DE102020105259A1 - Method for producing an expansion anchor and expansion anchor - Google Patents

Abstract

The invention relates to a method for producing an expansion anchor (1) which comprises an expandable expansion element (2) with which the expansion anchor (1) can be anchored in a borehole (3) in an anchoring base (4). The expansion element (2) comprises a metallic base body (5), on the outer side (6) of which a functional layer (7) is applied and, after application, at least part of the functional layer (7) becomes a cutting element (8) for cutting into a wall (9) ) of the borehole (3) is reshaped.

Description

The invention relates to a method for producing an expansion anchor with the features of the preamble of claim 1 and an expansion anchor according to the preamble of claim 12.

From the published patent application DE 101 08 844 A 1, an expansion anchor is known which has an expansion sleeve as an expansion element for anchoring in a borehole in an anchoring base. The expansion sleeve is made of sheet metal which is provided with a coating on the inside of the expansion sleeve and which was deformed in a punching and bending process after coating. The coating, a bonded varnish, is intended to reduce the friction between the expansion element and a shaft of the expansion anchor.

From the patent specification EP 1 807 629 B1 a further expansion anchor with an expansion sleeve as an expansion element for anchoring the expansion anchor in a borehole is known. The expansion sleeve has an edge as a cutting element at its front end. The edge was produced by reshaping on an outside of the base body of the expansion sleeve and has increased strength as a result of the reshaping. Due to the increased strength, the edge can cut into the wall of the borehole, which improves the hold of the expansion anchor in the borehole.

The object of the invention is to create an expansion anchor whose hold in the borehole is further improved.

According to the invention, this object is achieved by a method with the features of claim 1 for producing an expansion anchor and by an expansion anchor with the features of claim 12. The dependent claims claim preferred developments of the invention.

With the method according to the invention, an expansion anchor can be produced which comprises an expandable expansion element with which the expansion anchor can be anchored in a borehole in an anchoring base. Typical "expansion elements" are, for example, expansion sleeves, as they are known from bolt or sleeve anchors. In general, an expansion element is an element of an expansion anchor which, after the expansion anchor has been introduced into a borehole, can be expanded in its diameter, i.e. radially to a longitudinal axis of the expansion anchor, so that the expansion element is pressed against the wall of the borehole and the expansion anchor is thereby in the borehole is anchored. To expand the expansion element, the expansion anchor according to the invention or an expansion anchor produced according to the method according to the invention has in particular an expansion body, in particular in the form of an expansion cone or an expansion pin, which can be drawn or driven into the expansion element for expansion, as is known from commercially available expansion anchors. In addition to the bolt or sleeve anchors already mentioned above, so-called drop anchors, undercut anchors and also nail anchors are expansion anchors for the purposes of this invention, this list not being exhaustive.

The expansion element comprises a metallic base body, on the outside of which a functional layer is applied when the expansion element is manufactured. In relation to the expansion element or to parts of the expansion element, the “outside” is generally the side that is directed towards the wall of the borehole when the expansion anchor is installed as planned in a borehole, while the inside typically cooperates with an expansion body for expansion.

After the expansion, the outside of the expansion sleeve is at least partially in contact with the wall of the borehole. In order to ensure the best possible hold of the expansion element and thus the expansion anchor in a borehole, when the expansion element is produced, at least part of the functional layer is formed into a cutting element after it is applied to the outside, which cuts into a wall of the borehole when it is expanded.

A pipe section or sheet steel is typically used to manufacture the base body. In particular, the base body is made from a steel strip, preferably by severing, for example by cutting or punching, the functional layer being applied to the base body in particular prior to severing. If the functional layer was applied to the base body before the separation, the separation can take place together with the reshaping of the expansion element in a tool. In particular, the steel strip is many times longer than a base body after it has been severed. Typically, the steel strip is wound into a coil, i.e. a roll of steel strip, and is thus processed as an "endless belt". The material from which the base body is made is, for example, steel with the material number 1.4401 or 1.4404.

During reshaping, only the functional layer, but also the functional layer and the base body, can be reshaped, with only a part of the functional layer also being able to be reshaped. The reshaping can also take place only locally or over the entire outside of the functional layer. In particular, the functional layer is harder than the base body. In particular, the functional layer has a hardness of at least 55 HRC, in particular of at least 60 HRC and in particular of at least 65 HRC, while the base body has a hardness less than 55 HRC, in particular a hardness between 20 HRC and 40 HRC. "HRC" stands for the Rockwell hardness measured in the method according to scale C in accordance with DIN EN ISO 6508-1: 2016-12. The functional layer can already be harder than the basic body immediately after it has been applied to the base body, or only after reshaping, during which the functional layer regularly solidifies and the hardness increases.

In particular, a part of the base body is reshaped together with the functional layer during reshaping. In particular in the area of a contact surface in which the functional layer adjoins the base body or in which it is applied to it, the base body is also reshaped when the functional layer is reshaped. During the reshaping, the material of the functional layer and / or the base body can also be removed.

According to the invention, the functional layer is applied cohesively, that is to say that the functional layer and the base body are cohesively connected to one another on the contact surface. The connection can be made, for example, by gluing, in which the functional layer is glued to the base body. In particular, the functional layer can be welded onto the base body.

The functional layer is preferably applied to the base body by means of build-up welding, that is to say by means of surface application by means of melting and simultaneous application of the material from which the functional layer is made. This means that the functional layer is applied to the contact surface by build-up welding during the welding process. In particular, the application takes place by means of laser deposition welding, for example by means of laser wire or laser powder deposition welding. A defined application of the functional layer is guaranteed by build-up welding. Laser deposition welding, in particular, is a process-reliable process with which it is possible to apply even a spatially narrowly limited functional layer in a dimensionally accurate manner within a narrow tolerance range.

The base body and the functional layer are preferably reshaped together. “Together” means here that the forming takes place in one tool, in particular in a progressive tool, and in particular at the same time, in one process step. For example, when the functional layer is reshaped, the base body can also be bent or parts punched out of the base body at the same time. This can take place one after the other in a progressive tool or at the same time in one station of the tool. The joint processing of the base body and the functional layer ensures a very fast and reliable production of the expansion element of the expansion anchor according to the invention.

The deformation is preferably carried out by cold deformation, in particular by means of a press which has two mold halves: a matrix and a punch. In this case, the expansion element as a whole, or only the functional layer, or parts of the functional layer and / or the base body, is pressed into a desired shape without additional heating occurring. It can be advantageous for simple processing if there is still residual heat from the process of applying the functional layer, for example by welding.

In particular, the application of the functional layer and the reshaping take place in successive steps in a production line. “Production line” means that when the expansion element is manufactured, the base body is moved continuously and is moved from a work station, in which, for example, the functional layer is applied to the base body by means of laser deposition welding, to a station in which the forming takes place. In particular, the functional layer is applied continuously to an “endless belt” of a coil by means of laser deposition welding, and the expansion element is only separated from the rest of the endless belt during or after forming in a progressive tool. In particular, the build-up welding takes place while the strip is being moved in the production line, in particular when moving towards a progressive tool.

It is also preferred that the functional layer is applied to the base body in a locally limited manner. In this case, the functional layer is not applied over the entire surface to the outside of the base body, but only locally, in particular only where a cutting element is to be produced by the reshaping. The functional layer can be applied selectively, for example by applying a plurality of points spaced apart from one another in the circumferential direction or in the longitudinal direction of the finished expansion element to the base body. Alternatively, the functional layer can also be applied as a coherent line that extends, for example, over the entire circumference of the finished spreading element, with several lines spaced apart from one another also being possible.

In a further preferred embodiment of the method according to the invention, the functional layer is applied to a section of the expansion element that is at the front in the direction of insertion and this section reshaped. The deformation takes place at least in the front section of the expansion element in the insertion direction. The “direction of insertion” means the direction in which the expansion anchor produced by the method according to the invention is planned to be inserted into a borehole. The “front section of the expansion element in the direction of insertion” is thus the section of the expansion element which, when the expansion anchor is inserted into a borehole as planned, is the first to get into the borehole. Attaching the functional layer and thus the cutting element to the front section of the expansion element in the insertion direction has the advantage that the cutting element is arranged deep in the borehole when the expansion element is expanded and thus cuts into the wall of the borehole at a deep point, so that the expansion anchor has great anchoring forces can initiate into the anchoring ground. In particular, the cutting element forms the front end of the outside of the expansion element.

It is also preferred that the functional layer is made of an iron alloy. The functional layer can in particular be a steel or stainless steel, for example steel with the material number 1.4401 or 1.4037. If the base body is also made from steel or a stainless steel, the carbon content of the functional layer is in particular greater than the carbon content in the base body. In particular, the functional layer consists of a hardenable steel, in particular a steel with a carbon content that is greater than or equal to 0.2 percent by weight, which after welding and reshaping can be hardened in a manner known per se to a person skilled in the art, for example by tempering and quenching .

Particles made of a hard material can preferably be introduced into the functional layer. “Hard material” here means a material that is harder than the material that makes up the matrix of the functional layer in which the particles are embedded. The matrix consists in particular of an iron alloy, in particular of steel or stainless steel, as has already been described above for the functional layer. For example, the particles are made of a metal-like carbide, for example of tungsten carbide, of corundum or of an oxide, for example aluminum oxide, the list not being exhaustive. The particles are applied to the base body in particular by means of laser powder build-up welding with the matrix in which the particles are embedded, the particles being contained in the powder to be welded on. The particles are so hard that they cut into the anchorage. In particular, the particle is so hard that it can be used in building concrete of the compressive strength class C20 / 25 DIN EN 206: 2017-01 respectively DIN 1045-2: 2008-08 can cut into.

In a further preferred embodiment of the method according to the invention, the height of the cutting element is at least 10% of the thickness of the base body. In particular, the height is at least 20%, in particular at least 25% of the thickness of the base body. "Height" and "thickness" here mean the dimensions in the radial direction to the longitudinal axis of the finished expansion anchor, the height and thickness each being measured in the area of a contact area in which the functional layer adjoins the base body or via which the cutting element with the Base body is connected. The "longitudinal axis" runs parallel to or is identical to the direction in which the expansion anchor is inserted when the expansion anchor is inserted into a borehole as planned. Tests have shown that the functional layer, which is relatively thick in relation to the base body, reinforces the base body itself by the functional layer, so that when the cutting element formed from the functional layer is cut into a wall of a borehole, the base body does not fail. If, on the other hand, the thickness of the functional layer is chosen to be too thin, the base body may be deformed by the pressure that is exerted on the base body when the expansion element spreads open, so that the cutting element cannot penetrate the wall of the borehole, but the base body practically evades and flows away, so that the cutting element is no longer supported by the base body. For a particularly stable design of the expansion element in the area of the cutting element, it can be provided that the length of the expansion body measured in the longitudinal direction is also at least 10% of the thickness of the base body. In particular, the length is at least 20%, in particular at least 25% of the thickness of the base body. In particular, the length and the height of the expansion element are essentially the same. In particular, the length is greater than the height of the expansion element.

The expansion anchor according to the invention has an expansion element with a metallic base body. With the expansion element, the expansion anchor can be anchored in a borehole in an anchoring base in which a cutting element cuts into a wall of the borehole. For this purpose, the cutting element is arranged on an outside of the metallic base body. According to the invention, the cutting element is applied to the base body in a materially bonded manner. In particular, the cutting element is produced by reshaping from a functional layer applied to the base body, in particular by a method as described above. In addition, the cutting element of the expansion anchor according to the invention has flow lines as they are for Cold massive forming processes through the flow of the material to be formed, here the functional layer to the cutting element, are typical.

In the expansion anchor according to the invention, the contact surface via which the cutting element is connected to the base body preferably has a shape which deviates from the surface on the outside of the base body adjoining the contact surface. For example, the surface of the outside of the base body adjoining the contact surface is part of a cylindrical jacket surface which the expansion element of the expansion anchor has before it is expanded. On the other hand, the contact surface deviates from a lateral surface, since it was also reshaped by the reshaping of the functional layer into a cutting element. In particular, the contact surface has at least one depression and / or an elevation in relation to the radial direction to the longitudinal axis of the finished expansion anchor, and / or it is generally arched two-dimensionally.

It is also preferred that the cutting element has at least one underfill on its outside. "Underfilling" is an area in which the desired shape is not completely achieved by forming. If, for example, the cutting element is to have a flat surface or a conical or cylindrical surface, the cutting element would not touch the desired surface in the area of the underfill and only there. Generally speaking, underfilling is a local depression in relation to an area to be produced according to plan.

In a further preferred embodiment of the expansion anchor according to the invention, the cutting element consists of several layers welded on. These several layers together form the functional layer from which the cutting element is produced by reshaping.

The features and combinations of features, designs and configurations of the invention mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or drawn in a figure, are not only in the respectively specified or drawn combination, but also in basically any other combination Combinations or can be used individually. Embodiments of the invention are possible which do not have all the features of a dependent claim. Individual features of a claim can also be replaced by other disclosed features or combinations of features. Embodiments of the invention that do not have all the features of the exemplary embodiment are possible.

The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing.

• 1 das Aufbringen einer Funktionsschicht auf die Außenseite eines Grundkörpers beim Herstellen eines erfindungsgemäßen Spreizankers in einer Schnittdarstellung;
• 2 das Aufbringen in einer gegenüber der 1 um 90 Grad gedrehten Ansicht;
• 3 das Umformen der Funktionsschicht und des Grundkörpers;
• 4 den erfindungsgemäßen Spreizanker in einem Bohrloch in einer Schnittdarstellung; und
• 5 eine vergrößerte Darstellung des Ausschnitts V der 4.

Show it:

• 1 the application of a functional layer to the outside of a base body when producing an expansion anchor according to the invention in a sectional view;
• 2 applying in an opposite the 1 view rotated 90 degrees;
• 3 reshaping the functional layer and the base body;
• 4th the expansion anchor according to the invention in a borehole in a sectional view; and
• 5 an enlarged view of section V of 4th .

In the 1 until 3 are steps for producing an expansion anchor according to the invention 1 represented by a method according to the invention. The expansion anchor according to the invention 1 is like in 4th can be seen, a so-called bolt anchor, which has a shaft 22nd with a conical expansion body 10 having. The shaft 22nd , and thus the expansion anchor 1 , extends along a longitudinal axis L. to which the stem 22nd , except for a thread, not shown, is rotationally symmetrical. The expansion body 10 serves to spread open a spreading element 2 , which in the embodiment is in the form of an expansion sleeve 23 having around the shaft 22nd is bent in the circumferential direction and embraces this over a large part of the circumference. In 4th is the expansion sleeve 23 in an expanded state in a borehole 3 in an anchoring base 4th shown. In this expanded state, i.e. after the expansion anchor has been installed as planned 1 , is the conical expansion body 10 at least partially against the direction of introduction E. into which the expansion anchor 1 as planned in the borehole 3 was introduced into the expansion sleeve 23 retracted, thereby the expansion sleeve 23 against the wall 9 of the borehole 3 pressed and the expansion anchor 1 in the anchoring base 4th been anchored.

The expansion element of the expansion anchor according to the invention 1 comprises a metallic base body 5 , which in the exemplary embodiment consists of a steel with the material number 1.4401. As in the 1 until 3 is shown in the method according to the invention for producing the expansion anchor 1 first on the outside 6th of the main body 5 a locally limited functional layer 7th welded on, i.e. applied in a materially bonded manner. In the exemplary embodiment, the application takes place by means of laser powder build-up welding, that is to say in the form of a powder 12th made of a metal material, here a steel with the material number 1.4037, by means of a laser beam 11 on the main body 5 is welded on. In the powder 12th are particles 15th a hard material, here tungsten carbide, introduced in a distributed manner, which, as in 5 can be seen in which as a matrix 25th acting welded steel are embedded. This is where the functional layer 7th in two layers, a first layer 20th and a second layer 21 upset. It will be the first layer first 20th on the main body 5 welded on and onto the first layer 20th the second layer 21 . In the illustrated embodiment, the application takes place one after the other at two spatially separated stations in a production line.

The basic body 5 of the expansion element 2 is made from a steel band 24 produced by cutting off by means of punching, here from an "endless belt" from a coil. Before being separated, the functional layer is 7th welded on. As in 2 is indicated by the arrows, the functional layer is welded on 7th while the steel belt 24 on one edition 26th moved either continuously or incrementally. The steel belt 24 is located in a production line in which the steel strip 24 the expansion element 2 will be produced. The movement makes the steel belt 24 a progressive tool 27 ( 3 ) supplied, in which the expansion element 2 with the main body 5 and the functional layer 7th from the rest of the steel band 24 separated and the functional layer 7th together with the main body 5 in the one for the expansion element 2 intended shape is reshaped. The forming takes place by means of cold forming by pressing. This is where the functional layer 7th to a cutting element 8th reshaped that after being expanded into the wall 9 of the borehole 3 cuts into the 4th and 5 you can see.

As can be seen in the figures, the functional layer was 7th on the outside 6th des in the direction of introduction E. front section 13th of the expansion element 2 applied, here at the front end 14th of the expansion element 2 , and the entire section 13th was reshaped, with the base body 5 has been reduced in thickness in this area.

By cold forming the functional layer 7th to the cutting element 8th receives the cutting element 8th on the one hand, its desired shape, here that of a pointed cutting edge extending in the circumferential direction; on the other hand, the cutting element is created by the cold forming 8th hardened so that it has a greater hardness than before forming. If necessary, the cutting element can 8th can also be hardened using a customary hardening process. To like this in the 4th and 5 is shown when spreading into the wall 9 of the borehole 3 cut in and the expansion anchor 1 thus to anchor positively in the borehole, the cutting element 8th a hardness of at least 65 HRC. The hardness of the cutting element 8th is therefore larger than that of the main body 5 , especially its front undeformed part, which here has a hardness of 35 HRC.

By having the cutting element 8th initially as a functional layer 7th on the main body 5 welded on and then to the cutting element 8th has been formed, has a contact surface 16 over which the cutting element 8th with the main body 5 is connected to a shape that is connected by one to the contact surface 16 adjacent area 28 the outside 6th of the main body 5 deviates. While the contact area 16 concave inwards, i.e. to the longitudinal axis L. is pushed in, the one is on the contact surface 16 adjacent area 28 essentially flat, or it has the one for the expansion sleeve that has not been expanded 23 typical cylindrical shape.

As a result of the reshaping by pressing, the cutting element 8th also the flow lines typical for cold forming 17th on. They are also on the outside 19th of the cutting element 8th when forming at the transition from the first to the second welded-on layer 20th , 21 Underfills 18th developed.

So that the cutting element 8th into the wall 9 of the borehole 3 can cut when spreading, it is necessary that the cutting element 8th and the main body 5 in the area of the cutting element 8th are sufficiently stable that they do not deform or only slightly deform when the cutting element 8th against the wall 9 is pressed. For this reason, the cutting element 8th a height H on that is about the same as the thickness d of the main body 5 is. The height H and the thickness d become, as in 5 to be seen in the area of the transition from the contact surface 16 to the adjacent area 28 measured. Also the axial one, i.e. the one in the direction of the longitudinal axis L. measured length of the cutting element 8th corresponds essentially to the thickness in the exemplary embodiment d of the main body 5 what the stability of the expansion element 8th in the area of the cutting element 8th improved again.

Due to the inventive design of the expansion anchor 1 with a cutting element 8th that by reshaping from the to the base body 5 welded functional layer 7th is made, has the expansion anchor 1 a good hold in the borehole 3 on, which is improved over the known expansion anchors.

List of reference symbols

1

Expansion anchor

2

Expansion element

3

Borehole

4th

Anchoring base

5

Base body

6th

Outside of the main body 5

7th

Functional layer

8th

Cutting element

9

Wall of the borehole 3

10

Expansion body

11

laser beam

12th

powder

13th

front section of the expansion element 2

14th

front end of the expansion element 2

15th

Particles of a hard material

16

Contact area

17th

Flow line

18th

Underfill

19th

Outside of the cutting element 8

20th

first welded layer

21

second welded layer

22nd

shaft

23

Expansion sleeve

24

Steel belt

25th

matrix

26th

Edition

27

Progressive tool

28

to the contact surface 16 adjoining surface of the base body 5

d

Thickness of the main body 5

E.

Insertion direction of the expansion anchor 1 into the borehole 3

H

Height of the cutting element 8

L.

Longitudinal axis of the expansion anchor 1

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 10108844 A [0002]
• EP 1807629 B1 [0003]

Non-patent literature cited

• DIN EN 206: 2017-01 [0020]
• DIN 1045-2: 2008-08 [0020]

Claims (15)

A method for producing an expansion anchor (1) which comprises an expandable expansion element (2) with which the expansion anchor (1) can be anchored in a borehole (3) in an anchoring base (4), the expansion element (2) having a metallic base body ( 5), characterized in that a functional layer (7) is applied to the outside (6) of the base body (5) during the manufacture of the expansion element (2) and, after application, at least part of the functional layer (7) becomes a cutting element (8) is reshaped to cut into a wall (9) of the borehole (3). Procedure according to Claim 1 , characterized in that the functional layer (7) is applied cohesively. Procedure according to Claim 2 , characterized in that the functional layer (7) is applied by means of build-up welding. Method according to one of the Claims 1 until 3 , characterized in that the base body (5) and the functional layer (7) are reshaped together. Method according to one of the Claims 1 until 4th , characterized in that the forming takes place by cold forming. Method according to one of the Claims 1 until 5 , characterized in that the functional layer (7) is applied to the base body (5) in a locally limited manner. Method according to one of the Claims 1 until 6th , characterized in that the functional layer (7) is applied to a section of the expansion element (2) which is at the front in the introduction direction (E) and this section is reshaped. Method according to one of the Claims 1 until 7th , characterized in that the functional layer (7) is made of an iron alloy. Method according to one of the Claims 1 until 8th , characterized in that particles (15) of a hard material are introduced into the functional layer (7). Method according to one of the Claims 1 until 9 , characterized in that the height (h) of the cutting element (8) is at least 10% of the thickness (d) of the base body (5). Method according to one of the Claims 1 until 10 , characterized in that the base body (5) is produced by cutting from a steel strip (24) and the functional layer (7) is applied to the base body (5) prior to cutting off. Expansion anchor (1), which in particular according to a method according to Claims 1 until 11 is made, and which comprises an expansion element (2) with which it can be anchored in a borehole (3) in an anchoring base (4), the expansion element (2) comprising a metallic base body (5), on the outside (6) a cutting element (8) is arranged for cutting into a wall (9) of the borehole (3), characterized in that the cutting element (8) is materially applied to the base body (5), and that the cutting element (8) has flow lines (17 ) having. Expansion anchor after Claim 12 , characterized in that a contact surface (16) via which the cutting element (8) is connected to the base body (5) has a shape that differs from the surface (28) of the outside (6) adjoining the contact surface (16) of the base body (5) differs. Expansion anchor after Claim 12 or 13th , characterized in that the cutting element (8) has at least one underfill (18) on its outside (19). Expansion anchor according to one of the Claims 12 until 14th , characterized in that the cutting element (8) consists of several layers (20, 21) welded on.

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