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wall rupture
this defect usually appears in the corner near the side wall of tube, usually appears in the radius of die (rcd) nearby. In the mold design stage, is generally difficult to predict. The inverted W-shaped, appear in the top of the drawing direction and the cross was 45 ° grid. Cross-pin across the grid as a crossed, as when looking for the cause rupture of the wall, if not pay attention to, often do not have missed. It is a rare but more clearly the reasons for flaws.
square tube drawing, straight edge and corner distortion uneven. As the drawing progresses, the thickness increased only in the corner. Thus, the grinding of the blank holder, blank holder force focused on the corner, while also promoting the hardening.
end, bending and straightening of the force required to increase, drawing load concentrated in the corner, this trip drawing load peak load curve twice.
rupture and drawing the first peak corresponds to the second peak corresponds with the wall rupture. To average load, the first peak maximum. On the corner, in the late processing of the drawing load was concentrated to the corner, they often appear in the second peak of the wall rupture.
and carbon steel (mild steel) compared ,18-8 stainless steel as hardening serious, prone to wall rupture. Even if the drawing as a uniform cylinder of products that often can occur flatter screen option?
causes and elimination
(1) product shape.
① deep through the deep drawing.
Because the defect is generated when the deep drawing, such as the pull was reduced to solve the deep. However, the requirements must be drawing sheet size, use other methods to solve the examples are many.
② rd, rc too small.
Because the defect is in the square tube corner radius (rc) is too small to happen, so we should increase the rc. Die radius (rd) for small and deep drawing, they have produced the risk of wall rupture. If you have broken, we must make good ground (rd), its greater
(2) stamping conditions.
① BHF is too large.
they do not wrinkle, can reduce the BHF. If the cause of wrinkling is caused by the breakdown, the lower blank holder force must be prudent. If you happen across a thin flange on the crease, where they also break lights, it may be due to a good cushion pin height is not processing, mold accuracy, low precision presses, blank holder and the parallelism is not good collision occurred and other local causes. Must take appropriate action. The existence of these factors can be judged by the impact marks, impact marks if the normal shape of neat, if irregular, it indicates that there must be problems somewhere.
② poor lubrication.
processing oil is important. Difference whether the appropriate approach lubricants, is when the products taken out from the mold, if the products can not touch the high temperature to the extent necessary to reconsider the choice of lubricants and lubrication methods. In the drawing process, one of the most important factors is not the lubricant film rupture. Leaving the punch sidewall material softening temperature rise is caused by failure. Therefore, when deep drawing, the drawing should be to minimize the friction caused by the other, but also taking an active cooling solution.
③ rough shape wrong.
Experience, produced in the test phase of the wall drawing rupture, as long as the change in rough shape, you can eliminate the defects, such examples are many. Drawing tube side, the first using a square blank for deep drawing, rd position if they have broken, on the four corners of the cutting angle on the rough. At this stage, if a W-shaped broken down and the grid flaws, then the four corners of the cutting angle is too high. Cutaway shape, such as the four corners of the drawing produced notch when the flange, as long as the cutting angle decreases the amount of the appropriate number, can be eliminated, but can also stop the rupture.
④ poor positioning.
Even if the appropriate amount of
Cutaway, but if the rough positioning is not correct, as will as the cutting angle is too large, still have broken. In addition, when mass production, the use of three-point positioning device, positioning depends on the operator's hand, then tends to produce wall rupture.
⑤ buffer off bad.
off as long as the length of the buffer to make appropriate adjustments, defects can be removed.
(3) mold problem.
① mold surface roughness, and poor contact.
increase in the grinding surface of the die surface finish at the same time, but also to not form with the state of concentrated loads.
② mold parallelism,MBT Sini Shoes Men Denim, squareness errors.
for deep drawing, due to the increase in the height of the mold, the punch or die so the vertical, parallel backward, when close to the lower dead point, the gap changes in co-ordination and to become the cause of the breakdown of . Therefore, the molding is completed, you must check the parallelism and perpendicularity.
③ drawbead the position and shape is not good.
weaken the party when the tube drawing drawbead corner of the role.
(4) Material
① tensile strength is not enough.
② grain is too large, prone to the Ministry of wall cracks, it should reduce the grain material.
③ less deformation limit, and therefore the material into a large r value.
④ increase in sheet thickness, the test drawing.
vertical wall crack
by deformation if the initial processing, processing and post under tensile deformation, may have longitudinal cracks.
(1) product shape.
① deep through the big pull.
bulging longitudinal cracks caused over the limit; In addition, the finishing, the vertical or horizontal bulging in excess of the limit, will lead to rupture. In short, the direct cause of rupture, and the bulge is consistent overrun. Therefore, more than the limit deformation to rupture, from the form of speaking, is to pull through deep deep deep if the lower degree of tension, forming conditions will get better.
② die radius (rd) is too small.
because it is bulging deformation, if the material has deformed more than the limit, will have a rupture. Therefore, a reasonable rd Department both to prevent the flange cracks, but also supplementary material. Improve the material flow as one of the conditions is to increase the radius of die (rd). Although preventing the breakdown of the increase rd generation, but at this time rd large size than the drawings, for the rd to the drawing requirements, should be added to a finishing process.
(2) stamping conditions.
① BHF is too large.
basic drawing force adjustment method is to adjust the blank holder force. If you have broken, and the flange parts of shiny, it is because the blank holder force is too large. Therefore, when there is risk of rupture, it can slightly reduce the blank holder force to observe the changes of products.
② insufficient lubrication of the die surface.
With the increase of BHF, lubricating oil film strength should be increased correspondingly, to minimize friction.
③ bad rough shape.
greater if rough, forming conditions will get worse. Therefore, the need to reduce to a minimum rough. Can be close to the lower dead point, the rough to cross the draw bead, and then test the drawing.
(3) mold problem.
① drawbead the shape and position is wrong.
drawbead Although you can use to prevent the flange have wrinkles, but the side effects that have hindered the inflow of material, so, if they have broken into resistance because too much material, then, is easy to material flow, you need to with rough comprehensive analysis of the shape of drawbead with the location and shape.
② processing bad.
If the mold surface processing
bad, they can not improve the BHF. Therefore, with the wheels polished.
(4) material.
If you exceed the limit deformation, we need to replace the more advanced material, the other, but also increase the plate thickness.
corresponding parts of the punch shoulder
crack
the strength of the material is not enough, when the drawing load to the breaking load of material when the defect occurs.
defects produced in the punch shoulder part of the corresponding parts of R (rp Office), which marks the line is closer than the collision part of rp. Marks part of the collision ruptured line, as with other parts of the different, you can check the following situations were observed: either to be extended; or below the flange of the bright part of it; or have wrinkles. In addition, there are sometimes side wall of shiny parts.
initial transverse rupture was tongue.
causes and elimination
(1) product shape.
① deep through the big pull.
present, cylinder, square cylinder deep drawing limit is determined at the design stage. Thus, in the limit drawing near, use your smooth surface, flat material, integrated with the mold and grinding, processing lubricants, buffering pressure, press precision field conditions, the test drawing.
② punch radius (rp) is too small.
a correction to the appropriate value of the rp.
b rp over an hour on the drawings, first by drawing the appropriate value, and then increased a process, forming the required size.
③ die size (rd) is too small.
a correction to the appropriate value of the rd.
b rd over an hour on the drawings, first rd values ​​with the appropriate drawing, then add a process, shaped to the desired size.
④ side of the corner radius of the cylinder (rc) is too small.
a deep degree of the pull decreases;
b increase in a deep drawing process more;
c replaced by more advanced material;
d the sheet thickness.
(2) stamping conditions.
① BHF is too large.
BHF is too large, wrinkling does not occur in the flange surface. Crease plate surface roughness, die with, clearance, rp, rd, the type of oil and coating process conditions, resulting from the buffer blank sales force distribution, etc., affect the crease pressure. If the drawing of the above-mentioned conditions are appropriate, blank holder force will decrease, in the wrinkle, it will not rupture.
BHF is too large, the flange surface will be fully illuminated, so it is easy to judge.
② poor lubrication.
drawing processing and lubrication there is a very close relationship, especially in deep drawing process includes thinning, the temperature must be controlled products. If the conditions are good, drawing processing, what is not a problem of the choice of lubricants; conditions of poor drawing processing, poor choice if the oil will lead to rupture.
③ bad rough shape.
stage of the trial drawing to determine the rough shape of the work is an important one.
Blank must be the minimum size limit. When the cylinder with a square of rough drawing, the limit drawing ratio of about 0.58. In addition, if the drawing rate is too harsh, rp will have broken parts of the injuries, such as the cutting angle, you can prevent rupture.
square tube drawing with a billet can be carried out first, so you can create a beautiful product, but if you reach deep drawing limit, will have a break in the near rcp. If you have broken the four corners can be cut away part of the rough. However, if cut more, they would have flange wrinkling, a wall of the crack generation.
④ rough positioning is not good.
good shape even if the rough, but if not adjust the position or orientation right place, time, punch and blank generation of dislocation, also have a rupture or wrinkling.
In addition, with 500 tons of oil, and for larger sizes forming deep drawing parts (material is SUS304), low viscosity oil can be used for deep drawing. When using high viscosity oil for deep drawing, the drawing to a height of 1 / 4, rp site will be broken.
stainless steel and mild steel compared vulnerable to the impact speed, but if adequate cooling and lubrication, in practice, other aspects of the problem is more important than speed.
When high-speed blanking, even if the use of general space, cut all the shear plane is very good.
⑤ die poor installation.
the defect is installed by the poor die, the upper and lower mold caused by misalignment. Recently, almost all of the molds are equipped with guiding device, due to the fault generated in the mold has not rare.
⑥ the length of the buffer pin missing.
buffer off during use, as a result of bending, impact injuries, are often made of different lengths, in the drawing process, the buffer part of a long pin, which burst due to concentrated loads. In order to vary the length of the buffer to check off, in the mold adjustment phase, shaking off his hand back and forth, long sales due to the concentration under the weight of the blank holder, and become heavy, it is easy to understand.
⑦ rugged cushion.
when the press pin positions on the cushion of the depression, or waste fell from the pin hole of the buffer pad to cushion the pressure can not control. Press any activity table, as can a simple cleaning or maintenance, so this accident will not happen, but if it is a fixed table, for long periods of maintenance, once used, often to accidents.
⑧ pin cushion with bad.
buffer pins should in principle be assembled around the punch, however, there must be an appropriate interval. If the blank holder is thin, the buffer pin configuration is not the time, products, flanges, in a buffer area by the strong pull the pin to break. At this time, the end flange shape, will be extended as the tongue-like part, it is very easy understand.
In addition, the buffer around the pin configuration and shape of the punch is inconsistent, the flange surface will wrinkle, but also tend to be broke down. In the final analysis, when the thin blank holder, pin position there is significant impact, therefore, that the blank holder with sufficient strength, is the most fundamental problem.
⑨ wrinkling caused by rupture.
a blank size greater than the blank holder.
Blank Size
when large than the blank holder, drawing starts, the exposed part of the billet to produce wrinkle it with , in order to determine the
general, even the large stock of local bulging, its principles are still rough and then suppressed by the blank holder pressure.
b BHF small.
when BHF hours, rough surface will wrinkle, the wrinkles through the die radius (rd), they tend to rupture. Therefore, this occasion, wrinkles, and broken on the mix as a whole.
When using a high degree of hardening stainless steel square tube for deep drawing, there is a bright part of the produce at the crease near rd.
The wrinkle is generated
reasons for the breakdown, rd part if broken, first of all to improve the BHF, eliminate wrinkles, it is of paramount importance. Never increase or reduce the BHF rd.
light partly due to stock thickness increased, due to concentrated load to bear, therefore, improve the BHF at the same time, the point of contact between the mold to impressive levels, elimination of the thickened part of the material; as was distributed load, the flange surface to eliminate wrinkles, leaving the material flow easier.
c die radius (rd) is too large.
rd is too large, it will produce in the rd part of the crease after hardening, it functions as a drawbead drawing pieces that have broken. Thus, when carrying out deep drawing, rd should be as small as possible, so that the drawing is easy.
d wall of blank holder gap is too large (Figure 2).
For example, pressing the flange
cylinder or square tube drawing drawing local compression flange when the punch and blank holder side wall of the gap, must be greater than the die radius (rd) small.
If the gap is too large, when the material can not be snapping drawing rd, but to muster up, resulting in wrinkles, folds into the gap after the pressure into a certain shape, and become the reason to rupture.
Therefore, the processing of the blank holder side wall to have a reasonable gap, Tube clamping flange part and the clamping flange corner square tube section, the gap must be designed smaller than rd.
⑩ bad press accuracy.
accuracy of press
poor little effect for shallow drawing. When using a crank press for deep drawing, if the poor accuracy, the impact will be obvious to rupture. Therefore, to ensure machine precision, is the basis for drawing processing.
(3) relationship between mold.
① die rough surface.
for deep drawing, the blank holder and die polishing on both sides is not adequate, especially the deep drawing of stainless steel plate and aluminum plate, the more susceptible drawing scars. Therefore, the die must be 0.4S following mirror finish, this can completely eliminate the impact scars.
high surface pressure when the deep drawing, even if the elimination of collisions also tend to rupture, in order to make the surface more smooth, can be
② elimination of the blank holder collisions.
in the drawing process, in order not to produce concentrated load, thickness variation should be based on changes in die face contact state, the mold surface gap was uniform load.
drawing, if not eliminate the blank holder of the collision, will form a concentrated load and to rupture.
③ drawbead position and shape of adverse.
expansion force of the draw bead rupture caused by excessive, can change the draw bead shape, and determine the location of drawbead and materials into the process, that is determined through an integrated approach to determine the draw bead shape with rough relationship.
④ gap is too small.
corner drawing parts of the wall near the rd part, there are bright spots and produce rupture, which is caused by the gap is too small. Therefore, as long as the amendment to the gap, eliminating bright spots, to prevent rupture.
In addition, not all of the corner, but only light up and produce a corner broke down, the reason is not good guides or just a corner of the dimensional accuracy is poor; In addition,MBT Tataga shoes-Blue-W, because of convex and concave mold and pressed vertical edge difference between the circle in the drawing process produces changes in the gap, causing rupture and so on. Identify the causes and elimination of light parts, you can prevent rupture.
but the following exceptions: The square containers for shallow drawing, the punch corner radius (rcp) and the corner radius r over an hour, rcp Department will certainly break. In order to prevent rupture, it is best to increase the punch radius rcp to the appropriate values, but this way, the products of commercial value will drop. To this end, as long as the increase in an ironing, can achieve the product size requirements, but also to prevent the breakdown of the Ministry of rcp.
⑤ punch and blank holder gap is too large.
in the deep drawing process, when the punch and blank holder gap is too large, blank holder produces horizontal; rd is small, as is the case in Figure 2, material is not close to the rd Division, and entering the punch and blank holder formed between the crease, when the gap between the punch and die if not properly managed, will have a rupture.
blank holder in order to accurately move up and down, usually to punch the blank holder in the slide, or use the blank holder in the mold-oriented board-oriented approach.
⑥ stalemate arising due to thermal breakdown.
If mold properly, drawing heat is generated during the stalemate, when drawing materials tend to break. In addition, when the trial drawing with surface hardened without drawing dies, it often happens. In between drawing parts and molds polyethylene film and PVC film to prevent rupture and the occurrence of Deep wounds can also be hardened by heat treatment and surface treatment solution.
⑦ not rigid blank holder.
well as rigid blank holder, the material is only sold in the buffer area by the strong pull, and the blank holder plate surface deflection produced in other parts, which cause wrinkling and be broke down. If the buffer off the pressure reduced, the flange will all face wrinkling, due to the direct cause of wrinkling is broken, so I had better re-create a rigid blank holder.
(4) material.
① drawing performance is not good.
when drawing harsh conditions, but also allowed to increase process, it is necessary to improve the material performance.
a CCV value into a small test, r values ​​of large materials.
b develop a good deep drawing properties of materials.
tensile modulus of the defect often


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wall rupture
this defect usually appears in the corner near the side wall of tube, usually appears in the radius of die (rcd) nearby. In the mold design stage, is generally difficult to predict. The inverted W-shaped, appear in the top of the drawing direction and the cross was 45 ° grid. Cross-pin across the grid as a crossed, as when looking for the cause rupture of the wall, if not pay attention to, often do not have missed. It is a rare but more clearly the reasons for flaws.
square tube drawing, straight edge and corner distortion uneven. As the drawing progresses, the thickness increased only in the corner. Thus, the grinding of the blank holder, blank holder force focused on the corner, while also promoting the hardening.
end, bending and straightening of the force required to increase, drawing load concentrated in the corner, this trip drawing load peak load curve twice.
rupture and drawing the first peak corresponds to the second peak corresponds with the wall rupture. To average load, the first peak maximum. On the corner, in the late processing of the drawing load was concentrated to the corner, they often appear in the second peak of the wall rupture.
and carbon steel (mild steel) compared ,18-8 stainless steel as hardening serious, prone to wall rupture. Even if the drawing as a uniform cylinder of products that often can occur flatter screen option?
causes and elimination
(1) product shape.
① deep through the deep drawing.
Since the defect is generated when deep drawing, deep drawing, such as the degree of reduction can be solved. However, the requirements must be drawing sheet size, use other methods to solve the examples are many.
② rd, rc too small.
Because the defect is in the square tube corner radius (rc) is too small to happen, so we should increase the rc. Die radius (rd) for small and deep drawing, they have produced the risk of wall rupture. If you have broken, we must make good ground (rd), its greater
(2) stamping conditions.
① BHF is too large.
they do not wrinkle, can reduce the BHF. If the cause of wrinkling is caused by the breakdown, the lower blank holder force must be prudent. If you happen across a thin flange on the crease, where they also break lights, it may be due to a good cushion pin height is not processing, mold accuracy, low precision presses, blank holder and the parallelism is not good collision occurred and other local causes. Must take appropriate action. The existence of these factors can be judged by the impact marks, impact marks if the normal shape of neat, if irregular, it indicates that there must be problems somewhere.
② poor lubrication.
processing oil is important. Difference whether the appropriate approach lubricants, is when the products taken out from the mold, if the products can not touch the high temperature to the extent necessary to reconsider the choice of lubricants and lubrication methods. In the drawing process, one of the most important factors is not the lubricant film rupture. Leaving the punch sidewall material softening temperature rise is caused by failure. Therefore, when deep drawing, the drawing should be to minimize the friction caused by the other, but also taking an active cooling solution.
③ rough shape wrong.
Experience, produced in the test phase of the wall drawing rupture, as long as the change in rough shape, you can eliminate the defects, such examples are many. Drawing tube side, the first using a square blank for deep drawing, rd position if they have broken, on the four corners of the cutting angle on the rough. At this stage, if a W-shaped broken down and the grid flaws, then the four corners of the cutting angle is too high. Cutaway shape, such as the four corners of the drawing produced notch when the flange, as long as the cutting angle decreases the amount of the appropriate number, can be eliminated, but can also stop the rupture.
④ poor positioning.
Even if the appropriate amount of
Cutaway, but if the rough positioning is not correct, as will as the cutting angle is too large, still have broken. In addition, when mass production, the use of three-point positioning device, positioning depends on the operator's hand, then tends to produce wall rupture.
⑤ buffer off bad.
off as long as the length of the buffer to make appropriate adjustments, defects can be removed.
(3) mold problem.
① mold surface roughness, and poor contact.
increase in the grinding surface of the die surface finish at the same time, but also to not form with the state of concentrated loads.
② mold parallelism, squareness errors.
for deep drawing, due to the increase in the height of the mold, the punch or die so the vertical, parallel backward, when close to the lower dead point, the gap changes in co-ordination and to become the cause of the breakdown of . Therefore, the molding is completed, you must check the parallelism and perpendicularity.
③ drawbead the position and shape is not good.
weaken the party when the tube drawing drawbead corner of the role.
(4) Material
① tensile strength is not enough.
② grain is too large, prone to the Ministry of wall cracks, it should reduce the grain material.
③ less deformation limit, and therefore the material into a large r value.
④ increase in sheet thickness, the test drawing.
vertical wall crack
by deformation if the initial processing, processing and post under tensile deformation, may have longitudinal cracks.
(1) product shape.
① deep through the big pull.
bulging longitudinal cracks caused over the limit; In addition, the finishing, the vertical or horizontal bulging in excess of the limit, will lead to rupture. In short, the direct cause of rupture, and the bulge is consistent overrun. Therefore, more than the limit deformation to rupture, from the form of speaking, is to pull through deep deep deep if the lower degree of tension, forming conditions will get better.
② die radius (rd) is too small.
because it is bulging deformation, if the material has deformed more than the limit, will have a rupture. Therefore, a reasonable rd Department both to prevent the flange cracks, but also supplementary material. Improve the material flow as one of the conditions is to increase the radius of die (rd). Although preventing the breakdown of the increase rd generation, but at this time rd large size than the drawings, for the rd to the drawing requirements, should be added to a finishing process.
(2) stamping conditions.
① BHF is too large.
basic drawing force adjustment method is to adjust the blank holder force. If you have broken, and the flange parts of shiny, it is because the blank holder force is too large. Therefore, when there is risk of rupture, it can slightly reduce the blank holder force to observe the changes of products.
② insufficient lubrication of the die surface.
With the increase of BHF, lubricating oil film strength should be increased correspondingly, to minimize friction.
③ bad rough shape.
greater if rough, forming conditions will get worse. Therefore, the need to reduce to a minimum rough. Can be close to the lower dead point, the rough to cross the draw bead, and then test the drawing.
(3) mold problem.
① drawbead the shape and position is wrong.
drawbead Although you can use to prevent the flange have wrinkles, but the side effects that have hindered the inflow of material, so,你感冒了最常吃的药, if they have broken into resistance because too much material, then, is easy to material flow, you need to with rough comprehensive analysis of the shape of drawbead with the location and shape.
② processing bad.
If the mold surface processing
bad, they can not improve the BHF. Therefore, with the wheels polished.