WO2001025643A1

WO2001025643A1 - Anchoring screw

Info

Publication number: WO2001025643A1
Application number: PCT/SE2000/001855
Authority: WO
Inventors: Stefan Stolt
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-04
Filing date: 2000-09-26
Publication date: 2001-04-12
Anticipated expiration: 2002-04-04
Also published as: SE9903576D0; SE514766C2; SE9903576L; AU2000279761A1

Abstract

The invention concerns an anchoring screw comprising a screw body (1), which is formed with threads over at least a portion of its extension, a screw head (2) securely fastened at one end of the screw body, and an expandable retention element (3), which retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and which is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in which it is to be secured. It is characteristic of the screw that the screw head (2) is formed with faces (21) designed to be brought into engagement with a tool for rotation of the screw, at least one of said faces formed with an undercut relative to the screw axis, whereby it becomes possible to use the tool not only to transmit a rotary force but also to exert a pulling force on the screw body in the direction towards the screw head.

Description

ANCHORING SCREW

Technical Field

The present invention relates to an anchoring screw comprising a screw body, which is formed with threads over at least a portion of its extension, a screw head securely fastened at one end of the screw body, and an expandable retention element, which retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and which is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in order to be secured in the same.

Background

To-day, mounting objects to walls particularly of gypsum, tiles, lightweight concrete, LECA (light expanded clay aggregate) blocks or the like, requires a number of operations involving lifting and lowering the object to be mounted, such as cupboards and the like. The fitter must drill holes, insert plugs, change operative tools in the power driver, and so on. In addition, plugs are difficult to attach in tile walls and similar structures because of the porosity of the material.

Attempts have been made to integrate expandable retention elements, i.e. plugs, with the screw into one single unit. This solution is disclosed for instance in DE 1 142 224, which describes an anchoring screw comprising a screw body, which is formed with threads over at least a portion of its extension, a screw head securely fastened at one end of the screw body, and an expandable retention element, which retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and which is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in which it is to be secured.

This anchoring screw, too, does however require several operational steps, such as pre-drilling etcetera, in addition to the very step of tightening or driving the screw. In addition, the pre-drilling step often should be performed in several stages, involving initially drilling the hole with the aid of a small -diameter drill bit and subsequently widening the drill hole using a larger- diameter drill bit. Since the fitter usually uses the same tool for the drilling and screw-driving operations, the process necessitates that numerous changes of the operative parts of the tool be made, i.e. changes between driving and drilling bits. This likewise requires repeatedly lifting the objects to be mounted.

Another problem encountered with prior-art screws concerns the difficulty in making the retention elements anchor themselves in the material sufficiently to allow tightening with the aid of the threads. Unless the retention element is anchored, it merely rotates together with the rotating screw body, and it may be a ti e- consuming and cumbersome task to achieve such anchorage, particularly when working in less porous materials.

Several of the prior-art screws are difficult to remove once they are mounted, and often their removal cause ugly marks to the wall or result in parts of the screws being left projecting from the wall. Object of the Invention

Consequently, one object of the present invention is to provide an anchoring screw that allows the fitting job to be performed in a more simple and efficient manner. This object is achieved by means of an anchoring screw as defined in the appended claims.

Summary of the Invention

The invention concerns an anchoring screw comprising a screw body, which is formed with threads over at least a portion of its extension, a screw head securely fastened at one end of the screw body, and an expandable retention element, which retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and which is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in which it is to be secured. In addition, the screw head is formed with faces designed to be brought into engagement with a tool for rotation of the screw, at least one of said faces formed with an undercut relative to the screw axis, whereby it becomes possible to use the tool not only to transmit a rotary force but also to exert a pulling force on the screw body in the direction towards the screw head.

This arrangement makes it possible to drive the screw directly by means of the tool, thus causing the retention element to grip into the material in which it is to be secured. In this manner, the mounting work is facilitated most considerably. The design of the screw head as taught by the invention may be used also to attach to walls such fastener elements as picture hooks, threaded bars designed for mounting of elements and the like, and other types of fasteners.

It is particularly preferable to form the screw head with a screw slot, wherein at least one of the interior faces of the slot is formed with an undercut and wherein the faces of the screw slot extend at an angle relative to one another, such that a groove tapering towards one side is obtained. This causes the tool to be retained to the screw by wedging, which provides a more stable screw/groove interconnection. The arrangement also makes it easier to insert fasteners in the screw head.

Preferably also, at the end remote from the head, the screw is formed with an insertion tip, which is arranged on the screw body, preferably in a detachable but non-rotational manner, which insertion tip is adapted to allow it to penetrate into a non-pre-drilled material. The tip could, for instance comprise means, such as drill bits, bore cutters, threads or the like, arranged to penetrate into a material upon rotation of the tip in a first direction of rotation, the threads on the expandable retention element and on the screw body being such as to cause the retention element to move towards the screw head upon rotation of the screw body in the opposite direction of rotation. This arrangement allows the screw to be used also to achieve penetration into the material, making pre-drilling and similar operations superfluous, which facilitates the mounting work considerably. Consequently, it becomes possible to drive the screw directly into a wall or similar structural elements, followed by reversal of the screw-movement direction, whereupon the retention element, thanks to a slight pull exerted on the screw head, anchors the screw in the material. The entire mounting operation therefore may be performed in one single operational step without change of tool or the like.

It is also desirable that the anchoring screw comprises a cylindrical portion, which is located at the head end of the screw body and has a diameter essentially agreeing with the diameter of the insertion tip. Preferably, the cylindrical portion tapers towards the screw body in the direction away from the screw head. The arrangement stabilises the screw, when mounted, and eliminates play at the head-end of the screw.

The invention also concerns a fastener for attachment to an anchoring screw as defined above, said fastener comprising a first end adapted to be brought into engagement with the screw head and to be retained in its position of engagement by the faces of the undercut of said head, and a second end provided with fastening means for securing other objects intended to be fastened.

Finally, the invention also comprises tools for mounting an anchoring screw defined above, said tools comprising an active part, which is adapted to be caused to engage the screw head and which comprises faces of complementary configuration to the undercut of the screw head and adapted to allow a pulling force to be exerted on the screw head.

Brief Description of the Drawing Figures

One embodiment of the invention will be described in the following in more detail for exemplifying purposes and with reference to the accompanying drawings, wherein Fig 1 is a perspective view of a screw in accordance with a first embodiment of the invention;

Fig 2a is a lateral view of a screw in accordance with a second embodiment of the invention; Figs 2b-d are other views of structural components of the screw of Fig 2a;

Fig 2e shows an alternative screw tip that may be used in conjunction with the screw of Fig 2a; Fig 3 shows a tool that may be used to mount the screw of Fig 2a;

Fig 4 shows a fastener that may be fitted on the screw head of the screw of Fig 2a;

Fig 5 is a cross-sectional view illustrating mounting of the screw of Fig 2a in lightweight concrete or similar materials;

Fig 6 is a cross-sectional view illustrating a first mounting step of mounting the screw of Fig 2a in gypsum, wood or other materials; Fig 7 is a cross-sectional view illustrating a second mounting step of mounting the screw of Fig 2a in gypsum, wood or other materials;

Fig 8 is a cross-sectional view illustrating a third mounting step of mounting the screw of Fig 2a in gypsum, wood or other materials;

Figs 9a-b show another embodiment of a screw in accordance with the invention in views from above and from the side; and

Fig 10 shows an example of a tool for mounting the screw of Fig 9.

Description of Preferred Embodiments

Fig 1 illustrates a first embodiment of an anchoring screw in accordance with the invention. The anchoring screw comprises a screw body 1, which is formed with threads over a portion of its extension, a screw head 2 securely fastened at one end of the screw body, and an expandable retention element 3. The retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and it is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in which it is to be secured.

The screw head comprises faces 21 designed to be brought into engagement with a tool to rotate the screw, said faces formed with an undercut relative to the screw axis. This arrangement provides a possibility to exert a pulling force on the screw body in the direction towards the screw head by means of the screw tool .

Figs 2a and b show an alternative embodiment of the screw head of the screw in accordance with the invention. According to this embodiment the screw head is formed with a screw slot, the internal faces of which are formed with undercuts, whereby the faces at the top of the slot are closer to one another than at the bottom of the slot . Alternatively, only one of the faces is formed with an undercut. It is likewise possible to arrange the faces designed for engagement with the tool externally, such that they are turned away from one another.

In addition, the screw slot preferably could be arranged such that the screw-slot faces extend at an angle relative to one another in the manner shown in Fig 2b, whereby a slot tapering to one side is obtained. This arrangement provides a wedging effect to hold tools, fasteners, and similar implements, inserted in the slot, which gives a firmer engagement grip.

Preferably, the screw comprises an insertion tip 4 arranged at the screw body end remote from the screw head. The tip is designed to allow it to penetrate into a non-pre-drilled material. Preferably, the tip is detachably but non-rotationally secured on the screw body thanks to the provision on the screw body of an end part

11 having a non-circular cross section, and the tip is formed with an aperture 40 having a corresponding cross- sectional shape as illustrated in the exploded views of Figs 1 and 2d. A square or hexagonal cross-sectional shape could be used.

Owing to the detachable arrangement of the tip, it may be replaced when needed, and it can also be removed for dismounting purposes, as will be described in more detail below.

The tip may be formed with a conical or similarly shaped tip end, allowing the screw to be pressed into the material in which it is intended to be secured, in the same manner as a nail. Preferably, the tip is formed with bore-cutting faces 41, threads 42, or similar means instrumental in making the tip penetrate into the material when rotated. It is also desirable that the tip is non-rotationally connected to the screw body. In this respect, the screw suitably is configured in such a manner that the tip penetrates into the material upon rotation of the screw in a first direction of rotation, whereas the threads formed on the expandable retention element and on the screw body, respectively, are designed to make the retention element move towards the screw head upon rotation of the screw body in an opposite, second direction of rotation. It is suitable that the tip is formed with right-hand threads whereas the screw body and the retention element are formed with left-hand threads. The opposite arrangement is, of course, also possible. The type of tip that is suitable depends on the kind of material on works with, and other types of tips may also be possible. In addition, the anchoring screw preferably comprises a cylindrical portion 5, which preferably is located at the head end of the screw body. The portion should have a diameter essentially agreeing with the diameter of the insertion tip 4 in order to stabilise the screw head against the wall of the hole, when the screw is mounted. Advantageously, the cylindrical portion tapers towards the screw body in the direction away from the screw head, which facilitates insertion into the aperture as the screw is being mounted.

The expandable retention element likewise preferably comprises a holding element 31, which is threaded onto the screw body 1, and retention tongues 32 standing out from the screw body and projecting from holding element at least partly in a direction towards from the screw head. Advantageously the retention tongues are formed with pointed ends, as illustrated in Fig 2c in order to facilitate their anchorage in the material in which it is to be secured. Other types of expanding retention elements are also conceivable within the scope of protection of the invention.

Preferably, in the non-expanded position of the retention element, its radial extension is less that of the tip, to prevent it from accompanying the screw as the latter is being screwed or drilled into a material.

Preferably, the retention element advantageously is provided with dust or chip collection channels or the like. Advantageously the channels are in the form of external grooves having a smaller radial extension than surrounding parts. Chip channels of this kind allow chips, dust and similar debris arising from drilling by means of the screw, to be removed in a simple and efficient manner. This is of particular advantage when working with materials such as lightweight concrete that give off considerable amounts of dust and similar rest products .

Furthermore, the anchoring screw in accordance with the invention advantageously comprises a retention or locking ring 6 arranged to gather the retention tongues in abutment against the screw body before the screw is mounted in the screw hole as well as during the initial steps, when the screw is driven into the material. The retention ring preferably has an external extension exceeding that of the screw hole, ensuring that the retention ring is arrested in a position adjacent the hole mouth and in doing so releases the retention tongues as the screw is being inserted into the screw hole. The retention ring likewise should have an inner aperture of sufficient size to allow the cylindrical portion of the screw body to pass through it. In this manner the retention ring will act as a washer between the screw head and the material in which it is intended to be secured, thus providing protection against wear.

The invention likewise concerns a tool 7 to be used to mount an anchoring screw of the kind outlined above. Tools of this kind comprise an active part adapted to be brought into engagement with the screw head and being formed with faces of complementary configuration to the undercut of the screw head, said complementary faces designed to make it possible to exert a pulling force on the screw head, in addition to the rotational and the pressure forces. One example of a tool of this kind is shown in Fig 3, which tool is intended for mounting the screw shown in Fig 2a. The tool is of the type known as a bit to be attached in a power driver or a drilling machine with screw-driving function. The tool comprises a shank end 71 designed to be gripped by a chuck, a handle or the like, and preferably it has a non-circular cross- sectional shape, for example hexagonal. The active part 72 is located at the opposite end of the tool. This part is wedge-shaped and comprises external faces of a configuration complementary to the undercut of the screw head.

The invention also concerns fasteners 8 for attachment to an anchoring screw as defined above. Such fasteners, illustrated in Fig 4, comprise a first end 81 adapted for engagement with the screw head and to be retained in its position of engagement by the undercut of said head, and a second end 82 provided with fastening means for securing other objects intended to be fastened. The fastening means could be e.g. hooks, magnets, threaded bars, and the like.

The screw in accordance with the invention is particularly suitable for mounting in walls and similar structural elements of gypsum, bricks, leca building blocks and similar materials.

In order to further emphasise the advantages and function of the inventive anchoring screw a mounting operation, using the screw, will be described in the following. Fig 5 illustrates screw-mounting in a material the thickness of which exceeds the length of the screw. The screw is initially introduced into the material, which in this case could be e.g. lightweight concrete, by drilling it into the material as deep as possible, i.e. until the screw head 2 contacts the material. When the retention washer 6 abuts against the surface of the material, the hold on the retention element 3 is released. In the drilling operation, the retention element, owing to its opposite thread hand, will be forced to move towards the screw tip 4, but will not be able to force the screw tip off, while the tip works itself into the material. The direction of rotation is thereafter reversed while at the same time a pulling force is exerted on the screw, which is made possible thanks to the undercuts of the screw head 2. The retention element will then be forced into the material and be anchored therein. With the retention element in its anchored position, only the screw body will be allowed to rotate, whereas the retention element is stationary, and as a result, the screw head is tightened against the surface of the material .

Figs 6-8 illustrate mounting of the screw in accordance with the invention in a material, the thickness of which is smaller than the length of the screw. The screw is inserted into the material by drilling or screwing, which material in this case could be for example wood and/or gypsum. When the screw tip and the retention element have penetrated the material to the opposite side of the latter, a pulling force is exerted on the screw like in the example above, thereby anchoring the retention element. However, in this case the retention element anchors itself in the back of the material. The screw is thereafter rotated in the opposite direction.

When the screw in accordance with the invention is to be dismounted, it is rotated while at the same time a pulling force is exerted on the screw, the screw body 1 thus being unscrewed relative to the retention element 3. When the retention element 3 contacts the screw tip 4, the latter is forced to recede and comes off the screw body 1, and thereafter also the retention element 3 is detached from the screw body. The screw body 1 may then be pulled out, whereas the tip and the retention element remain embedded in the material . The damage to the surface of the material is, however, very limited, since only the hole is visible afterwards. The novel screw eliminates many of the inconveniences found in screws of prior-art screw construction. To fit a cupboard, for example, the fitter simply lifts it (to the desired position) and applies the screw directly by screwing or drilling, more often than not without pre-drilling being required, reverses the direction of the screwing movement and continues the screwing operation in the opposite direction while at the same time he pulls the screw slightly towards himself, thereby making the screw hold the cupboard fast . Figs 9a and 9b show a further embodiment of an anchoring screw in accordance with the invention. This embodiment differs from the previously described embodiment only with respect to the principal part of the screw, for which reason only this part is shown in the drawings. According to this embodiment, as the ones described previously, the screw head 2 comprises a screw slot 21 for rotation of the screw. In addition, undercuts are formed adjacent the screw slot 21 to allow a pulling force to be exerted on the screw body in a direction towards the screw head. In accordance with this embodiment the faces 21', designed to allow rotation of the screw, are arranged at an angle, whereby the faces disposed on the opposite sides are located closer to one another at the centre than at the periphery of the head. Preferably, the faces are essentially straight, such that a V-shaped recess is formed on either side of the centre of the head. Preferably, the faces form an acute angle relative to one another, the recess occupying less than half the area of the screw head.

An overhang 21" is arranged above the faces that are arranged to allow rotation, said faces 21' forming an undercut in the face 21 as a whole. The overhang projects across at least part of the recess and preferably essentially symmetrically on both sides. An aperture to allow insertion of a tool should, however, be provided between the overhang parts projecting from the two opposite sides. The aperture could, for example, by configured as a groove of even width.

A suitable tool 7' for mounting an anchoring screw in accordance with the embodiment of Fig 9 is shown in Figs 10a and 10b and it comprises an active part in the shape of an elongate member 72 ' , that is designed to allow it to be inserted into the slot in the screw head, and thereafter to be turned in such a manner, that parts of the member will be placed underneath the overhang. Preferably, the elongate member is formed on the end of a shaft 71', which is adapted to be fitted in a power screwdriver or a drilling machine having a screw driving function.

The invention has been described above by means of one embodiment. Numerous varieties of the invention are, however, possible. For example, it is possible to use the screw without the tip, which does, however require pre- drilling of the screw hole. In addition, it is not necessary for the tip to be detachable, although this is desirable on order to allow dismounting of the screw. The screw head, the retention element, the tip, as also other details, could be designed otherwise than described above and yet provide the same effect. These and other obvious varieties must be considered to be within the scope of protection of the invention as the latter is defined in the appended claims.

Claims

1. An anchoring screw comprising a screw body (1), which is formed with threads over at least a portion of its extension, a screw head (2) securely fastened at one end of the screw body, and an expandable retention element (3) , which retention element is mounted on the threaded portion of the screw body for rotation thereon by means of corresponding threads and which is arranged to expand when displaced in the direction towards the screw head relative to a surrounding material in which it is to be secured, c h a r a c t e r i s e d in that the screw head (2) is formed with faces (21) designed to be brought into engagement with a tool for rotation of the screw, at least one of said faces formed with an undercut relative to the screw axis, whereby it becomes possible to use the tool not only to transmit a rotary force but also to exert a pulling force on the screw body in the direction towards the screw head.

2. An anchoring screw as claimed in claim 1, wherein the screw head is formed with a screw slot, at least one of the interior faces of the slot being formed with an undercut, the faces thus being located more closely to one another at the top than at the bottom of said slot.

3. An anchoring screw as claimed in claim 2, wherein the faces of the screw slot also extend at an angle relative to one another, such that a groove tapering towards one side is obtained.

4. An anchoring screw as claimed in any one of the preceding claims, wherein at the end remote from the head, the screw is formed with an insertion tip (4) , which is arranged on the screw body, preferably in a detachable but non-rotational manner, which insertion tip is adapted to allow penetration into a non-pre-drilled material .

5. An anchoring screw as claimed in claim 4, wherein the tip comprises means, such as drill bits, bore cutters or threads, arranged to penetrate into a material upon rotation of the tip in a first direction of rotation, the threads on the expandable retention element and on the screw body being such as to cause the retention element to move towards the screw head upon rotation of the screw body in a second, opposite direction of rotation.

6. An anchoring screw as claimed in claim 4 or 5 , wherein said screw further comprises a cylindrical portion (5) , which is located at the head end of the screw body and has a diameter essentially agreeing with the diameter of the insertion tip, said cylindrical portion preferably tapering towards the screw body in the direction away from the screw head.

7. An anchoring screw as claimed in any one of the preceding claims, wherein the expandable retention element comprises a holding element (31) , which is threaded onto the screw body, and retention tongues (32) standing out from the screw body and projecting from said holding element at least partly in a direction towards the screw head.

8. An anchoring screw as claimed in claim 7, wherein a retention ring (6) is arranged to gather the retention tongues (32) in abutment against the screw body (1) before the screw is mounted in a screw hole, said locking ring preferably having an external extension exceeding that of the screw hole.

9. A fastener (8) for attachment to an anchoring screw as claimed in claim 1, said fastener comprising a first end (81) adapted to be brought into engagement with the screw head and to be retained in its position of engagement by the undercut of the faces of said head, and a second end provided with fastening means (82) for securing other objects intended to be fastened.

10. A tool (7) for mounting an anchoring screw as claimed in claim 1, said tool comprising an active part (72) , which is adapted to be caused to engage the screw head and which comprises faces of complementary configuration to the undercut of the screw head and adapted to allow a pulling force to be exerted on the screw head, in addition to a rotational force.