Production mold for full-plastic bumper of heavy truck

Abstract

The invention discloses a production mold for an all-plastic bumper of a heavy truck, which comprises an upper mold and a lower mold which are opposite to each other in the vertical direction, and the upper mold and the lower mold which are assembled enclose to form an injection molding cavity; an embedded hole is formed in a parting surface of the lower die, a nut is arranged in the embedded hole, an axial vertical sliding hole is formed in the inner bottom wall of the embedded hole, an ejector sleeve which slides in the vertical direction and is attached to the circumferential inner wall of the sliding hole in a sealed mode is arranged in the sliding hole, and a core rod which vertically extends upwards is further fixed to the lower die. The bottom face of the nut is attached to the inner bottom wall of the embedded hole, the top face of the ejector sleeve and the core rod in a sealed mode. According to the production mold for the all-plastic bumper of the heavy truck, the bottom surface of the nut is hermetically attached to the inner bottom wall of the pre-buried hole, the top surface of the ejector sleeve and the core rod during mold pressing, so that the sealing contact area is increased, and the possibility that an SMC material flows into the nut is reduced, so that the SMC material is prevented from being cured and formed on the inner wall of the nut, and subsequent product assembly is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of automobile parts production, in particular to a production mold for a full-plastic bumper of a heavy truck. Background Art

[0002] SMC is a sheet molding compound with high rigidity and strength. After being molded into a bumper, it can withstand various impact forces during the driving of heavy trucks and is corrosion-resistant. Compared with metal, it is lighter, which helps heavy trucks reduce their own weight and improve fuel economy.

[0003] When using a mold to mold an SMC bumper, in order to facilitate the later assembly, a pre-embedded nut is usually placed on the lower mold of the mold so that the plastic part formed after the SMC material is solidified and formed can be connected to the nut as a whole, so as to facilitate the later fixing and installation of the SMC all-plastic bumper on the car frame through the nut and bolt connection. However, during the use of the existing mold, due to the poor tightness of the nut and the mold, and during the molding process, the SMC material has a certain fluidity. After being subjected to pressure, the SMC material is easy to enter the inside of the nut through the gap between the end face of the nut and the connection surface of the mold, resulting in that after the SMC material is solidified and formed, part of the material entering the inside of the nut is attached to the thread of the nut, affecting the assembly of subsequent products; not only that, the nut in the prior art has a circumferential outer edge surface that is parallel to its axial direction as a whole. Although it can be connected to the SMC solidified plastic part as a whole, when subjected to an outward pulling force perpendicular to the mounting surface, the nut is separated from the plastic part, reducing the product quality of the final all-plastic bumper.

[0004] Therefore, it is necessary to improve the production mold of the all-plastic bumper of heavy truck in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a production mold for a heavy truck all-plastic bumper which improves product quality, prevents material from flowing into the nut to affect assembly, and prevents the nut from separating from the plastic part.

[0006] In order to achieve the above technical effects, the technical solution of the present invention is: a production mold for a heavy-duty truck all-plastic bumper, comprising: The upper mold and the lower mold facing each other vertically are used to connect the driving device to close and separate the molds, and the closed upper mold and the lower mold enclose to form an injection cavity; The parting surface of the lower mold is provided with an embedded hole, and an axially vertical nut with a closed top is provided in the embedded hole. The nut is used to integrally connect the plastic part formed by solidifying the SMC material injected into the injection cavity. The inner bottom wall of the embedded hole is provided with an axially vertical sliding hole, and a sleeve is provided in the sliding hole, which slides vertically and is sealed with its circumferential inner wall. The lower mold is also fixed with a core rod extending vertically upward, and the bottom surface of the nut is sealed with the inner bottom wall of the embedded hole, the top surface of the sleeve and the core rod.

[0007] Preferably, in order to further increase the contact area with the end face of the nut, the core rod includes a thick rod sealingly fitting with the circumferential inner wall of the sleeve and a thin rod coaxially fixed to the top of the thick rod and extending to the inside of the nut, and the top surface of the thick rod is sealingly fitting with the nut.

[0008] Preferably, in order to further increase the contact area of ​​the nut end face and enhance the sealing performance, the bottom surface of the nut circumferential outer edge is provided with an outer flange.

[0009] Preferably, in order to prevent the nut from detaching from the SMC plastic part after molding, a protrusion and / or a groove is provided on the circumferential outer edge between the two ends of the nut.

[0010] Preferably, in order to further enhance the sealing performance and improve the assembly connection accuracy between the nut and the plastic part, matching protrusions and depressions are provided between the fitting surfaces of the nut and the embedded hole, the sleeve and the thick rod.

[0011] Preferably, in order to enhance the sealing and prevent the SMC material from flowing into the nut, the protrusion is a protruding ring formed on at least one of the bottom wall of the embedded hole, the sleeve, and the top surface of the thick rod, and the recess is an annular groove formed on the bottom surface of the nut.

[0012] Preferably, in order to enhance the sealing performance between the nut and the bottom of the embedded hole of the lower die, the nut is magnetically connected to at least one of the lower die, the core rod and the sleeve.

[0013] Preferably, in order to enhance the sealing between the nut and the lower mold during molding, there is a gap between the core rod and the inner wall of the nut, and a negative pressure channel is provided on the core rod, one end of the negative pressure channel is provided on the outer surface of the thin rod, and the other end is used to connect a negative pressure pump.

[0014] Preferably, in order to further prevent the SMC material from entering the inside of the nut during the molding process, the top of the negative pressure channel is arranged at the top of the thin rod, and the top of the thin rod is sealed to the inner top wall of the nut through a sealing ring, and a boosting channel is arranged on the core rod, and the negative pressure channel is connected to the boosting channel through the negative pressure pump, and the core rod and the nut enclose a boosting chamber located outside the thin rod, and the boosting chamber is connected to the boosting channel.

[0015] Preferably, in order to facilitate the detection of the air pressure in the boost channel and the negative pressure channel, ensure the tight force between the nut and the lower mold, and prevent the SMC material from entering the nut during molding, both ends of the negative pressure pump are connected to a pressure gauge.

[0016] In summary, compared with the prior art, the production mold of the heavy-duty truck all-plastic bumper of the present invention increases the sealing contact area and reduces the possibility of SMC material flowing into the nut by sealing the bottom surface of the nut with the bottom wall of the embedded hole, the top surface of the sleeve and the core rod during molding, thereby preventing the SMC material from solidifying and forming on the inner wall of the nut, and facilitating the assembly of subsequent products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the first embodiment; Figure 2 is a simplified structural diagram of the first embodiment; Figure 3 yes Figure 2 Explosion diagram of Figure 4 yes Figure 1 The structural diagram after the upper mold is omitted; Figure 5 yes Figure 4 A schematic diagram of the cross-sectional structure of; Figure 6 yes Figure 5 A magnified view of part A; Figure 7 Schematic diagram of the connection structure of the sleeve, the core rod and the plastic part in the first embodiment; Figure 8 is a schematic structural diagram of a nut in the first embodiment; Fig. 9 is a schematic diagram of the connection structure between the plastic part and the nut in the first embodiment; Fig.10 is a cross-sectional view of the connection structure between the lower die and the nut in the second embodiment; Fig.11 is a schematic structural diagram of a nut according to a second embodiment; Fig.12 is a cross-sectional view of the connection structure between the lower die and the nut in the third embodiment; Fig.13is a schematic diagram of the connection structure between the lower die and the nut of the fourth embodiment; Fig.14 yes Fig.13 A schematic diagram of the cross-sectional structure of; Fig.15 yes Fig.14 A magnified view of part B; Fig.16 is a schematic diagram of the connection structure between the lower die and the nut of the fifth embodiment; Fig.17 yes Fig.16 A schematic diagram of the cross-sectional structure of; Fig.18 yes Figure 7 Enlarged view of part C; In the figure: 1. upper die; 2. lower die; 21. embedded hole; 211. sliding hole; 22. magnet; 3. sleeve; 31. convex ring; 4. core rod; 41. thick rod; 42. thin rod; 43. negative pressure channel; 44. boost channel; 45. sealing ring; 451. rubber ring; 5. nut; 51. outer flange; 52. groove; 53. ring groove; 6. negative pressure pump; 61. barometer; 62. air inlet shell; 63. air outlet shell; 64. air supply inlet pipe; 641. air supply valve; 65. residual air outlet pipe; 651. residual air valve; 7. plastic parts. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0019] First embodiment

[0020] like Figure 1-Figure 9 As shown, the production mold of the heavy truck all-plastic bumper of the first embodiment of the present invention comprises: The upper mold 1 and the lower mold 2 facing each other vertically are used to connect the driving device to close and separate the molds, and the closed upper mold 1 and the lower mold 2 enclose to form an injection cavity; The parting surface of the lower mold 2 is provided with an embedded hole 21, and an axially vertical and top-closed nut 5 is provided in the embedded hole 21. The nut 5 is used to integrally connect the plastic part 7 formed by solidifying the SMC material injected into the injection molding cavity. The inner bottom wall of the embedded hole 21 is provided with an axially vertical sliding hole 211. The sliding hole 211 is provided with a sleeve 3 that slides vertically and is sealed with its circumferential inner wall. The lower mold 2 is also fixed with a core rod 4 extending vertically upward. The bottom surface of the nut 5 is sealed with the inner bottom wall of the embedded hole 21, the top surface of the sleeve 3 and the core rod 4.

[0021] In this embodiment, the upper mold 1 is downward and horizontally arranged, the lower mold 2 is upward and horizontally arranged, and the driving device is a lifting device such as a hydraulic cylinder. When in use, the lower mold 2 is fixed in position, and the upper mold 1 is controlled by the driving device of the lifting device to move up and down just above the lower mold 2. In the mold separation state, there is a certain interval between the upper mold 1 and the lower mold 2, which is convenient for taking out the molded product or laying the sheet. In the mold closing state, the parting surface of the upper mold 1 is attached to the parting surface of the lower mold 2 to enclose and form an injection cavity. The SMC material between the two is solidified by the molding process to form a Figure 7 and Fig. 9 The plastic part 7 is shown, and the plastic part 7 can be integrally connected with the nut 5 pre-installed in the embedded hole 21 of the lower mold 2 to form an SMC all-plastic bumper. Then the lifting device drives the upper mold 1 to move upward and separate from the lower mold 2, that is, after the mold is separated, it moves upward through the sleeve 3 to act on the nut 5, thereby driving the nut 5 and the plastic part 7 to move upward, making it convenient to take out the product.

[0022] The lower mold 2 includes a horizontal base, a mold core fixedly arranged directly above the base by support legs, and a slide plate sliding between the base and the mold core in a vertical direction. The slide plate is fixedly connected to the bottom end of the core rod 4, and the bottom end of the sleeve is fixedly connected to the base and extends upward through the slide plate to be fixedly connected to the mold core.

[0023] Different from the prior art, before production, after the nut 5 is placed in the embedded hole 21, the bottom surface of the nut 5 is always in sealing contact with the inner bottom wall of the embedded hole 21. At the same time, the bottom surface of the nut 5 is also in sealing contact with the top surface of the sleeve 3 and the top surface of the core rod 4. Therefore, the sealing contact area of ​​the nut 5 is increased, thereby reducing the fluidity of the SMC material on the bottom surface of the nut 5 during the molding process. Since the top end of the nut 5 is closed, the SMC material can be prevented from entering the interior of the nut 5 through the bottom surface of the nut 5 to solidify and form. In this way, it is ensured that the SMC material will not adhere to the inner wall of the nut 5 during the molding process, thereby facilitating the subsequent assembly of the SMC all-plastic bumper.

[0024] A further improvement is that the core rod 4 includes a thick rod 41 sealingly fitted with the circumferential inner wall of the sleeve 3 and a thin rod 42 coaxially fixed to the top of the thick rod 41 and extending to the inside of the nut 5, and the top surface of the thick rod 41 is sealingly fitted with the nut 5.

[0025] The inner diameter of the nut 5 is between the thick rod 41 and the thin rod 42, the thin rod 42 extends into the nut 5, and the thick rod 41 is sealed and fitted with the bottom surface of the nut 5, thereby enhancing the sealing performance, so that there is a sufficiently large fitting protection area to prevent the SMC material from entering the nut 5 during the molding process. After the molding is completed, the sleeve 3 is pushed upward, and then the plastic part 7 is driven to separate from the parting surface of the lower mold 2 by pushing the nut 5, so as to facilitate the removal of the bumper product.

[0026] A further improvement is that an outer flange 51 is provided on the bottom surface of the circumferential outer edge of the nut 5 .

[0027] By providing the outer flange 51, the bottom surface area of ​​the nut 5 is increased, thereby increasing the contact area between the nut 5 and the inner bottom wall of the embedded hole 21 of the lower mold 2, further strengthening the sealing between the nut 5 and the lower mold 2 during the production process, thereby further preventing the SMC material from entering the inner wall of the nut 5 through the bottom surface of the nut 5 and adhering to the internal thread of the nut 5 during molding, ensuring the cleanliness of the inside of the nut 5 during the molding production process, thereby facilitating the assembly of the bumper and environmental parts produced later.

[0028] A further improvement is that a protrusion and / or a groove 52 is provided on the circumferential outer edge between the two ends of the nut 5 .

[0029] With the above design, by providing protrusions or grooves 52 on the circumferential outer edges of both ends of the nut 5, the plastic part 7 formed after the SMC is solidified can be in close contact with the protrusions and grooves 52 during the injection molding process. Specifically, a groove 52 is provided on the circumferential outer edge of the middle part of the nut 5, and the groove 52 is an annular groove. With this design, during molding, part of the SMC material can be filled into the groove 52, so that the molded plastic part 7 can form an undercut structure in the groove 52 of the nut 5, which can ensure that when the nut 5 is wrapped with the SMC material, when the nut 5 position part of the bumper product is subjected to an outward pulling force perpendicular to the mounting surface, the undercut structure at the groove 52 can effectively resist the pulling force, thereby preventing the nut 5 from being pulled out of the plastic part 7 and separating from the plastic part 7.

[0030] Second embodiment

[0031] like Figure 10-11 As shown, the production mold of the heavy truck all-plastic bumper of the second embodiment of the present invention is based on the first embodiment, with the difference that matching protrusions and depressions are provided between the fitting surfaces of the nut 5 and the embedded hole 21, the sleeve 3 and the thick rod 41.

[0032] By setting matching protrusions and depressions between the bottom surface of the nut 5 and the inner bottom wall of the embedded hole 21, the top of the sleeve 3 and the top of the thick rod 41, the sealing contact area is further increased, thereby increasing the resistance of the SMC material entering the inside of the nut 5 through the bottom surface of the nut 5 during molding, preventing the SMC material from adhering to the inner wall of the nut 5 and solidifying and forming, causing difficulties in assembling the subsequent bumper product and the heavy truck frame. In addition, through the matching protrusions and depressions, the horizontal positioning of the nut 5 can be achieved to prevent the nut 5 from being subjected to pressure from other aspects during the molding process, causing its horizontal position to move, affecting the molding position of the nut 5 on the plastic part 7. Therefore, by positioning the nut 5 with the protrusions and depressions, the molding position of the plastic part 7 obtained by the nut 5 after the final SMC material is solidified can be accurately controlled, thereby ensuring the quality of the heavy truck all-plastic bumper and facilitating the subsequent precise assembly.

[0033] Specifically, the protrusion is a protruding ring 31 formed on at least one of the inner bottom wall of the embedded hole 21, the top surface of the sleeve 3, and the top surface of the thick rod 41, and the recess is a ring groove 53 formed on the bottom surface of the nut 5.

[0034] With this design, the annular groove 53 is arranged on the bottom surface of the nut 5, so as to avoid the thickness of the bottom of the nut 5 being too large, which would cause the need to occupy extra space during assembly. Specifically, the annular groove 53 is a circular annular groove 53, and there are three of them, and the coaxial centerline is located on the bottom surface of the nut 5, and the convex part is three coaxial convex rings 31, which are respectively located on the inner bottom wall of the embedded hole 21, the top surface of the sleeve 3, and the top surface of the thick rod 41, and the diameters gradually decrease.

[0035] The three mutually matched annular grooves 53 and convex rings 31 mentioned above increase the precision of the lower mold 2 and the nut 5. When the SMC is injected, the amount of SMC material flowing into the nut 5 can be effectively reduced. The reasons are as follows: first, the three mutually matched annular grooves 53 and convex rings 31 mean that the bottom surface area of ​​the nut 5 is increased, and the gap on the bottom surface is extremely small during the injection molding process. In this way, the channel through which the SMC material can enter the inside of the nut 5 is greatly restricted, and the resistance through the bottom surface of the nut 5 is also greatly increased. Even under the injection molding pressure, it is difficult for the SMC material to find a gap large enough to enter inside the nut 5; secondly, through the three mutually cooperating annular grooves 53 and the convex ring 31, a sealing effect can be formed. When the mold is closed, the convex ring 31 fits tightly against the inner wall of the recess to form an effect similar to a sealing gasket, thereby preventing the SMC material from entering the inside of the nut 5 from the bottom of the nut 5; finally, the above structure can ensure that the position of the nut 5 in the embedded hole 21 is accurate and stable, preventing the nut 5 from being displaced or shaken due to the impact of material flow during the injection molding process, thereby avoiding the additional gap caused by the change in the position of the nut 5, and further preventing the possibility of the SMC material entering the inside of the nut 5.

[0036] Third embodiment

[0037] like Fig.12 As shown, the production mold of the heavy truck all-plastic bumper of the third embodiment of the present invention is based on the second embodiment, and the difference is that the nut 5 is magnetically connected to at least one of the lower mold 2, the core rod 4, and the sleeve 3.

[0038] Specifically, the nut 5 in this embodiment is a carbon steel nut 5 or the main production material is ferritic stainless steel or martensitic stainless steel to ensure that the nut 5 can be affected by the surrounding magnetic field.

[0039] An annular cavity is provided on the lower mold 2, which is adjacent to the bottom wall of the embedded hole 21 of the lower mold 2. The annular cavity is coaxial with the sliding hole 211, and the annular cavity is fixedly filled with a magnet 22. When the nut 5 is placed in the embedded hole 21, the nut 5 is affected by the magnetic field around the magnet 22, so that the nut 5 is magnetically fixed in the embedded hole 21.

[0040] After adopting the above design, by fixing the magnet 22 inside the lower mold 2, the magnet 22 is used to absorb the nut 5, so that the bottom surface of the nut 5 is tightly fitted on the bottom wall of the embedded hole 21, the pressure and sealing between the two are increased, the two are more closely matched, and the gap between the two is reduced or even eliminated, so that the SMC material is difficult to find a channel to enter the inside of the nut 5 during the injection molding process, thereby playing a blocking role for the SMC material; not only that, during the compression molding process, the pressure in the mold and the flow of the SMC material may cause the nut 5 to produce a small displacement, and the adsorption force of the magnet 22 can make the nut 5 more stably remain in the embedded hole 21, avoiding the generation of new gaps due to the displacement of the nut 5, not only preventing the SMC material from having the opportunity to flow in, but also locating the position of the nut 5, ensuring the connection position of the nut 5 and the plastic part 7 obtained by curing the SMC material in the final product, improving the product precision, and facilitating the later assembly.

[0041] Fourth embodiment

[0042] like Figure 13-Figure 15 As shown, the production mold of the heavy-duty truck all-plastic bumper of the fourth embodiment of the present invention is based on the third embodiment, with the difference that there is a gap between the core rod 4 and the inner wall of the nut 5, and a negative pressure channel 43 is provided on the core rod 4, one end of the negative pressure channel 43 is provided on the outer surface of the thin rod 42, and the other end is used to connect the negative pressure pump 6.

[0043] In the above structure, the thick rod 41 and the thin rod 42 of the core rod 4 are enclosed with the inner wall of the nut 5 to form an adsorption chamber, one end of the negative pressure channel 43 is connected to the adsorption chamber, and the other end is connected to the negative pressure pump 6, so that during molding, the negative pressure pump 6 is started, and the air inside the nut 5, that is, in the negative pressure chamber, is extracted through the negative pressure channel 43, so that there is an air pressure gap in the negative pressure chamber, and then the nut 5 is tightly fitted on the inner bottom wall of the embedded hole 21, thereby enhancing the sealing performance and preventing the SMC material from entering the nut 5 and solidifying during the molding process, thereby affecting the later assembly performance. At the same time, the negative pressure is used to make the nut 5 firmly adsorbed on the inner wall of the embedded hole 21, thereby preventing position displacement and ensuring the later assembly accuracy, thereby improving the quality of the SMC all-plastic bumper products produced by the mold.

[0044] A further improvement is that the top of the negative pressure channel 43 is arranged at the top of the thin rod 42 , and the top of the thin rod 42 is sealed and connected to the inner top wall of the nut 5 through a sealing ring 45 .

[0045] After adopting the above design, it is avoided that a certain negative pressure environment is formed inside the nut 5, which will attract a small amount of SMC material through the bottom of the nut 5 to enter and adhere to the inner wall of the nut 5, and the top surface of the thin rod 42 is sealed with the inner top wall of the nut 5, so that the internal space of the nut 5 can be divided into two parts, one part of which is connected with the negative pressure channel 43, and the internal air can be conveniently extracted by starting the negative pressure pump 6 to form a negative pressure environment, so as to ensure that the nut 5 can be firmly adsorbed on the inner bottom wall of the embedded hole 21 to prevent deviation and ensure the molding accuracy, while the internal air pressure of the other part is relatively large. The cavity wall of this part includes the threaded inner wall of the nut 5, which can effectively block the SMC material from entering the inner wall of the nut 5, avoiding the low air pressure in this part and attracting SMC to flow in.

[0046] A further improvement is that a barometer 61 is provided at the input end of the negative pressure pump 6, and the barometer 61 is used to detect the air pressure in the negative pressure channel 43. During the production process, when the air pressure is relatively high, the negative pressure pump 6 is started to extract the air at the top of the nut 5 to ensure that the nut 5 is firmly adsorbed on the inner bottom wall of the embedded hole 21, thereby increasing the pressure between the nut 5 and the inner bottom wall of the embedded hole 21, thereby strengthening the sealing of the two and preventing the SMC material from entering the inside of the nut 5 during injection molding.

[0047] Specifically, the negative pressure channel 43 is a negative pressure through hole on the core rod 4 coaxially arranged, there is a gap between the top of the negative pressure through hole and the inner top wall of the nut 5, there is a gap between the circumferential outer edge of the thin rod 42 and the circumferential inner wall of the nut 5, the sealing ring 45 is coaxially integrally formed at the top of the thin rod 42 and is located on the outside of the negative pressure channel 43, and an elastic rubber ring 451 is arranged on the top of the sealing ring 45, and the rubber ring 451 is clamped between the sealing ring 45 and the inner top wall of the nut 5 to ensure the sealing between the top of the core rod 4 and the inner top wall of the nut 5.

[0048] The air inlet end of the negative pressure pump 6 is fixedly connected to a hollow air inlet shell 62, which is connected to the bottom end of the negative pressure channel 43. The air inlet shell 62 is connected to a barometer 61 to detect the air pressure inside the sealing ring 45 and the negative pressure channel 43 through the internal air pressure of the air inlet shell 62.

[0049] Fifth embodiment

[0050] like Figure 16-Figure 18 As shown, the production mold of the heavy-duty truck all-plastic bumper of the fifth embodiment of the present invention is based on the fourth embodiment, with the difference that a boost channel 44 is provided on the core rod 4, the negative pressure channel 43 is connected with the boost channel 44 through the negative pressure pump 6, the core rod 4 and the nut 5 are enclosed to form a boost chamber located outside the thin rod 42, the boost chamber is connected with the boost channel 44, and the output end of the negative pressure pump 6 is connected with a barometer 61.

[0051] After adopting the above structure, during the injection molding process, the negative pressure pump 6 is started to extract the air in the negative pressure channel 43 and the sealing ring 45, reducing the air pressure inside the sealing ring 45, so that the nut 5 is firmly adsorbed on the inner bottom wall of the embedded hole 21. At the same time, the air extracted by the negative pressure pump 6 is delivered to the boosting channel 44 and the boosting cavity, so that the air pressure in the boosting cavity is increased. In this way, during the molding process, the high air pressure can resist the SMC material passing through the bottom surface of the nut 5 and prevent the SMC material from flowing into the nut 5 to solidify and form. In this way, the molding quality of the plastic part 7 is guaranteed. The air pressure in the boosting cavity can be detected by the barometer 61. When the air pressure drops, the negative pressure pump 6 can replenish gas into the boosting cavity in time to maintain high air pressure.

[0052] Therefore, during SMC injection molding, although the pressure in the mold will cause the SMC material to flow into the nut 5, due to the operation of the negative pressure pump 6, a high air pressure is formed in the pressurized cavity inside the nut 5, which counteracts the pressure in the mold, so that the inward pressure on the SMC material and the outward pressure of the air offset each other, thereby preventing the material from entering the nut 5. After the high-pressure air is injected into the nut 5, an airflow is formed at the edge of the bottom surface of the inner hole of the nut 5. This airflow plays a role in blocking the SMC material, so that the SMC material is solidified in the nut 5 to form a plastic part 7 integrally connected to the nut 5.

[0053] To be more specific, the boost channel 44 includes a first boost hole coaxially opened on the top surface of the thick rod 41 and located on the outside of the thin rod 42, and a second boost hole opened on the side wall of the thick rod 41 and connected to the first boost hole. The inner diameter of the outside of the first boost hole is consistent with the inner diameter of the nut 5. The output end of the negative pressure pump 6 is connected to an air outlet shell 63, and a barometer 61 is provided on the air outlet shell 63. The air outlet shell 63 is connected to an end of the second boost hole away from the first boost hole.

[0054] The air inlet shell 62 and the air outlet shell 63 are also fixedly connected with an air supply inlet pipe 64 and a residual air outlet pipe 65 respectively. The air supply inlet pipe 64 is provided with an air supply valve 641, and the residual air outlet pipe 65 is provided with a residual air valve 651. The end of the air supply inlet pipe 64 away from the air inlet shell 62 and the end of the residual air outlet pipe 65 away from the air outlet shell 63 are both connected to the outside.

[0055] Under normal use, the air supply valve 641 and the residual air valve 651 are both in a closed state.

[0056] When the air pressure in the air inlet shell 62 meets the negative pressure requirement, and the air pressure in the air outlet shell 63 is too low, the air supply valve 641 is opened, the residual air valve 651 is closed, and the negative pressure pump 6 extracts external air and delivers it to the boosting chamber, so that the pressure in the boosting chamber and the air outlet shell 63 continues to increase until the air pressure requirement of the air outlet shell 63 is met, and the air supply valve 641 and the residual air valve 651 are both closed; When the air pressure in the air inlet shell 62 meets the negative pressure requirement, and the air pressure in the air outlet shell 63 is too high, the air supply valve 641 is closed, and the residual air valve 651 is opened, so that the excess gas is discharged from the residual air outlet pipe 65, until the use requirement is met, and the air supply valve 641 and the residual air valve 651 are both closed; When the air pressure in the air outlet shell 63 meets the requirement and the air pressure in the air inlet shell 62 is too high, the air supply valve 641 is closed and the residual air valve 651 is opened. The negative pressure pump 6 extracts the air in the air inlet shell 62 and discharges it through the residual air outlet pipe 65. When the air pressure inside the air inlet shell 62 and the air outlet shell 63 meets the requirement, the air supply valve 641 and the residual air valve 651 are closed. When the air pressure in the air outlet shell 63 meets the requirement and the air pressure in the air inlet shell 62 is too high, the air supply valve 641 is opened and the residual air valve 651 is closed, so that the external air can enter the air inlet shell 62 through the air supply inlet pipe 64. After the air pressure inside the air inlet shell 62 and the air outlet shell 63 meets the requirement, the air supply valve 641 and the residual air valve 651 are closed. In this way, the above method can be used to accurately control the air pressure in the boost channel 44 and the negative pressure channel 43. By reducing the air pressure in the boost channel 44, the nut 5 is tightly attached to the inner bottom wall of the embedded hole 21, thereby enhancing the sealing performance and increasing the air pressure in the boost channel 44. The high pressure is used to prevent the SMC material from entering the nut 5 during the injection molding process, thereby ensuring the molding accuracy of the final product and facilitating subsequent assembly.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A production mold for a heavy truck all-plastic bumper, characterized in that: include: The upper mold and the lower mold facing each other vertically are used to connect the driving device to close and separate the molds, and the closed upper mold and the lower mold enclose to form an injection cavity; The parting surface of the lower mold is provided with an embedded hole, and an axially vertical nut with a closed top is provided in the embedded hole. The nut is used to integrally connect the plastic part formed by solidifying the SMC material injected into the injection cavity. The inner bottom wall of the embedded hole is provided with an axially vertical sliding hole, and a sleeve is provided in the sliding hole, which slides vertically and is sealed with its circumferential inner wall. The lower mold is also fixed with a core rod extending vertically upward, and the bottom surface of the nut is sealed with the inner bottom wall of the embedded hole, the top surface of the sleeve and the core rod.

2. The production mold for the heavy truck all-plastic bumper according to claim 1 is characterized by: The core rod comprises a thick rod which is sealed with the circumferential inner wall of the sleeve and a thin rod which is coaxially fixed to the top of the thick rod and extends to the inside of the nut. The top surface of the thick rod is sealed with the nut.

3. The production mold for the heavy truck all-plastic bumper according to claim 1 is characterized by: The bottom surface of the circumferential outer edge of the nut is provided with an outer flange.

4. The production mold for the heavy truck all-plastic bumper according to claim 1 is characterized by: A circumferential outer edge between the two ends of the nut is provided with a protrusion and / or a groove.

5. The production mold for the heavy truck all-plastic bumper according to claim 3 is characterized by: Matching convex parts and concave parts are arranged between the fitting surfaces of the nut and the embedded hole, the sleeve and the thick rod.

6. The production mold for the heavy truck all-plastic bumper according to claim 5 is characterized by: The protrusion is a protruding ring formed on at least one of the bottom wall of the embedded hole, the sleeve, and the top surface of the thick rod, and the recess is a ring groove formed on the bottom surface of the nut.

7. The production mold for the heavy truck all-plastic bumper according to claim 1 is characterized by: The nut is magnetically connected to at least one of the lower die, the core rod, and the sleeve.

8. The production mold for the heavy truck all-plastic bumper according to claim 1 is characterized by: There is a gap between the core rod and the inner wall of the nut. A negative pressure channel is arranged on the core rod. One end of the negative pressure channel is arranged on the outer surface of the thin rod, and the other end is used to connect to a negative pressure pump.

9. The production mold for the heavy truck all-plastic bumper according to claim 8, characterized in that: The top of the negative pressure channel is arranged at the top of the thin rod, and the top of the thin rod is sealed and connected to the inner top wall of the nut through a sealing ring. A boosting channel is arranged on the core rod, and the negative pressure channel is connected to the boosting channel through the negative pressure pump. The core rod and the nut enclose a boosting chamber located outside the thin rod, and the boosting chamber is connected to the boosting channel.

10. The production mold for the heavy truck all-plastic bumper according to claim 9, characterized in that: Both ends of the negative pressure pump are connected with a barometer.

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