Method of bending pipe material

Abstract

In a bending method of bending a pipe material of metal in pipe working, at first particles are fed into a flow passage of the pipe material, the particles being removable in a liquid phase. The pipe material with the particles is bent. The particles in an at least partially liquid phase are removed from the pipe material, to clean the flow passage. The particles are meltable, or soluble in dissolving liquid. Specifically, in the removing step, the dissolving liquid is supplied into the flow passage, the particles are dissolved in the dissolving liquid, and compressed air is blown in the flow passage to eject the fluid obtained by dissolving the particles in the dissolving liquid. The particles are granulated sugar, and the dissolving liquid is warmed water.

1 . A bending method of bending a pipe material of metal, comprising steps of:
 loading particles into a flow passage of said pipe material, said particles being processable in a liquid phase;   bending said pipe material with said particles; and   removing said particles in an at least partially liquid phase from said pipe material.   
   
   
       2 . A bending method as defined in  claim 1 , wherein said particles are meltable with heat, or soluble in dissolving liquid. 
   
   
       3 . A bending method as defined in  claim 2 , wherein said pipe material has first and second end openings;
 further comprising a step of closing said first end opening of said pipe material before said loading step.   
   
   
       4 . A bending method as defined in  claim 3 , further comprising a step of closing said second end opening after said loading step. 
   
   
       5 . A bending method as defined in  claim 2 , wherein said pipe material has first and second end openings;
 further comprising a step of closing said first and second end openings after said loading step.   
   
   
       6 . A bending method as defined in  claim 5 , further comprising a step of opening said first and second end openings after said bending step. 
   
   
       7 . A bending method as defined in  claim 2 , wherein in said removing step, said dissolving liquid is supplied into said flow passage to dissolve said particles. 
   
   
       8 . A bending method as defined in  claim 7 , wherein in said removing step, said dissolving liquid is supplied into said flow passage, and compressed air is blown in said flow passage to eject fluid obtained by dissolving said particles in said dissolving liquid. 
   
   
       9 . A bending method as defined in  claim 8 , wherein supply of said dissolving liquid and blow of said compressed air are carried out alternately and repeatedly. 
   
   
       10 . A bending method as defined in  claim 9 , wherein said flow passage is dried with said compressed air after said fluid is ejected. 
   
   
       11 . A bending method as defined in  claim 2 , wherein said particles are granulated sugar or salt, and said dissolving liquid is water or warmed water. 
   
   
       12 . A bending method as defined in  claim 2 , wherein in said removing step, said particles are melted with heat by heating said pipe. 
   
   
       13 . A bending method as defined in  claim 12 , wherein in said removing step, said pipe material is heated, and compressed air is blown in said flow passage to eject said fluid obtained by melting said particles.