In industrial production, metal molds are parts or products that use various presses and special tools installed on the presses to make metal materials into required shapes. This special tool is collectively called metal mold. Below, I will share with you the common problems and solutions of hardware mold maintenance, hoping to help you!
Jumping waste
Large die gap, short punch, the influence of material (hardness and brittleness), too fast stamping speed, adhesion caused by too sticky stamping oil or too fast oil droplets, chip divergence caused by stamping vibration, vacuum adsorption and insufficient degaussing of die core may all lead to waste chips being brought to the die surface.
(1), sharpness of the blade. The bigger the fillet of the cutting edge, the easier it is to cause the waste to rebound. For thin stainless steel, an inclined cutting edge can be used.
(2) For the regular waste, the complexity of the waste can be increased or a polyurethane ejector pin can be added to the punch to prevent the waste from jumping, and scratches can be added to the side of the die.
(3) The mold clearance is reasonable. Unreasonable die gap is easy to cause waste rebound. For small diameter holes, the clearance decreases by 10%, and the diameter is greater than 50.00 mm, and the clearance increases.
(4) Increase the depth of the mold. When stamping the die at each station, the requirements for the insert die are certain, and the insert die is small, which is easy to cause the waste to rebound.
⑤ Whether there is oil stain on the surface of the processed material.
⑥ Adjust the punching speed and oil concentration.
⑦ Vacuum adsorption is adopted.
⑧ Degaussing the punch, insert and material.
Crushed, scratched
(1), the material belt or mold is broken due to oil stain and waste chips, so it is necessary to wipe the oil stain and install an automatic air gun to remove the waste chips.
(2) The surface of the mold is not smooth, so the surface smoothness of the mold should be improved.
(3) The surface hardness of parts is not enough, and the surface needs chromium plating, carburizing and boronizing. (4), material strain and instability, reduce lubrication, increase compressive stress, adjust the spring force.
⑤. Repair the chip-jumping mold.
⑥ During the operation, if the product is scratched by mold positioning or other places, the mold positioning must be modified or reduced, and the operator should be educated to handle it carefully during the operation.
There are scratches on the outer surface of the workpiece after bending.
(1), raw materials with unsmooth, unclean and uneven surfaces.
(2) If there is waste in the formed blocks, remove the waste between the blocks.
③ If the forming block is not smooth, it should be electroplated and polished to improve the smoothness of the punch.
④ If the bending radius r of the punch is too small, increase the bending radius of the punch ⑤. If the bending gap of the die is too small, adjust the bending fit gap between the upper and lower dies.
6. female die molding block is formed by adding rollers.
Leakage punching
The occurrence of missing punch is generally caused by factors such as missing punch, missing punch after die repair, and sinking of punch. After the mold is repaired, the first part should be confirmed and compared with the sample to check whether there are any omissions. If the punch sinks, the hardness of the upper die pad should be improved.
Abnormal peeling
(1), the stripper is too tight with the punch, the stripper is inclined, the height of the copying screw is uneven, or other stripper devices are improper. The demoulding machine should be trimmed, and the screws of the demoulding machine adopt the combination form of sleeve and hexagon socket head screw.
(2) The die gap is small, and the punch needs a great demoulding force when it is separated from the material, which leads to the punch being killed by the material, so it is necessary to increase the gap of the lower die.
(3) The female die has an inverted cone, and the female die is trimmed.
(4) The blanking hole of the female die is not aligned with the discharging hole of the lower die seat, and the discharging hole is trimmed.
(5), check the status of processing materials. The material is dirty and attached to the die, which causes the punch to be bitten by the material and cannot be processed. Warped materials will clamp the punch after punching, and the warped materials need to be leveled before processing.
6, punch, die edge passivation to sharpen in time. A mold with a sharp blade can produce a beautiful cutting surface. If the cutting edge is blunt, extra punching force is needed, and the cross section of the workpiece is rough, resulting in great resistance, which leads to the punch being bitten by the material.
⑦ Proper use of oblique cutting edge punch.
⑧ Minimize wear, improve lubrication conditions, and lubricate plates and punches.
Pet-name ruby, spring or rubber elasticity is not enough or fatigue loss, replace the spring in time.
Attending, guide post and guide sleeve clearance is too large, repair or replace the guide post and guide sleeve.
◎ Accumulate parallelism error, and re-grind and assemble.
◎ The hole on the push block is not vertical, which makes the small punch offset. Repair or replace the pusher.
◎ If the punch or guide post is not installed vertically, reassemble it to ensure verticality.
Pay attention before using the punch.
① Clean the punch with a clean rag.
② Check the surface for scratches and dents. If there is, remove it with an oilstone.
(3) Apply oil to prevent rust in time.
(4) Be careful not to have any inclination when installing the punch. Tap gently with soft material tools such as nylon hammer. Only after the punch is correctly positioned can the bolt be tightened.
Installation and debugging of stamping die
Special care must be taken when installing and adjusting the mold. Because stamping dies, especially large and medium-sized stamping dies, are not only expensive, but also bulky and difficult to move, personal safety should always be put in the first place. A wooden board should be added between the upper die and the lower die of the stamping die for infinite devices. After cleaning the stamping table, put the die to be tested in the closed state at an appropriate position on the workbench. According to the process documents and the design requirements of the die, before the die is moved to the stage, adjust the stroke of the press slider to the bottom dead center and the position greater than the closing height of the die 10 ~ 15 mm, and adjust the slider connecting rod to move the die, so as to ensure that the die handle is aligned with the hole of the die handle, so as to achieve a proper die loading height. Generally, the lower die should be fixed (not tightened) before the upper die is fixed (tightened), and the T-bolt of the platen (lower die) should be tightened with a suitable torque wrench to ensure that the same bolt has a consistent and ideal pre-tightening force. It can effectively prevent the pre-tightening force from being too large or too small due to physical strength, gender and hand feel errors, and the pre-tightening force of the same thread is not equal, thus causing faults such as dislocation of the upper and lower dies, gap change and peeling of the cutting edge during stamping.
Before the mold test, fully lubricate the mold and prepare the materials needed for normal production. Start the die for 3 ~ 5 times in idle stroke, and try punching again after confirming that the die works normally. Adjust and control the depth of the punch into the female die, check and verify the performance and operational flexibility of the mechanisms and devices such as die guiding, feeding, pushing, side pressing and spring pressing, and then make appropriate adjustments to make them reach the best technical state. 3 pieces, 5 pieces and 10 pieces of large, medium, small and medium-sized molds were tested for initial inspection respectively. After passing the inspection, the test punch 10, 15 and 30 pieces shall be reinspected. After marking inspection, stamping surface and burr inspection, all dimensions and shape and position accuracy meet the requirements of the drawings before delivery to production.
Stamping burr
① If the chip gap is too large or uneven, readjust the chip gap.
(2) Improper material and heat treatment of the die result in the inverted cone or sharp cutting edge of the female die, so the material should be selected reasonably, the working part of the die is made of cemented carbide, and the heat treatment method is reasonable.
(3), stamping wear, grinding punch or insert.
④ If the punch enters the female die too deeply, adjust the depth of the punch entering the female die.
⑤ If the guiding structure is inaccurate or improper operation, check the guiding accuracy of the guide post and guide sleeve in the die and standardize the operation of the punch.
The bending edge is not straight and the size is unstable.
(1) Add line pressing or pre-bending process.
(2). The material pressure is not enough, increase the pressure.
③ Asymmetric wear or uneven bending force of the die fillet. Adjust the clearance of the die to make it uniform and polish the fillet of the die.
④ The height dimension cannot be less than the minimum limit dimension.
Prevent stamping noise
Punch press is the most critical and necessary equipment in sheet metal processing industry. The punch will produce mechanical transmission noise, stamping noise and pneumatic noise when it is working. The maximum noise can reach 1.25 dB(A), which greatly exceeds the noise index requirement of 85dB(A) and below stipulated by national standards, and causes extremely serious damage and pollution to operators and surrounding environment (such as offices, residential areas and conference rooms). Effectively controlling noise has become an urgent problem to be solved. Especially with the implementation of the first noise law in China, the scale of environmental protection industrialization is increasing day by day, which accelerates the urgency of noise control.
Starting with the noise source and die structure of the punch press, the following points should be paid attention to in reducing noise:
(1), pay attention to the maintenance and cleaning of the mold, and keep the cutting edge sharp.
(2) The shape, quantity, material and tangent length of the die-cutting edge should not be too large, and the die-cutting edge and parts should be stamped step by step with hypotenuse, so that the die can be cut into different depths at different positions, and the whole process can be truly cut off, rather than being squeezed off at the same time.
(3) The die-cutting edge must be perpendicular to the installation surface, and the gap between the convex and concave die-cutting edges should be reasonable. When discharging is difficult, the gap between the lower die and the discharging force can be increased, and the discharging plate with soft surface can be used.
(4), the cooperation accuracy between working templates, processing some exhaust slots.
⑤ Change the stop plate into small pieces, and change the stripper plate and the lower template into inserts to reduce the hit area.
⑥ The ejector pin source of stripper is changed to T-shaped ejector pin, and the spring is installed on the upper die base, and the ejector pin is matched with the die sleeve to ensure that the stripper still has a certain amount of free movement when the die is opened.
All landowners, keep good lubrication, mold without interference, smooth.
Today, the surfaces of the upper and lower die seats are all padded with aluminum plates for impact buffering.
Pet-name ruby, after debugging the mold, add a sound shield or sponge board on the punch for sound insulation.
Attending, improve the drilling accuracy, reduce the structural noise. Install vibration and noise reduction oil cylinder on the workbench, strengthen the lubrication of helical gear and install gear cover, and install muffler in the pneumatic system.
Extrusion thinning of curved surface
① If the fillet of the mold is too small, increase the fillet radius of the mold.
(2) If the gap between the punch and the die is too small, please correct it.
The bottom of the concave part is uneven.
(1). The material itself is uneven and needs to be leveled.
(2) The contact area between the roof and the material is small or the jacking force is insufficient, so it is necessary to adjust the jacking device to increase the jacking force.
(3) There is no ejector in the female die, so the ejector should be added or modified.
(4) Adding plastic procedures.
Flanging deformation of stainless steel
Before flanging, coating high-quality forming lubricant on the material can make the material better separate from the die and move smoothly on the surface of the lower die during forming. This makes the material have a better chance to distribute the stress generated during bending and stretching, and prevents the deformation of the edge of the forming flanging hole and the wear of the bottom of the flanging hole.
Material deformation
A large number of holes are punched in the material, which leads to poor flatness of the material, which may be caused by the accumulation of stamping stress. During punching, the material around the hole is pulled downward, which increases the tensile stress on the upper surface of the plate, and the downward punching movement also increases the compressive stress on the lower surface of the plate. The result is not obvious when the number of holes is small, but with the increase of the number of holes, the tensile stress and compressive stress also increase exponentially until the material is deformed.
One way to eliminate this deformation is to drill a hole every other hole, and then go back to drill the rest. Although this produces the same stress on the plate, it collapses the accumulation of tensile stress/compressive stress produced by stamping one after another in the same direction. This also makes the first batch of holes share part of the deformation effect of the second batch of holes.
The mould is badly worn.
① Replace the worn guide die assembly and punch in time.
(2) Check whether the mold gap is unreasonable (small) and increase the gap under the mold.
(3) Minimize wear, improve lubrication conditions, and lubricate the pallet and punch. Oil quantity and fuel injection times depend on the conditions of processing materials. Cold-rolled steel plates, corrosion-resistant steel plates and other materials without rust should be oiled in the mold, and the oiling points are guide sleeve, oiling port and lower mold. Light engine oil for engine oil. For materials with rust skin, when machining, the rust powder will be sucked between the punch and the guide sleeve, resulting in dirt, which makes the punch not
It can slide freely in the guide sleeve. In this case, if oiled, it will make the rust coat easier. Therefore, when washing this material, it is necessary to clean the oil, decompose it once a month, remove the dirt on the punch and the lower die with gasoline (diesel oil), and then clean it before reassembly. This can ensure that the mold has good lubrication performance.
(4) Improper grinding method will lead to mold annealing and aggravate wear. Soft abrasive grinding wheel should be used, a small amount of tools should be used, enough cooling liquid should be used, and the grinding wheel should be cleaned frequently.
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