Method of forming steel ductwork

Abstract

The method includes providing a segment bending machine (10, Figure 7) comprising: a body 24; a table 12 for supporting a sheet metal blank M; a clamping member 14 to move relative to the table between spaced and clamping positions (P2, P1, Figure 1); a clamping arm 26 moves the clamping member between the two positions; an angle bar 16 pivotally mounted to the table about pivot axis P; a bending leaf arm 20 rigidly coupled to the bar such that pivotal movement of the leaf arm causes corresponding pivoting of the angle bar about the axis. Providing an angle brace member 22 with a first engagement formation 22b coupled to the bending leaf arm and one of second engagement formations coupled to an abutment 24a on the body to define a first angle, a, between the table and bar which is not 180 degrees. Positioning a steel sheet metal blank between the table and the clamping member such that it is supported on the table and a portion of the angle bar. Pivotally moving the clamping arm to move the clamping member to the clamping position to bend the blank. Steel ductwork is then formed from the bent blank.

Description

Field This invention relates to a method of forming steel ductwork. Background Ductwork is used in buildings to transport air from heating, ventilation, and air-conditioning (HVAC) to areas of a building. Ductwork is generally formed from multiple box-section components which are joined together to form an air passage network. Components can for example be of rectangular section or round section and "square to round" transitions can be formed to connect these two types of section. Components can be straight sided to form longitudinal sections of the air passage network or curved to provide bends between sections. It is known to form ductwork from steel, a common choice being galvanised mild steel having a zinc coating. In order to form ductwork, it is known to use a CNC plasma cutting table to cut one or more blanks out of a sheet of mild steel. Once cut, a blank can be bent into a ductwork component. It is common for a blank to be bended a plurality of times to create either a complete section of ductwork having a polygonal cross section, such as a rectangular section, or the bank can be shaped through a series of bends to form a component part of a section of ducting. A segment bending machine, also known as a box and pan folder, is a type of hand operated machine used to bend sheet metal. A segment bending machine has a series of segmented fingers of varying lengths that can be adjusted to create different bend angles and lengths. The fingers can be removed or rearranged to accommodate different sizes and shapes of metal. The present inventor has devised a new method of forming steel ductwork which can provide one or more of the following advantages relative to know methods: faster creation of ductwork; more accurate bending angles. Summary of the Invention In accordance with a first aspect of the invention, there is provided a method of forming steel ductwork, the method comprising: providing a manually operated segment bending machine comprising: a body; a table for supporting a sheet metal bank; a clamping member movably mounted to move relative to the table between a spaced position and a clamping position; a clamping arm for moving the clamping member between the spaced position and the clamping position; an angle bar pivotally mounted adjacent to an edge of the table to pivot about a pivot axis; a bending leaf arm rigidly coupled to the angle bar such that pivotal movement of the bending leaf arm causes corresponding pivoting of the angle bar about the pivot axis; providing an angle brace member having a first engagement formation and a plurality of second engagement formations; coupling the first engagement formation to the bending leaf arm and coupling one of the plurality of second engagement formations to an abutment on the body to define an angle between the table and an upper surface of the angle bar which is not 180 degrees such that the table and the upper surface of the angle bar are not coplanar; positioning a steel sheet metal blank at a first position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar; pivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal bank to define a first fold line; and forming steel ductwork comprising the bent sheet metal blank. The method of using the segment bending machine according to embodiments of the invention thus enables a precise bend angle to be set and dictated by the angle brace. When a plurality of successive bends of the same bend angle are to be created, as is common, the process of creating a bend becomes a two-step process of i) aligning the blank and ii) operating the clamping arm to create the bend, rather than the three-step known of using a segment bending machine, which requires i) aligning the blank, ii) operating the clamping arm to clamp the blank between the clamping member and the table while the table and upper surface of the angle bar are coplanar and then iii) operating the bending leaf arm to create the fold line. The method can further comprise, prior to the step of forming steel ductwork comprising the bent sheet metal blank, performing the following steps one or more times: positioning the sheet metal blank at a distinct position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar; and pivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal bank to define a further fold line. The method can further comprise, prior to the step of forming steel ductwork comprising the bent sheet metal blank: uncoupling the first one of the plurality of second engagement formations from the abutment; coupling a second one of the plurality of second engagement formations to the abutment to define an second angle between the table and the upper surface of the angle bar which is not 180 degrees and which is distinct from the first angle; and performing the following steps one or more times: positioning the sheet metal blank at a distinct position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar; and pivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal bank to define a further fold line. Optionally: the angle brace member is an elongate, rectangular section bar having a width greater than a thickness and the plurality of second engagement formations each comprises a hole formed through the thickness of the rectangular section bar; the abutment comprises a pin mounted on the body; and the step of coupling one of the plurality of second engagement formations to the abutment on the body comprises moving the rectangular section bar to insert the pin in one of the plurality of holes. Optionally: the first engagement formation is defined by a portion of the rectangular section bar which is shaped to define a transverse recess relative to the length of the rectangular section bar, the transverse recess being sized to receive a portion of the bending leaf arm; and the step of coupling the first engagement formation to the bending leaf arm comprises moving the rectangular section bar to place the portion of the bending leaf arm in the transverse recess such that the recess faces generally away from the table. Optionally: the ductwork comprises a lobster back bend, tapered section, square to round section, rectangular section, or conical section, which are formed by bending the blank one or more times into required shapes and securing in shape by spot welding and / or mechanical fixing. Brief Description of the Drawings By way of example only, certain embodiments of the invention will now be described by reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of components of a known segment bending machine, illustrating how the clamping fingers can be raised and lowered; and Figure 2 is a schematic diagram of the segment bending machine of Figure 1, showing a sheet of metal clamped between the base and clamping fingers; Figure 3 is a schematic diagram of the segment bending machine of Figure 1, showing the metal bent at an angle; Figure 4 is a schematic diagram of the segment bending machine of Figure 1 including a bracing member according to an embodiment of the invention, illustrating a new way of introducing a sheet of metal; Figure 5 is a schematic diagram of the segment bending machine of Figure 4, illustrating a new way of bending the sheet of metal; Figures 6a and 6b are schematic side and plan view diagrams of parts of the segment bending machine of Figure 4, illustrating the bracing member; Figure 7 is a schematic perspective view diagram of the segment bending machine of Figure 4; and Figure 8 is a flow chart illustrating a method of producing steel ductwork according to an embodiment of the invention. Detailed Description Figure 1 is a schematic diagram of components of a known segment bending machine 100. The segment bending machine 100 is a machine that an operator can use to manually create a linear fold across a sheet of metal. Referring additionally to Figure 7, the segment bending machine 100 has a body 24 for supporting components on the segment bending machine 100 on a floor F. The body 24 support a table 12 which is orientated to be parallel with respect to the floor F and is spaced above the floor by a suitable working height, such as being roughly Im from the floor F; in one example, the working height can be 89cm. The table 12 is arranged to support a sheet metal blank that is to be bent. As illustrated in Figure 1, clamping member 14 is disposed above the table 12 and moveable mounted so as to be movable towards and away from the table 12 between a spaced position P2 in which a sheet of metal can be placed between the table 12 and clamping member 14 and a clamping position Pl in which the sheet of metal is clamped between the table and clamping member 14. A lower surface of the clamping member 14 is planar to define an engagement surface for engaging an upper surface of a sheet metal blank. The clamping member 14 is arranged to be raised and lowered by a clamping arm 26 via a displacement mechanism in a known manner. The clamping arm and / or displacement mechanism can be weighted to bias to clamping member 14 to assume or remain in the spaced position P2. An angle bar 16 is disposed adjacent to the front edge of the table 12 and pivotally mounted to be pivotable about a pivot axis P which is parallel and adjacent to the front edge of the table 12. An upper surface 16a of the angle bar 16 is planar. The angle bar 16 is mounted such that the upper surface 16a is coplanar with the table 12 when the angle bar 16 is at a particular angular position, which can be a default position to which it is weighted. A bending leaf apron 18 extends orthogonally from the upper surface of the angle bar in a downward direction such that the angle bar 16 and bending leaf apron 18 define a rigid, generally L shaped member when viewed from the side. A bending leaf arm 20 extends downwardly from the bending leaf apron 18 and is rigidly mounted relative to the bending leaf apron 18 such that pivotal movement of the bending leaf arm 20 creates corresponding pivotal movement of the angle bar 16. Referring additionally to Figure 2, in use, an operator places a sheet metal blank M on the table 12 with the pivot axis P denoting the intended bend line BA across the sheet metal blank M. The clamping handle 26 is then pivotally moved to linearly move the clamping member 14 from the spaced position P2 to the clamping position Pl and the sheet metal blank M is gripped between the table 12 and clamping member 14. Referring additionally to Figure 3, the operator may then pivotally move the bending leaf arm 20 though an angle a, which causes the angle bar 16 to pivot about the pivot axis P to place the upper surface of the angle bar 16 at a corresponding angle a with respect to the table 12, creating a bend in the metal sheet M along the bend line BA having a corresponding angle a. By following the above process, sheet metal blanks can be bent one or more times into a desired shape using the segment bending machine 100 and subsequently secured in shape to form metal ductwork. Known segment bending machines that can be used in embodiments the invention include an Edwards Kennard Box &Pan Folder Model 416 and a Morgan Rushworth BP100 14 Hand Box and Pan Folder. The present inventor has developed a modified segment bending machine which can be used in a new way to enable sheet metal blanks to be bended faster and / or with increased bend angle accuracy. Referring now to Figures 4 and 7, a segment bending machine 10 according to an embodiment of the invention is shown. The segment bending machine 10 is similar to the segment bending machine 100 of Figures 1 to 3 and like parts have been given the same reference numerals. For brevity, the following description will focus on the differences. The segment bending machine 10 includes an angle brace 22 configured to hold the bending leaf arm 20 at one of a plurality of angles, such that the upper surface of the angle bar 16 can be set at one of a corresponding plurality of angles relative to the table 12. The angle brace 22 is arranged to brace between the bending leaf arm 20 and a suitable abutment 24 on the body of the segment bending machine 10. With the angle brace 22 engaged and the clamping member 14 set at the spaced position P2, an operator can introduce place a sheet metal blank M on the table and align the intended bend line BA with the pivot axis P. Referring additionally to Figure 5, the operator can then pivotally move the clamping arm to move the clamping member 14 to the clamping position Pl, which bends the sheet metal blank M with the desired bend angle. A segment bending machine 10 according to embodiments of the invention thus enables a precise bend angle to be set and dictated by the angle brace 22. Referring additionally to Figures 6a and 6b, the angle brace 22 is an elongate member having a body portion 22a including a plurality of holes H extending along the body portion 22a. One end of the angle brace 22 includes an engagement formation 22b shaped for example to engage a bar 20a extending between side portions of the bending leaf arm 20. The engagement formation 22b can be shaped to define a recess for receiving and retaining the bar 20a. The abutment in this example is a vertical pin 24a welded to a cross member of the body 24. A such, with the bar 20a seated within the engagement formation 22b, the pin 24a can be inserted into one of the plurality of holes H by moving the angle brace 22 with the bending leaf arm 20 to set one of the plurality of bend angles. Figure 8 shows a method of forming steel ductwork using the segment bending machine 10 of Figures 4 to 7. At step 30, the method comprises providing a segment bending machine comprising: a body; a table for supporting a sheet metal bank; a clamping member movably mounted to move relative to the table between a spaced position and a clamping position; a clamping arm for moving the clamping member between the spaced position and the clamping position; an angle bar pivotally mounted adjacent to an edge of the table to pivot about a pivot axis; a bending leaf arm rigidly coupled to the angle bar such that pivotal movement of the bending leaf arm causes corresponding pivoting of the angle bar about the pivot axis. At step 32, the method comprises providing an angle brace member having a first engagement formation and a plurality of second engagement formations. At step 34, the method comprises coupling the first engagement formation to the bending leaf arm and coupling one of the plurality of second engagement formations to an abutment on the body to define one of a plurality of discrete angles between the table and an upper surface of the angle bar. At step 36, the method comprises positioning a sheet metal blank between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar. At step 38, the method comprises pivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal bank. At step 40, the method comprises forming steel ductwork comprising the bent sheet metal blank. The ductwork can for example comprise lobster back bends, tapered sections, square to round sections, rectangular sections, or conical sections, which are formed by bending blanks one or more times into required shapes and securing in shape by spot welding and / or mechanical fixing. Then method can comprise repeating steps 36 and 38 one or more times to further bend the sheet metal blank one or more times and can comprise repeating step 34 to change the bending angle. As will be appreciated, the steps of the method are performed manually, by hand. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of forming steel ductwork, the method comprising: providing a segment bending machine comprising: a body; a table for supporting a sheet metal blank; a clamping member movably mounted to move relative to the table between a spaced position and a clamping position; a clamping arm for moving the clamping member between the spaced position and the clamping position; an angle bar pivotally mounted adjacent to an edge of the table to pivot about a pivot axis; a bending leaf arm rigidly coupled to the angle bar such that pivotal movement of the bending leaf arm causes corresponding pivoting of the angle bar about the pivot axis;providing an angle brace member having a first engagement formation and a plurality of second engagement formations;coupling the first engagement formation to the bending leaf arm and coupling one of the plurality of second engagement formations to an abutment on the body to define a first angle between the table and an upper surface of the angle bar which is not 180 degrees;positioning a steel sheet metal blank at a first position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar;pivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal blank; andforming steel ductwork comprising the bent sheet metal blank.

2. The method of claim 1, further comprising, prior to the step of forming steel ductwork comprising the bent sheet metal blank, performing the following steps one or more times:positioning the sheet metal blank at a distinct position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar; andpivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal blank to define a further fold line.

3. The method of any preceding claim, further comprising, further comprising, prior to the step of forming steel ductwork comprising the bent sheet metal blank:uncoupling the first one of the plurality of second engagement formations from the abutment;30 04 25coupling a second one of the plurality of second engagement formations to the abutment to define a second angle between the table and the upper surface of the angle bar which is not 180 degrees and which is distinct from the first angle; andperforming the following steps one or more times:positioning the sheet metal blank at a distinct position between the table and the clamping member such that the sheet metal blank is supported on the table and a portion of the upper surface of the angle bar; andpivotally moving the clamping arm to move the clamping member to the clamping position to bend the sheet metal blank to define a further fold line.

4. The method of any preceding claim, wherein:the angle brace member is an elongate, rectangular section bar having a width greater than a thickness and the plurality of second engagement formations each comprises a hole formed through the thickness of the rectangular section bar;the abutment comprises a pin mounted on the body; andthe step of coupling one of the plurality of second engagement formations to the abutment on the body comprises moving the rectangular section bar to insert the pin in one of the plurality of holes.

5. The method of claim 4, wherein:the first engagement formation is defined by a portion of the rectangular section bar which is shaped to define a transverse recess relative to the length of the rectangular section bar, the transverse recess being sized to receive a portion of the bending leaf arm; andthe step of coupling the first engagement formation to the bending leaf arm comprises moving the rectangular section bar to place the portion of the bending leaf arm in the transverse recess such that the recess faces generally away from the table.

6. The method of any preceding claim, whereby the ductwork comprises a lobster back bend, tapered section, square to round section, rectangular section, or conical section, which are formed by bending the blank one or more times into required shapes and securing in shape by spot welding and / or mechanical fixing.

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