JPH0373376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metal processing, and more particularly to a method for manufacturing metal cones of complex cross-sectional shapes.

There are many articles in which ring-shaped metal structures are used. If the finished ring is of relatively thin thickness, significant material will be wasted during machining if the preform is formed into an inefficient shape. For these reasons, it is rarely preferred that the starting material be part of a billet or plate. Generally, the starting material is a forged or wrought material, a cast product, or a welded product.

The problem of manufacturing relatively brittle ring-forming features is particularly evident in the manufacture of gas turbine engines. Machines of this type are difficult to machine because the metals used in them have the required high strength properties. Furthermore, in aircraft applications,
Rings are often very thin to reduce weight. This means that a significant amount of material is wasted during machining due to the use of relatively tight tolerance forgings and castings.

Therefore, ring rolling is often used to produce ring-shaped preforms. Most commonly, the ring rolling method involves forming a first ring-shaped compact with a relatively low degree of processing, and then rolling that compact in a suitable machine to the desired diameter and cross-sectional area. This includes changing the value to a value close to that of the actual value. The starting material for forming the first ring-shaped compact is generally a forging or other form of wrought material such as a perforated plate.
It is also common practice to use a section of bar stock, roll it into a ring of a first diameter, and butt weld the ends of the bar stock where they face each other. In the case of ring rolling to a second, larger diameter, the weld is necessarily and preferably processed together with the original material.

Machines for ring rolling are generally described in the technical literature. U.S. Pat. No. 3,999,416 relates specifically to forming rings of a predetermined shape useful in gas turbine engines. The method disclosed in this patent includes continuous cold rolling between a plurality of shaped dies.

Manufacturing cones is more difficult than manufacturing straight cylinders. For example, the most common method for processing a flat metal plate into a truncated cone shape is to cut a metal plate of a predetermined shape from a flat metal plate, and then form it into a ring using a 3-roll rolling mill or a 4-roll rolling mill. It is to be. In this regard, Metals Park, Ohio, United States of America,
Published by American Society for Metals
Metals Handbook, Volume 8, Volume 4, Page 222,
and U.S. Patent No. 4195509, U.S. Patent No. 3623349, U.S. Patent No.
Please refer to No. 3279229.

Flat metal rolling is said to be more of an engineering than a science, as it has only been fully studied in the past 30 years. Ring rolling involves somewhat more complex geometries than flat materials, and therefore many aspects of the plastic mechanisms that form cylindrical rings are currently unknown. In this regard, the 1979 International
In Metal Reviews No. 4, pages 137-148, W.
“Rolling of
Please refer to "Rings". Thus, since there is no "science" of producing conical rings by rolling, technical improvements are much more necessary than scientific analysis as far as possible reduction of material waste and as much economy as possible is concerned. It is said that

One object of the present invention is to provide an efficient method for manufacturing a frusto-conical sheet metal cone with relatively precisely dimensioned article cross-sections. Another object of the present invention is to provide a method for forming nickel superalloys into shapes suitable for manufacturing gas turbine combustor liners.

Generally, the invention involves longitudinally rolling a workpiece such that the thickness of one portion of the cross section is reduced to a greater extent than the thickness of the other portion. This forms a curved trapezoid, which becomes conical when formed into a ring on a three-roll mill.

According to a preferred embodiment of the method of the invention, two rectilinear pieces of material each having a specific preformed contour are joined by longitudinal welding. For example, a rod-shaped material having a T-shaped cross-section is joined to a flat plate-shaped piece of material. The thus welded workpiece is then longitudinally rolled by passing it through contour rolls which reduce the thickness of one section more than the other. For example, the thickness of the first part is reduced by 10% and the thickness of the second part is reduced by 30%. The cross-sectional shape of the welded workpiece rolled by contour rolling is substantially equal to the profile required in the rolled ring. During the contour rolling process, the weld is preferably reduced in cross-section to help improve its properties. Since the reduction amounts are different, the length of the workpiece processed by contour rolling at one longitudinal side edge is longer than the length at the other longitudinal side edge. The workpiece is then formed into a circular shape by such methods as passing it through a conventional three roll mill. In repeated passes, the gap between the rolls is gradually reduced so that the workpiece is formed into a ring, the ends of which substantially abut. The shape of the circularly machined workpiece thus becomes substantially a truncated cone. Preferably, the ends of such a cone overlap each other and they are carefully trimmed and welded. The thus welded cone is then re-rolled or otherwise dimensioned to the final desired dimensions, depending on the accuracy required.

By varying the relative reduction in the cross-sectional area of longitudinally adjacent sections of the workpiece after it has been contour rolled and before it has been formed into a circular shape, a cone of arbitrary shape can be produced. can be manufactured. The difference in the length of the corresponding side edges approximately corresponds to the difference in the amount of reduction. Also, the cone angle is determined accordingly.

The method of the present invention requires only relatively simple profile rolls that are not subject to scuffing that can occur in other methods.
Furthermore, according to the method of the invention, inexpensive rolled material can be used as starting material and good welding properties in the circumferential direction can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

The present invention will now be described with respect to manufacturing a combustor liner cone for a gas turbine engine such as that described in commonly assigned U.S. Pat. No. 4,380,906. However, the present invention is also useful for manufacturing cones made of sheet metal for other uses.

The combustor liner is made of high temperature superalloy. The examples described below are alloy Hastelloy.
X (22wt%Cr, 18.5wt%Fe, 1.5wt%Co, 0.10wt
%C, 9wt%Mo, 0.6wt%W, balance Ni). The present invention is useful with any material that can be formed by rolling and welded to itself, including certain non-metallic materials.

Combustor liners are generally annular structures consisting of a series of interengaging frusto-conical segments. In this regard, for example, US Pat. No. 4,077,205
See No. 3978662. The shape of one typical combustor liner segment 40 is shown in FIG. The cone angle may vary, and as used herein, the cone angle is one-half the apex angle of the cone, which is the relationship between the cross section of the liner segment 40 and the central axis 42, as shown in FIG. The angle P between Typically, the cone angle of the combustor liner segment is up to 35°. According to the results of research and development to date, the present invention is useful for producing cones having cone angles of at least up to 54 degrees.

The following example is a preferred embodiment of the invention in producing a cone having a cross-sectional shape similar to that shown in FIGS. 1 and 2. Each manufacturing step is shown in FIG. Generally, rolling begins in a conventional shape, where the two materials are first contour rolled to a first set of precise dimensions, then welded together, contour rolled again, and then rounded, including a truncated cone. is formed into. In steps A1 to A3 shown in Figure 3, the diameter of 16 mm in step A1
The round bar is contour rolled into a workpiece 10 having a specific cross-sectional shape in steps A2 and A3. In this case, contour rolling is performed by passing it through a conventional high-speed two-high rolling mill multiple times, and in order to facilitate rolling and to avoid cracks in the material due to processing, between each contour rolling process, Annealing is performed at 1150°C for 1 hour. Workpiece 10 is the process
When A3 is compared with the conditions in process A1,
Its cross-sectional area has been substantially reduced and, of course, the length of the workpiece has been correspondingly substantially increased. As is well known, it is a feature of contour rolling that such results can be obtained. In Figure 3, process A3
The lateral dimensions of the workpiece in step A1 are increased by about 20% relative to the width of the material in step A1.

Similarly, the flat strip shown in step B1 is
It is contour rolled into a groove-shaped work piece 11 with flanges as shown at B2. Next, in step B3, the workpiece 11 is divided in the axial direction by this cutting or the like, thereby forming two independent workpieces 12 and 14. Workpiece 12 is used in subsequent steps and workpiece 14 is used to manufacture other assemblies.

In step C1, the workpiece 12 is butt welded to the workpiece 10 along the longitudinal weld 16;
This forms a welded workpiece 18.
What is important in each of the above steps is that the thickness T1 of the workpiece 12 is greater than the thickness T2 of the workpiece 10, and in this case the thickness is measured near the weld. It is a value. Filler metal is supplied to the weld during welding to bring the thickness of the weld to substantially T1, as required for successful welding.

In step C2, the workpiece 18 is then formed into a cross-sectional shape that closely approximates that required in the final article, except for some modifications in the preferred or optional steps described below. It is passed through a contour roll formed into a suitable shape. In this contour rolling step C2, the thickness T1 of the portion 12 is reduced to a new thickness T3, which is preferably slightly smaller than T2. In other words, the cross-sectional area of portion 10 is reduced by a relatively small amount or not at all, and portion 1
2 is substantially reduced. This results in the workpiece 18 becoming a curved trapezoid, as shown in FIG. 4, in which length L1 on the side of section 12 is longer than length L2 on the side of section 10. As long as the cross-sectional area of part 12 is greatly reduced, step C2
It is possible to substantially reduce the cross-sectional area of portion 10 in this case.

The inventors believe that when the thickness T3 is approximately 75% of the thickness T1, the process
It has been found that the number of passes of contour rolling required to form the work piece into the shape shown in C2 is one. Depending on the reduction amount and material properties, multiple rolling steps and annealing may be employed. As an example in this aspect of the invention, thickness T2 is 1.4 mm and thickness T1 is 1.65-1.78 mm. After step C2 is completed, the thickness T3 is about 1.27 mm. For a work piece with a length of about 3.04 m and a width of about 3.7 cm, length L1 was about 12% larger than length L2. The resulting cone angle nominally reflects changes in length and width of the workpiece. The ratio of the change in length of the side edges of the two parts 10 and 12 is somewhat smaller than the ratio of reduction in their cross-sectional area. This is a function of the complex dynamics of metal flow when machining workpieces with non-uniform cross-sections. By conducting sufficient experiments on a specific workpiece, the dimensional relationship of the workpiece before and after step C2 can be determined.

In the next step C3, the workpiece 18 is passed through a three-roll mill or a four-roll mill. These rolling mills are conventional ring forming machines as shown in FIG. Roll 20 is gradually moved toward stationary rolls 22 and 24 while workpieces 26 are continuously applied to the apparatus. Three roll forming continues until the ends of the workpiece overlap each other somewhat. The workpiece is then removed from the three-roll mill, its ends trimmed to the desired circumferential length, and then axially joined 28 as shown in FIG. 1 to form liner segments 40. Butt welded along.
Since length L1 is already longer than length L2,
A circular workpiece formed by butt welding as described above has a truncated conical shape.

The smaller side edge of the length of section 10 has an average diameter
D10, where the average diameter D10 is the average diameter of the portion formed by the larger side edges of the length of the portion 12.
Smaller than D12. Therefore, the cone angle of the two parts 10 butt-welded to each other in the longitudinal direction of the workpiece 18 is
and the relative reduction amount of 12. If a cone with a taper opposite to that described above is desired, the cross-sectional area of the workpiece 10 is reduced to a greater extent than the cross-sectional area of the workpiece 12.

For applications where good dimensional accuracy is required, such as in the case of combustor liners, the cone formed by the above series of steps can be used as an inflatable and removable or It may be expanded or contracted after welding using a machine with a regular outer die. Such machines were manufactured by Cemco, Louisville, Kentucky, USA.
Manufactured and sold by Inc. as Model H180-200. Stretch forming is commonly employed to increase the diameter by 0.5-5%. Other forming methods known in the art may be used to further change the dimensions of the cone after the longitudinal ends of the workpiece have been joined together at the axial weld.

A person skilled in the art in the processing of metal sheets will know that by cutting a trapezoidal workpiece from a flat metal material and passing the workpiece through a conventional three-roll rolling mill, the conical shape obtained by the method of the invention can be obtained. It will be understood that it is not possible to obtain a conical shape similar to the shape. In the above method, a cone can be formed by bringing the ends of a curved trapezoid into contact with each other, but the ends of the cone thus formed do not lie in mutually parallel planes. do not.

When manufacturing combustor liners for gas turbine engines, good properties are obtained along the longitudinal and circumferential welds 16 and 28 shown in FIGS. 1, 3, and 4. This is very important.
The thickness of the weld is therefore the reduced thickness of the workpiece,
That is, it is preferable to match the thickness T1 of the portion 12 in FIG. 3. This ensures that the welds are also machined properly. Process C3
After the workpieces have been axially welded to form the structure shown in FIG. Heat treated. As disclosed in detail in U.S. Pat. . That is, the cross-sectional area of the weld is preferably reduced by at least 20% and the weld is heat treated at 1150-1175°C for 1 hour.

Of course, it is not absolutely necessary for the two workpieces to be longitudinally welded when carrying out the method of the invention. For example, as shown in FIG. 6, step D1
The flat bar workpiece shown in may be formed into the first shape shown in step D2 by contour rolling. The processed piece in process D2 is the first part 3
0 and a second portion 32 continuous thereto. In the next step D3, the cross-sectional area of the first portion 30 is reduced, and the cross-sectional area of the second portion 32 is not reduced as much. This creates a cone with a taper opposite to that in the previous embodiment.

When manufacturing a cone having a complicated cross-sectional shape as shown, the method shown in FIG. 6 is generally not preferred for the following two reasons. Primarily,
In order to form a workpiece with the shape shown in step D2, the metal of the material must undergo excessive plastic movement. Second, two sets of coater rolls are used: a first set of contour rolls for forming into the shape shown in step D2 and a second set of contour rolls for forming into the shape shown in step D3. Needed. On the other hand, if the method shown in FIG. 3 is adopted, the contour roll used in the processing of step C2 can be used in the independent steps shown in steps A and B. In the preferred embodiment shown in FIG. 3, the maximum rolling force and mill size required are greater than the rolling force and size required in the embodiment shown in FIG. can also be reduced.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to such embodiments, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a combustor liner segment having a frusto-conical shape formed in accordance with the present invention. FIG. 2 is an enlarged cross-sectional view of the liner segment shown in FIG. 1; FIG. 3 is a process diagram showing one embodiment of the present invention. FIG. 4 is a perspective view showing a work piece formed in step C3 of the embodiment shown in FIG. FIG. 5 is an illustrative diagram showing three-roll forming for forming the work piece shown in FIG. 4 into a circular shape. FIG. 6 is a process diagram showing another embodiment of the method of the present invention in which welding is not performed. 10, 12, 14...Worked piece (part), 16...
...Welded part, 18... Welded work piece, 20...
Rolls, 22, 24... fixed roll, 26... workpiece, 28... axial joint, 30... first part, 32... second part, 40... liner segment, 42... central axis.

Claims (1)

[Claims] 1. A method for manufacturing a cone from a metal plate, comprising a step of providing a first workpiece of material having a first length, a first cross-sectional area, and a first thickness. and butt welding the first workpiece to a second workpiece of material having a second length, a second cross-sectional area, and a second thickness greater than the thickness of the first workpiece. forming a welded workpiece having a weld extending along the length of two butt-welded workpieces; and rolling said welded workpiece to perform a first operation. reducing the cross-sectional area of a second workpiece portion by an amount greater than the reduction in cross-sectional area of one portion, thereby uniformizing the thickness of the welded workpiece in the vicinity of the weld, thereby curving the welded workpiece by making the length of the second workpiece portion greater than the length of the first workpiece portion; said curvature such that the ends approach each other so that said second workpiece portion forms part of a cone having a larger average diameter than the average diameter of the portion comprising said first workpiece portion; rolling a welded workpiece into a circular shape;