Mandrel for manufacturing electrode assembly of cylindrical secondary battery

1 . A mandrel for manufacturing an electrode assembly, the mandrel comprising:

a first mandrel member having a semicircular cross-section and a predetermined length; and

a second mandrel member configured to define a cylindrical shape of the mandrel by being coupled to the first mandrel member while facing the first mandrel member,

wherein a concave-convex part is provided on joint surfaces of the first and second mandrel members,

wherein the concave-convex part includes a protrusion and a groove formed in a longitudinal direction so as to engage with each other, and

wherein the concave-convex part is formed on the joint surfaces except for a section in which an end of a stack constituting the electrode assembly is interposed.

2 . The mandrel of claim 1 , wherein the first and second mandrel members are asymmetrically formed in the longitudinal direction.

3 . The mandrel of claim 2 , wherein the joint surfaces of the first and second mandrel members are inclined at an angle of 0 to 1° with respect to a center axis of the mandrel in the longitudinal direction.

4 . The mandrel of claim 1 , wherein the concave-convex part is provided in plurality.

5 . The mandrel of claim 1 , wherein the protrusion and the groove each have a quadrangular cross-section.

6 . The mandrel of claim 5 , wherein a width and a height of the protrusion are 50% or less of a diameter of the mandrel.

7 . The mandrel of claim 5 , wherein an edge of the protrusion is rounded by 0.01 to 0.5 mm.

8 . The mandrel of claim 5 , wherein two opposite surfaces in a width direction of the protrusion are inclined at an angle of 80 to 100° with respect to the corresponding joint surface.