نحوه انتخاب دستگاه قالب گیری تزریقی دست دوم

How to choose a second-hand injection molding machine

The important factors that usually affect the selection of injection molding machine include mold, product, پلاستیک, molding requirements, و غیره. از این رو, the following information must be collected or obtained before making a selection: 1. Mold size (width, ارتفاع, ضخامت) , weight, special design, و غیره.; 2. The type and quantity of plastic used (single raw material or multiple plastics); 3. The appearance size (length, width, ارتفاع, ضخامت) and weight of the injection molded product; 4. Molding requirements, such as Quality conditions, production speed, و غیره. After obtaining the above information, you can follow the steps below to choose a suitable plastic injection molding machine:

1. Choose the right type:

Since there are many types of second-hand injection molding machines, it is necessary to correctly judge which type of injection molding machine or which series the product should be produced at the beginning, such as general thermoplastic or bakelite raw materials Or PET raw materials, و غیره., are single-color, double-color, multi-color, interlayer or mixed color, و غیره.

علاوه بر این, some products require high stability (closed loop), high precision, ultra-high injection rate, high injection pressure or rapid production (multi-loop), و غیره., and the appropriate series must also be selected for production.

2. Can fit the قالب تزریق:

Determine whether the “big column inner distance”, “mold thickness”, “minimum mold size” و “mold plate size” of the machine are appropriate according to the mold size, so as to confirm whether the mold can be placed.

توجه داشته باشید: ①The width and height of the mold must be smaller than or at least one side is smaller than the inner distance of the large column; ②The width and height of the mold should preferably be within the size range of the mold plate; ③The thickness of the mold should be between the mold thickness of the injection molding machine; ④The width and height of the mold must meet the minimum mold size recommended by the injection molding machine, and it is not acceptable if it is too small.

3. Take out injection molding products:

Determine whether the “ضربه باز شدن قالب” و “mold ejection stroke” are sufficient for the finished product to be taken out by the mold and the finished product.

①The mold opening stroke must be at least twice the height of the finished product in the direction of opening and closing the mold, and must include the length of the vertical sprue;

②The ejection stroke must be sufficient to eject the finished product.

4. Can lock the plastic solution:

The tonnage of “نیروی بستن” is determined by the product and plastic.

When the raw material is injected into the mold cavity at high pressure, it will generate a force to support the mold. از این رو, واحد گیره دستگاه قالب گیری تزریقی باید به اندازه کافی تامین شود “نیروی بستن” برای جلوگیری از کشیده شدن قالب. محاسبه نیروی گیره مورد نیاز به شرح زیر است:

① ناحیه پیش بینی شده محصول نهایی را در جهت باز و بسته شدن قالب از اندازه ظاهری محصول نهایی بدست آورید.; /سانتی متر مربع); ③فشار در قالب با مواد خام متفاوت است, و مواد خام کلی 350 ~ 400 کیلوگرم / سانتی متر مربع است; بیش از دو برابر. تا حالا, the specifications of the clamping unit have been preliminarily determined, and the tonnage of the model has been roughly determined. سپس, the following steps must be carried out to confirm which injection unit has a more suitable screw diameter.

5. Shot to fill the injection mold cavity:

Determine the required “injection volume” and select the appropriate “قطر پیچ” based on the weight of the finished product and the number of mold cavities.

To calculate the weight of the finished product, the number of mold cavities (one mold with several cavities) needs to be considered;

For the sake of stability, the injection volume must be more than 1.35 times the weight of the finished product, به این معنا که, the weight of the finished product must be within 75% of the injection volume.

6. Injection parameters of injection molding machine:

The conditions such as “screw compression ratio” و “فشار تزریق” are judged by the plastic. Some engineering plastics require a higher injection pressure and a suitable screw compression ratio design to have a better molding effect. از این رو, in order to make the finished product injection better, the injection pressure and compression ratio must also be considered when selecting the screw. . به طور کلی, a smaller diameter screw provides higher injection pressure.

7. سرعت تزریق of injection molding machine:

Confirmation of “سرعت تزریق”. Some finished products require high injection rate and fast injection to form stably, such as ultra-thin products. In this case, it may be necessary to confirm whether the injection rate and injection speed of the machine are sufficient , whether it needs to be equipped with pressure accumulator, closed loop control and other devices. Generally speaking, under the same conditions, the screw that can provide higher injection pressure usually has a lower injection rate, and on the contrary, the screw that can provide lower injection pressure usually has a higher injection rate.

از این رو, when selecting the diameter of the screw, the injection volume, injection pressure and injection rate (سرعت تزریق) need to be considered and traded off. علاوه بر این, multi-loop design can also be used to shorten the molding time with synchronous compound actions.

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