Demoulding of injection molded product is driven by injection molding machine to push ejector plate out of product, and there is only one demoulding direction. When product has bosses, holes, and grooves, it will form a buckle (undercut) if it is inconsistent with demoulding direction. At this time, mold needs to add a mechanism in other demoulding directions to allow undercut to be removed. Among them, one of the most commonly used mechanisms is lateral core pulling mechanism, commonly known as slider mechanism.
Advantages of oblique guide pin lateral core pulling structure: Compared with other mechanisms, it has good stability, simple structure, can be disassembled into small pieces for easy processing, easy mold matching and maintenance by fitters, and high work efficiency. Disadvantages: high processing cost and many parts. More than 60% of injection molds have core pulling mechanisms, which are one of the most basic mechanisms of injection mold. Many mechanisms are evolved from lateral core pulling mechanism of inclined guide column, such as structure of half mold, cylinder core pulling structure, structure of tunnel slider, etc.

When injection molding machine is opening mold (as shown in mold opening state as shown below), inclined guide column of fixed mold acts on slider, so that inclined guide column pushes slider outward, and slider moves backward. Limit screw and limit clamp limit moving distance of slider to prevent slider from falling. After core pulling mechanism is completed, product is pushed out by ejector rod to take out product. When injection mold is closed (as shown in mold closing state as shown below), fixed mold inclined guide column pushes slider inward, limit clamp limits moving distance of slider, shovel machine and wedge block lock slider to prevent slider from moving backward and running glue during injection molding.

 

 

Function: In process of injection molding, in order to prevent filling force of plastic from being greater than weight of slider, it is necessary to press slider to prevent it from moving backward. Usually, a shovel is used to fix slider or mold frame directly presses slider. Some will also add a backhoe double locking slider while having a shovel.
Components: shovel, backhoe, wear-resistant block.

Function: Glue surface and sealing surface of product are front position of slider, which is usually disassembled into a core. Large slider consists of three parts: core, main slider, and connecting block, which is convenient for maintenance and replacement. Small slider will be made into an integrated type.
Components: slider body, core, connecting block.

Function: Slider needs to control stroke to limit backward sliding position, inward sliding position and distance of slider.
Components: limit screw, limit block, ball screw.

Function: Slider needs power to move when working. Movement of slider depends on inclined guide pin. Here, slider is moved by inclined guide pin during mold opening process of injection molding machine. In order to prevent product's clamping force from being too large, a spring will be added to assist inclined guide pin to move at the first time when mold is opened.
Components: spring, inclined guide pin.

Function: It is mainly used to control movement direction of slider. Screws fixed by pressure plate only have assembly clearance, so a guide block is required to move along guide groove direction when slider moves.
Components: guide block, pressure strip, spring guide pin.

Function: Quality of mold cooling system directly affects quality and production efficiency of product. In injection molding, if slider is overheated, it will cause product to deform and shrink. It is also necessary to prevent other defects such as insufficient glue flow of overcooled products.
Components: water channel, hose, water nozzle, throat teeth.

 

1. Inclination angle (α) of inclined guide pin is calculated according to trigonometric function of slider stroke, and usually needs to be integer.
2. Pulling distance (S) of slider, safety value of small slider is taken (3-5mm) and then needs to be integer, and large slider is increased according to situation.
Pulling distance (S) of slider = buckle distance (s1) + safety value (k) (3~5mm)
3. Length (L) of inclined guide pin does not need to be integer, but it must be ensured that inclined guide pin is inserted into left 2/3 of slider when mold is closed. When inclined guide pin is longer than slider, mold plate needs to be avoided.
Length of inclined guide column (L) = pulling distance of slider (S) / tilt angle (sinα)
Working distance of inclined guide column (H) = pulling distance (S) x tilt angle (tanα)

 

Slider is usually selected with non-operating side and ground side as priority, followed by operating side, and finally sky side. Spring force on sky side must be greater than weight of slider, and slider limit position clamp must be installed to prevent slider from falling due to spring failure. Update spring and limit clamp in time according to spring service life of 300,000/500,000/1 million times.

Inclined guide column: 13°15°18°20°23°
Shovel machine: 15°17°20°23°25°
Principle: Tilt angle of shovel machine should be at least 2 degrees greater than tilt angle of inclined guide column, and the most commonly used value is 15°~20°. Minimum tilt angle is 13 degrees, and maximum tilt angle cannot exceed 35 degrees.

Diameter of inclined guide pin is determined according to size of slider. If slider width is less than 100mm, one inclined guide pin is used, and diameter of inclined guide pin is usually 8/10/12/16mm. Large sliders usually use two or more inclined guide pins with a diameter of 15-30mm. When using, try to reduce number of inclined guide pins used, as machining errors and inconsistent tilt angles are prone to occur, resulting in uneven force and slider jamming.