Blasting method for deburring junction part between main bore and branch bore

1. A blasting method for a junction between a large-diameter main bore in an article and a small-diameter branch bore branching off at an angle from the main bore in the article, comprising the steps of:

inserting a pillar-shaped rod from a first open end of the main bore with the leading end of the rod close to the junction without blocking the branch bore;

jetting a wet slurry made of a mixture of abrasives arid water from a blasting gun into the main bore from a second open end thereof;

colliding the wet slurry with the leading end of the rod to redirect the wet slurry toward the branch bore to drive the abrasives against the junction for removal of burrs located inside the article at the junction; and

providing an outer peripheral wall of the rod with a helical groove to produce a swirling motion in the blast of the wet slurry jetted into the main bore.

2. A blasting method according to claim 1 , wherein the wet slurry is jetted from outside the second open end of the main bore into the inside of the main bore by use of the blasting gun.

3. A blasting method according to claim 1 , wherein a nozzle of the blasting gun is inserted into the main bore and the wet slurry is jetted into the main bore.

4. A blasting method according to claim 1 , wherein the leading end of the rod has a substantially conical surface to assist in redirecting the jetted wet slurry toward the junction.

5. A blasting method for a junction between a large-diameter main bore in an article and a small-diameter branch bore branching off at an angle from the main bore in the article, comprising the steps of:

inserting a pillar-shaped rod from a first open end of the main bore with the leading end of the rod close to the junction without blocking the branch bore, wherein a metal boring drill is used as the rod;

jetting a wet slurry made of a mixture of abrasives and water from a blasting gun into the main bore from a second open end thereof; and

colliding the wet slurry with the leading end of the rod to redirect the wet slurry toward the branch bore to drive the abrasives against the junction for removal of burrs located inside the article at the junction.

6. A blasting method according to claim 5 , wherein the wet slurry is jetted from outside the second open end of the main bore into the inside of the main bore by use of the blasting gun.

7. A blasting method according to claim 5 , wherein a nozzle of the blasting gun is inserted into the main bore and the wet slurry is jetted into the main bore.

8. A process for blasting a junction inside an article as defined between a large-diameter main bore drilled through the article and a small-diameter branch bore branching off at an angle from the main bore, comprising the steps of:

inserting an elongate rod into the main bore from a first open end thereof to a point where a leading end of the rod is close to the junction but does not block the branch bore;

jetting a wet slurry containing abrasives therein into the main bore from a second open end thereof;

impacting the jetted wet slurry against the leading end of the rod to redirect the jetted wet slurry toward the branch bore to drive the abrasives against the junction for removal of burrs located inside the article; and

providing the leading end of the rod with a substantially conical surface to assist in redirecting the jetted wet slurry toward the junction.

9. A process according to claim 8 , wherein the rod has a cross section which is only slightly smaller than the cross section of the main bore.

10. A process for blasting a junction inside an article as defined between a large-diameter main bore drilled through the article and a small-diameter branch bore branching off at an angle from the main bore, comprising the steps of:

inserting an elongate rod into the main bore from a first open end thereof to a point where a leading end of the rod is close to the junction but does not block the branch bore;

jetting a wet slurry containing abrasives therein into the main bore from a second open end thereof;

impacting the jetted wet slurry against the leading end of the rod to redirect the jetted wet slurry toward the branch bore to drive the abrasives against the junction for removal of burrs located inside the article; and

providing the leading end of the rod with a substantially conical surface to assist in redirecting the jetted wet slurry toward the junction,

wherein a metal boring drill is used as the rod.

11. A process for blasting a junction inside an article as defined between a large-diameter main bore drilled through the article and a small-diameter branch bore branching off at an angle from the main bore, comprising the steps of:

inserting an elongate rod into the main bore from a first open end thereof to a point where a leading end of the rod is close to the junction but does not block the branch bore;

jetting a wet slurry containing abrasives therein into the main bore from a second open end thereof;

impacting the jetted wet slurry against the leading end of the rod to redirect the jetted wet slurry toward the branch bore to drive the abrasives against the junction for removal of burrs located inside the article;

providing the leading end of the rod with a substantially conical surface to assist in redirecting the jetted wet slurry toward the junction; and

providing an outer peripheral wall of the rod with a helical groove to produce a swirling motion in the wet slurry jetted into the main bore.