Common Defects and Preventive Measures of Stainless Steel Drawing Die

The selection of suitable convex and concave die fillets for stainless steel wire drawing is closely related to the size and distribution of stress. If the radius of the fillet is large, the pressing area of ​​the blank holder is insufficient, which will easily cause instability and wrinkling; if the fillet is too small, it increases the resistance of the material entering the die during deformation, making it difficult for the material to flow and transfer inward, thereby increasing the force transmission. area, which may cause cracking. Therefore, it is very important to choose a reasonable punch and concave die fillet radius. Under the effect of preventing cracks, the punch relative to the fillet radius rp/ is about 4. The degree of polar deformation of the die and punch will increase, and the relative fillet radius of the die will increase by 5mm~8mm, which helps prevent cracking.

4. Thin strip stretching is used for stainless steel stretching: previous testers have also confirmed that the thin strip stretching method can significantly reduce the maximum tangential residual stress of the stretched parts and effectively prevent longitudinal cracking. According to the degree of deformation and the thickness of the original plate, an appropriate thinning coefficient (usually 0.9t~0.95t) is selected. If the value is too small, the deformation stress of the deep-drawing part will increase sharply, resulting in the bottom cracking.

5. An intermediate annealing process is added to the deep drawing method for stainless steel drawing: after multiple deep drawing, an intermediate annealing process should be carried out, which can completely eliminate residual stress and restore the austenitic stainless steel structure. For high-strength steels, it is generally necessary to go through 1 to 2 stretching processes before moderate annealing. For example, 1Crl8Ni9Ti is usually heated at 1150~1170℃, heated for 30min, and then cooled in airflow or water. Moreover, whether it is the heat treatment between processes or the final heat treatment of the finished product, it should be carried out as soon as possible after stretching to avoid deformation or cracking of the workpiece due to internal stress due to long-term storage. However, both annealing and post-cleaning annealing increase product cycle time, which affects surface quality.

6. Use suitable lubricants for stainless steel drawing: using suitable lubricants has a significant effect on stainless steel deep drawing. The lubricant can form a film with certain toughness and ductility between the convex and concave dies, which is beneficial to the stretch forming of stainless steel. Due to the large deformation of stainless steel deep-drawing parts and the difficulty of forming, polyvinyl fluoride film can be used as a lubricant in actual production. PTFE membrane has good tear resistance, certain toughness and ductility, and is easy to clean. After coating the dry film, in the stretching process, the dry film can be deformed together with the blank, and can always separate the blank from the mold, and the film itself has a certain porosity and a large number of fiber cracks, so it can be stored in a certain amount. of lubricating oil.

The above-mentioned common defects and preventive measures of stainless steel drawing die, in the actual production process, the drawing die is prone to strain, and to solve this problem, the adhesive wear should be reduced by changing the characteristics of the contact pair. I hope the above can be helpful to readers.

Customized deep drawing

Our commitment is to provide you with tailored, high-quality, reliable parts, assemblies and sub-assemblies that meet co-built specifications. For this, we rely on our 30 manual and automatic presses from 6 to 350 tons, more than 12,000 molds and more than 2,000 square meters of workshop and storage space.

Stamping can handle the most demanding industries: agricultural equipment, aviation, railways, automotive, defense, machine building, electric motors, pumps, food processing, electronics, machinery subcontracting, nuclear power, energy, environment…

The pressing process makes it possible to design a wide variety of industrial parts.

Various shapes of parts: -drawings
Standard or special gasket on-lid-lid– the lid and surface of the gauge– many metal mechanical partsIndustrial products of various sizes:Standard, Standardized or Drawing. Thickness: between 0.2mm and 6mm (depending on material).

different materials Stamping:

– Cold Rolled Sheet, Hot Rolled Sheet, Galvanized Sheet
– Stainless Steel-
aluminum
– brass
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How to adjust the stamping die gap?

1. Washer method

The gasket method is to place the paper, metal plate or forming workpiece with uniform thickness and the same gap value around the edge of the female mold, then slowly close the mold, and place an equal-height cushion so that the male mold can enter the edge of the female mold, and observe the male mold. and the gap between the die. If the gap is not uniform, adjust the gap by tapping the punch fixing plate until it is uniform, then tighten the upper die fixing screw, then put the paper into the test punching hole, and observe the blanking of the paper until the gap is uniform. Finally, after clamping the upper mold base and the fixing plate, drill and ream the dowel pin holes together, and then punch the cylindrical pins. This method is widely used in small and medium punching dies, drawing dies, bending dies, etc. It is also suitable for controlling the wall thickness of plastic molds.

2. Copper plating method

For punching dies with complex shapes and a large number of punches, it is difficult to control the gap with the above method, so a layer of soft metal (such as copper plating) can be plated on the punch surface, and the coating thickness is equal to the punching gap value on one side , and then adjust, fix and position as above. There is no need to remove the coating after assembly, and it will fall off naturally during the cutting process.

3. Coating method

The coating method is to apply a layer of enamel or amino acid paint on the surface of the punch. When painting, you should choose paints of different viscosity according to the size of the gap, or control the thickness by painting multiple times. After painting, the punch assembly should be baked in a 100120 oven for 0.5-1 hour until the thickness of the paint layer is equal to the blanking gap value, which should be uniform, and then adjusted, fixed and positioned according to the above method.

Four, light transmission method

The light transmission method is to illuminate the bottom surface with light after the upper and lower molds are closed, observe the size of the light gap around the edge of the convex and concave mold, and judge whether the blanking gap is uniform. If the gap is not uniform, adjust, fix and position. This method is suitable for thin blanking dies that require high assembly fitters. For example, it is best to use a die gap gauge for inspection and adjustment.

浅谈不锈钢钣金加工几种效果

Mirror finish is used for pre-polishing and fine polishing. Pre-polishing uses a hard or harder buffing wheel to finish the finish of the stainless steel sheet metal finish and remove the roughness of the ground finish. Fine polishing uses soft to further process the pre-polished surface, remove the traces left by pre-polishing, and obtain a bright mirror surface.

The mercerizing effect is the process of using the brushing wheel installed on the grinding and polishing machine to process the surface of the stainless steel sheet metal to obtain decorative silk-grain brushing and satin finishing.

Sandblasting effect, using compressed air flow to spray sand or steel pellets, glass balls and other abrasives on the appearance of stainless steel sheet metal processing, so that it presents a beautiful, slightly rough sandy appearance.

In stainless steel operations, stainless steel is usually heated by coils, lashings, welding or fire on artificial surfaces to produce black scale. This gray-black scale is relatively strong and contains two EO4 components, NiCr2O4 and NiF. In the past, it was basically removed by strong etching with hydrofluoric and nitric acids. However, due to environmental pollution, harm to human body, high corrosion and high cost, the sheet metal processing industry gradually adopts chemical methods: non-polluting pickling passivation paste and non-toxic cleaning solution are used, and inorganic additives are added for leaching at room temperature.

How to deal with the rebound of metal stamping parts

When the metal stamping parts spring back, which is commonly referred to as springback, elastic deformation occurs due to insufficient plastic deformation during the stamping process. Once this problem occurs, it should be corrected in time, otherwise the shape and size of the stamping parts produced by processing will have a large error, which does not meet the requirements of the stamping process. Here are some solutions.1. Improve some structures in the workpiece design to reduce the rebound angle;

2. Consider reducing springback in mold design;

3. Adopt stretch bending process;

4. Use other process methods.

What to pay attention to in deep drawing

Considerations for Deep Drawing Stamping

When considering deep drawing stamping for your manufacturing needs, it is important to be aware of the following:

Reduced Material Waste: Deep drawing stamping uses a larger amount of base material than other metal forming processes for significantly reduced material waste.

Measurement is critical: not only is it important to ensure that die dimensions are accurate, it is equally essential to consider the material thickness and desired measurements. Incorrect measurements can result in thin walls and inaccurate dimensions.

Drafting and tapping: Due to the basic manufacturing process of deep drawing stamping, some drafting and tapping of the top of the component is unavoidable. This should be taken into account during the initial design phase.

Varied Material Thickness: Deep-drawn components will typically have different thicknesses with thinner walls and a thicker base. This can be mitigated by tooling after the drawing process is completed.

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In the processing industry, molds are indispensable equipment, and different processing industries choose different molds. Metal stamping dies and plastic processing dies are widely used in industrial production. As for the difference between them, many people will say that metal stamping dies are made of metal, and plastic processing dies are made of plastic. What is the essential difference between metal mold and plastic mold? What are their main areas of application? To understand the difference between the two, we must first understand what is a metal stamping die and what is a plastic die.

1. The difference between metal mold and plastic mold

1. Metal molds refer to stamping parts processed by using various presses and special tools in industrial production to process metal materials according to the shape required by the finished product. This special tool is often called a metal mold.

2. Plastic mold is a combination of plastic molds, which can be used for compression molding, extrusion molding, injection molding, blow molding and low plastic, and can be used as mold punch, die and auxiliary molding system. A range of plastic products that can be processed in various shapes and sizes.

3. From the perspective of the role of the mold, the metal mold is a mass production tool for metal products. The materials used are generally iron or copper or aluminum, the plastic molds are plastic products, and the raw materials used are also plastic raw materials.

4. The most fundamental difference between metal molds and plastic molds is the structure of the molds. Plastic molds have cooling systems, but metal molds do not. The molding principle of the product is also different. The plastic mold is cooled and formed after injection molding, and the metal mold is punched into a standard thickness steel plate.

5. Hardware molds and plastic molds are made of steel. Stamping metal molds generally use cold steel. If it is a pressure injection mold, hot-working steel is required. The plastic mold is generally hot-working steel. The mold is more complicated. Mold) There is no gating system and cooling system, which can be understood as: plastic mold processing is to cool plastic flow into the cavity in a closed space for cooling and forming.

Second, the metal stamping die has the following advantages

Due to the use of mold processing, metal stamping parts that cannot or are difficult to manufacture by other processing methods, are thin-walled, lightweight, have good rigidity, good surface quality and complex shapes can be obtained. The dimensional accuracy of the blanked parts is guaranteed by the mold, and the characteristics are exactly the same, so the general press can produce dozens of parts per minute, while the high-speed press can produce hundreds of parts per minute. Therefore, it is an efficient processing method.

3. Plastic processing molds have the following advantages

Plastic molds have high tolerances, low repetitive labor costs, and can use a variety of materials. The waste loss is far less than that of metal molds, and there is no need to continue to improve parts after plastic molds are formed.

The above is the relevant content of metal stamping dies and plastic dies. These two molds are suitable for different industries and different processing requirements, so the production methods of the molds will also be different. I hope the above will be helpful to readers.

What is the reason for the die processing of the drawing die?

During the processing of the drawing die, if the die clamping is not flexible enough, or there is a stuck situation, then the production should be stopped immediately, and the main reason for the stuck die should be found out and troubleshoot. Otherwise, it may expand the failure, resulting in mold damage.

First, the main reasons for the card mold are:

The mold is poorly guided and tilted. And there are foreign objects in the template, so that the template cannot be flatly attached; there is a problem with the strength design of the mold or uneven force. It will lead to the deformation of the mold, such as the hardness and thickness of the mold base and the template are too small, and it is very easy to be deformed by external force; the mold position is not installed correctly, and the positioning error of the upper and lower molds is too poor. Or the precision of the press is too low, causing the mold to interfere; the strength of the punch is low, and the position of the large and small punches is too close, which makes the lateral force of the mold unbalanced. At this time, the strength of the punch should be increased, and the guidance and protection of the stripper plate should be strengthened.

The above has explained the reasons for the occurrence of card molds in the processing of drawing molds, and different reasons will have different solutions, so we need to solve the problems in a targeted manner.

What are the common problems in the processing of metal stamping parts?

1. Some common problems and reasons in the processing of stamping parts

1. Roller printing: It is caused by foreign matter adhering to the cleaning roller or paper feeding roller (occurs at a fixed distance). Under normal circumstances, the foreign matter printed by the roller on the sheet can be removed.

2. Burrs: In the process of punching or chamfering, there is incomplete residual material, and burrs are generated in the part below the truncated surface of the steel plate. Based on the truncated surface, the iron powder generated here will damage the mold and produce Concave and convex.

3. The coil may be crushed or the edge is wrinkled: When the gap between the guide rollers on the die is small, the guide rollers of the uncoiler may be wrinkled, which is caused by the unyielding balance of the coil feed.

4. Concave and convex: The material is abnormally convex or concave due to foreign matter (iron filings, dust) mixed in the uncoiler.

5. Sliding mark: It is caused by the sliding of the roller, which occurs when it suddenly stops or accelerates.

When we design the mold, we must have reasonable clearance value, fillet radius and machining accuracy. When designing a bending die, effective measures should be taken to reduce the springback, and the springback should be subtracted from the die; reasonable rounded corners should be designed to prevent bending cracking. When deep drawing, use a blank holder to prevent wrinkling, and the pressure should be moderate; use appropriate lubrication to reduce the drawing resistance to prevent the die from sticking or the workpiece being pulled through.

There are many defects in metal stamping parts, such as scratches, cracks, raised dents, burrs, oxidation, etc. In the processing of metal stamping parts, we must pay attention to these details, so as to bring greater benefits. Spinning is a metal rotary machining process. During the processing, the blank is actively rotated with the spinning die or the spinning head is actively rotated around the blank and the spinning die. hollow revolving body parts.

Reshaping is the second reshaping of the product shape using the established tool shape. Mainly reflected in the pressing plane, spring feet, etc. In view of the elasticity of some materials, the quality of one-time forming cannot be guaranteed. Reprocessing is a basic stamping process that uses molds to separate materials. , forming and other stamping processes to prepare the blank, and can also cut and trim the formed stamping parts. Blanking is widely used in automobiles, home appliances, electronics, light industry, instrumentation, machinery, railways, communications, chemicals, textiles, aerospace and other industries. The blanking process accounts for about 50% to 60% of the entire stamping process.

Forming process:

(1) Bending: a plastic forming method that bends metal sheets, pipe fittings and profiles into a certain angle, curvature and shape. Bending is one of the main processes widely used in the production of stamping parts. The bending of metal materials is essentially an elastic-plastic deformation process. After unloading, the workpiece will produce elastic recovery deformation in the direction, which is called rebound. Springback affects the accuracy of the workpiece and is a technical key that must be considered in the bending process.

Hardware Fair – Metalworking

Hardware Fair - Metalworking This hardware fair specialized manufacture of metal stamping,SHEET METAL FABRICATION,CNC machining parts,stamping parts,machine parts,deep drawn, stamping die stainless steel stamping [caption id="attachment_6144" align="aligncenter" ...

Assembly principles and technical requirements of metal stamping dies

Metal stamping molds belong to single product production. The key to die assembly of metal stamping parts is how to ensure that the relative positions of the convex, concave and related parts can work reasonably when the mold is closed, and punch it to meet the product requirements. Below, the editor of Zhejiang Baifudu Electromechanical will share with you the assembly principles and technical requirements of metal stamping dies!

All kinds of parts that are processed and put into assembly of metal stamping parts must meet the requirements of the assembly process specified by various parts; for example, the relative position dimensional accuracy and step distance accuracy of multiple punch fixing plates and various holes must meet the requirements of the concave die. , the requirements of the discharge plate, the bolts and pins on the backing plate pass through the holes, and can be drawn according to the size of the drawing. The quenching, upper and lower surfaces should be strictly ground and smooth, and the overall die installed on the upper and lower die bases should be removed. In addition to the processing of all the holes to meet the requirements of the graphics, it is also necessary to process the bolt holes and pin holes, which can be assembled after heat treatment and finishing. The fixed mold base and guide plate must be connected. When assembling the screw holes and pin holes on the guide plate, the corresponding holes on the die should be used for drilling and reaming; although the type and structural characteristics of the hardware blanking die are not All the same, the assembly method and installation sequence adopted are also different, but the assembly principles should be followed.

Some components that constitute the mold entity are processed into dimensions and tolerances according to the dimensions and tolerances marked on the drawings during the manufacturing process (such as troughs, punching punches, guide posts, guide sleeves, die shanks, etc.). These parts are usually direct mount, some parts are only some sizes in the manufacturing process that can be processed according to the drawings. Need to match the relevant size. Some require mixing or blending prior to assembly, others require mating during assembly. The dimensions marked in the figure are for reference only, such as the die seat guide bushes or guide post fixing holes on the multiple punch fixing plates. Plate bolt holes, pin holes, etc. that need to be connected).

Therefore, the metal stamping die assembly is suitable for centralized assembly, and the repair method and adjustment assembly method are mostly used in the assembly process to ensure the assembly accuracy. In this way, higher assembly accuracy can be achieved, and the standard of parts processing is reduced, thereby achieving the accuracy standard for parts. The technical requirements for metal stamping die assembly are as follows:

1. The precision of the die base should meet the standard requirements (JB/T8050-1999 “Technical Conditions for Die Sets” (JB/T8071-1995) in the relevant die precision testing. The height of the die seal should meet the standards specified in the drawings.

2. For the assembled die, the upper die should slide smoothly and reliably along the guide post and the upper die.

3. The gap between the protruding dies should meet the standard specified in the drawing, and the distribution should be uniform. The working strokes of the convex and concave molds meet the technical requirements.

4. The relative position of positioning and stopper should meet the drawing standard. The distance between the mold guide plates must be consistent with the distance specified in the drawing; the guide surface should be parallel to the center line of the feeding direction of the die; the guide plate is equipped with a side pressure device, and the side pressure plate can slide flexibly and work reliably.

5. The relative positions of the unloading and ejecting equipment should meet the design standards, and there should be no inclination or unilateral deflection in the work to ensure that the parts or wastes are unloaded in time and ejected smoothly.

6. The fastener assembly should be reliable. The length of the bolt thread should not be less than the diameter of the bolt when connecting steel components. When connecting castings, it should not be less than the diameter of the bolt, and the diameter of the bolt should not be less than 1.5 times; The length should be greater than 1.5 times the diameter of the pin; the end face of the pin should not be exposed. The surface of the lower die seat and other parts.

7. The blanking hole or discharge trough should be unobstructed to ensure that parts or waste cannot be discharged at will.

8. Standard components must be interchangeable. The fit of the fixing screws and positioning pins with their holes should be normal.

9. The installation size of the metal stamping die on the press must meet the standard of the selection equipment; the lifting parts must be safe and reliable.

10. The die for metal stamping parts should be tested under manufacturing conditions, and the punched parts should meet the design standards.

The above introduces the relevant assembly and technical requirements of metal stamping dies. Stamping dies are the key equipment for stamping parts processing and have a direct impact on the quality of stamping parts. As the saying goes, if you want to do good work, you must first sharpen your tools before you can produce qualified products. I just hope the above can be of some help to the readers.

How to control the quality problems of metal stamping parts?

First, the main characteristics of metal stamping parts

1. Metal stamping parts are manufactured under the premise of low material consumption. The parts are light in weight and good in rigidity. After plastic deformation, the internal structure of the metal is improved, and the strength of the stamping parts is improved.

2. The dimensional accuracy of metal stamping parts is high, the size of the same mold is uniform, and the interchangeability is good. Meets general assembly and use requirements without further processing.

3. During the stamping process, since the surface of the material is not damaged, the surface quality is good, and the appearance is smooth and beautiful, which provides convenient conditions for surface coating, electroplating, phosphating and other surface treatments.

2. Control the quality problems of metal stamping parts

1. It is very important to test the first piece of metal stamping parts. In the first process before the mold is ready to be shipped, some stamping parts need to be trial-assembled, so that the relevant accessories can be trial-installed before production.

2. The hardware stamping parts are inspected according to the process time to prevent the variation in the stamping process, such as size problems when the production time is too long, and few holes caused by broken needles of the inserts.

3. Sampling inspection before the metal stamping parts flow into the next process to ensure the qualification of the material again.

The quality of metal stamping parts is very important for the quality of metal stamping parts, which is related to the use effect and longevity of stamping parts. The metal stamping parts mentioned above are the main products of Zhejiang Baifudu Electromechanical Co., Ltd., with many types, good die-casting effect and wide application range.

What are the effects of mold temperature on injection molding?

1. The influence of mold temperature on injection molding

1. Mold temperature is a variable in injection molding. No matter what kind of plastic is injected, it is necessary to ensure that the surface of the mold is basically wet. The hot mold surface keeps the plastic surface liquid long enough to build pressure within the cavity. Reproduction of the cavity surface is high if the cavity is filled and the cavity pressure can press the soft plastic against the metal before the frozen skin hardens. On the other hand, if the plastic entering the cavity at low pressure is suspended, no matter how short, its slight contact with the metal can cause smearing, sometimes called gate smearing.

2. For each plastic and plastic part, there is a limit on the surface temperature of the mold, beyond which one or more adverse effects may occur (for example: components can overflow burrs). Higher mold temperatures mean less resistance to flow. On many injection molding machines, this naturally means faster flow through gates and cavities, since the injection flow control valve used does not correct for this change, faster filling results in higher efficiency in sprues and cavities pressure.

3. It may cause flash burrs. Since the hotter model does not freeze the plastic that entered the flash edge area prior to high pressure buildup, the melt can flash around the ejector pin and spill into the parting line gap. This shows the need to have good injection rate control, which some modern flow control programmers do.

4. The increase in mold temperature will reduce the condensation layer of plastic in the cavity, making the molten material flow more easily in the cavity, resulting in greater part weight and better surface quality. At the same time, the increase in mold temperature will also increase the tensile strength of the part.  

What matters should be paid attention to in the process of mold processing?

1. Precautions for precision mold processing

1. The process is concise and detailed, and the processing content is expressed numerically as much as possible.

2. For the key and difficult points of processing, the process should be particularly emphasized.

3. Combination processing is required, and the process is clearly expressed.4. When inserts need to be processed separately, pay attention to the process requirements of processing accuracy.

5. After combined processing, the insert parts that need to be processed separately shall be the benchmark requirements for separate processing of process installation during combined processing.

6. Springs are the most easily damaged in mold processing, so choose mold springs with long fatigue life.

7. High machining accuracy requirements: a pair of molds is generally composed of concave molds, punches and mold bases, and some may also be multi-piece assembled modules. Therefore, the combination of the upper and lower molds, the combination of the insert and the cavity, and the splicing between the modules all require high machining accuracy. The dimensional accuracy of precision molds often reaches μm level.

8. Complex shape and surface: For some products such as car covers, aircraft parts, toys, and household appliances, the shape of the surface is composed of a variety of curved surfaces, so the mold cavity surface is very complex. Some surfaces must be processed mathematically.

9. Small batches: The production of molds is not mass production, and in many cases only one batch is produced.

10. There are many processes: various processes such as milling, boring, drilling, reaming and tapping are always used in mold processing.

11. The use of repeated production molds has a lifespan: when the use of a pair of molds exceeds its lifespan, a new mold must be replaced, so the production of molds is often repetitive.

12. In the production of profiling molds, there are sometimes neither drawings nor data, and profiling should be performed according to the actual objects. This requires high imitation precision and no deformation.

13. Excellent mold material, high hardness The main material of the mold is mostly made of high-quality alloy steel, especially the long-life mold, which is often made of ledeburite steel such as Crl2 and CrWMn.

The above are seven aspects that need to be paid attention to in the process of precision mold processing, so that we can produce high-quality molds, and at the same time, we must meet the processing requirements as much as possible in the selection of machine tools, such as the function of the CNC system should be strong, the machine tool precision should be high, The rigidity is better, the thermal stability is better, and it has the function of profiling.

Deep Punching

Deep drawing is a metal forming process in which parts are produced by stamping sheet metal into molds. It provides high-quality components, is produced quickly, and is often cheaper than other competitive methods. Deep pull parts have numerous applications in many industries such as consumer, medical, military and telecommunications. They can be made from various materials, including brass, stainless steel, alloys, and many others.