DESCRIPTION

The present invention relates to a process for installation of expansion anchor devices, which are used for securing a part to the surface of a structural support member, as well as an apparatus for carrying out the process.

Field of the invention

Said anchor devices, known in the art, comprise an expandable sleeve, having a main longitudinal extension with a proximal end and a distal end, which is placed within a hole formed in the structural support member that is designed to have the anchor applied thereto. Such sleeve has an axial cavity formed by frontally coupling at least one pair of concave half-sleeves, said half- sleeves having therein respective flat sliding surfaces for an expansion body.

The sliding surfaces of the half-sleeves converge toward the axis of the cavity, in the direction of the proximal end thereof.

The expansion body that is located within the axial cavity of the sleeve has an internally threaded hole and a contour that allows it to axially slide along the flat sliding surfaces of the cavity of the sleeve, but not to rotate about the axis.

Anchor devices of the above mentioned type are known and widely used, particularly in building and railroad construction.

One example of this anchor device is described in detail in EP 1 464 850

- Al .

The installation of the anchor device is known to previously require a hole to be formed in the structural support member in which the expandable sleeve of the anchor device is designed to be placed.

As a result, if the structural support member in which the hole is formed for housing the sleeve of the anchor device has different compression resistance values according to the direction in which compression against the cylindrical vertical wall of the hole is exerted, a random placement of the sleeve of the anchor device within the hole has been found to be susceptible of causing rupture of the structural support member, and hence failure of the anchoring force of the device, if the half-sleeves expand in a lower-resistance direction of the structural support member.

Since such direction involves a lower resistance, cracks and fractures may be formed in the area around the hole, thereby causing the grip of the anchor device to be loosened.

This condition particularly occurs when the structural support member has a shape with a main longitudinal extension and a limited transverse extension such as in the case of a railroad tie for supporting rails.

In the field of railroad construction, these anchor devices are used particularly, but without limitation, to fasten the base plates of the rails to the underlying ties, that may be made of wood or possibly reinforced concrete.

Problem of the prior art

The use of anchor devices implies the problem of orienting the sleeve of the device within the hole formed in the structural support member such that the half-sleeves open apart when stressed, and expand in the maximum-resistance direction of the structural member which, in the case of a concrete railroad tie, is the direction parallel to the longitudinal axis of the tie. The present process of installation of the anchor device helps to obviate the above problem.

The object of the present invention is to reduce the risks of failure that may result from expansion of the sleeve of an anchor device inserted with no positioning control into the hole of the structural member that is designed to support the part to be anchored, which consists for example, particularly in the railroad field, in the base plate of the rail to be supported by the tie.

This object is fulfilled by a process of installation of an expansion anchor device, which is used to secure a part to the surface of a structural support member, said device comprising an expandable sleeve having a main longitudinal extension with a proximal end and a distal end, to be placed within a hole formed in the structural member that is designed to have the anchor applied thereto, said sleeve having an axial cavity defined by front coupling of at least one pair of concave half-sleeves, said half-sleeves having therein respective flat sliding surfaces, the sliding surfaces of the half-sleeves converging toward the axis of the cavity and in the direction of the proximal end thereof, an expansion body placed within the axial cavity of the sleeve, said expansion body having an internally threaded hole and a contour that allows it to be axially displaced along such flat sliding surfaces of the cavity of the sleeve but not to be rotated about the axis, which is characterized in that, once the hole has been formed in the support member and once the sleeve has been placed in the hole, a sleeve orientation step is carried out such that the radial expansion of the sleeve, when caused by the displacement of the expansion body in the cavity of the sleeve, occurs in the highest-resistance direction of the structural support member. The invention will be now described in greater detail with reference to one exemplary embodiment, given by way of illustration and without limitation, and shown in the annexed drawings, in which:

- Figure 1 shows a lateral view of an anchor device of the present invention, in a closed position, installed in a hole before expansion, with a bolt therein;

- Figure 1A is a longitudinal sectional view of the anchor device in the position of Figure 1;

- Figure 2 shows a lateral view of the anchor device in a hole, after expansion, with the bolt therein;

- Figure 2A is a longitudinal sectional view of the anchor device in the position of Figure 2;

- Figure 3 shows a perspective view of the half-sleeve of the anchor device of Figures 1 and 2;

- Figure 4 shows a perspective view of the female half-sleeve of the anchor device of Figures 1 and 2;

- Figure 5 shows a perspective view of the conical expansion nut of the sleeve of the anchor device of Figures 1 and 2;

- Figure 6 shows an enlarged longitudinal sectional view of the male half- sleeve of the anchor device;

- Figure 6 A shows a view of the proximal end of the half-sleeve of Figure

6;

- Figure 6B shows a view of the distal end of the half-sleeve of Figure 6;

- Figure 7 shows an enlarged longitudinal sectional view of the female half- sleeve of the anchor device; - Figure 7A shows a view of the proximal end of the half-sleeve of Figure

7;

- Figure 7B shows a view of the distal end of the half-sleeve of Figure 7;

- Figure 8 shows a perspective view of the bushing associated with the handle of the apparatus of the invention for installation of the anchor device as shown in the previous figures;

- Figure 9 shows a perspective view of the apparatus of Figure 8, applied to the sleeve of an anchor device to be installed;

- Figure 10 shows a perspective view of the preloading bolt of the apparatus of Figure 9;

- Figure 11 shows a perspective view of the apparatus of Figure 8, in operation.

Detailed description

Referring to the above drawings, the anchor device associated with the installation apparatus of the invention comprises an expandable sleeve, generally referenced 1, having a main longitudinal extension along the axis X- X, with a proximal end 2 and a distal end 3, to be placed in a hole F formed in the structural member, generally referenced M in Figures 1 and 2, that is designed to have the anchor applied thereto.

The sleeve 1 has an axial cavity 4 formed by frontally coupling at least one pair of concave half-sleeves, referenced 5 and 6 respectively. These half- sleeves 5 and 6 have respective flat sliding surfaces 7 and 8 therein (see Figures 3 and 4), which converge toward the axis X-X of the cavity 4 in the direction of the proximal end 2 thereof.

The axial cavity 4 of the sleeve 1 houses an expansion body which consists, in the illustrated exemplary embodiment, of a nut 9 with an internally threaded through hole 10.

The contour of the nut 9 comprises at least two opposed flat walls 11 and 12, which converge toward the center of the threaded hole 10, and cooperate with the other two opposed flat walls 13 and 14 to impart a conical shape to the nut.

The pair of opposed walls 11 and 12 allow the nut 9 to be axially displaced along the flat sHding surfaces 7 and 8 of the cavity 4 of the sleeve 1 but not to be rotated about the axis X-X of the cavity.

The threaded hole 10 of the nut 9 is engaged with the threaded shank 15 of a bolt 16 having a head 17 and possibly an unthreaded section 18 directly adjacent to the head 17.

The rotation of the bolt 16 imparted by a conventional tool applied to the head 17, when the anchor device is placed in its seat, causes the nut 9 to be axially displaced in the chamber 4 of the sleeve 1 on the inclined surfaces 7 and 8 and the half-sleeves 5 and 6 to transversely open apart, with respect to the axis X-X, and engage with respective portions of the inner wall of the hole F in which they are housed.

Since the outer surface of the half-sleeves is formed with a high friction, e.g. with a plurality of depressions and radial projections, as the half-sleeves 5 and 6 move away from the axis X-X a pair of radially opposed apertures 19 are formed, and the device is firmly and stably secured in the hole F.

The half-sleeves 5 and 6 are conventionally held against each other by elastic bands, not shown, which are accommodated in respective circumferential grooves 20 and 21 formed on the outer surface of the half- sleeves.

Furthermore, at the distal end 3 of the sleeve 1, i.e. the one that is held in the hole F of the structural support member M, both half-sleeves 5 and 6 have respective radial ribs 22 and 23 projecting toward the axis X-X of the axial cavity 4, which define a shoulder for the nut 9 and prevent it from coming out of the cavity 4 through the distal end 3.

At the proximal end 2 of the cavity 4, the half-sleeve 5 has a pair of teeth 24 for engagement in corresponding notches 25, when the half-sleeves are mounted against each other.

The teeth 24 and the notches 25 form male-female coupling means which exert, once coupled, an action that prevents the half-sleeves 5 and 6 from axially sliding against each other, in the direction of the axis X-X.

Also, since the half-sleeves 5 and 6 are made of a rigid material, e.g. steel, when they move away from each other, they are still parallel to the axis X-X and the amplitude of the opposed apertures 19 is uniform all along its axial extent.

The length of the teeth 24 and the depth of the notches 25 are such as to ensure that the coupling is effective even when expansion is completed and the half-sleeved 5 and 6 have moved away from each other.

As noted from the above, the thrust that locks the anchor device is exerted on the circular wall of the hole F in which the device is accommodated, mainly in the direction in which the half-sleeves 5 and 6 have the freedom of moving away from each other.

According to the invention, the sleeve 1 of the anchor device is installed within the hole F of the structural support member M by orienting the half- sleeves 5 and 6 within the hole F, such that the direction in which they move away from the axis X-X of the cavity 4, as a result of the sliding movement of the nut 9 within the cavity 4, substantially coincides with the direction in which the structural support member M has the highest resistance to the thrusts exerted against the vertical wall of the hole F.

Furthermore, according to the invention, once the half-sleeves 5 and 6 have been oriented within the hole F, their orientation is not lost as the nut 9 is pulled to tension the anchor device, i.e. to finally secure it in its seat.

For this purpose, the process of installation of the anchor device involves the use of an apparatus that comprises a cylindrical bushing 26 having an axial through hole 27, front coupling means 28 placed at the end 29 of the bushing that, in operation, faces toward the sleeve 1 of the anchor device.

The front coupling means, that actually consist of a pair of teeth axially projecting out of the end 29 of the cylindrical bushing 26, are adapted for engagement with corresponding notches 30 formed on the ends of the half- sleeves 5 and 6, which define front counter-coupling means at the proximal end 2 of the sleeve 1 of the anchor device.

Said front coupling means 28 and counter coupling-means 30 are placed on the bushing 26 and the expandable sleeve 1 in such a position as to show the direction in which the sleeve 1 expands, i.e. the half-sleeves 5 and 6 move away from the axis X-X in the hole F.

A lever 31 is connected to the cylindrical bushing, and acts as a handle for the user to support the apparatus as it is engaged with the sleeve 1 when the latter is oriented.

The lever 31 is particularly connected to the bushing 26 by one fork- shaped end 32 and a pivot 33.

The apparatus for installation and orientation of the sleeve 1 of the anchor device is completed by a preloading bolt 34, which comprises a threaded section 35, whose threads are adapted to engage with those of the hole 10 of the expansion nut 9, and a cylindrical section 36 having a predetermined axial extent, and located close to the drive head 37.

The cylindrical section 36 has diametrical dimensions larger than the axial through hole 27 of the bushing 26 such that, as the threaded section 35 has been fully tightened in the nut 9, the upward movement of the latter in the axial cavity 4 is stopped when the end 38 of the cylindrical section 36 abuts the face 39 of the cylindrical bushing 26.

With the above described apparatus, the installation of the anchor device is carried out as follows.

Once the hole F for receiving the anchor device has been formed at the appropriate location in the structural support member M, e.g. a railroad tie, and once the sleeve 1 of the anchor device has been inserted into the hole, the bushing 26 is caused to abut the proximal end 2 of the sleeve 1, with the teeth 28 and the notches 30 of the half-sleeves 5 and 6 being frontally coupled.

As the bushing 26 is held in position by means of the lever 31, angular displacements are imparted to the sleeve 1 until the half-sleeves 5 and 6 are moved to their respective positions, aligned with the maximum-resistance direction of the structural support member M in which the hole F has been formed, such that the half-sleeves 5 and 6 move away from the axis X-X in such direction.

Now, the anchor device is preloaded, to prevent it from losing the orientation assigned to the half-sleeves 5 and 6.

Such preload is obtained using the bolt 34, which is introduced into the through hole 27 of the bushing 29 to engagement of the threaded section 35 in the hole 10 of the expansion nut 9.

The bolt 34 is tightened until the end 38 of its cylindrical section 36 abuts the end 39 of the bushing 26.

Now, the nut 9, also referring to Figure 11, has moved in the cavity 4 to a sufficient extent as to cause an initial expansion of the half-sleeves 5 and 6, which adequately adhere to the circular wall of the hole F, thereby preventing any angular displacement of the sleeve 1 during subsequent expansion of the device.

Once the bolt 34 has been loosened and removed from the sleeve 1 and the bushing 26, the expansion of the anchor device is obtained in the conventional manner, by introducing the conventional loading bolt 16 and engaging its threaded section 15 in the hole 10 of the expansion nut 9.

The displacement of the latter in the chamber 4 until full loading is achieved, allows maximum stability of the anchor device to be reached.

The invention as described above is susceptible to construction and dimensional variants without departure from the scope as defined in the following claims.