HK1090973A - Expanding anchor made of metal and placing tool therefor - Google Patents

Description

Metal expanding anchor bolt and its mounting tool

Technical Field

The invention relates to a metal expansion anchor having the features of claim 1.

Background

Such a expansible anchor for fixing a structural part to a foundation is known from EP 0217053B 1. The known expandable anchor has an anchor base body with an external thread as a fastening means and an expansion segment of reduced diameter which expands conically in the installation direction of the expandable anchor. An expansion sleeve is axially slidably mounted on the expansion section. The expansion sleeve has a base body on which expansion tongues projecting forward are formed along a given bending line. The expansion tongue can be expanded by pushing the expansion sleeve onto the expansion segment for anchoring the expansion anchor with an barb. The expansion sleeve has cutting edges at the end of the expansion tongue facing the borehole bottom, by means of which barbs can be produced. For this purpose, the known expandable anchor is inserted into a cylindrical bore hole and the expansion sleeve is driven onto the expansion part, for example by means of a hammer drill, and is set in rotation immediately. Thereby creating a radial removal in the form of a borehole expansion. Hard metal cutting inserts are proposed for forming the cutting edges. However, the mounting and fastening of such a cutting head in the expansion tongue requires considerable manufacturing expenditure in addition to the material expenditure. This makes the expansion anchor, which is produced in large numbers, expensive. However, if the cutting head is omitted from the known expandable anchor construction and attempts are made to replace it in order to impart sufficient rigidity and strength to the entire material of the expansion sleeve for the cutting edge to be formed on the expansion tongue itself, this fails when the expansion tongue expands, often tearing or breaking along a given bending line. The reason for this is that the given bending line is bent as for all known expansion tongue anchors due to the sleeve shape, whereby the desired longitudinal bending of the expansion tongue is difficult to achieve, since the bending acts as a reinforcement. This requirement is, however, exactly the opposite of the required hardness of the cutting edge, which hardness is used to ensure the effectiveness of the cutting edge also in high-strength concrete.

Disclosure of Invention

The object of the invention is therefore to provide an expansion tongue anchor of the type mentioned above which has a lower production outlay with the same or improved production rate.

This object is achieved according to the invention by a expansible anchor having the features of claim 1 and by an installation tool having the features of claim 6. The expandable anchor bolt according to the invention has an expansion sleeve made of hard steel. In order not to create the failure problem described above along a given bend line, this given bend line is straight. This difference is an important advantage of the present invention. Significantly less force is required to longitudinally bend the expansion tongue and this force is distributed substantially uniformly along a given bend line. The expansion sleeve can thus be made of a hard, high-strength material, which is correspondingly more brittle than the materials currently used. The expansion sleeve is preferably formed from a stamped and bent piece which is hardened after forming and then assembled.

In a preferred embodiment the expansion segment has one planar sliding surface for each expansion tongue a convenient workability is obtained for four sliding surfaces or expansion tongues, but more or fewer expansion tongues are also conceivable. The planar sliding surface has the advantage of a planar guidance of the expansion tongue, while a rotationally symmetrical conical expansion section acts as a straight contact. On the other hand, a basic advantage is that the torque transmission for the rotary movement of the cutting edge can be realized by the anchor bolt base body. While in the known expansion anchor the expansion sleeve has to be driven by a sleeve-shaped setting tool via the drive pawl, in the case of the expansion configuration according to the invention this disturbing torque transmission can be dispensed with. Instead, the anchor bolt base is set in rotation by a stable tool. The planar sliding surface serves as a guide for the expansion tongue, and the expansion sleeve merely has to slide axially relative to the rotating anchor bolt base. An expansible anchor bolt of this type preferably has a spacer sleeve for transmitting the impact of an installation tool on the expansion sleeve to its axial displacement. Of course, the two sleeves can also be formed integrally. However, a separate spacer sleeve has the advantage that the relatively expensive material of the expansion sleeve is used only at the locations where it is necessary. If the expansion sleeve is formed by a stamped and bent part, a smaller diameter than the nominal diameter can also be selected for this expansion sleeve in order to avoid unnecessary friction along the bore wall. The spacer sleeve, which does not have to rotate together, can be designed with a nominal diameter in order to be able to support the expandable anchor bolt without play against transverse forces.

In the case of a planar sliding surface, the anchor bolt base preferably has a wrench engagement surface on the fastening device. The wrench engagement surface can be formed, for example, by two flank flats in the case of an external thread as a fastening means, or by two flank grooves in the case of an internal thread as a fastening means. Care is taken here to retain a sufficient load-bearing threaded portion.

In order to be able to install such a expansible anchor, the invention proposes an installation tool with a corresponding wrench face and a drive face and an adapter device for fixing the installation tool in an impact drill. For the installation of the expansible anchor, this anchor is inserted via its anchor base into an installation tool, wherein the wrench action surface and the wrench surface are brought into engagement with one another. In the inserted state, the drive surface rests on the expansion sleeve or on the spacer sleeve, if present. The expandable anchor is then inserted into the borehole until it is positioned at the bottom of the borehole. The tool rotation/impact motion, which is produced, for example, by an impact drill, causes the anchor bolt main body and thus the cutting edges on the expansion sleeve to rotate and simultaneously drives the expansion sleeve through the expansion segment of the anchor bolt main body. This rotational movement serves to produce a removal of the cutting edge and thus an undercut in the drill hole. The installation tool is pulled out after the expansion is achieved.

An installation tool for an expandable anchor bolt with an external thread is provided, which has a sleeve-type partial body with a wrench surface on the inner side and a drive surface on the end face. A very simple construction is thereby achieved. For expanding anchors with an internal thread, a pin-type partial body with a wrench surface on the outer side, for example in the form of a rectangular cross section, is conceivable, wherein a shoulder is axially connected to this partial body for forming the drive surface.

Detailed Description

The invention is described in detail below with the aid of an embodiment shown in the drawing. The drawing shows a metallic expansion bolt 1 according to the invention and an installation tool 2 according to the invention. The expansible anchor 1 is used for fixing an object, not shown, to a base, also not shown. The expandable anchor bolt 1 has an anchor bolt base 3 with an external thread 4 as a fastening means for the structural component and an expansion segment 5 which decreases in diameter and expands conically in the direction of the anchor bolt end 6. A hard steel expansion sleeve 6 made of a stamped and bent part, which has a base body 7 and four expansion tongues 8, is mounted on the expansion section 5 in an axially slidable manner. The expansion tongue 8 is expanded radially outward against a borehole wall by an axial displacement in the direction of the anchor bolt end 6. The expansion tongues 8 have cutting edges 9 for creating an undercut. The expansion tongue 8 is connected to the base body 7 by a straight, predetermined bending line 10. This facilitates the longitudinal bending of the expansion tongue 8 without the hard steel breaking. This is also facilitated by the four flat sliding surfaces which serve to transmit a torque of the anchor bolt basic body 3 to the expansion sleeve 6. In order to transmit this torque from a tool, here the setting tool 2, to the anchor bolt carrier 3, this anchor bolt carrier has a wrench-action surface 12. In order to transmit an axial force to the expansion sleeve 6, the expandable anchor 1 has a spacer sleeve 13 which has an end face 14. The spacer sleeve 13 also serves to support the expandable anchor bolt 1 transversely in the borehole and thus corresponds in diameter to the nominal diameter.

The setting tool 2 has a sleeve-shaped part 15 with a spanner surface 16 on the inside and a drive surface 17 on the end face for transmitting impacts to the end face 14 of the spacer sleeve 13. For fixing the setting tool 2 in a hammer drill (not shown), the setting tool has an adapter 18 in the form of a standard groove.

In order to install the expansible anchor 1 by means of the setting tool 2 clamped in the hammer drill, the expansible anchor 1 is inserted into the setting tool 2, whereby the wrench face 16 engages the wrench active face 12 and the drive face 16 of the setting tool 2 rests on the end face 4 of the spacer sleeve 3. In this state, the expansion anchor 1 is inserted into a borehole, not shown, of a foundation until it is placed on the bottom of the borehole. The anchor bolt basic body 3 and thus the expansion sleeve 6 are set in rotation by a combined rotary/percussive motion of the hammer drill. At the same time, the expansion sleeve 6 is slid axially onto the expansion section 5 and the expansion tongues 8 are thereby expanded radially outward along the sliding surface 11, the cutting edge 9 being removed in the form of a radially expanding bore at this point by the rotation of the expansion sleeve 6. This extension acts as an undercut. This achieves a form-fitting anchoring in the borehole. After the completion of the setting process, the setting tool 2 is easily pulled out of the expansible anchor 1.

Claims (7)

1. A metallic expansion anchor (1) for fastening a structural part to a foundation, wherein the expansion anchor (1) has an anchor base body (3), fastening means (4) and an expansion portion (5) which decreases in diameter and which expands in the installation direction of the expansion anchor, on which expansion portion an expansion sleeve (6) is axially slidably inserted, which has expansion tongues (8) and at least one cutting edge (9) for producing an undercut, wherein the expansion tongues (8) are each connected to the base body (7) of the expansion sleeve (6) at a given bending line (10), characterized in that the expansion sleeve (6) is made of hardened steel and the given bending line (10) is a straight line.

2. The expandable anchor bolt according to claim 1, characterised in that the expansion sleeve (6) is a stamped and bent part.

3. The expandable anchor bolt according to claim 1, characterised in that the expansion section (5) has a planar sliding surface (11).

4. The expandable anchor as claimed in claim 1, in which the expandable anchor (1) has a spacer sleeve (13).

5. Expansion anchor according to claim 1, characterized in that the anchor base (3) has a wrench-action surface (12) at the fastening device (4).

6. An installation tool (2) for installing a expansible anchor (1), in particular an expansible anchor according to claim 5, characterized in that the installation tool (2) has a wrench face (16) corresponding to the wrench action face (12) of the expansible anchor (1), a drive face (17) and an adapter device (18).

7. The setting tool according to claim 6, characterized in that the setting tool (2) has a sleeve-type partial body (15) with a spanner surface (16) on the inner side and a drive surface (17) on the end face.