Lifter mechanism is generally used to mold product's internal or external undercuts, and can not be directly molded with movable mold side slider, also plays role of ejecting product.
General structure and category of lifter

 

Llifter is generally composed of two parts: body part and forming part. It is same as slider. Due to whether body part and forming part are combined, lifter can be classified into: integral lifter (as shown in Figure 1, which can also be called non-combined lifter) and non-integrated lifter (as shown in Figure 2, It can also be called combined lifter).
Note that because lifter is relatively small, we generally use integral lifter, and rarely use combined lifter. Integral lifter has a compact structure, good strength, and no room for damage. As for larger lifter, combined type can be used in design, which is more convenient to replace, easy to repair and maintain, processing is relatively simple.

 

 

In addition, due to different positioning structure of bottom end of lifter body, lifter can be classified into: cylindrical pin lifter (Figure 3) and T-block lifter (Figure 4). For these two types of lifters, cylindrical pin lifters are used in many designs, mainly because they are easy to process, easy to install and maintain. T-shaped block lifter is mainly used for products with higher precision requirements. It also needs to be matched with a special T-shaped base (as shown in Figure 5) (as shown in Figure 6), which is difficult to process and cooperate, and manufacturing cost will increase.

 

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

 

Prerequisite: Dimensions of mold plate, mold core, and mold base have been determined. Details are shown in figure below.

(1) Check drawing, analyze carefully, and determine size of dead angle, as shown in figure.

 

(2) Determine starting point of broken surface at 0° and determine its length (as shown in Figure AB). If you do not design 0° leaning surface, select point A as starting point of lifter slope.
(3) Take point B as reference, offset by one distance, as shown in BC, BC= ejection stroke.
(4) Taking point C as reference, offset a distance to opposite direction of oblique top movement, as shown in Figure CD. CD=Sloping top stroke (take an integer)=Dead angle size+Minimum safety amount greater than or equal to 3mm.
(5) Connect DB to get angle DBC. This angle is generally a decimal. We take an integer, which is M°. This angle is inclination angle of lifter slope we need.
(6) For other contents, design of other parts of lifter can be completed according to structure and requirements mentioned above.
In fact, main purpose of such a complicated content as above is to teach us how to find inclination angle of lifter. We can simplify it as shown below:

 

Like figure above, we can get trigonometric function tgM°=lifter stroke/ejection stroke. At this time, it is easy to find out how big M° is, and it can also be measured directly on drawing.
Lifter movement icon

 

Lifter example

 

Main points of lifter design
(1) Determine angle of sloping top according to actual stroke H, generally 3～12°, slope should be as small as possible; core pulling distance of sloping top is generally greater than product core pulling distance 3mm; strength of sloping top, slope of lifter and ejection distance must be coordinated;
(2) Determine width of lifter according to width of product buckle;
(3) Determine thickness of lifter according to width of lifter and product position of lifter (mainly depending on whether there is interference and whether gap of glue level on lifter is large), generally not less than 6.0;
(4) Determine form of guide chute according to size, thickness and total length of lifter. Guide chute is generally made of 40Cr material;
(5) Design guide block according to size of lifter; material is generally 40Cr, bronze;
(6) H13 shall be used for all lifter materials, and be nitrided;
(7) Lifter needs to be processed with oil grooves (except for top and bottom surfaces of lifter);
(8) Pay attention to placement direction of finished product, avoid hanging lifter, and increase accelerating roof when necessary;
(9) When drawing, lifter should be expressed in three views;
(10) Top surface of lifter is lower than product surface by 0.05mm to avoid straining surface;
(11) It is necessary to consider whether product will stick to lifter, and whether there is positioning to pull product;
(12) It is necessary to check whether head of lifter is reverse slope (ejection will shovel glue), and pay attention to whether lifter will interfere with other parts (such as other lifters, thimble, bone position), be sure to check;
(13) When product is very deep and there is a sloped top on the side, sloped top should be positioned by a step. Another situation is that lifter is on the side of product (product has a certain depth), and there is a deeper bone position on the side of lifter.