AU729030B2

AU729030B2 - Method of producing a transverse force bolt and transverse force bolt produced by this method

Info

Publication number: AU729030B2
Application number: AU15026/97A
Authority: AU
Inventors: Gottfried Breuer; Erich Muller
Original assignee: Pecon AG
Current assignee: Pecon AG
Priority date: 1997-02-28
Filing date: 1997-02-28
Publication date: 2001-01-25
Anticipated expiration: 2017-02-28
Also published as: AU1502697A

Description

4, if P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: METHOD OF PRODUCING A TRANSVERSE FORCE BOLT AND TRANSVERSE FORCE BOLT PRODUCED BY THIS METHOD The following statement is a full description of this invention, including the best method of performing it known to us: GH REF: P24824-A:CAS:RK Method of Producing a Transverse Force Bolt and Transverse Force Bolt Produced by this Method The instant invention relates to a method of producing a transverse force bolt, consisting of a steel core and a sheath of stainless steel, as well as to a transverse force bolt produced in accordance with this method.

Transverse force bolts are used for horizontal connection and force transfer between two structural components. They are particularly employed in the area of the

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expansion gaps between two concrete floor slabs, as well as o• ""for placing a slab with connected structural elements on staircase landings. The transverse force bolts are seated an both sides of the expansion gaps in appropriate bearing ooo sleeves. While a horizontal expansion movement must be permitted, it is intended to stop the relative vertical movement.

Transverse force bolts are inevitably subjected to .*.environmental actions and therefore they can become corroded.

Accordingly, many manufacturers have switched to the production of transverse force bolts from high-grade stainless steel. Such transverse force bolts are preferably made of chrome-nickel-molybdenum steel. This is extremely expensive and yet might not meet safety requirements in certain areas of application. In accordance with late findings, rods made completely of stainless steel tend to become hydrogen-embrittled, which reduces the strength of the material.

Based on the above considerations, a change was made by designing tension or compression rods of corroding steel for 1Aconnecting two concrete elements in such a way, that the rod is enclosed by a sleeve of corrosion-resistant material at least in the gap area, and that a hardening material is poured into the gap between the sleeve and the steel. While this solution in accordance with DE-A-38 01 121 has proven itself in connection with anchor bolts, for a number of reasons this system was not able to gain acceptance in connection with transverse force bolts.

The greatest problems occurred in connection with the exact embedding of the core in the sleeve and also during production of such transverse force bolts. For this reason Applicant made a change and cut sleeves of stainless steel, used these as a covering, into which shorter corroding steel S"rods were inserted as the core, closed the open ends with a plastic plug. This solution resulted in transverse force rods which have excellently proven themselves in respect to the S"material properties.

As already mentioned at the outset, the connection between two horizontal structural components made with the aid of transverse force rods was intended to practically stop movements in the vertical direction in respect to each other.

However, it was shown that the transverse force bolts of the last-named type, which were optimal in respect to their material composition, were not able to meet these requirements sufficiently. Insertion of a steel core into a sheath of stainless steel required some play. It is not possible for economical reasons to produce all components of a transverse force connection from calibrated elements. Even then the insertion free of play of a core into a sheath is impossible for purely technical reasons. Thus, with the known solution several tolerance areas result for reasons of production technology, which in the worst-case can add up. For another, the exterior dimensions at the core and the interior dimen- 2 sions the sheath constitute one tolerance field. For another, the exterior dimension of the sheath has a tolerance field and the interior dimension of the bearing sleeve, in which the transverse force bolt is seated, also has such a tolerance field. As already mentioned, all these tolerances can add up. The play obtained in this way therefore results in some degree of freedom of movement in the vertical direction between two horizontal structural components which are connected with each other by means of transverse force bolt connections. The vibrations occurring in the building element therefore lead to vertical movements, which result in a corresponding crack formation in the area at the transverse force rod connections.

In light of the above, it would be advantageous if the instant invention could provide a method for producing a transverse force bolt, consisting of a steel core and a sheath of stainless steel which would ameliorate some or all of the above mentioned problems in transverse force bolts produced in this manner.

Accordingly, in a first aspect, the present invention provides a method for producing a transverse force bolt, consisting of a steel core and a sheath of stainless steel, characterized by the following steps; dimensionally exact draw-in, free of play, of a steel core, consisting of steel rod of non-stainless steel, into a tube of stainless steel used as a sheath; cutting the rod formed in this manner to the desired transverse force bolt sizes; partial ejection of the core from the sheath and cutting off of the ejected portion of the core; pushing the core back by half the length of the ejected and cut off portion; closing of the open sheath ends.

If in the course of inserting the steel core into the sheath a calibration of the exterior dimensions of the sheath is performed, the tolerance field between the transverse force bolt and the bearing sleeve, in which the transverse force bolt is seated, is also reduced.

Depending on the area of application and the corresponding requirements it is possible for the transverse force bolt produced by means of the above mentioned method to be either closed with a plastic plug, or it is possible to S:24824A 3 insert disks made of stainless steel into the open ends of the sheath and to weld them in.

The course of production of the method in accordance with the invention is represented in the attached drawings, as well as two exemplary embodiments of the transverse force bolt produced in accordance with this production process.

Fig. 1 shows the different production steps from a) to h), and Fig. 2 shows a finished transverse force bolt produced in accordance with the above mentioned method with two different embodiments of the end closure.

S• The initial materials for producing a transverse force bolt in accordance with the method of the invention are, on the one hand, a core 1 consisting of sheet steel and, on the other hand, a sheath 2 consisting of a tube of stainless steel. In this case the core 1 can be made of conventional •ostructural steel. While the steps a) to c) to be described below usually are performed in appropriately equipped steel mills, the subsequent steps d) to h) can be performed by any company making technical building products. The semi-finished product, so to speak, is manufactured in steps a) to c), while the subsequent steps d) to h) relate to finishing in accordance with specific orders.

In a first step a) the said sheath of stainless steel is drawn in accordance with known technology over a correspondingly dimensioned steel rod 1, so that the steel rod then constitutes the core i. In the course of the draw-in process, the core 1 itself acts as a calibrating mandrel, because of 4 which the desired approximate freedom from play is assured.

Depending on the production facility it is possible to calibrate the size of the sheath of stainless steel simultaneously or directly afterward. An appropriate calibrating tool is shown purely schematically by 20 in step The drawing of the core 1 into the sheath 2 takes place with conventional rod material of several meters' length. The drawing in, which is extremely accurate to measurement and at least approximately free of play, of the steel core takes place with the addition of an oil which is particularly suitable for this. The semi-finished product, represented in is brought to the factory for producing technical building products.

The firm receiving the semi-finished product cuts the .rod material 3 to size into appropriate rod sections 4 step This is symbolically indicated by the saw blade 30. As ooeoo: S"schematically indicated under e) the core 1 is now pressed out of the sheath 2 by a length a. This protruding section is then cut off flush with the sheath end, as shown in f) Because of the oil used during draw-in, it is possible to press the core 1 out of the sheath 2 by means of appropriate

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hydraulic machines, without permanent deformations being noted.

However, some steel mills operate without oil when drawing in. In this case the cut-to-size rod sections 4 will be briefly heated on the outside prior to pressing them out, wherein the sheath 2 is heated more than the core i. This results in minimal expansion differences, which make the pressing of the core out of the sheath easier.

Following the cutting off of the ejected part 5 of the core i, the steel core is pressed back from the direction of the severed core into the sheath 1 by means of the same 5 hydraulic tool, this time by half the length of the severed piece 5, i.e. by a/2. This situation is shown in Fig. 1 A rod with a steel core 1 and a sheath 2 is produced in this way, wherein the open sheath ends 6 project past the steel core 1 on both sides. In the last production step in accordance with Fig. 1 the open sheath ends 6 are now closed. In the end, the finished transverse force rod 10 is obtained in this way.

A transverse force rod 10 produced in accordance with the invention is represented in Fig. 2. While the one half of the transverse force rod 10 is closed by means of a plastic plug 7, the other end is closed with a disk of stainless steel inserted into the open sheath end 6. Plastic plugs 7 are very suitable for some applications, in particular in the interiors of buildings. The required seal is achieved by appropriate seal lips 8 on the plastic plug 7. For applications with particularly large bearing strength, a disk 9 of stainless steel of as exact as possible measurements will be inserted into the open sheath end 6 and welded together with the sheath 2. Depending on the desired seal, the weld can either be made at points, or as a oo circumferential weld bead 11. The slightly increased strength in this case is not so much the result of a bearing effect of the disk 9, but is achieved by the absolute fixation of the .core 1 in the sheath 2. This results in a very strong sandwich structure.

As shown by the results of measurements during first tests, the strength of such a sandwich structure is greater than that of a one-piece transverse force bolt made of a solid rod. It is accordingly possible in respect to the dimensions to employ transverse force bolts with a smaller diameter. This is not only a financial advantage, but also leads to a size reduction of the bearing sleeve of the 6 transverse force bolt and therefore to an increased concrete covering of the bearing sleeve, which also has static structural advantages.

The wall thickness of the sheath 2 will basically be selected as a defined relation with the diameter of the steel core i. In the process it is possible to select astonishingly light wall thicknesses for the sheath. Conventional sizes of the wall thickness of the stainless steel tube from which the sheath 2 is made lie between 0.4 and 5.0 mm. The relatively light wall thickness of the sheath 2 of stainless steel of course results in further financial advantages.

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Claims

1. A method for producing a transverse force bolt, consisting of a steel core and a sheath of stainless steel, characterized by the following steps; dimensionally exact draw-in, free of play, of a steel core consisting of steel rod of non-stainless steel, into a tube of stainless steel used as a sheath cutting the rod formed in this manner to the desired transverse force bolt sizes; partial ejection of the core from the sheath and cutting off of the ejected portion of the core; pushing the core back by half the length of the ejected and cut off portion; closing of the open sheath ends. 0 0 0

2. The method in accordance with claim i, characte- o• rized in that the open sheath ends are closed by means of a plastic plug

3. The method in accordance with claim i, characte- rized in that the open sheath ends are closed by means of disks of stainless steel pushed into the opened ends and welded together with them. 8

4. The method in accordance with claim 1, characte- rized in that the exterior dimensions of the sheath are calibrated during the draw-in.

The method in accordance with claim i, characte- rized in that the cut to size rods are briefly heated from the outside prior to the partial ejection of the core from the sheath.

6. A transverse force bolt produced in accordance with one of claim 1 to 5, characterized in that the core is Sshorter than the sheath 4* a•

7. The transverse force bolt in accordance with claim characterized in that the thickness oft the sheath of stainless steel lies between 0.4 and 5.0 mm.

8. A method for producing a transverse force bolt substantially as herein described with reference to the accompanying drawings.

9. A transverse force bolt substantially as herein described with reference to the accompanying drawings. Dated this 27th day of February 1997 PECON AG By their Patent Attorney GRIFFITH HACK 9