Method and apparatus for making seamless pipe
The invention relates to a device and a method for producing a pipe ( 1 ) from a hollow block ( 2 ) which has an opening ( 3 ). The device has a rolling mill ( 30 ) for rolling the hollow block ( 2 ) via a rolling rod ( 21 ) introduced into the opening ( 3 ) of the hollow block ( 2 ), whereby the pipe ( 1 ) is produced. A retaining device ( 70 ) for retaining the pipe ( 1 ) is provided behind the rolling mill ( 30 ), and the device is further designed such that the rolling rod ( 21 ) can be drawn out of the pipe ( 1 ) after the rolling process while the pipe ( 1 ) is retained by the retaining device ( 70 ).
1. An apparatus for making a pipe from a tubular block having a passage, the apparatus comprising:
a mandrel rod in the passage and connected to the tubular block;
a shaft rod releasably connected to the mandrel rod for transmitting tensile and compressive force thereto in a travel direction of the tubular block and extending out of the passage opposite to the travel direction;
a roller mill for rolling the tubular block in a forward in the travel direction over the mandrel rod introduced into the passage of the tubular block such that the pipe is produced;
a dishing press upstream of the roller mill along a rolling travel path for deforming and pressing together partially or completely a portion of the tubular block for frictional form-fitting contact with the mandrel rod;
a clamp downstream in the direction of the roller mill for arresting the pipe; and
means for pulling the mandrel rod out of the pipe by exerting traction on the shaft rod while the pipe is arrested by the clamp.
2. The apparatus defined in claim 1 , wherein the shaft rod and the mandrel rod are screwed together.
3. The apparatus defined in claim 1 , further comprising:
means for, while the pipe is arrested by the clamp, retracting the mandrel rod by the means upstream in the travel direction along the travel path during rolling.
4. The apparatus defined in claim 1 , wherein the clamp has a retaining block that, while the mandrel rod is being pulled out of the pipe, is engageable with a rear end face of the pipe.
5. The apparatus defined in claim 1 , wherein the mandrel rod has a cooling conduit through which a fluid coolant can flow.
6. The apparatus defined in claim 5 , further comprising:
a cooling pipe in the cooling conduit that extends into the vicinity of a front end of the mandrel rod and can conduct the coolant there and deliver it through a passage of the cooling pipe into the cooling conduit.
7. A method of making a pipe from a tubular block having a passage, the method comprising the steps of:
introducing a mandrel rod in a forward travel direction defining a rolling travel path into the passage of the tubular block;
deforming and pressing together a portion of the tubular block partially or completely before rolling by a dishing press provided in the rolling travel path so that the tubular block and mandrel rod come into frictional form-fitting contact at the deformed portion;
releasably connecting a shaft rod to the mandrel rod with the shaft rod extending upstream in the travel direction of the block out of the block;
transporting an assembly of the mandrel rod and the tubular block along the travel path through a roller mill in order to roll the tubular block over the mandrel rod such the pipe is produced; and
arresting the pipe with a clamp and pulling the mandrel rod out of the passage of the pipe by exerting upstream traction on the shaft rod.
8. The method defined in claim 7 , wherein, further comprising the step, while the pipe is being held by the clamp, of
retracting the mandrel rod upstream in the travel direction along the travel path during rolling.
9. The method defined in claim 7 , wherein the clamp has a retaining block, the method further comprising the step, while the mandrel rod is being pulled out of the pipe, of:
bringing the retaining block into contact with an upstream end face of the pipe.
10. The method defined in claim 7 , further comprising the step of:
cooling the mandrel rod during rolling and/or while being pulled out of the pipe by flowing a fluid coolant in a conduit formed in the mandrel rod.
11. The method defined in claim 7 , wherein the mandrel rod is used for several directly successive rolling cycles, with a respective tubular block being rolled into a pipe in each cycle.