FI115787B - Method of connecting the protective tube to the drill bit and the corresponding joint - Google Patents

Description

115787

METHOD OF CONNECTING THE PROTECTION PIPE TO THE DRIVER AND

THE CORPORATE ASSOCIATION

The invention relates to a method and a joint for connecting a protective tube to a drill bit, wherein a circumferential annular groove is formed on the outer periphery of the blade and a ground shoe mounted around the blade

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An arrangement for connecting the guard tube to the blade, particularly to the periphery of the blade, is known as a groove on the outer periphery of the blade and a coupling ring consisting of two halves into a single ring with a protruding shoulder This allows the coupling ring to be locked around the blade by means of a shoulder. The leading edge of the protective tube is welded to said coupling ring, whereby the connection is completed.

The disadvantage of such a solution is to make a two-part ring, whereby assembling it from parts to a complete ring is already a labor-intensive step, and welding still causes · * ·: · 20 roundness in the ring, which must be removed from it. This is round: design is tricky when the tire is already mounted on the blade. : '::

It is further known from WO 00/31373 to fit a ground shoe by shrinking the blade to the outer circumference. In this method you have to build and hold an expensive crimping tool *. 25 for each different diameter.

Finnish Patent Publication 95618 discloses a securing connection of a tire blade to a ground shoe ring attached to a protective tube, whereby the ground shoe has a groove and the extension of the rear part of the tire blade overlaps the groove. The ring blade extension has a hole 30 in which a pin is inserted so that its end extends into the groove. The blade may rotate relative to the ground shoe but is locked axially. Further, there is known a variant in which the groove ··, * is in both the ground shoe and the extension of the blade, the grooves are aligned and a flexible round wire or the like is inserted into the groove which locks the parts axially but does not prevent mutual rotation. These solutions are not at all applicable to the transmission of force, such as pulling the protective tube into the hole by means of shocks applied to the blade. These solutions are only intended to prevent the blade from falling when the drill unit is raised upright for the onset drilling.

The protection tube and blade connection made and installed by the method of the invention solves the disadvantages and problems encountered in the manufacture of the force transmitting connection. The method according to the invention is characterized in that, in the first step of mounting, the coupling ring is pushed over the groove on the periphery of the blade, at least partially, the annular member the front edge of the protective tube is pushed into contact with said coupling ring and secured to the coupling ring, for example by welding, whereby the front edge of the protective tube 15 attached to the coupling ring prevents the ring member from moving in another opposite axial direction.

The joint according to the invention is characterized by a ring space between the groove and the engagement ring for a ring member to be fitted in the groove, wherein the engagement ring comprises at least a half groove on said ring member fitted to prevent the ring member • ·; moving in another opposite axial direction with respect to the previous one.

«· * · * *; An advantage of the invention is that when the coupling ring to be fitted on the groove on the outer periphery of the blade is made by turning without welding, it becomes absolutely circular, as is the case with the blade. the outer ring. Thus, these fit exactly as desired, and the ring can only be simply inserted into the circumference of the blade. Due to the design of the coupling ring, the force-transmitting ring member can also be placed only at one point as a cut-off ring on the blade; 30 only after positioning the coupling ring. The end of the protective tube is finally '·; · 'Easy to overlap with the coupling ring because the coupling ring is circular' and then secured by welding. The solution avoids the assembly of the ring '... · by welding, but still achieves a force-transmitting connection in the axial direction, which, however, allows the connection parts to rotate with each other.

115787 3

In the following, the invention will be explained in more detail with reference to the accompanying drawing, in which Fig. 1 is a side view and partially cut away of an assembly of knives.

Figure 2 shows the positioning of the ring member in the groove from the side.

Figure 3 shows the insertion of the end of the protective tube and welding to the coupling ring.

Fig. 1 shows a blade assembly comprising a punching blade 1 formed with a groove 7 circling the periphery of the blade. A groove 2 is inserted into the groove 7 with an inside diameter slightly larger than the diameter of the blade 1 7. The groove 7 also has an annular member 3 cut off at least at one point so that it can be tensioned in the groove 7.

The leading edge of the protective tube 4 is partially overlapped with the coupling ring 2 and welded on the outside by a seam 5. The ring member 3 cannot escape from the groove 7 and the coupling ring on its side 15 cannot get off the blade. The solution allows the blade 1 to pull the protective tube 4 into the hole. The protective tube 4 is generally not rotating and no attempt is made to rotate it. Blade 1, in turn, is almost invariably rotated. In this case, the ring member 3 acts as a sliding member between two parts, one of which rotates. Impacts are directed to the blade 1 via the surface 6.

Figure 2 illustrates a method for performing the assembly of a blade assembly.

* · * »« '' · First, connect the coupling ring 2, ie the ground shoe, to the groove 7. Groove 7 is so wide that

* * I

The half groove on the inside of the coupling ring 2 overrides the right edge of the groove 7 and I i * ;; a space is provided for the ring member 3 to accommodate it in the groove 7 and at the same time in the half groove of the engagement ring 2 • * The ring member 3 is tensioned in place by squeezing it to a slightly smaller diameter defined by the groove 7 25. The ring member 3 is preferably of circular cross-section with a ring of spring steel material and at least one point cut off.

Fig. 2 shows the leading edge of the protective tube 4, inserted into the shoulder-shaped space of the coupling ring 2, after which the protective tube is welded by a seam 5; * 30 rings. There is an axial travel between the parts 1 and 2 limited by the coupling ring 2 ';' colliding with the shoulder of the blade 1 which is the left edge of the groove 7 and on the other hand the collar 3 '' · colliding with the right edge of the groove 7.

»II», 4 115787

The joint according to the invention is capable of transmitting impact forces from the blade to the protective tube, whereby the protective tube is pulled into the hole by the joint. By means of the joint shown, the protective tube is pulled into the hole, in particular in a vertical drill, where the weight of the protective tube helps to pull it and thus the ring member is not subjected to heavy stress.

10 15 20 * 1 · I · »1 t I i 1 1 25 *» • 1 »30» »».

Claims (7)

115787 A method for connecting a protective tube (4) to a drill bit (1), comprising forming an annular groove (7) on the outer circumference of the blade 5 (1) and connecting the protective tube (4) from its front edge to the blade (1) , such as a coupling ring (2) which is secured to both said ring groove (7) and on the other hand to said protective tube (4) and is locked by means of at least one cut-off ring member (3) located in the joint at least partially over a groove (7) on the outer periphery of the blade (1), the next annular member (3) being disposed in the space between the engagement ring (2) and the groove (7) with respect to the coupling ring and finally to the protective tube (4) the leading edge 15 is pushed into contact with said coupling ring and secured to the coupling ring, e.g. by welding, whereby the front edge I of the protective tube secured to the coupling ring (2) prevents the ring member from moving in the second opposite axial direction. Method according to Claim 1, characterized in that the axial pulling force between the blade (1) and the guard tube (4) is transmitted through the annular member (3). The edge 115787 is arranged to prevent the annular member (3) from moving in another opposite axial direction with respect to the previous one. Connection according to Claim 4, characterized in that the annular member (3) has a circular cross-section. Connection according to claim 4, characterized in that the coupling ring (2) is partially overlapped with the protective tube (4). 10 Joining according to Claim 4, characterized in that an axial movement clearance is provided between the coupling ring (2) and the blade (1). 15