JP3618028B2 - Method of manufacturing sheet bending parts, integrated system of cutting and bending and products of bending work - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a sheet bending part, an integrated cutting and bending system and a product of bending work.
[0002]
[Prior art]
Conventionally, for example, an automatic bending apparatus as described in the applicant's Italian Patent No. T093A000818 is known.
[0003]
The system described in the above-mentioned Italian patent provides that the part to be bent is supported by a manipulator so that the area of the part to be bent lies on a vertical suspension plane. The bending is done by an oscillating bending machine having two tools that may be arranged in any configuration with respect to the part to be bent. The part is supported by the manipulator in such a way that the part can move in a limited amplitude with five degrees of freedom except for rotation about an axis perpendicular to the plane of the undeformed part of the sheet. Has been.
[0004]
In the system described herein, the part has one or more grips that may be cut into a shape corresponding to a development in the plane of the part to be bent and coupled to a manipulator. The parts are fed individually to the bending machine, possibly after a measurement step performed while it is held by a manipulator.
[0005]
Automatic bending machines bend the part with punches and dies that are shaped and dimensioned to be specific to the particular type of bending to be made in the part. The automatic bending machine further has an automatic device for changing the tool.
[0006]
[Problems to be solved by the invention]
By the way, in the conventional automatic bending machine described above, a problem often occurs when a gripping position that is not affected by bending is identified during the manufacture of a part having a complicated shape. Cannot be bent.
[0007]
A further problem is that it is often necessary to change tools while machining the same part. Although an automated system for changing tools is fast moving, it takes some time to change tools and during that period the system cannot be produced.
[0008]
The object of the present invention is to provide further development of the bending system described in the above-mentioned Italian patent T093A000818 and to achieve a greater efficiency of the bending cycle.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention provides that the profile of the development in the plane of at least one part to be bent is defined in a flat sheet, and one or more parts and the surrounding part of the sheet. Is to leave the joint between the two. The portion of the sheet surrounding the part or parts constitutes a frame that can be used to grip the part by a manipulator that feeds the part into the bending press. The part is bent while the part is joined to the peripheral part of the thin plate by the joint. When the bending operation is completed, the product is in the form of a plate with one or more parts, each of which has at least one bent edge and one or more joints Are connected to the peripheral portion of the thin plate, and after the bending operation, the peripheral portion and the connecting portion exist in the same plane. In the next step, the parts are separated from the frame by removing or destroying the joints.
[0010]
This integrated cutting and bending system for producing sheet bending parts allows the best use of the production capacity of the automatic bending apparatus by automatically manipulating the part during bending. That is, the presence of a frame around the part or parts to be bent creates a convenient gripping area that can always be used, even for parts of a significantly complex shape.
[0011]
As a result, multiple parts can be defined on a single plate, and the same bending tool can be used to make a certain number of bends in different parts before a tool change is required. Based on the fact that it is possible, the incidence of tool change operations can be significantly reduced.
[0012]
The method and system according to the present invention further reduce dead time for component insertion and removal. This is because the bending apparatus is prepared to machine a plurality of parts by one insertion / removal operation.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
First, referring to FIG. 1, a cutting contour 12 is defined in a thin plate (sheet metal) 10, and a plurality of development views are formed on the surfaces 14a, 14b, 14c and the surfaces 16a, 16b, 16c. . The cutting contour 12 is not physically applied to the surface of the sheet 10, but is stored in a control unit of a cutting machine, such as a punching machine or a laser cutting machine, arranged to perform the cutting of the sheet 10. . If desired, the cutting contour 12 may be formed as a single component contour as well.
[0015]
An interruption is provided at a predetermined position along the cutting path 12, and a coupling link (coupling) between the development in the plane of the parts 14a, 14b, 14c and 16a, 16b, 16c and the peripheral portion 18 of the sheet 10 is shown. Part).
[0016]
FIG. 2 shows the sheet 10 when the operation in which a through-cut 20 is made along a predetermined cutting path is completed. As already mentioned above, the through cut 20 is interrupted in length so that a series of connecting links (joints) are formed. As far as the parts 14a, 14b, 14c are concerned, the connecting link (joining part) is indicated by reference numeral 22, and in the case of the development on the surface of the parts 16a, 16b, 16c, each connecting link (joining part) is indicated by reference numeral 24 Is done.
[0017]
In FIG. 2, the bending line segments for parts 14a, 14b, 14c and parts 16a, 16b, 16c are indicated by numerals 26 and 28, respectively. The coupling links 22 and 24 may be arranged in such a way that the position affected by the coupling links 22 and 24 is not out of the plane of the sheet 10 by the bending being performed along the line segments 26 and 28. Understand.
[0018]
After the sheet 10 is prepared as shown in FIG. 2, the edges of the parts 14a, 14b, 14c and 16a, 16b, 16c are bent. In order to make these bends, the thin plate 10 is gripped by the gripping portion of the manipulator. The position where the part is gripped requires a peripheral portion 18 of the sheet 10 that forms a frame surrounding the sheet part to be bent.
[0019]
Therefore, the means for gripping the thin plate 10 does not disturb the bending operation. The bending is preferably carried out on the thin plate 10 held in a vertical plane in the manner described in Italian Patent T093A000818.
[0020]
The bending is performed with a V-shaped punch and die having the appropriate characteristics for the particular type of bending to be made. Specifically, the bending tool is of a length approximately equal to the length of the edge to be bent so as not to interfere with the peripheral portion 18 of the sheet 10 surrounding the part to be bent.
[0021]
An advantage of the present invention is that developments in the plane of two adjacent parts can have adjacent sides facing the same cut. For example, referring to FIG. 2, parts 14a and 14b have a side 30 in common, and parts 14a and 16a have a side 32 in common. This allows the best use of the area of the sheet 10 to be made and reduces the material consumed.
[0022]
With the method according to the invention, the bending machine is programmed to successively bend all the edges that can be bent by the same bending tool as in parts belonging to the same sheet 10. The bending tool is then replaced and the other edges of the part requiring different types of bending tools, eg different lengths, are bent continuously. If necessary, only one bending tool may be changed, and in most cases only the punch is changed.
[0023]
FIG. 3 shows the thin plate 10 when the bending operation is completed. In FIG. 3 it can be seen that the edge can also be bent to the opposite side of the sheet 10. This can be achieved, for example, by rotating the bending tool up to 180 ° with respect to the thin plate 10.
[0024]
After the bending operation, the sheet 10 is removed from the bending machine and conveyed to a station where the bent parts 14a, 14b, 14c and 16a, 16b, 16c are separated from the remaining portion 18 of the sheet 10. This separation can be realized by cutting the link (joining part).
[0025]
The advantages of the method according to the invention are evident from the above description compared to a bending method which provides a complete separation of the development in the plane of the part from the remaining part of the sheet 10 and the bending of it individually. It is. Indeed, with the method according to the invention, a single insertion / removal operation in an automatic bending machine may be performed for all parts belonging to the same sheet 10. Furthermore, the fact that a greater number of bends can be carried out successively with the same set of tools reduces the tool change time when the bending machine is not working. The method of operation described above results in better utilization of the machine work cycle and increases the overall efficiency of the bending system.
[0026]
Referring now to FIGS. 4-7, an integrated cutting and bending system that can be used to perform the method described above is indicated generally by the reference numeral 40.
[0027]
System 40 is essentially formed by a bending station 44 disposed with a cutting station 42.
[0028]
The cutting station 42 is constituted by a laser cutting machine, which has a stationary support structure 46 fixed to the bending station 44 and a horizontal guide, and a vertical beam 48 moves along the horizontal guide. Can do. The vertical beam 48 is moved horizontally by an electric nut 50 (FIG. 7) that engages the stationary horizontal screw 52. The beam 48 includes a vertical guide, and the laser focusing head 54 can move along the vertical guide.
[0029]
Therefore, in order to perform the cutting operation on the thin plate 10 held vertically in the cutting station 42, the laser head 54 can move to the vertical work plane at will. The laser head 54 is supplied with a laser beam in a conventional manner by a laser oscillator 56 and by a series of mirrors as commonly used in cutting and welding robots.
[0030]
The thin plate indicated by reference numeral 58 in the drawing is held on a vertical cutting plane by a frame 60 having a gripping portion 62 for gripping a peripheral region of the thin plate 58. A system, schematically illustrated by conveyor 64 in FIG. 4, for collecting and discharging chips is disposed below the cutting area. A suction hood 66 that can move with the vertical beam 48 may be provided in front of the laser head 54 opposite the laser head 54 through the thin plate 58. The front portion of the cutting station 42 may be closed by a sliding door 68.
[0031]
The cutting station 42 has a manipulator 70 for moving the thin plate 10 cut from the larger plate 58. The manipulator 70 includes a base 72 that can move horizontally and is driven by a nut 74 that engages the same screw 52 that contributes to the movement of the vertical beam 48 of the laser head 54. The base 72 includes an articulated arm 76 having a rotatable head 78 having a gripping portion 80 for gripping the thin plate 10.
[0032]
The manipulator 70 is arranged to grip the thin plate 10 separated from the larger plate 58. Since the larger plate 58 is arranged in a vertical plane, the manipulator 70 must grip the plate 10 before the peripheral cutting that separates the plate 10 from the rest of the larger plate 58 is completed. .
[0033]
This is done in the manner shown in FIGS. The laser cutting head 54 makes a through-cut 82 along the periphery of the sheet 10, but before the completion of the peripheral cutting (and thus before completely separating the sheet 10 from the larger sheet 58), the top of the sheet 10 Make indentation 84 in the larger sheet at the edge. Then, the grip portion 80 of the manipulator 70 is inserted into the recess 84 to grip the thin plate 10 as shown in FIG. After the thin plate 10 is gripped by the gripping portion 80, the cutting head 54 can complete the peripheral cutting 82 that separates the thin plate 10 from the larger plate 58. The cuts and links that define the unfolded view in the plane of one or more parts to be bent will be described in detail with reference to FIGS. 1 to 3 before the through cut 82 forming the lamina 10 is made. As is done on thin plates.
[0034]
After the gripper 80 grips the thin plate 10 and after the separation and cutting 82 is completed, the head 78 of the manipulator 70 is directed in the direction indicated by the arrow 86 in FIG. 8 to move the thin plate 10 away from the larger plate 58. And is moved to the position indicated by the dashed outline in FIG. The entire manipulator 70 is then moved horizontally to carry the sheet 10 to a position where the sheet 10 is received by the manipulator 70 at the bending station 44.
[0035]
The bending station 44 is preferably of the form described and illustrated in the applicant's Italian Patent T093A000818. Therefore, for a detailed description of the bending station 44, reference should be made to the above-mentioned patent application. For the purposes of this description, a bending that can perform a rotational movement around an axis parallel to the line of bending caused by numerical control to follow the movement of the component parts during the bending. It is sufficient to point out that the bending station 44 comprises a bending press 90 having tools 92 and 94. Furthermore, the punch and die of the bending station can perform a rotational movement about an axis perpendicular to the thin plate 10 in order to change the direction of bending in the plane of the thin plate 10.
[0036]
Sheet 10, which has already been contoured with one or more parts to be bent, is fed into bending press 90 by manipulator 96 that receives the parts from manipulator 70 at cutting station 42. The manipulator 96 is of the cartesian type and has a gripping head 98 that can be moved and accurately positioned at any position in the work area. The gripping head 98 has a feature that holds the thin plate 10 in such a manner that it can float in five degrees of freedom.
[0037]
Thus, the lamella 10 can make a small movement along the three linear axes X, Y, and Z as compared to the gripping head 98, with two around the two vertical axes inside the plane of the lamella 10. Rotational motion can be performed freely. In order to prevent errors due to its weight when positioning the sheet 10, the only limited degree of freedom of the sheet 10 is the degree of freedom corresponding to the rotation of the sheet 10 about an axis perpendicular to the plane of the sheet 10. It is.
[0038]
The floating suspension of the sheet 10 during bending is particularly beneficial among the capabilities of the present invention. This is because the gripping head 98 is able to absorb forces that attempt to cause the breaking of the connecting link between the part and the peripheral part of the sheet. The structural details of the floating suspension of the manipulator 96 are described in detail in Italian Patent T093A000818.
[0039]
The bending station 44 has an automatic device for changing the bending tools 92 and 94, the structural details and operation of which are described in detail in the Italian patent cited several times above. Bending is performed by a set of tools with a length approximately equal to the length of the edge to be bent. If the developments in the plane of several different parts are defined for the same sheet 10, the bending press 90 performs all the bendings of the same length of all parts belonging to the same sheet 10, Thereafter, it changes the tool in preparation for performing a different length of bending.
[0040]
Throughout the transfer and bending operations, the sheet 10 is held by a peripheral area surrounding one or more parts defined therein by peripheral cutting. Accordingly, the thin plate 10 forms a kind of frame that functions as a support for parts through bending work.
[0041]
When processing in the system 40 is complete, a product composed of one or more parts is produced, each of which has at least one bending edge, which is connected to the peripheral portion of the sheet 10 by a small link. Are combined. The bent part is separated from the support frame in the next step, for example by a machine that is specifically intended to cut the link or by fatigue that exerts a force on the link to cause it to break.
[0042]
As explained above, the thin plate 10 is separated from the larger plate 58 at the cutting station 42. The cutting of the thin plate 10 from the larger plate 58 is generally performed while leaving a frame around the larger plate 58. Thus, the larger plate material remaining after the removal of the various plates is constantly held in place by the positioning frame 60 with the gripping portion 62. The debris left after all useful boards have been removed from the larger board 58 is generally of a considerable size that may cause problems when it is discarded as cutting waste. Thus, after the last useful plate has been removed from the larger plate 58, it is dropped into the base collection system of the cutting station 42 by gravity and discarded as a much smaller piece of cutting waste than the previous plate 58. To break it down into pieces, the cutting head (laser head) 54 breaks up the remnants of the larger plate 58. The cutting head 54 preferably cuts the debris by a horizontal cut that includes the overall length of the debris and a gradual movement upward from the bottom.
[0043]
A further beneficial feature of the integrated cutting and bending system according to the present invention is that the cutting station 42 and bending station 44 can work in a manner related to each other or independently. The first working state provides a complete system 40 that is used alone as a cutting machine. In this case, the bending station 44 does not work while the cutting station 42 provides the part to be removed by the manipulator 70 when the part is cut from the larger plate 58. Furthermore, the system 40 can work alone as a bending machine, i.e. without the cutting station 42 working, the bending station 44 being pre-cut by the cutting station 42 or in advance by a different cutting or punching machine. The parts that have been made are supplied. The third working state is a state in which the cutting station 42 and the bending station 44 work simultaneously but independently, that is, the parts cut at the cutting station 42 are taken out and collected separately, and the bending is performed. The station 44 is in a state where parts that are not sent directly from the cutting station 42 are supplied. The last possible working state is that the cutting station 42 and the bending station 44 provide work related to each other, i.e. the bending station 44 is directly supplied with the parts sent from the cutting station 42. It is.
[0044]
In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change.
[0045]
【The invention's effect】
As can be understood from the embodiments as described above, according to the method of manufacturing a thin plate bending part according to claims 1 to 11 and the invention of the product of bending work according to claim 20 , at least one part to be bent is obtained. The profile of the development in the plane is defined in the thin plate, leaving the joint between one or more parts and the surrounding part of the thin plate intact. The portion of the sheet surrounding the part or parts constitutes a frame that can be used to grip the part by a manipulator that feeds the part into the bending press. The part can be bent while the part is joined to the peripheral part of the sheet by the joint. When the bending operation is completed, the product is in the form of a plate with one or more parts, each of which has at least one bent edge and one or more joints To the peripheral part of the sheet. In the next step, the part can be separated from the frame by removing or destroying the joint.
[0046]
Moreover, according to the invention of the system for manufacturing a thin plate bending part according to claims 12 to 19 , the automatic use of the part during the bending period makes the best use of the production capacity of the automatic bending apparatus. Can make it possible. That is, the presence of a frame around one or more parts to be bent can create a convenient gripping area that can always be used, even with highly complex shaped parts.
[0047]
As a result, multiple parts can be defined on a single plate, and the same bending tool can be used to make a certain number of bends in different parts before a tool change is required. Based on the fact that it is possible, the incidence of tool change operations can be significantly reduced.
[0048]
Furthermore, according to the method and system of the present invention, the dead time for inserting and removing parts can be reduced. This is because the bending apparatus is prepared to machine a plurality of parts by one insertion / removal operation.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing three different stages of a method according to the invention.
FIG. 2 is a schematic perspective view showing three different stages of the method according to the invention.
FIG. 3 is a schematic perspective view showing three different stages of the method according to the invention.
FIG. 4 is a schematic perspective view of an integrated cutting and bending system according to the present invention.
FIG. 5 is a side view depicting a partial cross-sectional view in the direction of arrow V in FIG. 4;
6 is a front view in the direction of arrow VI in FIG. 4;
7 is a plan view of the system of FIG.
8 is a schematic front view of a portion indicated by an arrow VIII in FIG. 4;
9 is a schematic perspective view of a portion indicated by an arrow IX in FIG.
10 is an enlarged perspective view of the details indicated by the arrow X in FIG. 9. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Thin plate 12 Cutting wheel part 14a, 14b, 14c, 16a, 16b, 16c Parts surface 18 Peripheral part 20 Through-cutting 22, 24 Link (connection part)
40 System 42 Cutting station 44 Bending station 54 Laser focusing head 70 Manipulator 80 Grip part 90 Bending press 92, 94 Bending tool 96 Manipulator 98 Gripping head

Claims (20)

A method of manufacturing a sheet component having at least one bending edge, comprising:
Producing a through cut (20) in a flat sheet (10) in order to define an unfolded profile in the plane (14a, 14b, 14c, 16a, 16b, 16c) of at least one part to be bent And in order to define the joints (22, 24) between the development on the faces (14a, 14b, 14c, 16a, 16b, 16c) and the peripheral part (18) of the thin plate (10) Producing the through-cut, wherein the through-cut (20) is interrupted at a predetermined position (22, 24) of the contour of the development in the plane (14a, 14b, 14c, 16a, 16b, 16c);
Bending at least one edge of the part (14a, 14b, 14c, 16a, 16b, 16c) while the part is joined to the peripheral part (18) of the thin plate (10) by the joining part (22, 24). When,
The provided Rutotomoni, after bending work, a method of manufacturing the bending part of the sheet, characterized in that the coupling portion and peripheral portion (18) and (22, 24) are present in the same plane. 2. A method for manufacturing a bent component of a thin plate according to claim 1, wherein the thin plate (10) is held in a substantially vertical plane during the cutting and bending operations. Bending is performed by a bending machine (90) having a punch (92) and a die (94) cooperating with each other;
The punch (92) and die (94) of the bending machine (90) can make a rotational movement about an axis parallel to the line of bending in order to follow the movement of a part of the part during bending. A method for producing a bent part of a thin plate according to claim 1 or 2. Bending is performed by a bending machine (90) having a punch (92) and a die (94) cooperating with each other;
The punch (92) and die (94) of the bending machine (90) can make a rotational movement about the vertical axis of the thin plate (10) in order to change the bending direction in the plane of the thin plate (10). A method for producing a bent part of a thin plate according to claim 1 or 2. 5. A development in the face of at least one set of adjacent parts belonging to the same thin plate (10) has two adjacent sides facing the same cut. Of manufacturing bent parts of thin sheet metal. Bending all edges to be bent by the same tool in parts (14a, 14b, 14c, 16a, 16b, 16c) belonging to the same sheet (10) in succession and then bending the edges to be bent by different tools 6. The method of manufacturing a thin bent part according to claim 1, further comprising the step of replacing one or both bending tools. The manipulator (98) in which the thin plate (10) has at least one gripping portion (62, 80) that grips a portion (18) surrounding the component (14a, 14b, 14c, 16a, 16b, 16c) of the thin plate (10). The method for producing a bent part of a thin plate according to any one of claims 1 to 6, wherein the bent part is held by the method. Sheets (10) containing the parts to be bent are produced by cutting larger sheets (58) located at the cutting station (42), and individual sheets (10) are separated from each larger sheet (58). A thin plate bending part according to any one of the preceding claims, characterized in that it is gripped and held by a manipulator (70) before the peripheral cutting to separate the thin plate (10) is completed. Method. In order to separate the thin plate (10) from the larger thin plate (58), a recess (84) is made at the edge of the thin plate (10), a gripping part (80) is placed in the recess (84), and the thin plate (10) 9. The method of manufacturing a bent part of a thin plate according to claim 8, characterized in that the gripper is gripped by a gripping part (80) and a peripheral cut is finished separating the thin plate (10) from the larger thin plate (58). . The larger sheet (58) material useful for bending that remains after all the sheet (10) has been removed is cut into small pieces that are collected as cutting debris at the base of the cutting station (42). 10. A method for manufacturing a bent part of a thin plate according to claim 8 or 9, characterized in that 2. The lamina (10) having a peripheral frame that supports one or more parts with at least one bending edge by a joint (22, 24) when bending is complete. A method for producing a bent part of a thin plate according to claim 10. In a system for manufacturing a sheet bent part, in order to define an unfolded profile in the plane (14a, 14b, 14c, 16a, 16b, 16c) of at least one part to be bent , A cutting device (42) for making a through-cut (20) in a thin plate (10, 58), a development view on a surface (14a, 14b, 14c, 16a, 16b, 16c) and a peripheral portion of the thin plate (10) In order to produce a joint with (18), the through cut (20) is a predetermined position (22, 24) of the contour of the developed view on the surface (14a, 14b, 14c, 16a, 16b, 16c). ) The cutting device (42) suspended at
Bending at least one edge of the part (14a, 14b, 14c, 16a, 16b, 16c) while the part is joined to the peripheral part (18) of the thin plate (10) by the joining part (22, 24). A bending machine (90) capable of
The provided Rutotomoni, bending machine (90), even after the bending operation, the binding portion (22, 24) surrounding part (18) and is a machine that performs bending to be present in the same plane Integrated cutting and bending system for manufacturing thin sheet bending parts. The manipulator (96) is placed in a substantially vertical plane (10) by a floating suspension that leaves the part free to perform small movements in space except for rotation about an axis perpendicular to the lamella (10). 13) and the suspension device is adapted to prevent forces that attempt to break the joints (22, 24) and to produce a bent part according to claim 12, Bending integrated system. The bending machine (90) has a punch (92) and a die (94) cooperating with each other;
That the punch (92) and die (94) of the bending machine (90) can make a rotational movement about an axis parallel to the bend line to follow the movement of a part of the part during bending. 14. An integrated cutting and bending system for producing a bent part according to claim 12 or claim 13. The bending machine (90) has a punch (92) and a die (94) cooperating with each other;
The punch (92) and die (94) of the bending machine (90) can make a rotational movement about an axis perpendicular to the sheet (10) to change the bending direction in the plane of the sheet (10). 14. An integrated cutting and bending system for producing a bent part according to claim 12 or claim 13. The cutting device (42) comprises a laser cutting head (54) capable of working in a vertical plane and means (60) for holding the thin plate (58) on the vertical cutting plane. An integrated cutting and bending system for producing a bent part according to any one of claims 12 to 15. 17. An intermediate manipulator (70) comprising a thin plate (10) in a cutting plane and carrying it to a manipulator (96) of a bending machine (44). Integrated cutting and bending system for the manufacture of bending parts. The intermediate manipulator (70) is prepared to grip the lamella (10) cut from the larger lamella (58) before the peripheral cut separating the lamella (10) from the larger lamella (58) is completed. 18. An integrated cutting and bending system for producing a bent part according to claim 17. The cutting device (42) and the bending machine (44) are prepared to work in an independent manner or in a manner related to each other, so that the cutting device (42) works alone, the bending machine (44). Working alone, working simultaneously with the cutting device (42) and bending machine (44) but independent of each other, or with the cutting device (42) and bending machine (44) working in conjunction with each other 19. The operation according to claim 12, characterized in that the bending machine (44) allows the operation to be fed directly with the thin plate (10) fed from the cutting device (42). Integrated cutting and bending system for producing the described bending parts. In the product of bending work generated from the flat plate (10) ,
At least one bent edge protruding from the face of the thin plate (10) before being cut off from the rest (18) of the thin plate (10) which is a part other than the product;
The remaining part of the sheet (10) is joined by a joint formed by an interruption (22, 24) in the cut (20) defining the development profile in the plane of the part (14a, 14b, 14c, 16a, 16b, 16c). A joining piece joined to part (18);
A product of bending work characterized in that the connecting portions (22, 24) and the surrounding portion (18) existed in the same plane before separation from the remaining portion (18) .

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