Hollow Forging Process for Main Shaft of Large Wind Turbine Generator

Abstract

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.

Claims

1. A hollow forging process for main shaft of large wind turbine generator, comprising the following steps: a first step of cutting off the dead head and the bottom of an ingot; a second step of upsetting and punching a hole; a third step of drawing-out; and a fourth step of local upsetting, drawing-out and shaping-up.

2. The hollow forging process for main shaft of large wind turbine generator according to claim 1, wherein, in the fourth step, the forged piece is shaped up by local upsetting and drawing-out through a turnplate; the turnplate comprises a circular turnplate base and a turnplate body connected to the turnplate base; a circular hole that matches the shape of the lower end of the main shaft to be processed is arranged on the turnplate body; a hole with a certain taper is arranged in the middle of the turnplate base, which may ensure both excircle and inner hole of the main shaft will not result in eccentricity in combination with a core rod of the same taper.

3. The hollow forging process for main shaft of large wind turbine generator according to claim 2, wherein, the overall core rod is a conic cylinder; the head of the core rod is cylindrical; the fillet radius of the end of the core rod is 30-50 mm and the taper of the core rod is 1:100.

4. The hollow forging process for main shaft of large wind turbine generator according to claim 1, wherein, in the third step, the process of drawing-out is conducted by a drawing-out core rod; the drawing-out core rod is overall cross-shaped; the transverse core rod body that forms the cross-shape abuts against a flange plate face of the main shaft during drawing-out so as to prevent material escaping from through-hole in the center of the main shaft.

5. The hollow forging process for main shaft of large wind turbine generator according to claim 1, wherein, in the second step, a plunger chip is used for punching the hole; the height of the plunger chip is greater than the depth of the punched hole after upsetting plus the necessary height allowing hanging tongs to remove the roughly processed ingot out of the plunger chip.

6. The hollow forging process for main shaft of large wind turbine generator according to claim 2, wherein, both the plunger chip and the turnplate are made of 5CrMnMo.

7. The hollow forging process for main shaft of large wind turbine generator according to claim 5, wherein, both the plunger chip and the turnplate are made of 5CrMnMo.

8. The hollow forging process for main shaft of large wind turbine generator according to claim 2, wherein, an outer gear ring is arranged around the periphery of the turnplate body; a gear is arranged to mesh with the outer gear ring; the shaft of the gear is connected to that of a motor that drives the gear to rotate; since the gear and the outer ring are engaged to each other, when the motor operates, the turnplate body will rotate to realize rotated upsetting.

9. The hollow forging process for main shaft of large wind turbine generator according to claim 1, wherein, the step for heating the steel ingot before the first step is to directly put a hot-charged steel ingot of above 600 C. into a furnace for heating up to 850 C. 20 C. and the temperature is maintained for 7 hours, and further reheating up to 1250 C. 10 C. and the temperature is maintained for 15 hours; in the first step, the dead head and the bottom of the ingot is cut off under the forging temperature of 1200-1220 C. and the temperature is maintained for 5 hours; in the second step of upsetting, the turnplate is adopted for rotated upsetting; and the plunger chip is adopted for punching the hole; the hanging tongs are adopted for removing the roughly processed ingot out of the plunger chip after proper upsetting and punching so as to put it back into the furnace for reheating up to 1250 C. 20 C. and the temperature is maintained for 8-10 hours; in the third step of drawing-out, the ingot is drawn out into an octagon shape with marks made; the roughly processed intermediate ingot is processed; the waste part at the T-end after shaping-up of pole part is cut off under 1230-850 C. and the ingot is put back into the furnace for reheating up to 1240 C. 20 C. and the temperature is maintained for 6-7 hours; in the fourth step of local upsetting, the ingot is drawn out to shape up under the temperature of 1230-900 C., and the roughly processed intermediate ingot is vertically inserted into a gasket group consisted of several folded gaskets that is placed on a movable turnplate formed with a lower turnplate and a upper gasket; while local upsetting, the upper junction plate and the upper anvil fixed on the upsetting plate are demounted and the upsetting plate on the movable cross beam is used for upsetting by 200 mm downward; then the upper junction plate and the upper anvil are mounted to reduce the contact area of upsetting; the methods of rotated upsetting and gradual rolling are adopted to reach the required size; after upsetting, the ingot is put back into the furnace for reheating up to 1230 C. 20 C. and the temperature is maintained for 5 hours.

10. The hollow forging process for main shaft of large wind turbine generator according to claim 1, wherein, the main shaft is made of 34CrNiMo6.

11. The hollow forging process for main shaft of large wind turbine generator according to claim 2, wherein, the main shaft is made of 34CrNiMo6.

12. The hollow forging process for main shaft of large wind turbine generator according to claim 3, wherein, the main shaft is made of 34CrNiMo6.

13. The hollow forging process for main shaft of large wind turbine generator according to claim 4, wherein, the main shaft is made of 34CrNiMo6.

14. The hollow forging process for main shaft of large wind turbine generator according to claim 9, wherein, the hot-charged steel ingot is a steel ingot with a surface temperature of above 650 C. soon after pouring and demoulding, and the hot-charged steel ingot is placed into a heat preserving barrel for 4-5 hours; the heat preserving barrel has a steel plate-welded outer shell, a lining of mineral wool and a cover on the top.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a structure diagram of the turnplate involved in the fourth step of the hollow forging process for main shaft of large wind turbine generator in the Invention;

[0019] FIG. 2 is a sectional view of the state diagram of upsetting main shaft in FIG. 1;

[0020] FIG. 3 is a structure diagram of the core rod in FIG. 2;

[0021] FIG. 4 is a state diagram of the drawing-out core rod not inserted into the through-hole in the center of the shaft in the third step.

[0022] Marks in the figures: 1. turnplate base; 2. turnplate body; 3. circular hole; 4. hole; 5. core rod; 6. main shaft of wind turbine generator; 7. drawing-out core rod; 8. outer gear ring; 9. gear.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The embodiments of the Invention will be further described in combination with the drawings as follows to make the technical features, purpose, and effectiveness of the Invention clearer.

[0024] A hollow forging process for main shaft of large wind turbine generator comprises 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; as shown in FIGS. 1-4, the turnplate comprises a circular turnplate base 1 and a turnplate body 2 connected to the turnplate base 1; a circular hole 3 that matches the shape of the lower end of the main shaft 6 to be processed is arranged on the turnplate body 2; a hole 4 with a certain taper is arranged in the middle of the turnplate base 1, which may ensure both excircle and inner hole of the main shaft 6 will not result in eccentricity in combination with a core rod 5 of the same taper. The overall core rod 5 is a conic cylinder; the head of the core rod 5 is cylindrical; the fillet radius of the end of the core rod 5 is 30-50 mm and the taper of the core rod 5 is 1:100. In the third step, the process of drawing-out is conducted with a drawing-out core rod 7; the drawing-out core rod 7 is overall cross-shaped; the transverse core rod body that forms the cross-shape abuts against the flange plate face 61 of the main shaft 6 during drawing-out so as to prevent material escaping from through-hole in the center of the main shaft 6. In the second step, a plunger chip is used for punching the hole; the height of the plunger chip is greater than the depth of the punched hole after upsetting plus the necessary height allowing hanging tongs to remove the roughly processed ingot out of the plunger chip. Both the plunger chip and the turnplate are made of 5CrMnMo. An outer gear ring 8 is arranged around the periphery of the turnplate body 2; a gear 9 is arranged to mesh with the outer gear ring 8; the shaft of the gear is connected to that of a motor shaft that drives the gear 9 to rotate; since the gear 9 and the outer ring 8 are engaged to each other, when the motor operates, the turnplate body 2 will rotate to realize rotated upsetting. The step for heating the steel ingot before the first step is to directly put a hot-charged steel ingot of above 600 C. into a furnace for heating up to 850 C. 20 C. and the temperature is maintained for 7 hours, and further reheating up to 1250 C. 10 C. and the temperature is maintained for 15 hours;

[0025] The hot-charged steel ingot refers to a steel ingot with a surface temperature of above 650 C. soon after pouring and demoulding. It is placed into a heat preserving barrel for 4-5 hours; the heat preserving barrel has a steel plate-welded outer shell, a lining of mineral wool and a cover on the top;

[0026] In the first step, the dead head and the bottom of the ingot are cut off under the forging temperature of 1200-1220 C. and the temperature is maintained for 5 hours; in the second step, the turnplate is adopted for rotated upsetting; and the plunger chip is adopted for hole punching the hole; the hanging tongs are adopted for removing the roughly processed ingot out of the plunger chip after proper upsetting and punching so as to put it back into the furnace for reheating up to 1250 C. 20 C. and the temperature is maintained for 8-10 hours; in the third step of drawing-out, the ingot is drawn out into an octagon shape with marks made; the roughly processed intermediate ingot is processed; the waste part at the T-end after shaping-up of pole part is cut off under 1230-850 C. and the ingot is put back into the furnace for reheating up to 1240 C. 20 C. and the temperature is maintained for 6-7 hours; in the fourth step of local upsetting, the ingot is drawn out to shape up under the temperature of 1230-900 C., and the roughly processed intermediate ingot is vertically inserted into a gasket group consisted of several folded gaskets that is placed on a movable turnplate formed with a lower turnplate and a upper gasket; while local upsetting, the upper junction plate and the upper anvil fixed on the upsetting plate are demounted and the upsetting plate on the movable cross beam is used for upsetting down by 200 mm downward; then the upper junction plate and the upper anvil are mounted to reduce the contact area of upsetting; the methods of rotated upsetting and gradual rolling are adopted to reach the required size; after upsetting, the ingot is put back into the furnace for reheating up to 1230 C. 20 C. and the temperature is maintained for 5 hours. The main shaft is made of 34CrNiMo6.

[0027] The above is only a further detailed description for the Invention in combination with the specific preferred technical schemes and the embodiments of the Invention are not limited to it. For a person skilled in the art, the simple deductions or substitutions carried out under the premise of not departing from the concept of the Invention will fall within the protection scope of the Invention.