What is a side core pulling mechanism and what is a core pulling mechanism?

Any mechanism that can obtain lateral core-pulling or lateral parting and resetting action to get out of the position of the product inverted, low and other positions is called a row mechanism. Using the mold opening action of molding, the diagonal brace tip and the slider produce a relative movement trend, so that the slider is separated from the barb in two motion forms along the mold opening direction and the horizontal direction.

The mechanism that can pull the core laterally or parting laterally and the reset action to get out of the position of the product inverted buckle and low depression is called the row mechanism, and the diagonal brace tip and the slider produce a relative movement trend by using the mold opening action of molding, so that the slider can be separated from the barb in two motion forms along the mold opening direction and the horizontal direction;

Classification: 1. Manual lateral parting core-pulling mechanism This kind of mechanism is to manually take out the side core and plastic parts from the mold together after the mold is opened, and the side core is pulled out outside the mold, or the movable core is taken out by a person or hand tool before the mold is opened;

2. Hydraulic or pneumatic lateral parting core-pulling mechanism This kind of machine teasing and cleaning mechanism relies on the power provided by the hydraulic system or pneumatic system, and is equipped with a special bending hydraulic cylinder and cylinder on the mold, and carries out lateral parting, core pulling and reset through the reciprocating motion of the piston;

3. Motorized lateral parting core-pulling mechanism This kind of mechanism uses the mold opening movement of the injection molding machine and changes its direction of movement to carry out lateral parting of the mold or extract the side core from the plastic part.

Core pull is used to deal with the position that cannot be demolded on the parting surface of the product, and it belongs to the "barb treatment system", which is a structure of the mold.

Definition of core pull: a mechanism to ensure the smooth demoulding of the product, also known as a slider.

For example, if there is a hole on the side of the plastic part, after the mold is opened, if the core of the hole is not removed, the product cannot be ejected.

At this time, the mold structure should adopt the structure of the slider, make the core of the hole into a movable one, use the oblique vertical ruler guide pillar to cooperate with the fixed mold, and move the slider with the opening or closing of the mold. This movement is called core pulling.

This kind of mechanism is to manually remove the side core and the plastic part from the mold after the mold is opened, and the side core is pulled out outside the mold, or the movable core is taken out by manual or hand tools before the mold is opened. The mold structure corresponding to this kind of mechanism is simple, the cost is low, but the production efficiency is low, the labor intensity is large, and it is limited by manpower, so it is only used in special occasions, such as trial production of new products.

Medium for small batch production of small plastic parts.

2) Hydraulic or pneumatic lateral parting core-pulling mechanism.

This kind of mechanism relies on the power provided by the hydraulic system or pneumatic system, and is equipped with special hydraulic cylinders and cylinders on the mold, and carries out lateral parting, core pulling and reset through the reciprocating motion of the piston. This type of mechanism is characterized by large shaft pulling force, flexible action, not limited by the mold opening process, and stable movement. The new injection molding machine itself comes with this device, which is very convenient to use.

However, at present, the general injection molding machine is not equipped with such a device, and needs to be equipped with pneumatic or hydraulic components, and the cost is high, so the application is limited to a certain extent. It is often used in large injection molds.

3) Motorized lateral parting core-pulling mechanism.

This kind of mechanism uses the mold opening motion of the injection molding machine, and after changing the direction of its movement, the mold is side-parted or the side core is extracted from the plastic part. This kind of mechanism has the advantages of easy operation, high production efficiency, easy to realize automatic production, etc., although its mold structure is more complex, but it is still a kind of lateral parting core-pulling mechanism that is widely used in production.

1) Determination of the core pulling distance.

The core-pulling distance of the lateral core-pulling mechanism refers to the distance that the side cores move in the direction of shaft pull-out when the side cores are pumped from the forming position to the position that does not interfere with the removal of the plastic parts. There are many forms of side holes or side concaves, and there is no need to calculate them in detail one by one, which can generally be determined in this way

s = s1 + 2 ~ 3)

where s - minimum core pulling distance (mm); S1 – The side cores are drawn to a minimum distance (mm) that does not affect the mold opening

2) Determination of core-pulling force.

The so-called core-pulling force is the force required to extract the side core from the plastic part. When the cavity is cooled and solidified, the plastic parts will shrink, so as to wrap the core, and the shaft pulling resistance caused by this wrapping force and the friction required for mechanical sliding must be overcome during the core pulling.

For cores that are coarse in blind holes, it is necessary to overcome the resistance caused by atmospheric pressure when pulling cores. There are many factors that affect the core-pulling force, such as the surface area of the core-forming part.

and its geometry, wall thickness, the variety of Zhaodian pure plastic, shrinkage, friction factor of molded parts, the number of core pulls on the same side of plastic parts at the same time, injection pressure, holding time, cooling time, demoulding slope, etc.

During the core-pulling process, the core-pulling force is maximum at the moment of the start of the extraction and then rapidly decreases. The core-pulling force we are going to calculate is the force required to start the pulling. Because the core has a demoulding slope in the design, so under the effect of the core-pulling force f, the positive pressure of the plastic part on the core is reduced, and the calculation method is different because the structure of the side of the core has two types of through holes and blind holes.

1) Calculation of through-hole core-pulling force f-pass (n) F-pass = PA (fcos -sin) 1 + FSIN C0S formula where p - positive pressure (MPa) on the unit area of the core when the plastic part shrinks, generally 8 12MPa; a—the side area of the plastic part wrapping core (mm2); f—friction factor, f= .

2) Calculation of blind hole core pulling force f blind (n) In blind hole core pulling, atmospheric pressure must also be overcome.

Therefore, the core-pulling force required is larger. It is calculated as follows: f blind = f pass + where a--- projected area perpendicular to the core in the direction of the core pull.

mm2)。