A gate pulling device for BMC injection mold

Abstract

This application relates to the field of injection molding technology and discloses a sprue ejection device for BMC injection molds, aiming to solve the problem of sprue sleeve blockage affecting mold manufacturing efficiency. The invention, through the setting of an ejection mechanism, after the material solidifies in the mold, a sliding rod drives an annular cutter upwards and extends into the sprue sleeve, causing the annular cutter to cut off the part connecting the sprue shank to the molded part and push the sprue shank away from the sprue sleeve. This action avoids the sprue shank being pulled and broken inside the sprue sleeve when the mold opens, thereby reducing the probability of sprue shank blockage and making the mold manufacturing efficiency less affected.

Description

Technical Field

[0001] This application relates to the field of injection molding technology, and in particular to a gate pulling device for BMC injection molds. Background Technology

[0002] BMC injection molding is a polymer material molding and processing technology, belonging to the thermosetting plastic injection molding process. Some existing BMC injection molding processes mainly involve mixing recycled BMC material with virgin BMC material, then melting and injecting it into a mold to solidify and form the material. BMC material has excellent electrical insulation properties and good heat resistance.

[0003] In some existing BMC injection molds, the molten two-component mixture (recycled BMC material and virgin BMC material) enters the mold through the sprue sleeve and solidifies inside. Some of the molded material forms a sprue stalk inside the sprue sleeve. Because BMC material is brittle and the sprue stalk has a certain length, it is easy for the sprue stalk to break off inside the sprue sleeve when the mold is separated, causing the sprue sleeve to become blocked. This affects the injection of material in subsequent injection operations, thus impacting the efficiency of mold production. Summary of the Invention

[0004] This application proposes a gate pulling device for BMC injection molds, which has the advantage of reducing the probability of the sprue clogging the gate sleeve, thereby solving the problem of gate sleeve clogging affecting mold production efficiency.

[0005] To achieve the above objectives, this application adopts the following technical solution: a gate pulling device for BMC injection molds, comprising: an upper mold, a lower mold fitted to the lower side of the upper mold, the upper mold and the lower mold together forming a molding cavity for molding BMC material, a stripper rod longitudinally and slidably installed inside the lower mold, the lower end of the stripper rod extending out of the lower mold, a gate sleeve fixedly installed in the middle position inside the upper mold, a guide channel opened inside the upper mold, the gate sleeve communicating with the molding cavity through the guide channel, and a stripping mechanism provided inside the lower mold at a position corresponding to the gate sleeve, the stripping mechanism comprising: A sliding rod is slidably installed inside the lower mold and corresponds to the position of the sprue sleeve. The lower end of the sliding rod extends out of the lower mold, and the diameter of the sliding rod inside the lower mold is smaller than the diameter of the inner cavity of the sprue sleeve. A ring-shaped cutter is fixedly installed at the upper end of the slide bar, and the outer surface of the ring-shaped cutter forms a smooth transition with the arc-shaped surface of the slide bar; An elastic scraper ring is fixedly sleeved on the outer side of the annular cutter, and the elastic scraper ring forms an interference fit with the inner wall of the gate sleeve. Both the stripping rod and the slide rod are driven by corresponding jacking mechanisms.

[0006] Furthermore, the stripping mechanism also includes: An electric cylinder has an installation space inside the lower side of the slide rod. The electric cylinder is fixedly installed in the installation space, and the connecting rod of the electric cylinder runs longitudinally through the slide rod. A circular sealing block is slidably mounted on the inside of an annular cutter, and the end of the connecting rod away from the electric cylinder is fixedly connected to the circular sealing block.

[0007] Furthermore, the annular cutter is made of YG8 cemented carbide, and the surface of the annular cutter is coated with DLC (diamond-like carbon). The slide rod is made of SKD61 alloy steel and undergoes deep nitriding treatment. The electric cylinder has two thrust modes with different sizes, and the thrust of the small thrust mode is 50% of the thrust of the large thrust mode.

[0008] Furthermore, the slide bar is internally equipped with a suction mechanism, which includes: An annular suction tube is fixedly installed on the inside of the annular cutter and located on the circular sealing block facing away from the sprue sleeve. The annular suction tube is located on the outside of the connecting rod. The suction port is circumferentially and equidistantly opened inside the annular cutter and located on the side of the elastic scraper facing the gate sleeve. A straight suction tube is located below the annular suction tube. The straight suction tube passes through the slide rod and extends into the mounting space of the slide rod. A collection component is installed in the mounting space of the slide bar, and the collection component, the straight suction tube, the annular suction tube, and the suction port are connected in sequence.

[0009] Furthermore, both the annular straw and the straight straw are made of polytetrafluoroethylene, and the inner walls of both the annular straw and the straight straw are coated with an anti-stick coating. The inner diameter of both the annular straw and the straight straw is greater than 1.5 mm. The suction port is designed with a flared structure, with the smaller diameter end of the suction port facing the annular straw.

[0010] Furthermore, the collection component includes: The collection tank is fixedly installed on the upper inner wall of the slide bar installation space. The straight suction pipe is connected to the collection tank. The collection tank is a split structure that is fixedly assembled. A suction pump is installed on the side of the collection tank facing away from the annular cutter, and the suction end of the suction pump is fixedly connected to the collection tank. The support ring is fixedly installed on the inner wall of the collection tank; The filter screen is placed on the support ring.

[0011] Furthermore, the collection tank is made of transparent PC material, the filter screen is a sintered stainless steel mesh, and the mesh size of the filter screen is 100 mesh.

[0012] Furthermore, contact blocks are fixedly installed at equal intervals on the inner wall of the sprue bushing. The contact blocks are hemispherical in shape and have a diameter of 1.5 mm.

[0013] Furthermore, the surface of the contact block is chrome-plated and polished, with a chrome plating layer thickness of 0.02 mm. The outer layer of the elastic scraper ring is made of polyurethane + glass fiber reinforced material, and the inner layer of the elastic scraper ring is a soft PU buffer layer.

[0014] This application has the following beneficial effects: This application provides a gate pulling device for BMC injection molds. Through the setting of the stripping mechanism, after the material solidifies in the mold, the slide rod drives the annular cutter to move upward and extend into the gate sleeve, so that the annular cutter cuts off the part connecting the sprue to the molded part and pushes the sprue away from the gate sleeve. Through this action, the sprue is prevented from being pulled and broken in the gate sleeve when the mold is opened, thereby reducing the probability of the sprue clogging the gate sleeve and making the efficiency of mold production less affected.

[0015] With the material stripping mechanism in place, during the process of the annular cutter entering the sprue sleeve, the elastic scraper ring on the outside of the annular cutter will enter the sprue sleeve with a delay. The elastic scraper ring is deformed by the pressure of the inner wall of the sprue sleeve and moves axially against the inner wall of the sprue sleeve. The elastic scraping force peels off the solidified residue in the scratches caused by glass fiber grinding on the inner wall of the sprue sleeve, preventing the residue from carbonizing and mixing into the new adhesive, which would cause black spots and impurities in subsequent products and affect the quality of the molded parts.

[0016] By setting up the suction mechanism and the stripping mechanism, a negative pressure is generated at the suction port during the process of the annular cutter cutting off the material shank and pushing it out. This suctions in the glass fiber debris and small residue scraped off by the elastic scraper ring, preventing the scraped residue from falling back into the sprue sleeve when the annular cutter resets. This avoids the need for secondary cleaning inside the sprue sleeve, making the efficiency of mold production less affected. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, illustrate embodiments disclosed in this application and, together with the specification, serve to explain the principles disclosed in this application.

[0018] This application can be more clearly understood with reference to the accompanying drawings and the following detailed description, wherein: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the upper and lower molds of the present invention; Figure 3 This is a schematic diagram of the internal structure of the slide bar of the present invention; Figure 4 This is a schematic diagram of the inner structure of the annular cutter of the present invention; Figure 5 This is a schematic diagram of the component structure of the present invention.

[0019] In the diagram: 1. Upper mold; 2. Lower mold; 3. Stripper rod; 4. Sprue sleeve; 5. Material guide channel; 6. Stripping mechanism; 60. Slide rod; 61. Annular cutter; 62. Electric cylinder; 63. Connecting rod; 64. Circular sealing block; 65. Elastic scraper ring; 7. Suction mechanism; 70. Annular suction pipe; 71. Suction port; 72. Straight suction pipe; 73. Collection assembly; 730. Collection tank; 731. Suction pump; 732. Support ring; 733. Filter screen; 8. Contact block. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Example 1: Please refer to Figures 1-5 A gate ejector device for BMC injection molds includes an upper mold 1, a lower mold 2 fitted to the lower side of the upper mold 1, a groove in the upper mold 1 and a protrusion on the upper surface of the lower mold 2 forming a molding cavity for molding BMC material, a stripper rod 3 longitudinally and slidably installed inside the lower mold 2 at positions corresponding to the protrusions, the upper end face of the stripper rod 3 smoothly transitioning to the upper surface of the protrusions, the lower end of the stripper rod 3 extending out of the lower mold 2, a gate sleeve 4 fixedly installed in the middle position inside the upper mold 1, and a guide channel 5 opened inside the upper mold 1 at a position between the molding cavity and the gate sleeve 4, the gate sleeve 4 communicating with the molding cavity through the guide channel 5, and the lower mold 2... Inside the mold 2, corresponding to the position of the sprue sleeve 4, there is a stripping mechanism 6. The stripping mechanism 6 includes a slide rod 60 and an annular cutter 61. The slide rod 60 is sealed and slidably installed inside the lower mold 2 and is directly corresponding to the position of the sprue sleeve 4. The lower end of the slide rod 60 extends out of the lower mold 2. The diameter of the slide rod 60 inside the lower mold 2 is smaller than the diameter of the inner cavity of the sprue sleeve 4. The annular cutter 61 is fixedly installed on the upper end of the slide rod 60. The outer side of the annular cutter 61 and the arc surface of the slide rod 60 form a smooth transition (the gap between the outer diameter of the annular cutter 61 and the inner diameter of the sprue sleeve 4 is controlled at 0.01 to 0.02 mm). The stripping rod 3 and the slide rod 60 are both driven by the corresponding ejector mechanism inside the mold.

[0022] During use, BMC material enters the molding cavity through the sprue sleeve 4 and the guide channel 5. After a period of time, the BMC material solidifies and forms a molded part (a molded part is formed in the molding cavity, solidified material is formed in the guide channel 5, and a sprue shank is formed in the sprue sleeve 4; only the molded part is the desired workpiece). Then, the jacking mechanism first moves the slide rod 60, causing the slide rod 60 to move the annular cutter 61 close to the sprue sleeve 4, thereby cutting off the part connecting the sprue shank 4 and the solidified material in the guide channel 5. Afterward, the slide rod 60 moves the annular cutter 61 into the sprue sleeve. 4. This action causes the sprue to be pushed out of the sprue sleeve 4 by the annular cutter 61. This action prevents the sprue from being pulled and breaking inside the sprue sleeve 4 when the upper mold 1 and lower mold 2 are opened later (when the upper mold 1 and lower mold 2 are opened, the molded part will be on the lower mold 2, so that the molded part drives the sprue to keep in contact with the lower mold 2, so that the upper mold 1, which is away from the lower mold 2, will drive the sprue sleeve 4 away from the sprue, so that the sprue and the sprue sleeve 4 will pull each other). This reduces the probability of the sprue blocking the sprue sleeve 4, so that the efficiency of mold production is not easily affected. Next, remove the ejected material handle and reset the slide bar 60 to drive the annular cutter 61. Then, separate the upper mold 1 from the lower mold 2 and move the ejector mechanism to move the ejector bar 3 so that the ejector bar 3 lifts the molded part on the lower mold 2. Finally, remove the molded part and reset the ejector bar 3, upper mold 1 and lower mold 2.

[0023] To prevent tearing at the connection between the spool and the molded part, which could affect the quality of the molded part, please refer to [link / reference needed]. Figures 1-5 The unloading mechanism 6 also includes an electric cylinder 62, a connecting rod 63 and a circular sealing block 64. An installation space is provided on the lower side of the slide rod 60. The electric cylinder 62 is fixedly installed in the installation space. The connecting rod 63 of the electric cylinder 62 runs longitudinally through the slide rod 60. The circular sealing block 64 is slidably installed on the inner side of the annular cutter 61. The end of the connecting rod 63 away from the electric cylinder 62 is fixedly connected to the circular sealing block 64.

[0024] Before the BMC material enters the molding cavity through the sprue sleeve 4 and the guide channel 5, the electric cylinder 62 drives the circular sealing block 64 to move via the connecting rod 63, so that the circular sealing block 64 is extremely close to the blade of the annular cutter 61. Then, before the jacking mechanism drives the slide rod 60 and the annular cutter 61 to move, the electric cylinder 62 drives the circular sealing block 64 to reset via the connecting rod 63, so that there is a feeding space between the inner side of the annular cutter 61 and the material shank. Through this action, it is prevented that some BMC material enters the inner side of the annular cutter 61 and solidifies during injection. When the slide rod 60 drives the annular cutter 61 to move, the blade of the annular cutter 61 first contacts the part where the material shank is connected to the solidified material, and then cuts off this part by the blade of the annular cutter 61. This prevents the slide rod 60 (before (or simultaneously with) the annular cutter 61) from applying a pushing force to the material shank, so that the connection between the material shank and the molded part will not tear, thus avoiding affecting the quality of the molded part.

[0025] To clean the residual material from the inner wall of the sprue bushing 4, please refer to [link / reference needed]. Figures 1-5 The unloading mechanism 6 also includes an elastic scraper ring 65, which is fixedly sleeved on the outer side of the annular cutter 61, and the elastic scraper ring 65 forms an interference fit with the inner wall of the gate sleeve 4.

[0026] During the process of the annular cutter 61 entering the sprue sleeve 4, the elastic scraper ring 65 on the outer side of the annular cutter 61 will lag behind (the blade of the annular cutter 61 enters the sprue sleeve 4 first, and the elastic scraper ring 65 enters later) and enter the sprue sleeve 4. It will be deformed by the pressure of the inner wall of the sprue sleeve 4, and then move axially close to the inner wall of the sprue sleeve 4. The elastic scraping force will peel off the solidified residue on the inner wall of the sprue sleeve 4 (within the scratches caused by glass fiber grinding), so as to avoid the residue from carbonizing and mixing into the new adhesive, which would cause black spots and impurities in the subsequent products and affect the quality of the subsequent molded parts. In addition, the elastic scraper ring 65, which is squeezed by the inner wall of the sprue bushing 4, will generate radial pressure on the inner wall of the sprue bushing 4. The sprue bushing 4 (usually made of SKD61 or H13 mold steel with a hardness ≥50HRC) has the dual characteristics of high rigidity and micro-elasticity. The high rigidity of the sprue bushing 4 ensures that the radial pressure applied by the elastic scraper ring 65 will not be absorbed by the plastic deformation of the inner wall of the sprue bushing 4, but can be efficiently transmitted along the circumferential and axial directions of the inner wall of the sprue bushing 4. Under the radial pressure of the elastic scraper ring 65, the inner wall of the sprue bushing 4 will produce micron-level elastic deformation. Specifically, the inner wall of the sprue bushing 4 in the area squeezed by the elastic scraper ring 65 will produce a small bulge deformation towards the inner center of the sprue bushing 4 (the deformation amount is about 0.003-0.008mm). (Positively correlated with the interference fit of the elastic scraper ring 65 and the thickness of the inner wall of the sprue sleeve 4), after the material stalk is cured, it adheres tightly to the inner wall of the sprue sleeve 4 due to the shrinkage effect, and the gap between the two approaches zero (molecular-level contact). When the elastic scraper ring 65 applies radial pressure at a certain position, the micro-protrusion deformation of the inner wall of the sprue sleeve 4 towards the center will directly squeeze the cylindrical side of the material stalk that is tightly attached to its surface, forcing the material stalk to produce a small elastic deformation, pushing out the protrusion of the material stalk embedded in the scratch of the inner wall of the sprue sleeve 4, destroying the mechanical interlocking point. At the same time, the small deformation of the material stalk will increase the molecular distance between it and the inner wall of the sprue sleeve 4, weakening the van der Waals force. Through the above actions, the connection force between the material stalk and the inner wall of the sprue sleeve 4 is reduced, so that the annular cutter 61 can easily push out the material stalk, avoiding material stalk breakage and residue.

[0027] The annular cutter 61 is made of YG8 cemented carbide with a DLC diamond-like coating. The slide bar 60 is made of SKD61 alloy steel and undergoes deep nitriding treatment, with a surface hardness ≥65HRC. The electric cylinder 62 has two thrust modes with different sizes. The thrust of the small thrust mode is 50% of the thrust of the large thrust mode.

[0028] The wear resistance is improved by the above-mentioned arrangement of the annular cutter 61 and the slide bar 60. By setting two propulsion modes for the electric cylinder 62, the high propulsion mode is adapted to the annular cutter 61 to cut off the connection between the material shank and the molded part, ensuring that the position is cut off smoothly. The low propulsion mode is adapted to the subsequent slide rod 60 to drive the elastic scraper ring 65 to scrape the inner wall of the gate sleeve 4, ensuring that the elastic scraper ring 65 fits the inner wall of the gate sleeve 4 with moderate pressure, which not only ensures the scraping effect, but also avoids excessive wear of the elastic scraper ring 65.

[0029] Example 2: To prevent residual material from falling back after being scraped by the elastic scraper ring 65, please refer to... Figures 1-5The slide rod 60 is equipped with a suction mechanism 7, which includes an annular suction tube 70, a suction port 71, a straight suction tube 72, and a collection component 73. The annular suction tube 70 is fixedly installed on the inner side of the annular cutter 61 and on the circular sealing block 64 facing away from the sprue sleeve 4. The annular suction tube 70 is located on the outer side of the connecting rod 63. The suction port 71 is circumferentially and equidistantly opened on the inner side of the annular cutter 61 and on the side of the elastic scraper ring 65 facing the sprue sleeve 4. The straight suction tube 72 is provided on the lower side of the annular suction tube 70. The straight suction tube 72 passes through the slide rod 60 and extends into the installation space of the slide rod 60. The collection component 73 is installed in the installation space of the slide rod 60. The collection component 73, the straight suction tube 72, the annular suction tube 70 and the suction port 71 are connected in sequence.

[0030] During the process of the slide bar 60 driving the elastic scraper ring 65 into the sprue sleeve 4, the collecting component 73 generates a negative pressure suction force. This negative pressure passes through the straight suction pipe 72, the annular suction pipe 70 and the suction port 71, thereby sucking the glass fiber debris and small residue scraped off by the elastic scraper ring 65 into the collecting component 73. This prevents the scraped residue from falling back into the sprue sleeve 4 when the annular cutter 61 resets, thus avoiding the need for secondary cleaning inside the sprue sleeve 4. This makes the efficiency of mold production less affected. When the annular cutter 61 resets, the collecting component 73 stops operating.

[0031] Please see Figures 1-5 Both the annular straw 70 and the straight straw 72 are made of polytetrafluoroethylene (PTFE) with an anti-stick coating on the inner wall. The inner diameter of both the annular straw 70 and the straight straw 72 is greater than 1.5 mm. The suction port 71 is designed with a flared structure, with the smaller diameter end of the suction port 71 facing the annular straw 70.

[0032] By setting up the annular suction tube 70 and the straight suction tube 72, the adhesion and blockage of glass fiber debris are prevented, and the glass fiber debris and small residue scraped off by the elastic scraper ring 65 are discharged smoothly, thereby avoiding the need for secondary cleaning inside the sprue sleeve 4, and making the efficiency of mold production less affected. By setting the suction port 71, the adsorption range is expanded, the amount of glass fiber debris and small residues scraped off by the elastic scraper ring 65 is reduced, and the need for secondary cleaning inside the sprue sleeve 4 is avoided, so that the efficiency of mold production is not easily affected.

[0033] Please see Figures 1-5The collection component 73 includes a collection tank 730, a suction pump 731, a support ring 732, and a filter screen 733. The collection tank 730 is threadedly installed on the upper inner wall of the mounting space of the slide bar 60. The straight suction pipe 72 is connected to the collection tank 730. The collection tank 730 is a split structure with a threaded assembly. The suction pump 731 is provided on the side of the collection tank 730 facing away from the annular cutter 61. The suction end of the suction pump 731 is threadedly connected to the collection tank 730. The support ring 732 is fixedly installed on the inner wall of the collection tank 730, and the filter screen 733 is placed on the support ring 732.

[0034] During the process of the slide bar 60 driving the elastic scraper ring 65 into the sprue sleeve 4, the suction pump 731 operates and generates negative pressure suction. This negative pressure passes through the straight suction pipe 72, the annular suction pipe 70 and the suction port 71, thereby sucking the glass fiber debris and small residue scraped off by the elastic scraper ring 65 into the surface of the filter screen 733 in the collection tank 730. This prevents the scraped residue from falling back into the sprue sleeve 4 when the annular cutter 61 resets, thus avoiding the need for secondary cleaning inside the sprue sleeve 4. This makes the efficiency of mold production less affected. When the annular cutter 61 resets, the suction pump 731 stops operating.

[0035] The collection tank 730 is made of transparent PC material, and the filter screen 733 is made of stainless steel sintered mesh with a mesh size of 80 to 100 mesh.

[0036] The aforementioned collection tank 730 facilitates the observation of residual material collection by staff, allowing for timely replacement of the collection tank 730 and ensuring uninterrupted collection of residual material. This avoids the need for secondary cleaning of the sprue sleeve 4, thus minimizing the impact on mold production efficiency. Simultaneously, the mesh size of the filter screen 733 is matched to the residual material particle size, causing the residual material to be blocked and collected on the surface of the filter screen 733, preventing it from entering the suction pump 731 and affecting its operation.

[0037] Example 3: To improve the scraping effect of residual material, please refer to... Figures 1-5 Contact blocks 8 are fixedly installed at equal intervals on the inner wall of the sprue sleeve 4. The contact blocks 8 are hemispherical in shape and have a rounded transition with the inner wall of the sprue sleeve 4. The diameter of the contact blocks 8 is one to one and a half millimeters.

[0038] During the process of the slide bar 60 driving the elastic scraper ring 65 into the sprue sleeve 4, the elastic scraper ring 65 scrapes the contact block 8 and generates a slight vibration. This vibration is transmitted to the inner wall of the sprue sleeve 4, thereby breaking the adhesion between the residual material and the inner wall of the sprue sleeve 4, assisting the elastic scraper ring 65 in peeling off stubborn residual material, making it easier for the elastic scraper ring 65 to scrape off and for the suction port 71 to be negatively adsorbed, removing deeply adhered residual material, avoiding the carbonization of residual material and mixing with new rubber material, which would cause black spots and impurities in subsequent products, and avoid affecting the quality of subsequent molded parts; Meanwhile, when the elastic scraper ring 65 moves inside the sprue sleeve 4, the mechanical obstruction of the contact block 8 causes the elastic scraper ring 65 to generate high-frequency micro-vibration (the vibration frequency is determined by the pushing speed of the slide bar 60 and the spacing of the contact block 8, usually 50-100Hz). This vibration is directly transmitted to the material stalk pushed by the annular cutter 61 through the rigid connection between the elastic scraper ring 65 and the annular cutter 61, causing the tiny gap between the material stalk and the inner wall of the sprue sleeve 4 to continuously expand, making the material stalk become loose and suspended, reducing the connection force between the material stalk and the inner wall of the sprue sleeve 4, so that the annular cutter 61 can easily push the material stalk out, avoiding material stalk breakage and residue; In addition, when the material handle becomes loose and suspended, the suction port 71 generates negative pressure, which causes outside air to be drawn in through the gap between the material handle and the inner wall of the sprue sleeve 4. This air forms an air cushion layer, which reduces the connection force between the material handle and the inner wall of the sprue sleeve 4, allowing the annular cutter 61 to easily push the material handle out, thus preventing the material handle from breaking and remaining.

[0039] The surface of contact block 8 is chrome-plated and polished, with a chrome plating layer thickness of 0.02 mm. The outer layer of the elastic scraper ring 65 is made of polyurethane + glass fiber reinforced material (PU90A + 10% glass fiber), and the inner layer is a soft PU buffer layer.

[0040] By setting the contact block 8 as described above, its surface hardness is improved and residual material adhesion is reduced (the contact block 8 will not lock with the solidified material handle: the size of the contact block 8 is extremely small, and the shrinkage direction of the material handle after solidification is radial shrinkage towards the center of the material handle, rather than wrapping around the contact block 8 outward, so that there will be a gap between the material handle and the contact block 8 after solidification; the surface of the contact block 8 is polished and has a 0.02mm thick hard chrome plating layer. The surface energy of the chrome plating layer is extremely low, and the BMC adhesive has poor adhesion to it. At the same time, the ultra-smooth surface has no microscopic scratches that can be embedded in the glass fiber, so it is impossible to form microscopic interlocking points). Meanwhile, the layered structure design of the elastic scraper ring 65 can amplify the vibration effect (the elastic deformation of the inner soft PU can store vibration energy and then release it to the material handle interface, thereby improving the vibration drag reduction effect by more than 20%).

Claims

1. A gate-pulling apparatus for a BMC injection mold, comprising: An upper mold (1) is provided, and a lower mold (2) is fitted to the lower side of the upper mold (1). The upper mold (1) and the lower mold (2) together form a molding cavity for molding BMC material. A stripper rod (3) is longitudinally and slidably installed inside the lower mold (2). The lower end of the stripper rod (3) extends out of the lower mold (2). A sprue sleeve (4) is fixedly installed in the middle position inside the upper mold (1). A guide channel (5) is provided inside the upper mold (1). The sprue sleeve (4) communicates with the molding cavity through the guide channel (5). The lower mold (2) is characterized by having a stripping mechanism (6) inside the lower mold (2) and corresponding to the position of the sprue sleeve (4). The stripping mechanism (6) includes: The slide rod (60) is sealed and slidably installed inside the lower mold (2) and corresponds to the position of the sprue sleeve (4). The lower end of the slide rod (60) extends out of the lower mold (2). The diameter of the slide rod (60) inside the lower mold (2) is smaller than the diameter of the inner cavity of the sprue sleeve (4). A ring cutter (61) is fixedly installed on the upper end of the slide bar (60), and the outer side of the ring cutter (61) forms a smooth transition with the arc surface of the slide bar (60); The elastic scraper ring (65) is fixedly sleeved on the outer side of the annular cutter (61), and the elastic scraper ring (65) forms an interference fit with the inner wall of the gate sleeve (4). Both the stripping rod (3) and the slide rod (60) are driven by their respective jacking mechanisms.

2. The gate-pulling apparatus for BMC injection mold according to claim 1, wherein, The unloading mechanism (6) further includes: An installation space is provided inside the lower side of the electric cylinder (62) and the slide rod (60). The electric cylinder (62) is fixedly installed in the installation space, and the connecting rod (63) of the electric cylinder (62) passes through the slide rod (60) longitudinally. A circular sealing block (64) is slidably mounted on the inner side of the annular cutter (61), and the end of the connecting rod (63) away from the electric cylinder (62) is fixedly connected to the circular sealing block (64).

3. The gate-pulling apparatus for BMC injection mold according to claim 2, wherein, The annular cutter (61) is made of YG8 cemented carbide, and the surface of the annular cutter (61) is coated with DLC diamond-like carbon. The slide rod (60) is made of SKD61 alloy steel and is subjected to deep nitriding treatment. The electric cylinder (62) has two thrust modes with different sizes. The thrust of the small thrust mode is 50% of the thrust of the large thrust mode.

4. The gate-pulling apparatus for BMC injection mold according to claim 2, wherein, The slide bar (60) is internally provided with a suction mechanism (7), which includes: The annular suction tube (70) is fixedly installed on the inner side of the annular cutter (61) and located on the circular sealing block (64) facing away from the gate sleeve (4). The annular suction tube (70) is located on the outer side of the connecting rod (63). The suction port (71) is circumferentially equidistantly opened inside the annular cutter (61) and located on the side of the elastic scraper ring (65) facing the gate sleeve (4); A straight suction tube (72) is provided on the lower side of the annular suction tube (70). The straight suction tube (72) passes through the slide rod (60) and extends into the installation space of the slide rod (60). The collection component (73) is installed in the installation space of the slide bar (60), and the collection component (73), the straight suction tube (72), the annular suction tube (70) and the suction port (71) are connected in sequence.

5. The gate-pulling apparatus for BMC injection mold according to claim 4, wherein, Both the annular straw (70) and the straight straw (72) are made of polytetrafluoroethylene. The inner walls of both the annular straw (70) and the straight straw (72) are coated with an anti-stick coating. The inner diameter of both the annular straw (70) and the straight straw (72) is greater than 1.5 mm. The suction port (71) is a flared structure with the smaller diameter end of the suction port (71) facing the annular straw (70).

6. A gate pulling device for BMC injection molds according to claim 4, characterized in that, The collection component (73) includes: The collection tank (730) is fixedly installed on the upper inner wall of the sliding rod (60) installation space. The straight suction pipe (72) is connected to the collection tank (730). The collection tank (730) is a split structure with fixed assembly. A suction pump (731) is installed on the side of the collection tank (730) facing away from the annular cutter (61), and the suction end of the suction pump (731) is fixedly connected to the collection tank (730). The support ring (732) is fixedly installed on the inner wall of the collection tank (730); The filter (733) is placed on the support ring (732).

7. A gate pulling device for BMC injection molds according to claim 6, characterized in that, The collection tank (730) is made of transparent PC material, and the filter screen (733) is a stainless steel sintered mesh with a mesh count of 100.

8. A gate pulling device for BMC injection molds according to claim 6, characterized in that, Contact blocks (8) are fixedly installed at equal intervals on the inner wall of the sprue sleeve (4). The contact blocks (8) are hemispherical in shape and have a diameter of 1.5 mm.

9. A gate pulling device for BMC injection molds according to claim 8, characterized in that, The surface of the contact block (8) is chrome-plated and polished, and the thickness of the chrome plating layer is 0.02 mm. The outer layer of the elastic scraper (65) is made of polyurethane + glass fiber reinforced material, and the inner layer of the elastic scraper (65) is a soft PU buffer layer.

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