BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a method of swaging.

FIELD OF THE INVENTION

In International Patent Application Number WO 2004/055327 there is disclosed a yielding rock bolt which is arranged to be inserted into a rock body. A hole is drilled and filled with a bonding material such as resin which bonds with an outer facade of the yielding rock bolt. In order for the yielding rock bolt to react to a rock movement effectively, an inner shaft must undergo extrusion through a fixed anchor member.

The present invention relates, in particular, to a method of swaging an anchor member to a solid metal shaft to form a component of the yielding rock bolt.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention there is provided a method of swaging, in order to mount an anchor member on a solid shaft to form a component of a yielding rock bolt, characterized in that the anchor member is mounted about the shaft, the anchor member and the shaft are placed in a swage press comprising three or more swage press members which are equiangularly disposed about the anchor, and applying the swage press members simultaneously to the anchor member laterally so as to apply pressure to the anchor member and cause the anchor member to be deformed inwardly and the shaft to be also inwardly deformed correspondingly.

DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective representation of a swage press being used in accordance with the method of the present invention to swage an anchor member onto a shaft;

Figure 2 is a cross-sectional view of the anchor member used in accordance with the present invention, before swaging;

Figure 3 is a longitudinal cross-sectional view showing the relative position of the shaft and the anchor member, in accordance with the present invention, before being swaged;

Figure 4 is a transverse cross sectional view of the apparatus of figure 3; and

Figure 5 is a longitudinal cross-sectional image similar to figure 2 showing, in part, a portion of a yielding rock bolt after being swaged in accordance with the method of the present invention.

DESCRIPTION OF THE INVENTION

In the drawings, there is shown a swage press 10, a shaft 12 and an anchor member 14 which is a substantially cylindrical member with a longitudinal bore 40. In figure 2 a cross-sectional illustration shows a preferred embodiment of the bore 40 of the anchor member 14 having an internal bore surface 41. The bore 40 comprises a relatively wide and parallel distal portion 42, a relatively narrow and parallel mid portion 44 and a proximal tapered portion 46. The portion 42 is connected to the mid portion 44 by a step 43. The tapered portion 46 is connected to the mid portion 44 by an annular recess 45.

The bore 40 is arranged to receive the shaft 12. Further, the shaft 12 is preferably encased in a debonding sheath 18 as shown in figure 1. The sheath 18 is arranged to engage snugly with the anchor member 14 by being located in the distal portion 42 of the anchor member 14 as shown in figure 3. The mid portion 44 is dimensioned to receive the shaft 12 alone.

The anchor member 14 may be manufactured from hardened heat treated steel such as 41/40 steel and the internal bore surface 41 of the anchor member 14 may be nitrided to prevent molecular welding with the shaft 12.

With reference to figure 3, the anchor member bore 40 receives the shaft 12, and is laterally disposed between the debonding sheath 18 fitted with a fixing means 26 (shown in figure 1), and a jacket member 16. The shaft 12 is dimensioned such that, prior to swaging, the anchor member 14 may be mounted about the shaft 12 with no interference. When the anchor member 14 is fitted to the shaft 12, it receives a radially compressive lateral deforming force from a plurality of swage press members 50 of a swage press 10. The jacket member 16 is mounted about a proximal step 47 at the proximal end of the anchor member 14 as can be seen in figure 3.

As shown in figure 1 , the swage press members 50 are equiangularly disposed about an outer lateral surface 48 of the anchor member 14. The apparatus contains at least three (3) and preferably from six (6) to ten (10) of the swage press members 50. In use, the swage press members 50 are simultaneously urged, upon operation of the swage press 10 toward a central point corresponding with a longitudinal axis of the shaft 12.

An inner engaging surface 52 of each swage press member 50 is characterised by an arcuate profile complementary to the outer lateral surface 48 of the anchor member 14 with which it is to engage.

Upon swaging, the swage press members 50 engage with the anchor member 14 and communicate radially compressive deforming forces to the anchor member 14 mounted on the shaft 12. The anchor member 14 undergoes a lateral deformation inwardly at a swaged portion 54 as shown in figure 5 thereof and engages with the shaft 12 in a constrictive relationship.

The constrictive relationship of the anchor swaged portion 54 and the adjacent shaft 12 effects a lateral yielding at a shaft swaged portion 56 shown in figure 5. The shaft swaged portion 56 corresponds in shape and proportion to the anchor swaged portion 54 at the inner surface 41 of the bore 40. Thus, the portion 56 is of narrower cross-sectional size compared to the remainder of the shaft 12. With reference to figure 5, the anchor swaged portion 54 is in engagement with the relatively narrow shaft swaged portion 56 and is laterally disposed between non swaged portions of the shaft 12.

The disclosed arrangement causes the shaft 12 and anchor member 14 to operate as an essential component of a yielding rock bolt 10. In practice the yielding rock bolt 10 is arranged to harness a rock face movement whereby the shaft 12 is forced to yield as it undergoes an extrusion through the anchor member swaged portion 54, thereby effecting a controlled and predictable rock face movement.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.