METHOD OF MANUFACTURING DOOR FRAME FOR WIND TOWER

Abstract

Disclosed herein is a method of manufacturing a door frame for a wind tower. The method includes a first step of forging a circular planar substance, thereby forming a through hole in a central portion of the substance, a second step of heating the substance that was processed in the first step, a third step of ring-rolling the heated substance around the through hole in an annular shape such that a circumstance of a center hole of the substance is equal to a length of a center line of the door frame, a fourth step of upset-forging the annular substance so that opposite sides of the substance are pressed to form linear sections, and a fifth step of fine-finishing the substance that was processed by the fourth step, thus completing the door frame.

Description

FIELD OF THE INVENTION

The present invention relates generally to methods of manufacturing door frames for wind towers and, more particularly, to a method of manufacturing a door frame installed in a wind tower.

BACKGROUND OF THE INVENTION

Limited oil resources will become exhausted someday. Thus, a lot of research has recently been done into alternative energies which can substitute for the resources and many different kinds of technologies aiming to develop alternative energy have been proposed. Particularly, many technologies for generating electricity from natural energy sources have been studied because the conclusion was reached that natural energy sources, such as the sun, wind, water, etc., are almost infinite and can be used as ideal alternative energy sources. A wind power generation technology in which blades are rotated by wind power so that electricity is generated is at the stage of practical application.

However, in wind power generation, a vast land area and large expenses are required to install single wind power generating equipment and system.

Various ways to reduce the production cost of wind power generating equipment have recently been proposed.

FIG. 1 is a perspective view showing a typical wind tower.

Typically, a propeller 5 is provided on the upper end of a wind tower 1 and connected to a generation part 4. To allow a worker to inspect the generation part 4, a door 2 with a door frame is installed at a predetermined position in the wind tower 1.

As shown in FIG. 2, forming the door frame 20 includes forging a raw substance 10 (a slab or ingot) in a planar shape, rough-machining the substance 10, and fine-finishing it thereby producing a final product.

However, in the conventional manufacturing method, a large amount of cut-out portions 12 are removed from the raw substance during rough-machining and fine-finishing, thus increasing waste of material and the time it takes to manufacture it.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing a door frame for a wind tower which can reduce the cost and time required to manufacture the door frame.

In order to accomplish the above object, the present invention provides a method of manufacturing a door frame for a wind tower, including a first step of forging a circular planar substance, thereby forming a through hole in a central portion of the substance, a second step of heating the substance that was processed in the first step, a third step of ring-rolling the heated substance around the through hole in an annular shape such that a circumstance of a center hole of the substance is equal to a length of a center line of the door frame, a fourth step of upset-forging the annular substance so that opposite sides of the substance are pressed to form linear sections, and a fifth step of fine-finishing the substance that was processed by the fourth step, thus completing the door frame.

Preferably, a ratio (t/w) of a thickness (t) to a width (w) of the substance processed by the fine-finishing may range from 0.5 to 1.

In the fifth step, a length ratio (a/b) of the linear section (a) formed in each of the opposite sides of the substance to a curved section (b) may be 0.7 or more.

Further, a ratio (w/L) of a width (w) to a height (L) of the substance processed by the fine-finishing may be 0.1 or more.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view showing a typical wind tower;

FIG. 2 is a view illustrating an example of a conventional method of manufacturing a door frame for a wind tower;

FIGS. 3A through 3E are views illustrating a method of manufacturing a door frame for a wind tower, according to an embodiment of the present invention;

FIGS. 4A and 4B are views comparing a final product to an intermediate product which has been processed at a third step of the door frame manufacturing method according to the embodiment of the present invention;

FIG. 5 is a plan view of a door frame for a wind tower which is manufactured by the door frame manufacturing method according to the present invention; and

FIG. 6 is a perspective view of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

FIGS. 3A through 3E are views illustrating a method of manufacturing a door frame for a wind tower, according to the embodiment of the present invention.

As shown in FIGS. 3A through 3E, the door frame manufacturing method according to the present invention includes five steps. As shown in FIG. 3A, in a first step, a through hole is formed through a central portion of a circular planar substance by a forging process. In a second step, the substance that has been processed in the first step is heated. As shown in FIG. 3B, the substance that has been heated at the second step is shaped into an annular shape around the through hole by a ring rolling method, in a third step. As shown in FIGS. 3C and 3D, in a fourth step, opposite sides of the annular substance are pressed by upset forging to form linear sections therein. As shown in FIG. 3E, in a fifth step, the substance that has been processed in the fourth step is fine-finished, thus producing a door frame.

In detail, first, before the first step, the substance is heated to a predetermined temperature by a furnace and machined in a circular planar shape by a rough-shaping process which is a pre-forging process.

The substance that has passed through the preliminary step is processed by the first step so that the through hole 110 is formed through the central portion of the substance by punching.

Subsequently, the second step is performed, which is carrying out a heating process required to conduct the ring rolling process of the third step. In the third step, the diameter of the annular substance is extended.

The ring rolling method refers to a method in which an annular substance is pressed by a forging machine, including a main roll, a rolling mandrel and an axle roll which is provided at each of upper and lower sides, so that the diameter of the substance is extended into a desired shape.

Here, the circumference of the center hole of the substance that has been processed by the ring rolling method in the third step corresponds to the length of a center line of the door frame which is a final product.

FIGS. 4A and 4B are views comparing the final product to the substance that has been processed in the third step of the door frame manufacturing method according to the embodiment of the present invention.

The present invention must be designed such that the circumstance of the center hole 14 of the substance 10 of FIG. 4A that has been processed in the third step is the same as the length of the center line 24 of the door frame 20 of FIG. 4B which is the final product.

Subsequently, as shown in FIGS. 3C and 3D, in the fourth step, the opposite sides of the annular substance are pressed by upset forging so that the linear sections are formed in the substance. As shown in FIG. 3E, the fifth step includes fine-finishing the substance that has been processed in the fourth step, thus completing the door frame.

Meanwhile, in the fourth step, the substance 100 must be re-heated to a predetermined temperature when upset forging it. The heated substance 100 is placed on a lower mold 50, and an upper mold 60 is pressed by a press so that a linear section is formed in each of the opposite sides of the substance 100. In the fifth step, the substance is fine-finished, thus completing the final product.

Several conditions must be met in order for upset forging to be used to make the linear sections.

A ratio (t/w) of a thickness t to a width w of the substance, which has been processed in the fifth step which is the final step, must range from 0.5 to 1. A length ratio (a/b) of a linear section a, which is formed in each of the opposite sides of the substance, to a curved section b must be 0.7 or more. A ratio (w/L) of the width w to a height L of the substance must be 0.1 or more.

FIG. 5 is a plan view of the door frame manufactured by the door frame manufacturing method according to the present invention. FIG. 6 is a perspective view of FIG. 5.

As shown in FIG. 5, each of the linear sections a which are formed on the opposite sides of the substance must be shorter than the curved section b (in detail, having an elliptical shape) which is formed in each of both ends of the substance, and the ratio (a/b) must be 0.7 or more. If the linear section is excessively long, the substance may be deformed during the forging process.

Furthermore, if the width w of the substance is excessively small with respect to the height L of the substance, or if the thickness t of the substance is excessively small or large with respect to the width w of the substance, the substance may also be deformed during the upset forging process. Therefore, the ratio (t/w) of the thickness t to the width w of the substance must range from 0.5 to 1, and the ratio (w/L) of the width w to the height L of the substance must be 0.1 or more.

As described above, a method of manufacturing a door frame for a wind tower according to the present invention includes shaping a substance in a shape similar to that of the door frame through ring-rolling and upset-forging processes, and fine-finishing it, thus completing a final product. Therefore, unlike the conventional art, a rough machining process can be omitted. Thereby, the cost and time required to manufacture the door frame can be markedly reduced.

The critical technical spirit of the present invention is to provide a method of a door frame for a wind tower. Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A method of manufacturing a door frame for a wind tower, comprising:

forging a circular planar substance, thereby forming a through hole in a central portion of the substance;

heating the substance processed by the forging;

ring-rolling the heated substance around the through hole in an annular shape such that a circumstance of a center hole of the substance is equal to a length of a center line of the door frame;

upset-forging the annular substance so that opposite sides of the substance are pressed to form linear sections; and

fine-finishing the substance processed by the upset-forging, thus completing the door frame.

2. The method as set forth in claim 1, wherein a ratio (t/w) of a thickness (t) to a width (w) of the substance processed by the fine-finishing ranges from 0.5 to 1.

3. The method as set forth in claim 1, wherein in the fine-finishing the substance, a length ratio (a/b) of the linear section (a) formed in each of the opposite sides of the substance to a curved section (b) is 0.7 or more.

4. The method as set forth in claim 1, wherein a ratio (w/L) of a width (w) to a height (L) of the substance processed by the fine-finishing is 0.1 or more.