DE2435152A1 - EXPANSION DOWEL - Google Patents

Description

DR BERG DIP L.-ING. STAPF mpL ING SCHWABE DR. C *. CAUDMAlR

PATENTANWÄLTE, MONCHENSO · M AU ERK I RC K ERSTR. 45

Attorney's file 25 274 July 22, 197 ¹ *

HILTI AKTIENGESELLSCHAFT IN SCHAAN (Fürstenturn Liechtenstein)

Expansion dowel

The invention relates to a dowel with radially expandable, axially stable expansion shell and the expansion shell penetrating, axially displaceable expansion element, the expansion element and the inner wall of the expansion shell is directed in the same direction and inclined with respect to the dowel axis have radially opposite areas.

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Dowels of the type mentioned are inserted into a borehole in a building material and by spreading the expansion shell against the wall of the borehole anchored in the latter. In this way with the mostly hard building material such as Masonry, rock or the like connected dowels are attached to any objects, so the dowel is usually is loaded on train.

Most known expansion anchors are used for anchoring the dowel required expansion of the expansion shell by axially displacing the expansion element in relation to the expansion shell, the run-up surfaces inclined to the dowel axis of The expansion element and expansion shell slide on each other. During the spreading process occurs both on the run-up surfaces and friction between the expansion shell and the wall of the borehole.

When designing such dowels, it is important to pay particular attention to that the friction between the expansion shell and the wall of the borehole is greater than the friction on the run-up surfaces is. Otherwise the dowel will not be adequately anchored because the expansion shell will move when the expansion element is moved is shifted in the same direction. Especially with dowels, the expansion element of which is an anchor rod that can be axially displaced in the expansion shell is formed, too much friction on the run-up surfaces has a disadvantageous effect, because this causes the spreading shell to both during the spreading process as well as during the subsequent Tensile load on the anchor rod, instead of being sufficiently expanded, is shifted in the borehole.

To ensure that the friction on the contact surfaces in Relation to the friction between the expansion shell and the borehole does not reach a value that is too high, a value for the run-up surfaces is as good as possible flat angle of inclination chosen. In this case, however, the expansion element must be axially large in order to achieve the expansion Can be shifted away, which is technologically advanced due to large

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sen slip has a detrimental effect

In order to reduce the friction on the contact surfaces, the contact surfaces are provided with lubricants in the case of expansion anchors of the type in question. However, this has only led to very limited success, since lubricants have the functional disadvantage that they are displaced by the contact surfaces precisely during the spreading phase, in which the surface pressure is greatest. The desired lubricating effect is therefore not given at the crucial moment. On the other hand, there is the problem that the dowels are supplied by the manufacturer in a lubricated state, but are only used after a long period of time. The lubricity leaves during this
Most of the time, he "significantly after."

A further disadvantage of the dowels known up to now is that due to the great friction between the
A considerable part of the axial force applied to the spreading element for overcoming the frictional resistance is lost, as a result of which insufficient anchoring values are achieved in relation to the applied axial force.

The invention is based on the object of creating a dowel of the type described, in which a considerable reduction in the friction between the run-on surfaces
secure anchoring is guaranteed.

According to the invention, the object is achieved in that in the area the run-up surfaces are arranged rolling elements.

By mutual axial displacement of the expansion shell and expansion element, the rolling elements roll along the contact surfaces, so that rolling friction occurs. The latter is essential
smaller and offers considerably less resistance to the spreading process than when the

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Friction caused by known dowels on contact surfaces. It stands accordingly more force is available for expanding and pressing the expansion shell against the wall of the borehole, so that significantly higher anchoring values can be achieved with the same expansion force. This also applies to dowels with an anchor rod In the event of a load, additional expansion is guaranteed. The arrangement of several rolling elements, evenly distributed on a circumferential line in the areas of the run-on surfaces, is guaranteed centric expansion of the anchor and thus an even load distribution.

In a further embodiment of the invention, the rolling elements are designed as balls. Balls are extremely economical to manufacture Mass-produced items that are available in any size and quality.

For dowels, which are intended for extreme loads and for anchoring in very hard building materials, are suitable for a further proposal of the invention as a rolling element arranged transversely to the dowel axis cylinder. As a result of the line contact with the run-on surfaces, cylinders have the considerable advantage of relatively low surface pressure. In addition, due to its transverse position, the expansion shell can be rotated relative to the expansion element prevent.

One or both of the mutually associated run-on surfaces preferably have guide tracks for the rolling elements that extend along the dowel axis. This ensures that the rolling elements roll on the run-up surfaces in the direction of the dowel axis and maintain their predetermined mutual angular spacing on the circumference of the run-on surfaces. By arranging guide tracks on each of the run-on surfaces, an exact rotation lock between the expansion shell and expansion element is also achieved. This is particularly advantageous with so-called anchor dowels, where the expansion element is designed as a protruding threaded rod.

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det is and is also loaded on rotation. For the sake of simplicity, the guideways are, for example, depending on the type of rolling elements designed as rectangular grooves or fillets, and expediently run parallel to the axis in their longitudinal extent of the dowel.

According to a further development of the invention, along the dowel axis rolling elements arranged one behind the other and provided with spacers in between are provided. This will a further reduction in the specific surface pressure between the rolling elements and the run-on surfaces is achieved. With long This also has the advantage of a large spreading surface, so that at least a large part of the surface of the treads The expansion shell is in frictional contact with the borehole, which further increases the pull-out values. A big Flat spreading is particularly advantageous when the anchor is set in relatively soft building materials such as aerated concrete will. The spacers are z. B. in the type of cages, as they are known per se in ball bearings, formed and ensure that the functionally correct position of the individual rolling elements is maintained. In this variant of the dowel, however, particular care must be taken that the row of rolling elements arranged one behind the other is shorter than the length of the ramp is to provide a taxiway for the Ensure rolling elements.

If the expansion element is designed as an anchor rod, it is according to the invention This is an advantage if the contact surfaces widen towards the front end of the dowel. Will the anchor rod Pulled backwards, as also occurs in the case of load, the expansion shell becomes this way with increasing radial force pressed against the wall of the borehole, which increases the anchorage value.

In contrast, according to a further proposal of the invention,

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in the case of dowels, the expansion shell takes over the loading forces. useful if the run-up surfaces taper towards the front end of the dowel. The expansion element is in such Dowels are usually either driven in or screwed in. In the case of internal thread anchors, it is advisable to use the expansion element to be countersunk so that a sufficient internal thread area is exposed.

The running surfaces are preferably for reasons of ease of manufacture formed by jackets of opposite cones. This makes the expansion shell proportional to the axial advance of the Spreading element expanded.

However, it can also be advantageous for special applications be that the expansion of the expansion shell is not proportional to the advance of the expansion element. In this case they are Contours of the run-on surfaces instead of inclined to the dowel axis Straight lines, for example designed as concave or convex bulges.

Particularly when using cylinders as rolling elements, it is expedient in a further embodiment of the invention to use the run-up surfaces train as flats. The flats can be both on the circumference of the circular cross-section of the Be arranged expansion element or the inner wall of the expansion shell, as well as form the entire surface area of a spatial body with a polygonal cross-section. ,

According to a further proposal of the invention, the run-up surfaces at the opposite ends of the shoulders directed radially towards one another. On the one hand, these shoulders prevent that the rolling elements can escape from the space between the contact surfaces in the unspread state of the dowel and on the other hand, ensure that the dowel is not overstretched. These two functions are either used individually or together fulfilled, depending on whether the corresponding casserole

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areas assigned to only one or, if necessary, two pairs of shoulders are. If the run-up surfaces are formed, for example, by jackets of opposite cones, the shoulders can be used as Be designed ring bead.

The expansion shell and the expansion element advantageously have a plurality of run-on surfaces arranged one behind the other in the axial direction on. As a result, the entire length of the expansion shell can be spread, with the addition of a relatively small amount axial advance of the expansion element a large expansion of the expansion shell can be achieved.

If the aim is to spread the spreading shell over the entire area, then the run-on surfaces are lined up directly without an axial gap arranged. In this case, there is a sawtooth-like outer contour of the surfaces bearing the running surfaces of expansion element and expansion shell.

According to a further proposal of the invention is the expansion shell formed divided several times along the dowel axis. Pipe bridges are thus formed, through which a particularly good adaptability the expansion shell is reached on any unevenness on the wall of the borehole. The individual pieces of pipe can be held together to form a tube unit, for example by brackets, clamps, elastic cuffs or similar means will.

Becomes a particularly easy and large expandability of the spreader shell required, the same is preferably formed in several parts along its circumference. The pipe segments thus formed allow in particular the use of such dowels in relatively soft or elastic building materials. Particularly proven has, for example, a spreader shell made up of four segments. In certain applications it is useful if the spreader shell is only slotted over part of the length.

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3b1S2

In order to be able to introduce into the borehole the multi-part expansion shell, which is formed in several parts by longitudinal separation, the expansion shell preferably surrounded by holding members, for example elastic rings or cuffs. In addition, the storage becomes such This makes dowels easier.

The invention will now be illustrated by way of example Drawings explained in more detail, namely show:

Fig. 1 shows an unspread dowel in section, with an external thread and balls as rolling elements,

Fig. La is a section along the line a-a of Fig. 1,

2 shows an unspread dowel in section, with internal thread and balls as rolling elements,

2a shows a section along the line a-a of FIG. 2,

3 shows an unspread dowel, partially in section, with an external thread and several balls arranged one behind the other as rolling elements,

Fig. 3a shows a section along the line a-a of Fig. 3,

4 shows an unspread dowel in section, with external thread and cylinders as rolling elements,

Fig. 4a, a section along the line a-a of Fig. 4,

5 shows an unspread dowel in section, with external thread and balls as rolling elements, and a plurality Cushions,

FIG. 5a shows a section along the line a-a of FIG. 5.

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The dowel shown in Fig. 1 ordered from an expanding shell 1, an expansion element 2 designed as an anchor rod and balls as rolling elements. The expansion shell 1 has over part of its Length of slots 4 to favor the radial evaluation. Furthermore, the expansion shell 1 is penetrated by a longitudinally directed through hole 5, the front part of which widens towards the front and forms a run-on surface 6 for the balls 3. The ramp 6 is limited to the front by a circumferential shoulder 7, so that the balls 3 in the unspread position of the dowel do not step forward. The spreading element 2 has a correspondingly widening towards the front in the front area Outer surface, which is also used as a ramp surface 8 for the balls 3 serves. The run-up surface 8 is provided with longitudinal grooves as a guide Approximate tracks 9 for the balls 3 provided.

If the dowel is inserted into a borehole and the expansion element is pulled back, the balls 3 roll on the conical run-up surfaces 6, 8, whereby the expansion shell 1 is expanded radially and is fixed to the wall of the borehole, not shown.

Fig. 2 shows a dowel, which in turn essentially consists of an expansion shell 11, an expansion element 12 and balls 13 as rolling elements. In the front area, the spreader shell Longitudinal slots 14, whereby the radial expansion of this part is facilitated. A ring 15 is located on the jacket of the expansion shell 11 placed on the outside diameter of the expansion shell 11 slightly survives and thus the provisional jamming of the dowel in the borehole, not shown, before it is expanded serves. Furthermore, the expansion shell 11 is penetrated by an axial bore, the front zone being tapered towards the front Conical bore is formed, the wall of which forms a ramp surface 16. The ramp surface 16 is parallel to the Groove-shaped guide tracks 17 arranged on the dowel axis. The outlets of the guideways 17 are designed as shoulders 18.

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forms. The rear area of the axial bore has an internal thread 19. The expansion element 12 is screwed into this. The front part of the expansion element 12 serves as a ramp surface 20 and has the shape of a truncated cone which tapers towards the front. The balls are between the run-on surfaces 16, 20 13 guided in the guideways 17. By rotating the expansion element 12, it moves in the expansion shell 11, whereby the balls 13 on the run-up surfaces inclined to the dowel axis 16, 20 unroll. The expansion shell 11 is thereby expanded radially and in this way lies on the wall of the borehole fixed. If the balls 13 have rolled over the run-up surfaces 16, they run up on the shoulders 18, whereby a Spreading of the dowel is prevented.

The dowel according to FIG. 3 has an expanding shell, designated as a whole by 21, which is divided into shell shells by separating slots 22. The half-shells 23 are held together to form a unit by annular holding members 24. These holding members 24 protrude beyond the outer diameter of the expansion shell 21 and thus also serve to temporarily clamp the dowel in the receiving opening. The expansion shell 21 is penetrated by an axial bore which widens conically towards the front over its entire length, the wall of which forms a ramp surface 25. The rear and front outlets of the axial bore are designed as annular shoulders 26. Guide tracks 27 run along the run-up surface 25 for balls 28 lined up one behind the other. The front part of the spreading element 29 is designed as a ramp ^{surface 30 in the form of an outer cone 1 which} widens towards the front and whose outer surface is delimited towards the front by shoulders 31. The ramp surface 30 also has groove-shaped guide tracks 32 for the balls 28. The balls 28 are held at a distance from one another by a spacer 33.

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The rear part of the expansion element 29 has an external thread 34 for suspending loads.

4 shows a dowel, the total of which is designated by 35 Spreader shell consists of four segments 36 which are combined by a divided, annular holding member 37. the Spreader shell 35 is penetrated by a passage opening which has a circular cross-section in the rear area 38, while the adjoining front zone widens like a truncated pyramid towards the front, the outer surfaces of which are the Form run-up surfaces 39 for the rolling elements. The ramp surfaces 39 are forward by shoulders 40 in the form of a projection limited. A bolt-shaped expansion element 41 is inserted in the passage opening so as to be axially displaceable. The rear Part of the expansion element 41 has a thread 42, while the front one with forwardly widening ramp surfaces

43 is provided, which is carried forward by a bulbous shoulder

44 are limited. Between the run-up surfaces 39 of the passage opening and the run-up surfaces 43 are arranged four roller bodies designed as cylinders 45, which when the expansion element is displaced 41 cause the expansion shell 35 to widen.

The anchor shown in Fig. 5 has one in several pieces of pipe 46 subdivided spreading shell designated as a whole with 47. Brackets 48 hold the pipe sections 46 together to form a unit. The pipe sections 46 are divided by separating slits 49 to facilitate expansion and are of annular shape Retaining members 50 includes. The wall of the axial bore of each pipe section 46 is conical towards the rear over a partial area widening formed as a ramp surface 51, this The ramp surface 51 is bounded towards the rear by an annular shoulder 52. The axial bores of the pipe sections 46 are of one axially displaceable expansion element 53 in the form of an anchor bolt penetrates therein, the jacket of which is an equal number

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conical sections that widen towards the rear as run-up surfaces 54 has how pipe pieces 46 with run-on surfaces 51 are present. Also the run-up surfaces 54 of the expansion element 53 run out at shoulders 55. Between each run-up surface 54 and the associated run-up surface 51 are Balls 56 are used which, when the expansion element 53 is displaced, widen the pipe sections 46 »TJm the expansion element falling out To prevent 53 to the rear from the expansion shell 47, the expansion element 53 has a collar at the front end whose diameter is greater than that of the axial bore of the pipe sections 46. The rear face of the expansion shell 47 is covered by a washer 58.

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Claims (14)

Claims L.J dowel with radially expandable, axially stable expansion shell. ^ - and the spreader penetrating, axially displaceable Spreading element, the spreading element and the inner wall of the spreading shell facing in the same direction, opposite the dowel axis inclined ramp surfaces (6, 8; 16, 20; 25, 30; 39, 43; 51, 54) have radially opposite regions, characterized in that in Rolling bodies are arranged in the area of the run-on surfaces. 2. Dowel according to claim 1, characterized in that the Rolling bodies are designed as balls (3, 13, 28, 56). 3. Dowel according to claim 1, characterized in that the rolling elements as cylinders arranged transversely to the dowel axis (45) are formed. 4. Dowel according to claim 1 to 3, characterized in that one or both of the associated ramp surfaces (6, 8; 16, 20; 25, 30) have guide tracks (9, 17; 27, 32) for the rolling elements that extend along the dowel axis. 5. Dowel according to claim 1 to 4, characterized in that arranged one behind the other along the dowel axis, with intervening Rolling bodies provided with spacers (33) are provided. 6. Dowel according to claim 1 to 5, characterized in that the Äuflaufflächen (6, 8; 25, 30; 39, 43; 51, 54;) extend towards the front end of the dowel. 7. Dowel according to claim 1 to 5, characterized in that the ramp surfaces (16, 20) are against the front end of the 509887/0031 Taper the dowel. 8. Dowel according to claim 1 to T _1, characterized in that the run-up surfaces (6, 8; 16, 20; 25, 30; 51, 54) are formed by jackets of opposite cones. 9. Dowel according to claim 1 to 7, characterized in that the ramp surfaces (39, 43) as one or more Flats are formed. 10. Dowel according to claim 1 to 9, characterized in that the ramp surfaces (6, 8; 16, 20; 25, 30; 39, 43; 51, 54) shoulders (7, 18; 25, 31; 40, 44; 52, 55) facing one another at their opposite ends exhibit. 11. Dowel according to claim 1 to 10, characterized in that the expansion shell (47) and expansion element (53) several have run-on surfaces (51, 54) arranged one behind the other in the axial direction. 12. Dowel according to claim 1 to 11, characterized in that the expansion shell (47) is in several parts along the dowel axis is trained. 13. Dowel according to claim 1 to 12, characterized in that the expansion shell (21, 35, 47) along its circumference Is formed in several parts. 14. Dowel according to claim 13, characterized in that the Spreizschale- (21, 35, 47) is surrounded by holding members (24, 37, 50). 509887/0031 Blank page