Claims:WE CLAIM:
1. A method of bending a convex profile bend on pressed curved erosion sheet comprising steps of:

- taking a tube (06) of length X, diameter of which is same as that of work piece (09) required,
- welding the tube (06) on machine clamp (04),
- welding another tube (05) of length Y and of diameter same as that of the work piece on machine pressure die (02),
- mounting a former (03) according to required radius of bend and diameter on rotary bending machine,
- placement of the work piece (09) on the die (02),
- pressing of the clamp (04) towards the work piece (09).

2. The method of bending a convex profile bend on pressed curved erosion sheet as claimed in claim 1, wherein the work piece (09), curvature of which encompasses the tube (05) according to the location of bending and pressure is applied through hydraulic cylinders (not shown) to the former so as to hold the work piece (09).

3. The method of bending a convex profile bend on pressed curved erosion sheet as claimed in claim 1 or 2, wherein said pressing of the clamp (04) is followed by bending by setting the required bend angle.

4. A method of bending a concave profile bend on pressed curved erosion sheet comprising steps of:-

- taking a tube (08) of length X1 having diameter same as that of work piece (09),
- bending the tube at length of X1-?X from the start thereof to obtain a bent tube (08),
- placement of the bent tube (08) on former (03) mounted on rotary bending machine,
- placement of workpiece (09) on the bent tube,
- raising a pressure die (02) towards the work piece (09),
- raising of clamp (04) towards the work piece (09) for bending.

5. The method of bending a concave profile bend on pressed curved erosion sheet as claimed in claim 4, wherein the former (03) is mounted on the machine according to the required radius of bend and diameter of the work piece (09) and in the same position and location as it is bent and welded thereto.

6. The method of bending a concave profile bend on pressed curved erosion sheet as claimed in claim 4 or 5, wherein the work piece (09), curvature of which encompasses the bend tube (08) and according to the location where the bend is required.

7. The method of bending a concave profile bend on pressed curved erosion sheet as claimed in claim 4-6, wherein the clamp (04) is raised towards the work piece (09) followed by bending.

8. The method of bending a concave profile bend on pressed curved erosion sheet as claimed in claim 4-7, wherein the bending is carried out according to the required angle of bend.
, Description:A method of bending a convex and a concave profile bend on pressed curved erosion sheet

FIELD OF INVENTION
[001] The present invention relates to a method of bending a convex and a concave profile bend on pressed curved erosion sheet. The method can be implemented for bending 9OO and other angle bend on pressed curved erosion sheets in rotary bending machines.

BACKGROUND OF THE INVENTION

[002] In high temperature and high pressure boilers, erosion on tubes occurs due to repeated impingement of ash particles on the tubes. This reduces the thickness of the tubes, which may lead to failure in service. In order to avoid this, erosion sheets were introduced. The same is of stainless steel material and 2mm thickness, which can withstand erosion and corrosion. These erosion sheets are designed to be placed over the tubes which are prone to erosion and are of the same profile as the original tube. Said sheets are placed only on the side exposed to the ash and not on the inner side of the tubes. The profiles of the tubes include straight portions, bends in single plane and multi planes. At the bent portion, the erosion sheets are to be bent in both convex as well as concave profiles. For this purpose, the sheets are required to be bent and presently there are no provisions available for bending these profiles. Hence a method has to be devised so as to bend these profiles with the available resources.

OBJECTS OF THE INVENTION

[003] Primary object of invention is to propose a method of manufacturing angle bend of curved erosion sheets of both convex and concave profile in a bending machine.

[004] Another object of invention is to propose a suitable former and pressure die for manufacturing these bends.

SUMMARY OF THE INVENTION

[005] The present invention proposes a method of bending erosion sheets in a rotary bending machine. This includes various profiles. The inventors have developed a method to bend these profiles with modification made in the former, follower jaw and clamp of a rotary bending machine.

[006] The sheet has to be firstly bent to half the curvature of the tube, according to the tube diameter. It can be done by any pressing operation, with a die designed according to the diameter of the tube and length of the sheet. Now with the sheet bent to half the curvature of the tube, it has to be further bent to suit the tube in bend location.

[007] The sheets are to be bent in both convex and concave directions as per the requirement. The present invention deals with developing a method of angle bending the sheet curved erosion which is prepared through pressing operation according to the curvature of the tube to the required profile.

[008] For bending convex profile on sheets, a tube of diameter same as the boiler tube for which the sheet has to be attached is taken and welded on the clamp of 100mm and also on the follower jaw of 500mm. A former according to the radius of the bend and the diameter of the boiler tube is mounted on the rotary bending machine. Now the work piece is placed on the welded follower jaw and the bending operation is completed by applying pressure on the follower jaw and clamp towards the former and bend it to the required radius of bend and angle of bend as required.

[009] For bending concave profile on the sheets, a tube of X1 length and of the diameter same as that of the boiler tube is bent to the required radius of the boiler tube and welded on the former which again is mounted on the rotary bending machine according to the radius and the diameter of the boiler tube. The follower jaw and clamp without any tube welding is mounted according to the diameter of the boiler tube. Here, the bending operation is carried out by placing the sheet on the tube welded on the former and by applying pressure on the die/follower jaw and clamp towards the former.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[010] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein: -
Figure 1 shows: The bending profile of a convex profile bend and the corresponding modifications made in the pressure die and the clamp according to present invention.
Figure 2 shows: The bending profile of a concave profile bend and the corresponding modifications made in the former in accordance with present invention.
Figure 3 shows: The work piece of invention.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS

[011] The instant invention makes a disclosure in respect of an invention pertaining to a method of bending a convex and a concave profile bend on pressed curved erosion sheet. An already pressed curved erosion sheet is taken for bending a convex/concave profile bend.

[012] The invention introduces a method of preparing angle bend of curved erosion sheets of both convex and concave profile in a rotary bending machine as illustrated in the fig. 1-3.

[013] A straight tube of two lengths (6 and 5) is welded on the clamp (04) and pressure die (02) respectively for bending a convex profile bend (01). A bent tube (08) is welded on the former (03) for bending concave profile bends (07). The diameter of the curved sheet can be modified and can be of any size according to the capacity of the bending machine.

[014] The angle of bend can be anything of the range 1o to 180o.

[015] Now, the above will be discussed one by one hereinunder.

[016] A work piece constituting pressed curved erosion sheet (09) is taken. For bending a convex profile bend (01) on said pressed curved erosion sheet (09), a tube of length X (06), diameter of which is same as that of the work piece (09) required is taken and welded on the machine clamp (04). Further, a tube of length Y (05), diameter of which is same as that of the work piece (09) required is taken and welded on the machine pressure die (02). A former (03) according to the required radius of bend and diameter is mounted on the rotary bending machine. Now the work piece (09) is placed on the pressure die (02) such that it’s curvature encompasses the tube (05) welded to the pressure die (02) according to the location where the bend is required and pressure is applied through hydraulic cylinders (not shown) to the former so as to hold the work piece (09). Thereafter, the clamp (04) is pressed towards the work piece (09) and then the bending operation is started and completed by setting the bend angle according to the requirement.

[017] The above forms first embodiment of invention. The second embodiment is as follows.

For bending a concave profile bend (07) on the pressed curved erosion sheet (09), a tube of length X1 (08) having diameter same as that of the work piece (09) is taken and bent at X1-?X from the start of the tube, so that the rest ?X portion is bent. Now this bend (08) is placed on the former (03) which is mounted on the machine according to the required radius of bend and diameter of the work piece (09) and in the same position and location as it was bent and welded to it. Now the work piece (09) is placed on the bend (08) such that it’s curvature encompasses the bend tube (08) and according to the location where the bend is required. Now the pressure die (02) is raised towards the work piece (09) through hydraulic cylinders (not shown) to hold the work piece (09) while bending. Then the clamp (04) is also raised towards the work piece (09) and the bending operation is started and completed according to the required angle of bend.

WORKING EXAMPLES

[018] For bending a convex profile bend (01) on said pressed curved erosion sheet (09), a tube of length 100mm (06), diameter of which same as that of the work piece (09) required is taken and welded on the machine clamp (04). Further, a tube of length 500mm (05), diameter of which same as that of the work piece (09) required is taken and welded on the machine pressure die (02). A former (03) according to the required radius of bend and diameter is mounted on the rotary bending machine. Now the work piece (09) is placed on the pressure die (02) such that it’s curvature encompasses the tube (05) welded to the pressure die (02) according to the location where the bend is required and pressure is applied through hydraulic cylinders (not shown) to the former so as to hold the work piece (09). Thereafter, the clamp (04) is pressed towards the work piece (09) and then the bending operation is started and completed by setting the bend angle according to the requirement.

[019] For bending a concave profile bend (07) on the pressed curved erosion sheet (09), a tube of length 150mm (08), having diameter same as that of the work piece (09) is taken and bent at 50mm from the start of the tube, so that the rest 100mm portion is bent. Now this bend (08) is placed on the former (03) which is mounted on the machine according to the required radius of bend and diameter of the work piece (09) and in the same position and location as it was bent and welded to it. Now the work piece (09) is placed on the bend (08) such that it’s curvature encompasses the bend tube (08) and according to the location where the bend is required. Now the pressure die (02) is raised towards the work piece (09) through hydraulic cylinders (not shown) to hold the work piece (09) while bending. Then the clamp (04) is also raised towards the work piece (09) and the bending operation is started and completed according to the required angle of bend.

[020] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[021] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-