Generator stator core disc-shaped structure finger pressing device and use method

Abstract

The invention discloses a generator stator core disc-shaped structure finger-pressing device and a using method, the finger-pressing device is simple and efficient in structure, the problem that the iron core lifting and clamping function is reduced after a conventional flat plate finger-pressing plate is heavily pressed is solved, and along with long-term electromagnetic vibration, the disc-shaped structure finger-pressing device is not prone to falling under the heavy pressure of a stator core. The inner circle side of the shiatsu plate does not sink, the phenomena of loosening, sheet stringing, corrosion and tooth breaking of the finger part of the stator core are avoided, the effect is good, the running stability of a generator of a tubular unit is improved, and a maintenance-free state of a power plant can be realized for a long time. Meanwhile, according to the process method of the finger pressing device of the disc-shaped structure, the three-axis linkage function of a numerical control gantry machining center is fully utilized, a hard alloy disc milling cutter is selected, and numerical control programming arc feeding and gradual retreating type step profiling cutting are adopted, so that machining of a butterfly-shaped molded line is achieved; and meanwhile, the requirement that the surface roughness of the shiatsu plate device is Ra3.2 microns and no tool connecting trace exists is met, the machining quality is good, and innovation is achieved.

Description

Technical Field

[0001] The invention belongs to the field of generator manufacturing, and in particular relates to a finger pressing device for a disc-shaped structure of a generator stator core and a use method thereof. Background Art

[0002] The stator core of large generators relies on a finger pressure plate device to clamp the core to ensure the tightness of the stator core, resist electromagnetic vibration during power generation operation, and avoid loosening of the strands. The finger pressure plate device is a key core component, and its manufacturing quality and life directly determine the operating efficiency, safety and stability of the power station stator core assembly.

[0003] At present, all cross-flow units adopt a fan-shaped finger pressure plate and a straight plate flat clamping structure. After installation and use, the inner circle finger of the lower finger pressure plate will sink under the heavy pressure of the stator core, and the finger pressure plate's function of lifting and clamping the core will fail. With long-term electromagnetic vibration, the stator core fingers will become loose, which is prone to stringing, corrosion, and broken teeth. It is necessary to develop a new structure and process to solve the problem of low clamping efficiency of the finger pressure plate.

[0004] Therefore, it is of practical significance to develop a finger pressure device and a processing method for a disc-shaped structure of a generator stator core to solve the above problems. Summary of the invention

[0005] In order to solve the problem that the finger pressure plate has a reduced function of lifting and clamping the iron core, and that the fingers of the stator iron core become loose with long-term electromagnetic vibration, and are prone to stringing, corrosion, and broken teeth, the present invention needs to develop a new structure and process to solve the problem of low effectiveness of the finger pressure plate. Further, a finger pressure device for a generator stator iron core disc-shaped structure is provided, which is composed of a fan-shaped plate, a finger pressure plate, and a windshield. The fan-shaped plate is a fan-shaped ring plate, a total of 1 piece, and the finger pressure plate is a strip forged steel plate, a total of 12 pieces. The finger pressure plates are arranged in a ring and welded on the fan-shaped plane of the fan-shaped plate. The windshield is a Q235B thin steel plate, a total of 2 pieces, which are welded to the overall outer circular vertical surface of the 12 finger pressure plates and welded into a whole.

[0006] In the above-mentioned finger pressure device for the disc-shaped structure of the stator core of the generator, the fan-shaped plate is a fan-shaped plate, provided with 6 light holes and 6 threaded holes, and provided with 3 square-mouthed grooves.

[0007] In the above-mentioned finger pressure device for the disc-shaped structure of the generator stator core, the finger pressure piece is a 228*24*35mm strip forged 40Mn18Cr3 steel plate, which is used after passing the 90° bending test without cracks, and there are 12 pieces in total.

[0008] The present invention also provides a method for using the generator stator core disc-shaped finger pressure device, which uses the generator stator core disc-shaped finger pressure device as described above, and is characterized by comprising the following steps:

[0009] S1. The fan-shaped plate is finely machined in the CNC machining center with the upper and lower planes and the surrounding areas to the drawing size, and 6 light holes, 6 threaded holes and 3 square grooves are finely machined to the drawing size; the finger press plate is finely machined in the CNC machining center with the upper and lower planes and the surrounding areas to the drawing size;

[0010] S2. Use the stator sector plate as the sample for positioning, assemble the sector plate and 12 finger pressure plates, and position the deviation between the center of the finger pressure plate and the center of the stator sector plate ≤±1mm, 12 finger pressure plates;

[0011] S3. Use welding tools to press the sector plate and 12 finger pressure pieces tightly. Spot weld the finger pressure piece and the sector plate at 3 points evenly spaced. After temporary fixation, use the stator sector plate again to check that the deviation between the center of the finger pressure piece and the center of the stator sector finger is ≤±1mm, and the horizontality of the 12 pressure fingers is not greater than 0.5mm.

[0012] S4, full welding, the weld angle is 10mm, each finger pressure piece is evenly distributed with 4 30mm long welds, the welding requires the use of stator sector pieces as a sample, and the level of 12 pressure fingers after welding is no more than 0.5mm;

[0013] S5. After the stator core disc-shaped finger pressure device is welded, it is processed in a CNC machining center. The curved surface processing requirements are as follows: the upper plane of the finger pressure piece of the finger pressure device is processed, the inner circle side plane is 0.8mm higher than the outer circle side plane, the circumferential runout of the upper plane with the same radius is ≤0.15mm, and the radial inclination of the upper plane is ΔP=1:285.

[0014] Furthermore, in the method of using the above-mentioned generator stator core disc structure finger pressure device, the S1, the CNC machining center is a CNC gantry center milling machine, the tool used is a high-speed steel end mill, the cutting depth is 0.5mm-0.8mm, the feed speed is 20mm / min-40mm / min, and the spindle speed is 650r / min-800r / min.

[0015] Furthermore, in the method for using the above-mentioned finger pressure device for the disc-shaped structure of the stator core of the generator, the S2, the stator sector is a 50W270 cold-rolled silicon steel sheet, and the product stator sector is a basic sheet.

[0016] Furthermore, in the method for using the above-mentioned finger pressing device for the disc-shaped structure of the stator core of the generator, the S3, the welding tool pressing tire is a special tool for the welding structure, which has both positioning and clamping and fixing functions.

[0017] Furthermore, in the method for using the above-mentioned finger pressure device for the disc-shaped structure of the stator core of the generator, the S4, the full welding uses a welding material of φ1.2 welding wire AWS ER316L, and the weld is subjected to PT flaw detection in accordance with ASM Volume VIII.

[0018] Further, in the method for using the above-mentioned finger pressure device for the disc-shaped structure of the stator core of the generator, in the S5, the CNC machining center is a CNC gantry center milling machine, the tool used is a carbide layer cutting disc, the cutting depth is 0.002mm, the feed speed is 30mm / min-50mm / min, and the spindle speed is 350r / min-400r / min;

[0019] In the method for using the above-mentioned finger pressing device for the disc-shaped structure of the stator core of the generator, the S5, curved surface processing specifically includes the following steps:

[0020] S51. Calculation of radial slope of upper plane: ΔP = ΔL / ΔH

[0021] Where: ΔP is the slope rate, unit is mm / mm; ΔL is the radial length of the finger pressure piece, unit is mm; ΔH is the height difference between the inner and outer circles, unit is mm;

[0022] The calculated radial slope ratio ΔP = 1:285;

[0023] S52, basic plane processing: the finger pressure device is installed in the CNC gantry machining center, the magnetic tire is firmly sucked, the bottom plane of the fan-shaped plate and the inner circle of the finger pressure piece are finely processed to the drawing size, and the upper plane of the finger pressure piece is roughly processed with a reserve of 1mm. After rough processing, the aging time is ≥24h to release the stress;

[0024] S53, disc-shaped surface processing: the finger pressure device is installed in the CNC gantry machining center, and the magnetic tire firmly absorbs the fan-shaped plate of the finger pressure device, with an adsorption gap of ≤0.05mm. The disc-shaped surface is processed in rough and fine manner, with a roughness of ≤Ra3.2μm. According to the CNC programming plan, the three-axis linkage of the cutter head is used, and the circumferential movement trajectory of the cutter head is: the X-axis and Y-axis synthesize the arc-shaped tool path trajectory, the circumferential direction of the cutter head starts at the first finger pressure piece, and the end position is the last finger pressure piece; the radial trajectory of the cutter head is: starting from the outer circle and ending at the inner circle (in a step-by-step retreat, and the end point of each layer needs to retreat 0.02mm); a total of 400 layers are cut, and the cutting depth of each layer is 0.002mm;

[0025] S54. After processing, clean thoroughly, remove sharp corners and burrs, and apply paint for protection.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention proposes a finger pressure device with a disc-shaped structure for a generator stator core. The finger pressure device has a simple and efficient structure and solves the problem that the core lifting and clamping function of a conventional flat finger pressure plate is reduced after heavy pressure. With long-term electromagnetic vibration, the inner circle side of the finger pressure plate of the disc-shaped structure finger pressure device will not sink under the heavy pressure of the stator core, thereby avoiding loosening, stringing, corrosion and tooth breakage of the stator core fingers. The effect is good, the stability of the operation of the cross-flow unit generator is improved, and the maintenance-free state of the power plant can be achieved for a long time.

[0028] At the same time, the present invention also provides a processing method for a disc-shaped structure finger pressure device, which makes full use of the three-axis linkage function of the CNC gantry machining center, selects a carbide disc milling cutter, adopts CNC programming arc tool movement, and gradually retreats the ladder profiling cutting, thereby realizing the butterfly line processing, and at the same time meets the requirement that the surface roughness of the finger pressure plate device is Ra3.2μm without tool joint marks, with excellent processing quality, and is the first to prove innovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a top view schematic diagram of the stator core disc-shaped structure finger pressure device of the present invention;

[0030] Figure 2 It is a cross-sectional schematic diagram of the stator core disc-shaped structure finger pressing device of the present invention;

[0031] Figure 3 It is a schematic diagram of the stator core disc-shaped structure finger pressing device (5) of the present invention;

[0032] Markings in the figure: 1-sector plate; 2-finger pressure plate; 3-wind shield; 4-stator sector plate; 5-tire pressure plate. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0034] Specific implementation method 1: refer to Figures 1 to 3 This embodiment describes a finger pressure device for a disc-shaped structure of a stator core of a generator. The finger pressure device structure is implemented by the following technical solution steps:

[0035] The disc-shaped finger pressure device is composed of a fan-shaped plate 1, a finger pressure piece 2, and a wind shield 3. The fan-shaped plate 1 is a fan-shaped ring plate, a total of 1 piece, the finger pressure piece 2 is a strip forged steel plate, a total of 12 pieces, the finger pressure piece 2 is arranged in a ring shape and welded on the fan-shaped plane of the fan-shaped plate 1, and the wind shield 3 is a Q235B thin steel plate, a total of 2 pieces, welded to the overall outer circular vertical surface of the 12 finger pressure pieces 2, and welded into a whole.

[0036] Specific implementation method 2: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the specific embodiment 1. In this embodiment, the fan-shaped plate 1 is a fan-shaped plate, provided with 6 light holes and 6 threaded holes, and provided with 3 square grooves.

[0037] Specific implementation method three: refer to Figures 1 to 3This embodiment is described. This embodiment further limits the specific embodiment 1. In this embodiment, the finger pressure sheet 2 is a 228*24*35mm strip forged 40Mn18Cr3 steel plate, which is used after passing the 90° bending test without cracks. There are 12 pieces in total.

[0038] Specific implementation method 4: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the use method of the specific embodiment 1. In this embodiment, the use method of the generator stator core disc-shaped structure finger pressure device is divided into the following steps:

[0039] S1, fan-shaped plate 1 is finely processed in the CNC machining center to the upper and lower planes and the surrounding area to the drawing size, and 6 light holes, 6 threaded holes and 3 square grooves are finely processed to the drawing size; finger pressure plate 2 is finely processed in the CNC machining center to the upper and lower planes and the surrounding area to the drawing size to the drawing size;

[0040] S2. Use the stator sector 4 as the template for positioning, assemble the sector plate 1 and 12 finger pressing pieces 2, and position the deviation between the center of the finger pressing piece 2 and the center of the stator sector 4 ≤±1mm, 12 finger pressing pieces 2;

[0041] S3. Use a welding tool to press the tire tightly against the sector plate 1 and the 12 finger pressing pieces 2. Spot weld the finger pressing piece 2 and the sector plate 1 at 3 points evenly distributed. After temporary fixation, use the stator sector plate 4 again to check that the deviation between the center of the finger pressing piece and the center of the stator sector finger is ≤±1mm, and the horizontality of the 12 pressing fingers is not greater than 0.5mm;

[0042] S4, full welding, the weld angle is 10mm, each finger pressure piece 2 is evenly distributed with 4 30mm long welds, the welding requirement is to use the stator sector piece 4 as a sample, and the level of 12 pressure fingers after welding is no more than 0.5mm;

[0043] S5. After the stator core disc-shaped finger pressure device is welded, it is processed in a CNC machining center. The curved surface processing requirements are as follows: the upper plane of the finger pressure piece 2 of the finger pressure device is processed, the inner circle side plane is 0.8mm higher than the outer circle side plane, the circumferential runout of the upper plane with the same radius is ≤0.15mm, and the radial inclination of the upper plane is ΔP=1:285.

[0044] Specific implementation method five: refer to Figures 1 to 3 To explain this embodiment, this embodiment further limits S1 described in the specific embodiment four. In this embodiment, the CNC machining center is a CNC gantry center milling machine, the tool used is a high-speed steel end mill, the cutting depth is 0.5mm-0.8mm, the feed speed is 20mm / min-40mm / min, and the spindle speed is 650r / min-800r / min.

[0045] Specific implementation method six: refer to Figures 1 to 3This embodiment is described. This embodiment further limits the S2 described in the specific embodiment four. In this embodiment, the S2 stator sector 4 is a 50W270 cold-rolled silicon steel sheet, which is the basic sheet of the product stator sector.

[0046] In this embodiment, the product stator sector piece 4 is used as a sample for inspection of the welding of the finger pressure piece 2, which has higher accuracy and precision.

[0047] Specific implementation method seven: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the S3 described in the specific embodiment 4. In this embodiment, the S3 welding tool press tire 5 is a special tool for welding structure, which has both positioning and clamping functions.

[0048] Specific implementation method eight: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the S4 described in the specific embodiment four. In this embodiment, the S4 full weld uses a φ1.2 welding wire AWSER316L, and the weld is subjected to PT testing in accordance with ASM Volume VIII.

[0049] In this embodiment, the φ1.2 welding wire AWS ER316L welding material and the material of the finger pressure sheet 2 non-magnetic steel 40Mn18Cr3 have better welding matching performance. During the welding process, small specifications are adopted for welding, the welding current is not greater than 240A, and the interlayer temperature is not higher than 150°C.

[0050] Specific implementation method nine: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the S5 described in the specific embodiment 4. In this embodiment, the S5 CNC machining center is a CNC gantry center milling machine, the tool used is a carbide layer cutting disc, the cutting depth is 0.002mm, the feed speed is 30mm / min-50mm / min, and the spindle speed is 350r / min-400r / min;

[0051] Specific implementation method ten: refer to Figures 1 to 3 This embodiment is described. This embodiment further limits the S5 described in the specific embodiment 4. In this embodiment, the S5 curved surface processing includes the following steps:

[0052] S51. Calculation of radial slope of upper plane: ΔP = ΔL / ΔH

[0053] Where: ΔP is the slope rate, unit is mm / mm; ΔL is the radial length of the finger pressure piece, unit is mm; ΔH is the height difference between the inner and outer circles, unit is mm;

[0054] The calculated radial slope ratio ΔP = 1:285;

[0055] S52, basic plane processing: the finger pressure device is installed in the CNC gantry processing center, and the magnetic tire is firmly sucked. The bottom plane of the fan-shaped plate 1 and the inner circle of the finger pressure piece 2 are finely processed to the size of the drawing. The upper plane of the finger pressure piece 2 is roughly processed with a reserve of 1mm. After rough processing, the aging time is ≥24h to release the stress;

[0056] S53, disc-shaped surface processing: the finger pressure device is installed in the CNC gantry machining center, and the magnetic tire firmly absorbs the fan-shaped plate 1 of the finger pressure device, the adsorption gap is ≤0.05mm, and the disc-shaped surface is processed roughly and finely, with a roughness of ≤Ra3.2μm. According to the CNC programming plan, the three-axis linkage of the cutter head, the circumferential movement trajectory of the cutter head is: the X-axis and Y-axis synthesize the arc-shaped tool path trajectory, the circumferential direction of the cutter head starts at the finger pressure piece 2-1, and the end position is the finger pressure piece 2-12; the radial trajectory of the cutter head is: starting from the outer circle and ending at the inner circle (in a step-by-step retreat, each layer end point needs to retreat 0.02mm); a total of 400 layers are cut, and the cutting depth of each layer is 0.002mm;

[0057] S54. After processing, clean thoroughly, remove sharp corners and burrs, and apply paint for protection.

[0058] In this embodiment, before machining the curved surface, the upper and lower planes of the finger pressure device are finely machined. During the process, time-effect stress release is performed, and the machining stress deformation of the surface welding workpiece is affected. On this basis, CNC programming is performed to finely machine the curved surface with higher stability and accuracy.

[0059] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it should be clear to those skilled in the art that the technical solutions described in the above embodiments may be modified, or some or all of the technical features therein may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A finger pressing device for a disc-shaped structure of a generator stator core, characterized in that: The utility model is composed of a fan-shaped plate (1), a finger-pressing plate (2), and a windshield (3). The fan-shaped plate (1) is a fan-shaped ring plate, a total of one piece, the finger-pressing plate (2) is a strip-shaped forged steel plate, a total of 12 pieces, the finger-pressing plates (2) are arranged in a ring shape and welded on the fan-shaped plane of the fan-shaped plate (1), and the windshield (3) is a Q235B thin steel plate, a total of two pieces, which are welded to the overall outer circular vertical surface of the 12 finger-pressing plates (2) to form a whole.

2. A finger pressure device for a disc-shaped structure of a generator stator core according to claim 1, characterized in that: The sector plate (1) is a sector ring plate, provided with 6 light holes and 6 threaded holes, and provided with 3 square grooves.

3. A finger pressure device for a disc-shaped structure of a generator stator core according to claim 1, characterized in that: The finger pressure sheet (2) is a 228*24*35mm strip forged 40Mn18Cr3 steel plate, which is used after passing the 90° bending test without cracks. There are 12 pieces in total.

4. A finger pressing device for a disc-shaped structure of a generator stator core and a method of using the same as claimed in any one of claims 1 to 3, characterized in that: The usage process is as follows: S41, the fan-shaped plate (1) is finely processed in a CNC machining center to have its upper and lower planes and periphery to the drawing size, and 6 light holes are finely processed with a position tolerance of Φ0.5 and 6 threaded holes and 3 square grooves to the drawing size; the finger pressing plate (2) is finely processed in a CNC machining center to have its upper and lower planes and periphery to the drawing size to the drawing size; S42, using the stator sector (4) as a template for positioning, assembling the sector plate (1) and the 12 finger pressing pieces (2), positioning the deviation between the center of the finger pressing piece (2) and the center of the finger of the stator sector (4) to be ≤±1mm, and the 12 finger pressing pieces (2); S43, using a welding tool to press the tire (5) to press the sector plate (1) and the 12 finger pressing pieces (2), spot welding the finger pressing piece (2) and the sector plate (1) at three points evenly distributed, and after temporary fixation, use the stator sector plate (4) again to check that the deviation between the center of the finger pressing piece (2) and the center of the stator sector plate (4) is ≤±1mm, and the horizontality of the 12 pressing fingers is not greater than 0.5mm; S44, full welding, the weld is 10mm in angle, each finger pressure piece (2) is evenly distributed with 4 30mm long welds, the welding requires the use of the stator sector piece (4) as a sample, and the level of the 12 pressure fingers after welding is no more than 0.5mm; S45. After the stator core disc-shaped structure finger pressure device is welded, it is processed in a CNC machining center. The curved surface processing requirements are as follows: the upper plane of the finger pressure piece (2) of the finger pressure device is processed, the inner circle side plane is 0.8mm higher than the outer circle side plane, the circumferential runout of the upper plane with the same radius is ≤0.15mm, and the radial inclination of the upper plane is ΔP=1:

285.

5. The generator stator core disc-shaped finger pressing device and the method of using the same according to claim 4, characterized in that: The S41, CNC machining center is a CNC gantry center milling machine, the tool used is a high-speed steel end mill, the cutting depth is 0.5mm-0.8mm, the feed speed is 20mm / min-40mm / min, and the spindle speed is 650r / min-800r / min.

6. The generator stator core disc-shaped finger pressing device and the method of using the same according to claim 4, characterized in that: The S42, stator sector (4) is a 50W270 cold-rolled silicon steel sheet, which is the basic sheet of the product stator sector.

7. The generator stator core disc-shaped finger pressing device and the method of using the same according to claim 4, characterized in that: The welding tool press (5) described in S43 is a special tool for welding structure.

8. The generator stator core disc-shaped finger pressing device and the method of using the same according to claim 4, characterized in that: The S44 full weld uses φ1.2 welding wire AWS ER316L as welding material, and the weld is subjected to PT testing in accordance with ASM Volume VIII.

9. The generator stator core disc-shaped structure finger pressing device and use method according to claim 4, characterized in that: The S45 CNC machining center is a CNC gantry center milling machine, the tool used is a carbide layer cutting disc, the cutting depth is 0.002mm, the feed speed is 30mm / min-50mm / min, and the spindle speed is 350r / min-400r / min.

10. The generator stator core disc-shaped finger pressing device and the method of using the same according to claim 4, characterized in that: The S45, curved surface processing comprises the following steps: S451, calculation of radial slope of upper plane: ΔP = ΔL / ΔH Wherein: ΔP is the slope rate, in millimeters / millimeters; ΔL is the radial length of the finger pressure piece (2), in millimeters; ΔH is the height difference between the inner and outer circles, in millimeters; The calculated radial slope ratio ΔP = 1:285; S452, basic plane processing: the finger pressure device is mounted on the CNC gantry processing center, and the magnetic tire is firmly sucked. The bottom plane of the fan-shaped plate (1) and the inner circle of the finger pressure piece (2) are finely processed to the size of the drawing. The upper plane of the finger pressure piece (2) is roughly processed with a reserve of 1mm. After rough processing, the aging is ≥24h and the stress is released; S453, disc-shaped surface processing: the finger pressure device is mounted on the CNC gantry machining center, the magnetic tire firmly absorbs the fan-shaped plate (1) of the finger pressure device, the adsorption gap is ≤0.05mm, the disc-shaped surface is processed roughly and finely, the roughness is ≤Ra3.2μm, according to the CNC programming plan, the three axes of the cutter head are linked, the circumferential movement trajectory of the cutter head is: the X-axis and Y-axis synthesize the arc-shaped tool path trajectory, the circumferential direction of the cutter head starts at the finger pressure plate (2-1), and the end position is the finger pressure plate (2-12); the radial trajectory of the cutter head is; Starting from the outer circle and ending at the inner circle, it is a step-by-step retreat. Each layer’s end point needs to be retreated 0.02mm. A total of 400 layers were cut, with a cutting depth of 0.002mm per layer; S454. After processing, clean thoroughly, remove sharp corners and burrs, and apply paint for protection.

Images