Rare special topic of plastic mold lifter

Time：2022-04-02 10:09:31 / Popularity： / Source：

【Use of lifter】

Lifter mechanism is generally used to shape inner or outer barb of product, it cannot be directly formed with sliding block on movable die side, and it also plays role of ejecting product.

【General structure and category of lifter】

Lifter is generally composed of two parts: body part and forming part. It is same as slider, depending on whether body part and forming part are combined, lifter can be classified into: integral lifter (as shown in Figure 1, it can also be called non-combined lifter) and non-integral lifter (as shown in Figure 2, also known as combined lifter). Note that since lifter is relatively small, we generally use integral lifter and rarely use combined lifter. Integral lifter has a compact structure, good strength, and cannot be damaged. For larger lifters, combined type can be used in design, which is more convenient to replace, easy to repair and maintain, and relatively simple to process. Tip: If picture is not clear, please click picture to enlarge it.

In addition, due to different positioning structures of bottom end of lifter body, lifter can be classified into: cylindrical pin lifter (as shown in Figure 3) and T-block lifter (as shown in Figure 4). For these two types of lifters, cylindrical pin type lifters are widely used in design, main reason is that processing is convenient, installation and maintenance are easy. T-shaped block lifter is mainly used for larger products with higher precision requirements. It also needs to be matched with a special T-shaped base (as shown in Fig. 5) (as shown in Fig. 6). It is difficult to process and cooperate, and manufacturing cost is also high will increase.

【Principle of movement of lifter】

As shown in Figure 7, lifter is placed in inclined hole of a fixed mold plate, and lifter is matched with inclined hole. Give lifter a thrust from bottom to top to push lifter to move upward for a certain distance. After that, it is found that lifter not only moves upwards under forced action of inclined hole and thrust, but also moves a certain distance in inclined direction of lifter (position gap shown in the figure). During ejection process, since product moves in a vertical line, lifter not only moves in a vertical line, but also moves in opposite direction of dead angle, so that dead angle can be dealt with.

【Design of lifter】

Prerequisites: Dimensions of mold plate, mold core, and mold base have been determined. Details are shown in figure below.
(1). Check drawing, analyze it carefully, and determine size of dead angle, as shown in figure.

(2) Determine starting point of 0° by broken surface, and determine its length (as shown in Figure AB). If 0° break surface is not designed, select point A as starting point of lifter slope.
(3) Based on point B, offset a distance, as shown in figure BC, BC = ejection stroke.
(4) Based on point C, offset a distance in opposite direction of movement of lifter, as shown in Figure CD. CD = stroke of lifter (integer) = size of dead angle + minimum safety amount greater than or equal to 3mm.
(5) Connect DB to get angle DBC. This angle is usually a decimal. We take an integer, which is M°. This angle is inclination angle of lifter slope we need.
(6) Other parts can be designed according to structure and requirements mentioned above.
In fact, main purpose of such complicated content as above is to teach us how to find inclination angle of lifter. We can simplify it as shown below:

Like above picture, we can get trigonometric function tgM°= lifter stroke/top out stroke. At this time, it is very easy to ask how big M° is, and it can also be measured directly on drawing.

【Slope movement diagram】

【Example of lifter】

【Key points of lifter design】

(1) Determine angle of lifter according to actual stroke H, generally 3~12°, and slope should be as small as possible; core-pulling distance of lifter is generally greater than core-pulling distance of product by 3mm; strength of lifter, slope of lifter and ejection distance should be coordinated;
(2) Determine width of lifter according to width of product buckle;
(3) According to width of lifter and position of product where lifter is located (mainly depends on whether there is interference and whether drop of glue level on lifter is large), determine thickness of lifter, generally not less than 6.0;
(4) Form of guide chute is determined according to size difficulty, thickness and total length of lifter, and guide chute is generally made of 40Cr material;
(5) Design guide block according to size of lifter; materials are generally 40Cr, bronze;
(6) H13 is used for all lifter materials, and is treated with nitriding;
(7) Oil grooves need to be processed for lifter (except top and bottom surfaces of lifter);
(8) Pay attention to placement direction of finished product, avoid hanging lifter, and increase acceleration roof if necessary;
(9) When drawing, lifter should be expressed in three views;
(10) Top surface of lifter is 0.05mm lower than product surface to avoid straining surface;
(11) It is necessary to consider whether product will stick to lifter and whether it has been positioned to hold product;
(12) It is necessary to check whether head of lifter has a reverse slope (ejection will shovel glue), and pay attention to whether lifter will interfere with other components (such as other lifters, thimbles, bone positions), and be sure to check;
(13) When product is very deep and there is a lifter on the side, a step should be added to the sloping roof for positioning. There is also a situation that lifter is on the side of product (product has a certain depth), and side of lifter has a deeper bone position.

Gud Mould Industry Co., Ltd