What should I pay attention to when designing and manufacturing blow molds?

1) The most important point in blow mold design is to design an effective cooling system. In order to achieve maximum cooling, the cooling channel should be as close to the mold cavity as possible. Unlike extrusion blow molds, the cooling medium flow channel of injection blow molds is usually perpendicular to the mold cavity to minimize the width of the mold.

The mold is generally used as a cooling medium with water. In order to improve the cooling efficiency, 5 15 chilled water can be used for cooling. When designing large rectangular planes, pay particular attention to shrinkage margins and surface concave*.

For this reason, it is better to design the plane as an arch. (2) The blow mold can be made of a relatively inexpensive material similar to the extrusion blow mold. The difference is that the accuracy of the inlay bottleneck die is extremely high, so that the assembly of the mandrel is proper, and each side of the bottleneck mold should be 0 larger than the parison neck ring

Answer: The material selected to make the extrusion blow molding die should be high-strength steel, such as high-speed steel, tool steel, heat-resistant steel, etc. These materials have good thermal strength, abrasion resistance, corrosion resistance and impact resistance, which can meet the high requirements of extrusion blow molding molds.

In addition, light metal materials such as aluminum alloy and copper alloy can also be selected, which have high thermal conductivity and good corrosion resistance, and can meet the requirements of extrusion blow molds. When selecting materials for opening and closing, the performance, cost and availability of materials should be comprehensively considered according to the requirements of the extrusion blow molding mold to ensure the quality and service life of the mold. In addition, when manufacturing extrusion blow molding molds, attention should be paid to the structural design of the mold to ensure the accuracy and service life of the mold.

Personal tips: When manufacturing extrusion blow molding molds, attention should be paid to the structural design of the mold to ensure the accuracy and service life of the mold, and the performance, cost and availability of the material should be comprehensively considered according to the use requirements of the extrusion blow molding mold to ensure the quality and service life of the mold.

The design and manufacture of blow molding molds with fast cycle and long life are required for the development of the blow molding industry. The factors that determine the efficiency of the mold are: l) material; 2) cooling; 3) Blank cutting design; 4) Exhaust.

The material from which the mold is made must have high thermal conductivity and sufficient cutting edge strength. Aluminum 70 75 is currently the high-grade alloy used to make most molds. Due to the good machinability of this metal, the mold cavity is usually machine-cut.

PO copper alloy molds also have high heat transfer and good corrosion resistance. However, its cost is high, it is expensive, and because its specific gravity is three times that of aluminum, it may be more serious in the wear and tear of the molding machinery. PO steel alloy molds are easy to repair with welding or inlaying.

The thermal conductivity of cast aluminum molds is worse than that of cutting aluminum molds. The cutting edge of the mold cavity usually needs to be inlaid with copper alloy or stainless steel, because the strength and hardness of cast aluminum cannot meet the requirements of the cutting edge.

Kirk alloy (zinc) castings can be made on steel master molds. The mold cavity and base plate are poured to a definite size. Since the Kirk alloy is not strong enough to cut the plastic, the operating holes and shoulder areas are inlaid with copper alloy or stainless steel.

The base and neck are also set with these two metals. Casting molds can also be made of copper alloys. Casting by steel cavities is relatively easy because it is cast by pressure or gravity.

These cavities have many delicate parts produced from steel master molds or ceramic molds.

Cooling is a challenging and important part of mold design. Borehole cooling lines are installed where cooling is most needed. For better production control, most molds are designed with several separate cooling zones.

The neck and bottom need to be the most drained and therefore require the most efficient cooling.

Blank cut. The design depth of the cut area can be a significant factor in the yield and quality of the part. The cutting area is where excess plastic enters the part during blow molding. The type and shape of the cutout may determine how well a part is welded. String 6

For harder resins, steel or copper alloys are required as the cutting materials. Sometimes the cutting area is blown with air to accelerate the cooling of the plastic, remove excess material, and prevent distortion of the part.

Exhaust. When a part is blown molded, the mold must be vented in order for the gas to escape quickly. The most common and economical method of venting is surface venting.

Deep sandblasting or texturing of the mold cavity can also help with venting. Another important reason to vent (for parts where the plastic has to be blown into tight cells) is to show the details.

Take you to know the materials used to make molds, and it is very important to do a good job in mold selection.

1) Equidistant opening and closing mold Equidistant opening and closing mold structure is the two halves of the mold body that constitute the cavity of the product, and the horizontal or vertical up and down direction can be used to open and close the mold at equal distance; It can also be fixed by a template, and the opening and closing of the mold can be completed by moving by another template. (2) Hinged mold The structure of the hinged mold is characterized by the fact that the two halves of the mold body that make up the product cavity are connected by hinges, and the two halves of the template are manually or mechanically. , pneumatic pressure, hydraulic drive, with the hinge as the fulcrum, along the fixed arc action, to complete the opening and closing of the two halves of the template.

This kind of mold has a simple structure and is relatively easy to manufacture, and is more suitable for blow molding of hollow products with simple structure and shape. Due to the small clamping force, blow molding larger hollow products are prone to flash. (4) There are many types of hollow products of special structural form molding, for the molding of hollow products with some special form structure, such as the molding of hollow products with double-wall structure, box with air interlayer and special-shaped hollow products with multi-layer material composite molding, special structural form molds should be applied to meet the needs of product molding.

If you don't have a model, you will do a prototype first, and then copy the number, 2D ranking, 3D parting, place a material order, CNC machining, EDM EDM EDM, fitter fit mold, save mold, try mold, modify the mold under the project, and you can put the mold production without problems!

The mold base must be the standard mold base of the mold base factory, and if you want to buy a thick frame at a low cost, that is, the inner mold frame is not processed.

Required materials: 1. CAD file product information;

2. Materials used; Because the shape of the gate and the final size of the mold cavity should be determined according to the shrinkage rate of the plastic;

3. Estimate the production volume and production cycle to confirm that several products should be injected into one mold.

1. Main mold production:

1) There are many materials for making the main mold, and the materials that are generally required to be used as the main mold are easy to form, easy to rest, and have the characteristics of good stability. Such as wood, plaster, wax, etc. We usually use wood. According to the product drawings or mold drawings, the wooden master mold is made by the woodworker.

2. Main mold trimming:

1) The main mold must be repaired before the production mold can be reproduced. Trimming includes putty, shaping, size correction, and reinforcement. This process is mainly to do basic treatment on the surface and the whole of the wooden mold to ensure that the wooden mold is consistent with the drawings in size and form.

3. Surface treatment of the main mold:

1) In this process, there are spraying gel coat, gel coat curing, grinding, polishing, mold release wax, etc. Spray the gel coat on the main mold processed in the previous process, and then wait for the gel coat to cure, and then use sandpaper to polish the gel coat surface after the gel coat is cured.

2) Generally, from dozens of sizes of coarse sandpaper to about 1,000 sizes of fine sandpaper. After punching the sandpaper, the polishing mold begins, and finally the release product is added. Until this point, the production of the main mold is over. Next, you can use the master mold to make the production mold.

3) In addition, some small tools should be used, such as grinders, polishing wheels, gel coat spray guns, air pumps (or other air sources).

4. Reproduction of production molds

1) Spray mold gel coat: Since the production mold is started, it is necessary to use the mold gel coat with better performance to ensure the final effect of the mold. And the jet is required to reach a certain thickness (.

2) Mold layup: After the mold gelcoat is initially solidified, you can start laying. The layering process can not be too fast, generally a day to lay 2 layers of fiberglass cloth or fiberglass felt. A certain amount of mold resin should be used for layup. The performance of this resin is better than that of ordinary resins.

3) In the process of laying, workers should match glue, that is, add an accelerator and curing agent to the resin, and then apply glue with gluing tools, lay a layer of glass fiber fabric and coat a layer of glue, and at the same time use an iron roller to flatten the fabric, drain away the bubbles, and make the glue uniform.

4) After reaching the specified thickness, the ply is finished. In general, the thickness of the mold should reach 3 times the thickness of the product. Therefore, the lay-up time is generally longer, which can last up to 6 days.

5) Mold curing and reinforcement: The mold can be cured naturally or warmed, but it is generally best to have a natural curing period. After the natural curing period, the mold should be strengthened so that the mold will not be damaged during the production process.

6) Surface treatment of the production mold: After the production mold is cured to the required time, it can be lifted from the main mold, and the mold can be started by the workers manually, or the mold can be started with high-pressure gas. The production mold after the mold is lifted also needs to be surface treated, including sandpaper, polishing, marking the process line, and demoulding products.

After getting the product, do a process analysis, such as: make all the problem points into PPT feedback to the customer (such as product structure problems, process problems, parting lines, etc.) - make a structural diagram (commonly known as a ranking chart) - review and modification - 3D parting - review and modification - start processing under the processing drawing - assembly - T1 mold trial - mold repair - no problem on the packaging and delivery;

Generally, the mold base should buy the standard mold base of the mold base factory as much as possible, and come back to assemble it. Large molds need to be ordered for processing by yourself or order non-standard parts in the mold base factory!

Usually do the product first, and then design the mold according to the product, review the drawings, and then order the mold base, blank, processing, mold matching, mold trial, mold modification, I do mold design and manufacturing, if you buy the blank to process it will be cheaper! The difference in cost depends on the weight of the mold, the heavier the mold base, the more expensive!

Mold opening is a very critical step from product design to production, which can not be underestimated.

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1.The process is different, blow molding is injection + blowing; Injection molding is injection + pressing; Rotational molding is extrusion + pressing; The blow molding must have the head left by pulling the blowing pipe, the injection molding must have a gate section, and the rotational molding must have a burr without cutting.

2.Generally speaking, injection molding is a solid core, and blow molding and rotational molding are empty cores. The surface of the injection molded part is bright, and the surface of blow molding and rotational molding is uneven.

Compared with rotational molding, at least blow molding has a blow port. This is a general comparison. I don't know if you can understand it!

3.Plastic shrinkage and its influencing factors.

Thermoplastics are characterized by expanding when heated, shrinking when cooling, and of course shrinking when pressurized. In the injection molding process, the molten plastic is first injected into the mold cavity, and after the filling, the melt cools and solidifies, and shrinkage occurs when the plastic part is removed from the mold, which is called forming shrinkage. During the period between the removal of the mold and the stabilization of the part, there will still be a slight change in size, and one change is that it will continue to shrink, which is called post-shrinkage.

Another variation is that some hygroscopic plastics swell due to moisture absorption. For example, when the water content of nylon 610 is 3%, the size increase is 2%; The water content of glass fiber reinforced nylon 66 is 40%, and the size increase is. But the main role played by this is the shrinkage of forming.

At present, the methods for determining the shrinkage rate of various plastics (shrinkage after forming shrinkage) are generally recommended to the provisions of DIN 16901 in the German national standard. That is, the difference between the size of the mold cavity at 23 hours and the corresponding plastic part size measured under the conditions of 23 hours and relative humidity of 50 5% after being placed for 24 hours after forming.

For mold fitters, since they can make injection molds, they can also make blow molds. And the blow mold is simpler than the injection mold. There is no essential difference between the two.

1) It can form products with complex shapes;

2) It can effectively clamp the parison to ensure the strength of the joint of the product;

3) It can be dispersed or effectively vented;

4) It can quickly carry and evenly cool the product, and reduce the temperature gradient in the mold wall to reduce the molding time and warpage of the product.