 and 13 are provided.

In the following description, the holding of screws is shown and explained as an exemplary embodiment.

1 and 2, the right support jaw 10 is shown in its rest position, which also represents the operating position. The left support jaw 9, however, is shown in the pivoted-back position. In use, of course, both support jaws 9 and 10 are in the same position.

The support jaws 9, 10 are aligned approximately transversely to the screw-in axis 14 and project freely from their pivot bearing 15, 16 in the direction of the screw-in axis 14. In the direction opposite to the screwing-in direction E, the support jaws 9, 10 are spring-loaded against a stop 17, 18. In the screwing direction E, however, the support jaws 9, 10 are designed to be pivotable.

As can be seen in particular from FIGS. 7 to 9, the support jaws 9, 10 are made plate-shaped and have central, approximately semicircular indentations 19 at their free ends. When the ends of the two support jaws 9, 10 are directed towards each other, the two indentations 19 form an approximately circular passage opening in which the shaft 20 of the screw 2 to be inserted is held. So that, if necessary, the support jaws 9, 10 can be pivoted without problems even when the screw 2 is inserted or when the same is inserted, the indentations 19 are designed to be approximately semi-conical in the direction of the screw nut 6.

As can be seen in FIGS. 1 and 2 and in particular in FIG. 10, the support jaws 9, 10 form an acute angle α with the screw-in axis 14 in their rest position directed towards the screw-in axis 14. The support jaws 9, 10 are thus slightly inclined towards the screw nut 6. It is thus ensured that when the support jaws 9, 10 are loaded in the direction transverse to the screw-in axis 14, they cannot pivot downward, but, in contrast, are pressed even more firmly against the corresponding stop 17 or 18.

The support jaws 9, 10 have inclined end surfaces 21, these inclined end surfaces being able to originate only from one surface 22 or 23 or, as shown, from both surfaces 22, 23. These inclined end surfaces 21 form an acute angle with the screw-in axis 14, which is towards or away from the screw nut 6 or open on both sides.

One or two side surfaces 24, 25 merge into the oblique end surfaces 21 with an acute-angled bevel 26, 27, 28 or a corresponding rounding. This enables the shaft 20 to be pressed in from the side. With a corresponding pressure on the shaft 20, the support jaws 9, 10 move downward in the screwing-in direction through these acute-angled bevels and thus allow the shaft 20 of the screw 2 to penetrate into the through opening formed by the indentations 19.

At the end facing away from the indentation 19, the support jaws 9, 10 have bearing eyes 29, 30 so that they can be supported in the supporting part 8 by means of corresponding bolts 31. For supporting and holding the support jaws 9, 10, the supporting part 8 is designed in a yoke-like manner, its legs 32, 33, which project freely parallel to one another at a distance, have the pivot bearings 15, 16 and the stops 17, 18 for the support jaws 9, 10. The support jaws 9, 10 are held so as to be pivotable through an angle of approximately 90 ° and are entirely opposed to the force of a spring 34 Legs 32, 33 can be swiveled in. In Fig. 11, the support jaw 9 shown has not yet been completely pivoted into the leg 33, and could therefore be moved further. This pivoting movement can take place until the support jaw 9 comes into contact with a section 35 that is indented for this purpose at the stop 17.

Despite this design with two cantilevered legs 32 and 33, a very stable construction can be created, since only a window-like opening in the respective leg 32, 33 for receiving the bearing for the support jaws 9, 10 and for receiving the stops 17, 18 36 must be provided. The support jaws 9, 10 are thus freely accessible from the outside on two sides, so that correspondingly long screws can be inserted into the device 1 very easily by hand.

As a result of this special configuration of the support part 8, the free ends of the legs 32, 33 are also suitable for serving as supports and for support on the workpiece to be screwed.

The supporting part 8 is telescopic on the structure 5 which can be fixed on the drive unit 4, i.e. on a tubular body 39 of the same, guided. The supporting part 8 is held in a lower rest position by means of a helical spring 40. During the screwing-in process, the component 5 is pushed into the supporting part 8, namely until a stop ring 37 abuts a stop element 38.

The special arrangement and design of the support jaws 9 and 10 is particularly important for the device 1 described here, although further design variants are possible. Modifications would be conceivable here, both in terms of design and form. However, it is always special Meaning that the support jaws 9, 10 project approximately freely from their pivot bearing 15, 16 in the direction of the screw-in axis 14, oriented approximately transversely to the screw-in axis 14.

Claims (6)

1. A device for holding screws (2), in particular self-boring and self-tapping screws (2), when being screwed in, comprising a component (5) which can be secured to the housing (3) of a drive unit (4), a screw boss (6) which is designed to accommodate at least one portion of the drive end (7) of a screw (2) and which can be coupled with the drive, and at least two supporting jaws (9, 10) which are pivotable about pivot bearings (15, 16) aligned transversely to the screwing-in axis (14) and which, in their rest position, leave free an opening for the shank (20) of a screw (2), wherein, in their rest position, the supporting jaws (9, 10) aligned approximately transversely to the screwing-in axis (14) project freely from their pivot bearing (15, 16) in the direction of the screwing-in axis (14), characterised in that, in their rest position, the supporting jaws (9, 10) bear against a stop member (17, 18) spring-loaded in a direction counter to the screwing-in direction (E), are designed to be pivotable from the rest position in screwing-in direction (E) and in their rest position directed towards the screwing-in axis (14) they form an acute angle (α) with the screwing-in axis (14), i.e. are slightly inclined towards the screw boss (6).
2. A device according to Claim 1, characterised in that the supporting jaws (9, 10) have inclined end surfaces (21) so that the end surfaces (21) form an acute angle with the screwing-in axis (14), which angle is open towards the screw boss (6) and/or facing away therefrom.
3. A device according to Claim 2, characterised in that at least one of the two lateral surfaces (24, 25) of the supporting jaws (9, 10) merges with an acute-angle bevelled portion (26, 27, 28) or a rounded portion into the inclined end surfaces (21) thereof.
4. A device according to Claim 1, characterised in that for mounting and holding the supporting jaws (9, 10) there is provided a yoke-like support part (8), the freely projecting arms (32, 33) of which spaced apart parallel to one another have the pivot bearings (15, 16) and stop members (17, 18) for the supporting jaws (9, 10).
5. A device according to Claim 4, characterised in that the supporting jaws (9, 10) are supported pivotably through an angle of approximately 90° and can be pivoted in, against the force of a spring (34), fully into the arms (32, 33) of the support part (8).
6. A device according to Claim 4 or 5, characterised in that the free ends of the arms (32, 33) of the yoke-like support part (8) are in the form of supports and are designed to bear against the workpiece to be screw-fastened.

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