A dome pin for injection mold

Abstract

This invention relates to an ejector pin for injection molds, comprising an ejector pin body consisting of a shaft and a base. The top of the shaft has a venting ring groove and multiple venting holes. The venting ring groove is arranged circumferentially around the shaft, dividing the top of the shaft into a top surface block. The diameter of the top surface block is smaller than the diameter of the shaft. A vertically arranged venting channel is located in the center of the ejector pin body. Multiple venting holes are distributed within the shaft. The outlet end of each venting hole connects to the venting channel, and the inlet end connects to the inner side of the venting ring groove. The bottom surface of the base has a venting groove, and the bottom end of the venting channel is connected to the venting groove. Compared with the prior art, this invention achieves full-circumferential venting of the top surface block, resulting in fast gas discharge and good effect. It also has the advantages of effectively preventing venting hole blockage and having a wide range of applications.

Description

Technical Field

[0001] This invention relates to the field of injection molding tools, and more particularly to an ejector pin for injection molds. Background Technology

[0002] During injection molding and mold closing, it is essential to promptly vent the gases from the mold. These gases include not only air in the cavity but also air in the runners and decomposition gases produced by the molten plastic. Insufficient venting in the mold can cause defects on the product surface such as weld lines, bubbles, air marks, missing material, and unclear outlines. In terms of processing, it can lead to filling difficulties, flash in some areas, and in severe cases, scorch marks on the surface. Simultaneously, it reduces the mold filling speed, prolongs the molding cycle, and may even cause machine downtime, significantly increasing production costs.

[0003] Currently, ejector pins with venting structures are commonly used for venting during the production process. The original function of the ejector pin is to push the finished product out of the mold cavity; by incorporating venting structures on the ejector pin, the cavity can be vented. For example... Figure 5 As shown, the most common venting structure for the ejector pin is to cut the side of the ejector pin to a certain extent (at point A) to form a venting groove, so that the gas generated during injection molding can be buffered and stored in the venting groove. However, this structure has limited gas capacity, and for injection molds with large venting volume, a larger cutting degree is required, which affects the assembly stability of the ejector pin itself and makes it easy for it to bite and wear against the mold core.

[0004] For example, Chinese utility model patent CN202571239U discloses a mold venting ejector pin structure. This structure uses venting stripes on the top surface of the ejector pin and venting holes below the pin body. Venting is achieved by connecting the venting stripes and venting holes through a venting cavity. However, this structure is prone to causing waste injection molding material to directly clog the venting stripes, affecting its service life. Furthermore, the venting holes on the pin body require specific molds for use, resulting in poor applicability. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a round ejector pin for injection molds, which optimizes the venting of injection molds, improves the molding quality of molds, and extends the service life of the round ejector pin itself.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An ejector pin for injection molds includes an ejector pin body composed of a rod and a base. The top end of the rod is provided with an exhaust ring groove and multiple exhaust holes. The exhaust ring groove is arranged circumferentially around the rod, dividing the top end of the rod into a top surface block. The diameter of the top surface block is smaller than the diameter of the rod. The ejector pin body has a vertically arranged exhaust channel in the center. The multiple exhaust holes are distributed inside the rod. The outlet end of each exhaust hole is connected to the exhaust channel, and the inlet end is connected to the inner side of the exhaust ring groove. The bottom surface of the base is provided with an exhaust groove, and the bottom end of the exhaust channel is connected to the exhaust groove.

[0008] Furthermore, the plurality of exhaust holes are evenly distributed along the circumference of the rod body within the exhaust ring groove.

[0009] Furthermore, the shaft has four vent holes arranged in a cross shape.

[0010] Furthermore, the multiple exhaust vents are horizontally distributed within the rod body.

[0011] Furthermore, the exhaust port is inclined, with its outlet end higher than its inlet end.

[0012] Furthermore, the angle between the exhaust vent and the horizontal plane is 5 to 40 degrees.

[0013] Furthermore, the exhaust groove extends through the bottom surface of the base.

[0014] Furthermore, the ejector pin body is made of high-speed tool steel.

[0015] Furthermore, the distance between the side surface of the top block and the side surface of the rod body is 0.01 to 0.03 mm.

[0016] Furthermore, the exhaust channel is cylindrical or cubical.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention achieves full-circumferential venting of the top block through the design of the top block and the venting ring groove, resulting in fast gas discharge and good effect; the venting ring groove plays a role in blocking and protecting the venting holes; the venting groove is set on the bottom surface of the base, which cleverly utilizes the open structure of the base, making the present invention adaptable to various types of molds.

[0019] 2. The vent holes are evenly distributed along the circumference of the rod, so that the dome pin is subjected to uniform force and wear during venting, which significantly improves the service life.

[0020] 3. Multiple vent holes are angled to further prevent waste from entering the venting channel and causing blockage, thus improving operational stability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of Embodiment 1.

[0022] Figure 2 This is a schematic diagram of the internal structure of Example 1.

[0023] Figure 3 This is a cross-sectional schematic diagram of Example 1.

[0024] Figure 4 This is a cross-sectional schematic diagram of Example 2.

[0025] Figure 5 These are schematic diagrams of the top and cross-section of an existing dome pin.

[0026] Reference numerals: 1. Rod body, 11. Exhaust ring groove, 12. Exhaust through hole, 13. Top surface block, 14. Exhaust channel, 2. Base, 21. Exhaust groove. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] like Figures 1-3 As shown, this embodiment provides a round ejector pin for injection molds, including an ejector pin body composed of a rod body 1 and a base 2. The top end of the rod body 1 is provided with an exhaust ring groove 11 and multiple exhaust through holes 12. The exhaust ring groove 11 is arranged circumferentially around the rod body 1, dividing the top end of the rod body 1 to form a top surface block 13. The diameter of the top surface block 13 is smaller than the diameter of the rod body 1. Specifically, the distance between the side surface of the top surface block 13 and the side surface of the rod body 1 is 0.01–0.03 mm, and in this embodiment, 0.02 mm is used. The ejector pin body has a vertically arranged exhaust channel 14 in the center, and multiple exhaust through holes 12 are distributed within the rod body 1. The outlet end of each exhaust through hole 12 is connected to the exhaust channel 14, and the inlet end is connected to the inner side surface of the exhaust ring groove 11. The bottom surface of the base 2 is provided with an exhaust groove 21, and the bottom end of the exhaust channel 14 is connected to the exhaust groove 21, which penetrates the bottom surface of the base 2.

[0029] In this embodiment, four vent holes 12 are specifically used, evenly distributed in a cross shape within the rod body 1. Furthermore, the vent holes 12 are horizontally distributed. The even distribution of the vent holes 12 along the circumference of the rod body 1 ensures uniform force on the ejector pin during venting, resulting in uniform wear and significantly improving service life. The vent channel 14 can be cylindrical, cubic, or other shapes. The ejector pin body is made of SKH51 high-speed tool steel (Chinese GB: W6Mo5Cr4V2).

[0030] In this embodiment, the gas generated during injection is introduced into the venting ring groove 11 through the gap formed by the height difference between the side of the top block 13 and the side of the rod body 1. The gas in the venting ring groove 11 then enters the venting groove 21 at the bottom through the venting hole 12 and the venting channel 14, and finally is led out of the mold, quickly completing the injection process. This embodiment, through the design of the top block 13 and the venting ring groove 11, achieves circumferential venting of the top block 13, resulting in fast and effective gas discharge. The venting ring groove 11 acts as a blocking and protective barrier for the venting hole 12. The venting groove 21 is cleverly designed on the bottom surface of the base 2, utilizing the open structure of the base 2 to allow the ejector pin to adapt to various types of molds.

[0031] like Figure 4 As shown, in another embodiment, the outlet end of the exhaust vent 12 is higher than the inlet end, causing the exhaust vent 12 to be inclined. Generally, the angle of inclination between the exhaust vent 12 and the horizontal plane is 5–40 degrees; in this embodiment, 20 degrees is used. The inclined exhaust vent 12 further prevents waste from entering the exhaust channel 14 and causing blockage, improving operational stability.

[0032] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A round ejector pin for injection molds, comprising an ejector pin body consisting of a shaft (1) and a base (2), characterized in that, The top of the rod body (1) is provided with an exhaust ring groove (11) and multiple exhaust through holes (12). The exhaust ring groove (11) is arranged around the circumference of the rod body (1) and divides the top of the rod body (1) into a top surface block (13). The diameter of the top surface block (13) is smaller than the diameter of the rod body (1). The center of the pin body has a vertically arranged exhaust channel (14). The multiple exhaust through holes (12) are distributed inside the rod body (1). The outlet end of each exhaust through hole (12) is connected to the exhaust channel (14), and the inlet end is connected to the inner side of the exhaust ring groove (11). The bottom surface of the base (2) is provided with an exhaust groove (21). The bottom end of the exhaust channel (14) is connected to the exhaust groove (21). The exhaust groove (21) penetrates the bottom surface of the base (2). The plurality of exhaust through holes (12) are evenly distributed along the circumference of the rod body (1) in the exhaust ring groove (11); The exhaust port (12) is inclined, with its outlet end higher than its inlet end.

2. The dome pin for injection molds according to claim 1, characterized in that, The shaft (1) has four exhaust holes (12) arranged in a cross shape.

3. The ejector pin for injection molds according to claim 1, characterized in that, The multiple exhaust holes (12) are horizontally distributed inside the rod body (1).

4. The ejector pin for injection molds according to claim 1, characterized in that, The angle between the exhaust port (12) and the horizontal plane is 5 to 40 degrees.

5. A dome pin for an injection mold according to claim 1, characterized in that, The ejector pin body is made of high-speed tool steel.

6. A dome pin for an injection mold according to claim 1, characterized in that, The distance between the side of the top block (13) and the side of the rod (1) is 0.01~0.03mm.

7. A dome pin for injection molds according to claim 1, characterized in that, The exhaust channel (14) is cylindrical or cubic.

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