Method of disassembling a cold head and lifting-up jig

1. A method of disassembling a cold head provided with a displacer that extends in an axial direction, a cylinder that accommodates the displacer, and a displacer drive unit that is fastened to the cylinder and is connected to the displacer such that the displacer is driven in the axial direction, the method comprising:

mounting a lifting-up jig onto the displacer drive unit;

unfastening the displacer drive unit from the cylinder; and

operating the lifting-up jig such that the displacer drive unit is lifted up from the cylinder together with the displacer,

wherein the lifting-up jig is provided with a lifting-up jig main body that includes a lifting-up bolt hole and a lifting-up bolt that is screwed into the lifting-up bolt hole,

wherein the mounting of the lifting-up jig includes attaching the lifting-up jig main body to the displacer drive unit such that the lifting-up bolt is disposed to be parallel to the axial direction of the cold head, and

wherein the operating of the lifting-up jig includes rotating the lifting-up bolt relative to the lifting-up jig main body with the lifting-up bolt not moving in the axial direction.

2. The method according to claim 1 , further comprising:

detaching the displacer drive unit from the displacer together with the lifting-up jig.

3. The method according to claim 1 , further comprising:

mounting a displacer holding jig onto the displacer; and

detaching the displacer drive unit from the displacer together with the lifting-up jig,

wherein the displacer is held by the displacer holding jig in a state of being lifted up from the cylinder.

4. The method according to claim 1 , further comprising:

mounting a displacer extraction jig onto the displacer; and

raising the displacer extraction jig together with the displacer such that the displacer is extracted from the cylinder.

5. A method of disassembling a cold head provided with a displacer that extends in an axial direction, a cylinder that accommodates the displacer, and a displacer drive unit that is fastened to the cylinder and is connected to the displacer such that the displacer is driven in the axial direction, the method comprising:

mounting a lifting-up jig onto the displacer drive unit;

unfastening the displacer drive unit from the cylinder;

operating the lifting-up jig such that the displacer drive unit is lifted up from the cylinder together with the displacer; and

detaching the displacer drive unit from the displacer together with the lifting-up jig.

6. The method according to claim 5 , further comprising:

mounting a displacer holding jig onto the displacer,

wherein the displacer is held by the displacer holding jig in a state of being lifted up from the cylinder.

7. The method according to claim 5 , further comprising:

mounting a displacer extraction jig onto the displacer; and

raising the displacer extraction jig together with the displacer such that the displacer is extracted from the cylinder.

8. A method of disassembling a cold head provided with a displacer that extends in an axial direction, a cylinder that accommodates the displacer, and a displacer drive unit that is fastened to the cylinder and is connected to the displacer such that the displacer is driven in the axial direction, the method comprising:

mounting a lifting-up jig onto the displacer drive unit;

unfastening the displacer drive unit from the cylinder;

operating the lifting-up jig such that the displacer drive unit is lifted up from the cylinder together with the displacer;

mounting a displacer extraction jig onto the displacer; and

raising the displacer extraction jig together with the displacer such that the displacer is extracted from the cylinder.