DE20110720U1 - Socket connection for reinforcing bars - Google Patents

Description

LEMCKE · BROMMER & PARTNER

PATENT ATTORNEYS

BISMARCKSTR. 16 ■ D-7B1 33 KARLSRUHE

29 June 2001 19 127 (A/gr)

Schock Development Company Ltd.
Vimbucher Strasse 2

76534 Baden-Baden

Socket connection for reinforcing bars

LEMCKE · BROMMER a PARTNER

PATENT ATTORNEYS

BISMARCKSTB. 16 ■ D-761 33 KARLSRUHE

29 June 2001 19 127 (A/gr)

Description

The present invention relates to a socket connection for reinforcing steel bars, wherein the reinforcing steel bars can each be connected at their ends to be connected to one end of a male or female socket part, wherein the male socket part has a pin with an external thread at its other end, while the female socket part has a bore with a corresponding internal thread at its other end, so that both socket parts can be screwed together.

In the course of an optimized construction process or for static requirements, it is often necessary to connect axially successive reinforcing bars to one another. In addition to overlapping the reinforcing bars, in which the end sections of the reinforcing bars overlap and these overlapping areas are welded together, it is also known to connect the reinforcing bars using the screw sockets mentioned above.

The male and female socket parts are connected to the reinforcing steel bar either by pressing them onto the corresponding bar end or by a screw connection, in which a special thread is first applied to the bar end, onto which the socket part is then screwed. The two socket parts themselves are then connected by screwing the cylindrical external thread of the male socket part to the cylindrical internal thread of the female socket part.

In order to obtain building approval for such a socket connection, it is necessary to limit the slippage of the joints between the reinforcing bars in order to avoid cracks in the concrete. This means that the forces acting in the concrete should not cause any axial displacement.

between the bars. A total offset of all joints involved, i.e. the joint between the first reinforcing bar and the female socket part, between the female socket part and the male socket part and between the male socket part and the second reinforcing bar, of no more than 0.1 mm is permissible.

In order to limit the slip between the male socket part and the female socket part as much as possible, it is known in the art to tighten the male/female thread with a defined force, for example a torque wrench, in order to generate an axial preload force that counteracts the thread's tendency to slip against correspondingly acting forces. However, torque wrenches are often not available on construction sites; in addition, achieving a defined preload force is often not guaranteed.

Based on this state of the art, it is therefore the object of this invention to improve the known socket connection for reinforcing bars in such a way that the prescribed maximum offset can be maintained even without a torque wrench.

This object is achieved according to the invention in that the external thread of the male socket part has an end section which has a larger diameter and/or a different thread pitch than the rest of the thread, so that it can be clamped into the internal thread of the female socket part when screwed in by eliminating the usual play between the threads of the male and female socket parts in the region of this end section.

By screwing in the end section, a tension is created between the male socket part and the female socket part there and in the corresponding section of the internal thread, which eliminates the usual play between the female and male socket parts in this area. This means that the relative movement between the male and female socket parts can be reliably kept below the prescribed limit.

Advantageously, the geometry of the end section of the male socket part, in particular its conicity, is designed in such a way that a defined screw-in depth of its pin into the bore of the female socket part reduces the play between the threads of the female socket part, resulting in a predetermined slip limit between the male and female socket parts. This makes it possible to generate a defined clamping force that corresponds to that which must be generated in a conventional manner when applying a certain tightening torque using a torque wrench. By simply screwing the two socket parts together, a certain slip behavior can be guaranteed on site without using a torque wrench.

It is very advantageous if the female socket part has a reduced material cross-section at the end assigned to the male socket part, so that the hole can widen when the conical end section of the pin is screwed in. This is particularly advantageous when using reinforcing steel bars with a comparatively large diameter, as threads with relatively large pitches and tolerances are then used. With these large threads, it is difficult to design the male socket exactly during production so that a defined reduction in play and thus a defined slip limitation is created. By reducing the material cross-section of the female socket part, it is now possible for the latter to expand when the two socket parts are screwed together, with the ring tensile strength of the female socket part being adapted to the corresponding requirements in this reduced material cross-section. &igr;

The reduced material cross-section can be formed by reducing the outer diameter, by slots or the like. The decisive factor is that the hole can be widened when the two socket parts are screwed together.

The reduced material cross-section is expediently formed by a diameter reduction and additionally by slots, in particular several longitudinal slots distributed over the circumference.

As far as the conicity of the conical end section of the male socket part that is drawn outwards is concerned, many possibilities are conceivable. Tests by the applicant have shown that it is advisable to draw the conical end section outwards at an angle of about 1° relative to the remaining cylindrical or conical section. The external diameter of the conical end section does not have to increase linearly either, but can instead increase degressively or progressively and, if necessary, be combined with a cylindrical section of larger diameter, so that a type of thread step is created.

In order to make it easier for the employees on the construction site to set the predetermined tightening torque, it is particularly advantageous if the predetermined slip limitation is present when the last thread of the conical end section is completely covered by the free end of the bore when the pin is screwed in.

If both a reduced material cross-section of the female socket part and the conical end section of the pin of the male socket part are provided, this reduced material cross-section and the conical end section are advantageously matched to one another in such a way that a predetermined slip limit can be set by a defined screw-in depth of the pin into the hole. The female and male socket parts are therefore matched to one another during production in such a way that when these two elements are screwed together on site, a slip limit is created that can otherwise only be set with a torque wrench using a precisely adjustable tightening torque.

Further advantageous embodiments and features of the invention will become apparent from the following description of an embodiment and from the drawings relating to this embodiment.

!.5

Showing:

Figure 1 shows a male socket part according to the invention in longitudinal section along the

middle level;

Figure 2(a) - (c) a corresponding female socket part in longitudinal section along

the middle plane, in oblique view and in plan view from the front.

Figure 1 shows a male socket part 1 of a socket connection for reinforcing bars not shown here, which is pressed onto a reinforcing bar to be connected with its free end 2 or screwed onto it using a thread. For this purpose, the free end 2 has a concentric bore 3 adapted to the outer diameter of the reinforcing bar.

At the other free end of the male socket part 1, a cylindrical pin 4 is formed which has an external thread 5. With this external thread, the socket part 1 can be screwed into a bore 11 shown in Figures 2(a)-2(c) of a female socket part 10 with an internal thread 12 arranged in this bore 11.

It is now essential that the external thread 5 of the pin 4 consists largely of a cylindrical external thread 5a, whereas a rear end section 5b of the thread is provided which is conically drawn radially outwards by approximately 1°. In contrast, the internal thread 12 of the female socket part 10 is designed as a cylindrical thread over its entire length. When the two socket parts 1, 10 are screwed together, the cylindrical section 5a usually first engages in the internal thread 12 of the female socket part 10. If the pin 4 is then screwed deep enough into the internal thread 12, the tapered end section 5b of the external thread 5 gradually engages the internal thread 12 and causes a clamping between this thread section 5b and the corresponding section of the internal thread 12. This creates a preload force between the two sleeve parts 1, 10, which acts in both the axial and radial directions. The axial component in particular counteracts forces that would pull the two sleeve parts 1, 10 apart in the axial direction.

As can be seen in Figure 2a, the female socket part 10 has a reduced material cross-section 13 at its end associated with the male socket part 1. This reduced material cross-section 13 is achieved on the one hand by a reduction in the outer diameter of the female socket part 10, and on the other hand by longitudinal slots 14 arranged in the region of the reduced diameter, which expediently have a somewhat greater axial length than the conical threaded section 5b.

When screwing the pin 4 of the male socket part 1 into the bore of the female socket part 10, the area of the reduced material cross-section 13 is expanded outwards by the conical end section 5b. When producing the two socket parts 1, 10, this reduced material cross-section 13 and the conical thread section 5b of the pin 4 were coordinated with one another in such a way that a predetermined tightening torque can be set by a defined screwing depth of the pin 4 into the bore 11. The predetermined tightening torque is achieved when the last thread of the conical thread section 5b of the pin 4 is completely covered by the area of the reduced material cross-section 13 or by the bore 11.

For further clarification, Figure 2 (c) shows the female socket part 10 in plan view from the end of the reduced material cross-section 13.

It should be noted that the pin 4 of the male socket part 1 can also be conical with a conical external thread and the corresponding bore 11 of the female socket part 10 can then also be conical with a conical internal thread. In this case, too, it is crucial that the external thread of the pin 4 has a conical end section that is drawn outwards compared to the rest of the thread, i.e. has a greater conicity than the rest of the thread.

A kinematic reversal is also within the scope of the invention, i.e. that the internal thread 12 has an inner end section with a smaller diameter and/or different thread pitch.

Claims (8)

1. Socket connection for reinforcing bars, wherein the reinforcing bars can be connected at their ends to be connected to one end of a male ( 1 ) or female socket part ( 10 ), wherein the male socket part ( 1 ) has a pin ( 4 ) with an external thread ( 5 , 5a ) at its other end, while the female socket part ( 10 ) has a bore ( 11 ) with an internal thread ( 12 ) at its other end, so that both socket parts ( 1 , 10 ) can be screwed together, characterized in that the external thread ( 5 ) of the male socket part ( 1 ) has an end section ( 5b ) which can be clamped into the internal thread ( 12 ) of the female socket part ( 10 ) by means of a larger diameter and/or a different thread pitch when screwed into the female socket part (10). by eliminating the usual play between the engaging threads. 2. Socket connection according to claim 1, characterized in that the conical end section ( 5 b) of the male socket part ( 1 ) is designed in its geometry, preferably in its conicity, such that a defined screw-in depth of its pin ( 4 ) into the bore ( 11 ) of the female socket part ( 10 ) achieves a tension between the two threads, which results in a defined slip limitation between the male and female socket parts. 3. Socket connection according to claim 1, characterized in that the female socket part ( 10 ) has a reduced material cross-section ( 13 ) at its end associated with the male socket part ( 1 ), so that when screwing in the preferably conical end section ( 5b ) of the pin ( 4 ), a widening of the bore ( 11 ) is possible. 4. Socket connection according to claim 3, characterized in that the reduced material cross-section ( 13 ) is formed by a diameter reduction, by slots ( 14 ) or the like. 5. Socket connection according to claim 3, characterized in that the reduced material cross-section ( 13 ) is formed by a diameter reduction and additionally by slots ( 14 ), in particular longitudinal slots ( 14 ). 6. Socket connection according to claim 3, characterized in that the reduced material cross-section ( 13 ) of the female socket part ( 10 ) and the end section ( 5b ) of the pin ( 4 ) are coordinated with one another in such a way that a predetermined slip limitation can be set by a defined screw-in depth of the pin ( 4 ) into the bore ( 11 ). 7. Socket connection according to claim 1, characterized in that the end section ( 5 b) of the male socket part ( 1 ) is drawn outwards approximately conically at an angle of approximately 1° relative to the remaining thread ( 5 a). 8. Socket connection according to at least claim 2, characterized in that the defined slip limitation is set when the last thread of the end section ( 5b ) is completely covered by the free end of the bore ( 11 ) when screwing in the pin ( 4 ).