| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent decline in thickness accuracy of a forged product due to thermal expansion caused by temperature fluctuation of a mold and a bolster, etc.SOLUTION: A hot forging device 1 includes: upper and lower bolsters 3, 4 having tapered recesses 9, 10 formed thereon; tapered upper and lower plates 5, 6 engaging with the recesses 9, 10, respectively; and upper and lower molds 7, 8 mounted to the upper and the lower plates 5, 6, respectively. The upper and the lower plates 5, 6 are formed of a material having a thermal expansion coefficient smaller than that of the upper and the lower bolsters 3, 4. When heat conduction of a hot workpiece causes thermal expansion of the upper and the lower plates 5, 6 and the upper and the lower bolsters 3, 4, increase amount of width of the recesses 9, 10 of the upper and the lower bolsters 3, 4 is made larger than that of width of engagement parts 11, 12 of the upper and the lower plates 5, 6. Thus, engagement positions of the upper and the lower plates 5, 6 with the recesses 9, 10 of the upper and the lower bolsters 3, 4 move to bottom sides of the recesses 9, 10, and the movement amount is offset by the thermal expansion in the height directions of the upper and the lower molds 7, 8. As a result, height of the upper and the lower molds 7, 8 is maintained at a fixed level before and after the thermal expansion, so as to enable prevention of decline in thickness accuracy of a forged product.</p> |
