Rubber-coating device for steel wire

1. A rubber coating device for a steel wire, the rubber coating device comprising:

a heating device that heats a heat medium to a predetermined temperature range;

a heat transfer roller that is in contact with a steel wire, wherein the heat transfer roller includes a space for the heat medium; and

an extrusion machine that coats the steel wire heated by the heat transfer roller with rubber, wherein

the heat medium is water,

the predetermined temperature range includes a boiling point of the heat medium,

the heat transfer roller includes an outer circumferential surface including a groove around which the steel wire is wound,

the heat transfer roller includes a rotation shaft, and

a supply passage that supplies the heat medium to the space for the heat medium in the heat transfer roller and a discharge passage that discharges the heat medium out of the space for the heat medium are included inside the rotation shaft.

2. The rubber coating device according to claim 1 , wherein the supply passage is located at an inner side of the discharge passage inside the rotation shaft.

3. The rubber coating device according to claim 2 , wherein

the heat transfer roller includes a circular partition plate concentric to the heat transfer roller in the space for the heat medium,

the partition plate partitions the space for the heat medium into a first heating chamber connected to the supply passage and a second heat chamber connected to the discharge passage, and

an outer circumferential portion of the first heating chamber is in communication with an outer circumferential portion of the second heating chamber.

4. The rubber coating device according to claim 1 , wherein

the heat transfer roller includes a first heat transfer roller and a second heat transfer roller, and

the steel wire is wound around the first heat transfer roller and the second heat transfer roller a number of times.