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Design of injection mold reset and first reset mechanism-Shanghai Mulan Injection Mold Processing Factory
1. Reset mechanism
After the injection molded part is demoulded, the demoulding mechanism needs to return to its original position to facilitate the demoulding of the next injection molded part. There are many forms of reset mechanisms, and the most commonly used is to use the return lever to reset. When demoulding, the push rod can push the injection molded part out of the mold; when closing the mold, the fixed template pushes the return rod to reset the demoulding mechanism.
(1) Screw-type reset rod reset mechanism: When the mold is closed, the reset of the push rod is completed by the reset screw. Due to the large gap between the reset screw and the hole passing through the movable template and the backing plate of the movable template, the displacement of the push rod cannot be guaranteed, and a guide column is required for guidance. In order to ensure the accurate reset of the demoulding mechanism, the A surface of the movable template needs to be ground flat with the reset screw.
(2) Return rod reset mechanism: the end face of the return rod must be flush with the parting surface. After the mold is opened, the injection molded part is pushed out of the mold cavity under the action of the push rod; when the mold is closed, the return lever pushes the demoulding mechanism to reset under the action of the fixed template.
(3) Push rod and reset rod reset mechanism: the upper end surface of the push rod must be flush with the parting surface. This is a commonly used reset mechanism of the demoulding mechanism. Its characteristic is that part of the end face of the push rod is in contact with the injection molded part, and the other part is in contact with the fixed template, so that when ejecting, the push rod plays the role of ejecting the injection molded part. When the mold is closed, the push rod plays the role of reset again.
Second, first reset the mechanism
The design of injection mold reset and first reset mechanism, when the core of the injection mold core-pulling mechanism overlaps with the projection of the push rod of the demoulding mechanism, if the demoulding mechanism cannot be reset before the core-pulling mechanism, the push rod and core will occur collision. At this time, the push rod must be reset before the core of the core-pulling mechanism. This mechanism that resets the push rod first is called the first reset mechanism. There are many types of first reset mechanism, and here only introduce the push rod and reset rod reset mechanism for spring type, inclined pin type, rack and pinion type and hinge type first reset mechanism. In addition, there are first reset mechanisms such as connecting rod type, pendulum block type, sliding shaft type and lever type.
(1) One of the spring first reset mechanisms: Shanghai Mulan Injection Mold Processing Factory has a spring on the return lever, which can be used for general reset or first reset. Due to reasons such as spring friction, shaking and fatigue, it is prone to failure after a long time of use, and needs to be replaced in time. If it is not replaced in time, the invalid spring cannot realize the first reset of the demoulding mechanism, which will cause the push rod of the injection mold to collide with the core of the core-pulling mechanism and be damaged. When the push rod is ejected, the spring is compressed. After the injection molded part is demolded, due to the disappearance of the demoulding force, the spring restores its length so that the demoulding mechanism is reset first, and then the return lever is reset under the action of the fixed template. The disadvantage of this mechanism is that it is complicated to replace the spring, and the movable mold part of the mold needs to be removed.
(2) The second spring return mechanism: This mechanism is installed on the outside of the mold, which is convenient for assembly and replacement, and can be used universally, but it is only suitable for small injection molds.
(3) Inclined pin type first reset mechanism: Since the side core and the push rod will interfere during the mold closing process, the demoulding mechanism should be reset first. A reset rod is arranged beside the inclined hole of the slide block, and a small plane is formed on one end of the bent pin. When the demoulding mechanism is ejected after the mold is opened, the bent pin has left the reset rod, and at this time, the bent pin is just above the reset rod. When closing the mold, the bent pin first pushes the reset rod, and thus also pushes the push plate to make the push rod reset first.
(4) Rack and pinion type first reset mechanism: the lower rack is fixed on the push rod plate. When the table is fast, the upper rack drives the gear to rotate, and the gear drives the lower rack to reset downward, so that the push tube is reset first. When the top of the upper rack is close to the push plate, the push tube can be reset.
(5) Hinge-type first reset mechanism: when the mold is closed, before the side core moves to the position of the push rod, the wedge plate has pushed the hinge mechanism composed of connecting rods to make the push plate retreat, so that the push rod is reset first, avoiding the Interference between side core and push rod. The reset lever is used for reset.
The design of injection mold reset and first reset mechanism, Shanghai Mulan Injection Mold Processing Factory said that the reset mechanism and first reset mechanism of injection mold are one of the important mechanisms of injection mold. The reset mechanism is a mechanism that can restore the demoulding mechanism of the injection mold to the state to be demoulded, and can also make the demoulding mechanism enter the demoulding state at all times. The reset mechanism of the injection mold can realize the automation of the injection mold in the process of molding. The first reset mechanism of the injection mold is set in order to avoid the movement interference between the push rod of the injection mold demoulding mechanism and the core of the core pulling mechanism. The first reset mechanism of the injection mold can reset the push rod before the core of the core pulling mechanism after the injection molded part is demoulded, so as to avoid the occurrence of motion collision.