Manual and mechanical straightening and bending of metal. Modern transport Technological map of metal bending safety precautions
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Metal bending and straightening
Types of defects when straightening and bending metals and safety rules
Types of marriage. The main types of defects when straightening metal are nicks on the treated surfaces from the edge of the hammer and dents - traces from the hammer head, which has an irregular and unsmooth surface. These defects are usually a consequence of the inability to strike correctly with a hammer or the result of using a hammer whose head has dents and nicks.
When bending metal, defects occur due to wrong sizes bent workpieces, oblique bending and damage to machined surfaces. The reasons for these types of defects are: incorrect marking of bending points, careless clamping of the workpiece in a vice (above or below the marking mark), applying too strong blows, and using incorrectly sized mandrels.
When winding springs, defects can result from incorrect choice of wire diameter, mandrel, internal or external diameter of the spring, spring length and number of turns. If you are attentive and serious about your work, it is not difficult to avoid marriage.
Safety precautions. In order to ensure safety when straightening workpieces on sheet-straightening machines, it is necessary first of all to check the condition of grounding and the serviceability of enclosing devices. Starting and switching devices are checked by repeatedly starting the machine idle and turning it off.
When straightening workpieces that have cutouts (windows), the workpiece must be fed by the edge, and not by the cutouts, since hands may be pulled onto the rolls along with the part. To avoid injuring your hands while editing, you need to use canvas gloves.
When working on bending machines With manual drive You should check the condition of the bending rulers, traverses and screw clamp. It is prohibited to bend metal whose thickness is greater than that indicated in the machine’s passport.
When working on bending presses and roll forming machines, first of all, you need to read the safety instructions, check the condition of grounding, guards, starting and switching devices, and the correct installation of dies and rollers.
When straightening and bending, you need to work with a hammer well placed on the handle. Hammer heads should not have cracks, nicks or burrs. It is necessary to systematically check the hammer attachment on the handle.
Metal straightening and bending
By bending the thickness of the strip into a circle, we obtain a cylindrical ring; Moreover, the outer part of the metal will stretch out somewhat, and the inner part will shrink. Consequently, the length of the workpiece will correspond to the circle located in the middle between the outer and inner circles of the ring.
In a cold state, small diameter pipes up to 20 mm are bent. Hot bending of pipes with filler is carried out for pipes with a diameter of more than 100 mm. Hot bending of pipes with filler is carried out in the following order:
1. One end of the pipe is closed with a stopper.
2. To prevent crushing, bulging and the appearance of cracks when bending pipes, they are filled with fine, dry, river sand, which is sifted through a sieve with mesh size of 2 mm, and too fine sand not suitable.
3. The second end of the pipe is closed with a wooden plug, which should have holes or grooves for the release of gas formed when the pipe is heated.
5. Put on gloves.
6. Install the pipe.
7. Heat the pipe blowtorch or flame gas burner to cherry red color over a short length equal to 6 diameters.
8. Bend the pipe according to the copier.
9. Check the pipe bend with a template.
10. At the end of bending, knock out or burn out the plugs and pour out sand.
It is recommended to bend the pipe with one heating, since repeated heating deteriorates the quality of the metal. When heating, pay attention to the heating of the sand. Excessive overheating of individual areas should not be allowed. Scale bounces off the highly heated part of the pipe. In cases of overheating, the pipe is cooled to a cherry red color before bending. If the pipe is bent at an angle of 90 degrees, then a section equal to 6 pipe diameters is heated; if the pipe is bent at an angle of 60 degrees, then a section equal to 4 pipe diameters is heated; if at an angle of 45 degrees, then 3 pipe diameters.
Welded pipes must be positioned during bending so that the weld seam is located in the neutral layer, otherwise it may separate. When bending, the following defects are possible: oblique bends and mechanical damage to the treated surface, as a result of incorrect marking or clamping of the part in a vice, as well as the application of strong blows.
Round bars with a diameter of over 30 mm, shafts and pipes are straightened screw presses, by pressing with a prismatic tip. The check is carried out by an indicator. The deviation of the indicator arrow will show the amount of non-straightness.
Safety precautions when straightening metal:
· Hammer handles must be free of cracks with strikers securely attached to them.
· The hammer head must have a smooth, polished and slightly convex surface.
· When editing, be sure to wear gloves.
· Workpieces must be securely fastened.
· When straightening a strip or rod, they must touch the plate at least in two points.
Safety precautions when bending metal.
· Securely fasten parts in a bench vise or in fixtures.
· Work only on properly functioning equipment and devices.
· Machinist's hammers must have good pens and be tightly seated.
· When working on bending machines, strictly follow the safety rules set out in special instructions.
· When bending hot pipes, wear gloves.
Types of marriage. The main types of defects when straightening metal are nicks on the treated surfaces from the edge of the hammer, dents - traces from the hammer head, which has an irregular and unsmooth surface. These defects are usually a consequence of the inability to strike correctly with a hammer or the result of using a hammer whose sides have dents and nicks.
When bending metal, scrap results from incorrect dimensions of bent workpieces, oblique bending and damage to processed surfaces. The reasons for these types of defects are: incorrect marking of bending points, careless clamping of the workpiece in a vice (above or below the marking mark), applying too strong blows, and using incorrectly sized mandrels.
When winding springs, defects can result from incorrect choice of wire diameter, mandrel of the inner or outer diameter of the spring, spring length and number of turns. If you are attentive and serious about your work, it is not difficult to avoid marriage.
Safety precautions. In order to ensure safety when straightening workpieces on sheet-straightening machines, it is necessary first of all to check the condition of grounding and the serviceability of enclosing devices. Starting and switching devices are checked by repeatedly starting the machine idle and turning it off.
When straightening workpieces that have cutouts (windows), the workpiece must be fed by the edge, and not by the cutouts, since hands may be pulled onto the rolls along with the part. To avoid injuring your hands while editing, you need to use canvas gloves.
When straightening and bending, you need to work with a hammer well placed on the handle. Hammer heads should not have cracks, nicks or burrs. It is necessary to systematically check the hammer attachment on the handle.
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- 224.50 KbPipes without dents, bulges, or folds are considered to be correctly bent.
Safety rules for straightening and bending metal.
Hammers and sledgehammers must have securely jammed, strong handles without knots or cracks.
The working parts of hammers, bits, linings, mandrels should not have riveting.
Scraps of metal must be collected and placed in a designated box to avoid cuts to the legs and arms.
Clean sheets only with a wire brush and then with rags or ends.
Metal straightening should only be done on reliable supports that prevent the metal from sliding off upon impact.
The auxiliary worker should hold the metal only with blacksmith's tongs when straightening.
When filling a pipe with sand before bending, it is necessary to make a hole in the end of one of the plugs to allow gases to escape, otherwise the pipe may rupture.
When bending hot pipes, only hold them in gloves to avoid hand burns.
- Types and reasons of marriage.
When editing, the main types of defects are dents, marks from the hammer head, which has an unsmooth and irregular shape, and nicks on the treated surface from the ribs of the hammer.
These types of defects are the result of incorrect blows and the use of a hammer whose strikers have nicks and gouges.
When bending metal, defects most often include oblique bends and damage to the treated surface. Such defects appear as a result of incorrect marking or securing the part in a vice above or below marking line, as well as incorrect strikes.
- Conclusion
Manual straightening is carried out with special hammers with a round, radius or insertable soft metal striker. Thin sheet metal is straightened with a mallet (wooden hammer).
When straightening metal, it is very important to choose the right places to strike. The force of the impact must be commensurate with the amount of curvature of the metal and reduced as it moves from the greatest deflection to the least.
In case of a large bend of the strip, blows are applied to the edge with the toe of a hammer to one-sidedly stretch (lengthen) the bending points.
Strips with a twisted bend are straightened using the unwinding method. The straightening is checked “by eye”, and if there are high requirements for the straightness of the strip, with a straight edge or on a test plate.
Round metal can be straightened on a slab or on an anvil. If the rod has several bends, then the extreme ones are straightened first, and then those located in the middle.
The most difficult part is editing sheet metal. The sheet is placed on the plate with the convex side up. The blows are applied with a hammer from the edge of the sheet towards the convexity. Under the influence of impacts, the flat part of the sheet will be stretched, and the convex part will straighten.
When straightening hardened sheet metal, apply gentle but frequent blows with the toe of a hammer in the direction from the concavity to its edges. The upper layers of metal are stretched and the part is straightened.
Shafts and round workpieces of large cross-section are straightened using a manual screw or hydraulic press.
Manual bending is done in a vice using a hammer and various devices. The sequence of bending depends on the size of the contour and the material of the workpiece.
Bending of thin sheet metal is done with a mallet. When using various mandrels for bending metals, their shape must correspond to the shape of the part profile, taking into account the deformation of the metal.
When bending a workpiece, it is important to correctly determine its dimensions. The length of the workpiece is calculated according to the drawing, taking into account the radii of all bends. For parts that are bent at right angles without rounding on the inside, the bending allowance of the workpiece should be from 0.6 to 0.8 times the thickness of the metal.
When plastic deformation of metal occurs during bending, the elasticity of the material must be taken into account: after the load is removed, the bending angle increases slightly.
The manufacture of parts with very small bending radii is associated with the danger of rupture of the outer layer of the workpiece at the bending point. The size of the minimum permissible bending radius depends on the mechanical properties of the workpiece material, the bending technology and the quality of the workpiece surface. Parts with small radii of curvature must be made of plastic materials or pre-annealed.
When manufacturing products, sometimes it becomes necessary to obtain curved sections of pipes bent at different angles. Solid drawn and welded pipes, as well as pipes made of non-ferrous metals and alloys.
Pipe bending is done with or without filler (usually dry river sand). This depends on the pipe material, its diameter and bending radius. The filler protects the pipe walls from the formation of folds and wrinkles (corrugations) in places of bending.
8. List of used literature
1. Makienko N.I. “Plumbing” 2nd edition, revised. and additional M. Proftekhizdat, 2002.-384, Moscow
2. Makienko N.I. “Plumbing with the basics of materials science.” Selkhozgiz, 2008
3. Mitrofanov L.D. “Industrial training plumbing" Proftekhizdat, 2010.
4. Slavin D.O. “Technology of metals”. Uchpedgiz, 2010
9. Application
Appendix No. 1.
Rice. 1. Editing metals: a - correct plate, b - direction of force and location of impacts during editing.
Appendix No. 2.
Rice. 2. Techniques for straightening (straightening) hardened parts of squares.
Appendix No. 3.
Rice. 3. Bending the metal of a double square in a vice.
Appendix No. 4.
Rice. 4. Pipe bending:
a - in the device: 1 - frame, 2 - movable roller, 3 - fixed roller, 4 - lever, 5 - handle, 6 - clamp, 7 - pipe; b – manually.
10.Review
For the written examination paper of a student of group No. 32
FULL NAME.
BOU NPO "Vocational School No. 18".
By profession: "Tractor driver - agricultural production operator"_________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ___________________
Performed under the guidance of: industrial training master ______________________________ ______________________________ ______________________________ ______________________________ ____________
General characteristics of the written examination work________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ________________
positive aspects of work ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________
shortcomings in the explanatory note and its design ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ __________________
conclusion (work evaluation) ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ __________________
Reviewer: ______________________________ ______________________________ ______
(full name, position, place of work)
______________________________ ______________________________ ______
"______" "__________" 20______
Deputy Director for Management and Development ____________________________N. N. Dedkova (signature)
"______" "_________" 2012
Short description
This work talks about some of the locksmith work that a mechanic repairman must be able to perform.
The first part consistently presents theoretical information that reveals the essence of the processes of straightening and bending metals, as well as information about the tools, means and objects of labor of a mechanic used in performing these operations.
The second part discusses safety precautions when performing this type of work. The third part contains the necessary reference materials theoretical and practical nature, which can be used when performing practical work.
Content
Introduction 4
Basic information about the process of straightening and bending metal 7
Metal straightening 10
Types of metal straightening 10
Toolkit Basics 11
Characteristics of the editing process 11
Edit strip metal 12
Sheet metal straightening 13
Straightening of bar material 13
Editing (straightening) of hardened parts 13
Metal bending 15
Characteristics of the bending process 15
Safety rules for straightening and bending metal 18
Types and reasons of marriage 19
Conclusion 20
References 22
Appendix 23
Review 25
CONCLUSION
Occupational safety rules when bending metal
* securely secure workpieces in a bench vise or other devices;
* work only on working equipment;
* plumber's hammers must have good handles, be tightly seated and wedged;
* do not place mandrels and tools on the edge of the workbench;
* do not hold when bending wire left hand close to the fold;
* do not stand behind the worker;
* perform the work carefully so as not to damage your fingers;
* work in gloves and buttoned-up gowns.
So, tools must be selected based on how complex the work you are going to do is.
But you should always remember that the more perfect a particular tool is, the better the work can be done, and, in addition, it will be easier and more enjoyable for you to create or repair something with your own hands, using perfect technology.
The student must know: purpose and methods of metal bending; tools and devices; technical equipment; organization and rules for maintaining the workplace; basics of industrial sanitation.
The student must be able to: V correct sequence bending bars, strip steel, rolled angle steel; bend pipes in cold and hot conditions; organize correctly workplace; comply with safety regulations; eliminate defects that occur during metal bending.
1. Why is the length of the workpiece for subsequent bending calculated along the neutral line?
2. Why does deformation not occur when using filler when bending pipes?
3. In what cases and why are hammers with soft inserts used when bending?
4. What is taken into account when choosing percussion instrument for bending?
5. Why is it not necessary to use special bending devices when bending pipes?
use of filler?
6. What phenomena occur during bending?
7. What pipe bending methods are used in practice?
8. What defects occur when bending metal and how to eliminate them?
9. What tools and devices are used when bending metal and what are they used for?
10. What safety rules must be followed when bending metal?
General information and filing techniques"
Target: introduce students to technical requirements for the upcoming work in the metalwork shop; teach how to use tools and devices, the sequence of filing techniques for various workpieces, cylindrical rods, shaped surfaces complex profile; with safety rules when filing metal; with labor protection and fire safety
