A method of performing pressing on a workpiece using a press machine. The pressing method includes: performing pressing on the workpiece between a lower die and an upper die by causing the upper die to approach the lower die by using the hydraulic cylinder in a state in which the workpiece is disposed between the lower die and the upper die, and performing the pressing on the workpiece between the lower die and the upper die, in a state in which a shape of each of the frame, the lower die and the upper die has a rotationally symmetric shape about the reference axis and in which the workpiece center axis coincides with the reference axis.

The present invention relates to a method for manufacturing a universal joint using a pipe. The shaft joint of the universal joint is manufactured by: a material preparation step of preparing a material by cutting a pipe to a predetermined length; a shaft formation step of forming a shaft by reducing the outer diameter of a shaft formation portion by forming the outside of the shaft formation portion with a forming machine; a cutting step of bisecting the non-reduced head formation portion by forming a split across the non-reduced head formation portion in an axial direction; a yoke formation step of forming both opposite members of a yoke in a head by pressing the bisected head formation portion; a pinhole formation step of forming a pinhole across the yoke; and a spline shaft formation step of forming a spline shaft on the outer surface of the reduced hollow shaft.

The present invention relates to a method for manufacturing a universal joint using a pipe. The shaft joint of the universal joint is manufactured by: a material preparation step of preparing a material by cutting a pipe to a predetermined length; a shaft formation step of forming a shaft by reducing the outer diameter of a shaft formation portion by forming the outside of the shaft formation portion with a forming machine; a cutting step of bisecting the non-reduced head formation portion by forming a split across the non-reduced head formation portion in an axial direction; a yoke formation step of forming both opposite members of a yoke in a head by pressing the bisected head formation portion; a pinhole formation step of forming a pinhole across the yoke; and a spline shaft formation step of forming a spline shaft on the outer surface of the reduced hollow shaft.

Provided is a method for internal splitting in the cross-section of the end of a metal plate or a metal rod. The method permits free-adjustment of the width and length of incision of the internal split and gives smooth and even surfaces to the cut face of the internal split for an accurate internal splitting in the cross-section of the end of a metal plate or a metal rod only at the desired position. The invention also provides a method for manufacturing a metal container and a metal pipe by that splitting method and a method for joining metal components. The present invention includes the steps of: a process to form a crevice by abutting a splitting punch or a cleaving punch on the cross-section of the end of the metal plate or the metal rod using a means for determining the width of the internal split; and a process to advance the internal splitting further by repeating the press-splitting on the crevice multiple times using a splitting punch or a cleaving punch. The invented method uses a clamping die, at least one side of which has an opening and a clamping margin to pinch both sides of the metal plate or two opposed positions on the circumference of the metal rod. Every time of each operation step, the clamping die is positioned in advance in accordance with the position of the tip of the intended internal split.

Provided is a method for internal splitting in the cross-section of the end of a metal plate or a metal rod. The method permits free-adjustment of the width and length of incision of the internal split and gives smooth and even surfaces to the cut face of the internal split for an accurate internal splitting in the cross-section of the end of a metal plate or a metal rod only at the desired position. The invention also provides a method for manufacturing a metal container and a metal pipe by that splitting method and a method for joining metal components. The present invention includes the steps of: a process to form a crevice by abutting a splitting punch or a cleaving punch on the cross-section of the end of the metal plate or the metal rod using a means for determining the width of the internal split; and a process to advance the internal splitting further by repeating the press-splitting on the crevice multiple times using a splitting punch or a cleaving punch. The invented method uses a clamping die, at least one side of which has an opening and a clamping margin to pinch both sides of the metal plate or two opposed positions on the circumference of the metal rod. Every time of each operation step, the clamping die is positioned in advance in accordance with the position of the tip of the intended internal split.

A hollow forging process for main shaft of large wind turbine generator, wherein, comprising the following steps as: the first step of cutting off the dead head and the bottom of an ingot; the second step of upsetting and punching a hole; the third step of drawing-out; and the fourth step of local upsetting, drawing-out and shaping-up. In the fourth step, the forged piece is shaped up by local upsetting and drawing-out through a turnplate. The hollow forging process for main shaft created by the invention can save the costs for enterprise to purchase large equipment and makes it possible to forge the main shaft of large wind turbine generator with a free forging oil press with a smaller size.

A hollow forging process for main shaft of large wind turbine generator, wherein, comprising the following steps as: the first step of cutting off the dead head and the bottom of an ingot; the second step of upsetting and punching a hole; the third step of drawing-out; and the fourth step of local upsetting, drawing-out and shaping-up. In the fourth step, the forged piece is shaped up by local upsetting and drawing-out through a turnplate. The hollow forging process for main shaft created by the invention can save the costs for enterprise to purchase large equipment and makes it possible to forge the main shaft of large wind turbine generator with a free forging oil press with a smaller size.

A superalloy seamless pipe and a preparation method thereof are provided. The superalloy seamless pipe comprises the following components in percentages by weight: C: 0.01-0.06%, Si: 0.40-1.00%, Mn: 0.30-1.00%, P?0.025%, S?0.020%, Cr: 15.00-17.00%, Ni: 44.00-46.00%, Al: 2.90-3.90%, Ce: 0.01-0.03%, Ti: 0.10-0.30%, N: 0.03-0.08%, and the balance of Fe and inevitable impurities.

A compound profiling forging method for a wind turbine main shaft includes: making a billet into a flat square billet, returning the billet into a furnace and holding a temperature at 1250? C.; preliminary punching, including: upsetting and drawing out the billet twice, and carrying out punching and rolling; preparing a piercing punch and a punching block, putting the billet in the punching block, putting the piercing punch into a hole of the billet, and operating an oil press to press the piercing punch to be flush with the billet; heating the billet, holding a temperature at 850? C., putting the billet in the punching block, preparing a female die and a punch, and inserting the piercing punch into an inner hole of the billet to carry out flange upsetting; and drawing out the shaft body of the billet in sequence, with a forging temperature range of 850-1250? C.

A compound profiling forging method for a wind turbine main shaft includes: making a billet into a flat square billet, returning the billet into a furnace and holding a temperature at 1250? C.; preliminary punching, including: upsetting and drawing out the billet twice, and carrying out punching and rolling; preparing a piercing punch and a punching block, putting the billet in the punching block, putting the piercing punch into a hole of the billet, and operating an oil press to press the piercing punch to be flush with the billet; heating the billet, holding a temperature at 850? C., putting the billet in the punching block, preparing a female die and a punch, and inserting the piercing punch into an inner hole of the billet to carry out flange upsetting; and drawing out the shaft body of the billet in sequence, with a forging temperature range of 850-1250? C.