A screw plugging foam molding process

Abstract

This invention relates to the field of plugging technology, specifically to a plugging foaming and molding process that solves the following problems: reducing infrastructure investment, eliminating safety hazards, improving production efficiency, and expanding the precision processing pathways for expandable polystyrene. The entire process is simplified as follows: pre-expansion of beads, heating in a vulcanizing machine, upper mold temperature 130℃, lower mold temperature 120℃, weighing and quantitatively loading into the mold, inverting the mold and holding it at a constant temperature for 3 minutes, placing the mold upright and holding it at a constant temperature for 3 minutes, immersing in water for cooling, and removing the plugging beads for dehumidification and drying. Using vulcanizing machine molding instead of steam hot pressing ensures stability during the preparation process and enables precision parts processing. This plugging processing technology eliminates the need for workshop investment, reduces infrastructure investment, eliminates safety hazards, improves production efficiency, expands the precision processing pathways for expandable polystyrene, and most importantly, ensures the production of high-precision foamed parts, thus having a promotional effect on the processing of precision parts from expandable polystyrene.

Description

Technical Field

[0001] This invention relates to the field of screw plugging technology, specifically to a screw plugging foaming and molding process. Background Technology

[0002] The raw material for screw plugging is expandable polystyrene beads. The original process used high-pressure water boiling, but this process has the following problems:

[0003] 1. High infrastructure costs. The processing equipment used for high-pressure boiling is a pressure cooker, which generates a large amount of water vapor during the heating and depressurization process. The water vapor spreads everywhere through air circulation, which can easily corrode surrounding equipment and products. Dehumidification equipment is required, which increases manufacturing costs.

[0004] 2. There are certain safety hazards. Pressure cookers generate high temperatures and pressures during use. If the pressure cooker is not operated correctly or other abnormal problems occur (such as a blocked pressure relief valve, or the use of an inferior pressure cooker), it is easy to cause the pressure cooker to explode or splash, which can be harmful to the human body and even endanger life. Therefore, it is necessary to increase safety protection measures.

[0005] 3. Low production efficiency. The foaming of the plug is formed in a pressure cooker, and each time it is opened, it needs to be reheated and depressurized. The entire auxiliary process is time-consuming, resulting in low production efficiency.

[0006] The current process for foaming plugs is as follows: pre-expanding beads → weighing → loading into a mold → placing the mold in a pressure cooker → pressurizing to the boiling point and holding for 6 minutes → depressurizing → removing the mold → immersing in water for cooling → removing the plugs and dehumidifying and drying. The biggest drawback of this process is the high air humidity, the safety hazards during pressurization and depressurization, and the inconvenience of adding protective devices, resulting in low production efficiency.

[0007] Currently, expandable polystyrene beads are commonly produced using hot steam foaming molding. The principle involves placing cured polystyrene beads into the mold cavity. Within a short time, hot steam is introduced directly into the cavity through vents in the mold wall, causing the beads to soften and expand. Due to the confinement of the mold frame, the expanded beads are forced to fill the entire gap and adhere together. After cooling and setting, they are removed from the mold, resulting in the foamed plastic product. Because expandable polystyrene has a very low density of only 0.018 g / cm³, this process is suitable for parts with loose dimensional tolerances, primarily for packaging and building materials. It cannot meet the requirements for parts with strict tolerances. By improving the processing technology, expandable polystyrene can be processed into precision parts. Summary of the Invention

[0008] Based on the above description, the present invention provides a plugging foam molding process to solve the following problems: reduce infrastructure investment, eliminate safety hazards, improve production efficiency, and expand the precision processing methods of expandable polystyrene.

[0009] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0010] A screw plugging foam molding process, the screw plugging foam molding process comprising:

[0011] Step S1: Spread expandable polystyrene granules in an iron tray and place the iron tray in an oven for pre-foaming;

[0012] Step S2: Heat the vulcanizing machine, control the temperature of the upper mold to 130±10℃, and the temperature of the lower mold to be 10℃ lower than that of the upper mold;

[0013] Step S3: Weigh a fixed amount of pre-foamed granules, pour them into the mold, and lock the mold.

[0014] Step S4: Adjust the mold so that the small end of the plug is facing down and the large end is facing up, and place it into the vulcanizing machine. The vulcanizing machine closes the mold and heats and keeps the mold warm for 3 minutes.

[0015] Step S5: Turn the mold over so that the small end of the plug is facing up and the large end is facing down, and then put it into the vulcanizing machine. After the vulcanizing machine closes the mold, heat and keep it warm for 3 minutes.

[0016] Step S6: Remove the mold and let it cool, then remove the plug and dry it.

[0017] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0018] This solution improves the processing technology of expandable polystyrene by using a vulcanizing machine for molding instead of steam hot pressing, which ensures stability during the preparation process, enables precision parts processing, and reduces input costs.

[0019] Based on the above technical solution, the present invention can be further improved as follows.

[0020] Furthermore, in step S1, the oven is heated at 40°C for 3 hours, and then heated to 70°C and held for 10 minutes.

[0021] Furthermore, in step S3, the mold is locked and vibrated to make the material particles fill the cavity evenly.

[0022] Furthermore, after the mold vibrates the material particles, the mold is fitted with an insulation sleeve on the outside before being sent into the vulcanizing machine.

[0023] Furthermore, the mold is a four-cavity mold, and the mold is edge-locking.

[0024] Furthermore, in step S3, the material particles are weighed using an electronic scale with a sensitivity of 0.01g.

[0025] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0026] The plugging process of this invention does not require workshop investment, reduces infrastructure investment, eliminates safety hazards, improves production efficiency, expands the precision processing methods of expandable polystyrene, and most importantly, can ensure the production of high-precision foamed parts. It has a promotional effect in the processing of precision parts from expandable polystyrene. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view of the plug described in this invention. Detailed Implementation

[0028] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] It is understood that spatial relation terms such as “below,” “under,” “below,” “below,” “above,” “above,” etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “below,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0031] like Figure 1 The image shown is a cross-sectional view of the plug screw. The end with the smaller diameter is called the small end, and the end with the larger diameter is called the large end.

[0032] This invention discloses a foaming molding process for plugging screws. It utilizes a vulcanizing machine to foam expandable polystyrene, and the stable pressure and temperature of the vulcanizing machine enable plugging processing, resulting in dimensional stability that meets product requirements. The specific processing flow is as follows:

[0033] Step S1: Place expandable polystyrene beads in an iron tray, spread them evenly in the tray, and spread them to a height of no more than 2 cm. Then place them in an oven for pre-foaming at 40℃ for 3 hours. Then adjust the temperature to 70℃ and continue for 10 minutes.

[0034] Step S2: While waiting for the material particles to pre-foam, heat the vulcanizing machine, control the temperature of the upper mold plate to be 130±10℃, and the temperature of the lower mold plate to be 10℃ lower than that of the upper mold plate.

[0035] Step S3: During the heating of the vulcanizing machine, accurately weigh the required pre-foamed granules using an electronic scale with a sensitivity of 0.01g.

[0036] Step S4: Pour the weighed granules into the mold, lock the mold, and then put the mold into the insulation jacket.

[0037] Step S5: Invert the mold so that the small end is down and the large end is up, then gently shake it to make the granules fill the mold cavity evenly. Place the mold wrapped in the heat insulation sleeve onto the vulcanizing machine plate, turn on the power, close the upper and lower mold plates, and heat and keep warm for 3 minutes according to the preset temperature in step S2.

[0038] Step S6: Then adjust the mold so that the large end is down and the small end is up, and continue heating and keeping it warm for 3 minutes.

[0039] Step S7: Remove the mold and immerse it in water to cool.

[0040] Step S8: Remove the plug and then dry it in an oven to remove moisture.

[0041] The mold consists of an upper mold body and a lower mold body, and the internal mold cavity is a four-cavity mold. The mold has symmetrical wrench locking devices on both sides.

[0042] Due to the structure of the plug, the temperature of the upper mold plate inside the vulcanizing machine varies, which greatly affects the density and uniformity of the small-particle foam. This, in turn, affects the internal strength of the finished plug. The data obtained after conducting production experiments at different temperatures are as follows:

[0043] The table below compares the pressure data of the plug opening from three experiments with the upper template temperature set to 110, 120, 130 and 140℃ respectively. The unit of opening pressure is megapascals.

[0044]

[0045] The opening pressure of the finished plug must meet 3-5 MPa. Based on the above data, the preferred data is as follows: In step S2, the upper mold temperature is preferably 130℃, and this temperature value can be extended to 130±10℃. Considering the specific structure of the plug, a corresponding mold is designed. The component structure of the mold determines the different distances between the mold plate and the mold cavity inside the vulcanizing machine. The distance between the lower mold plate and the mold cavity is shorter. After the mold of this scheme was finalized, after multiple experiments, it was found that a temperature difference of 10 degrees Celsius between the upper mold plate and the lower mold plate can ensure that the plug is heated evenly from top to bottom.

[0046] The most crucial steps described above are S2, S4, S5, and S6:

[0047] The different temperature control of the upper and lower mold plates in S2 is due to the structure of the plug screw, which makes the distance between the lower mold plate and the lower mold body shorter than that of the upper mold plate, thus heating up faster. The temperature difference is to better ensure uniform heating of the mold. S4 is mainly because the mold has four cavities, and the edge locking helps to ensure balanced force on the mold during operation, preventing the granules from tilting to one side or overflowing. In addition, the heat insulation sleeve is added to prevent heat loss and ensure that the granules can fully foam. S5 is because the lower mold plate is directly attached to the mold and heats up the fastest, and the heat conduction is fast. Since the small end is thick, placing the small end on the lower mold plate can achieve uniform foaming the fastest. S6 is to ensure that both the upper and lower surfaces of the mold are fully heated and uniform, ensuring that the plug screw fully foams in the mold cavity and achieves uniform density.

[0048] This solution uses expandable polystyrene beads for foaming. Existing technologies commonly employ hot steam foaming, which involves placing cured polystyrene beads into the mold cavity. Within a short time, hot steam is introduced directly into the cavity through vents in the mold wall, causing the beads to soften and expand. Due to the mold frame's constraint, the expanded beads are forced to fill the gaps and adhere together. After cooling and setting, the beads are removed from the mold, yielding the foamed plastic product. However, steam foaming temperatures are difficult to reach 100℃, typically fluctuating between 95-99℃. Therefore, high-pressure equipment is required to maintain the temperature, necessitating depressurization and reheating after each use, which is time-consuming and labor-intensive.

[0049] In terms of efficiency, the process of this invention allows one person to handle one mold with four cavities and produce 320 pieces in 8 hours; the old process requires one person to handle one pressure cooker with two single molds and produce about 60-70 pieces in 8 hours. This is mainly because the process of adding water and depressurizing in the middle of the pressure cooker takes up a lot of time and cannot be improved.

[0050] In terms of equipment costs, the new foaming process utilizes our existing vulcanizing machines without the need for new equipment investment. Only the mold cost needs to be calculated, which is around 1,000 yuan. For factories without such equipment, the cost of equipping a single vulcanizing machine is 20,000 to 40,000 yuan. The pressure cooker steam requires a separate workshop and dehumidification and ventilation equipment, as well as a workbench and electric pressure cooker. Excluding the workshop, the cost of a single pressure cooker is approximately 20,000 yuan.

[0051] This solution improves the processing technology of expandable polystyrene by using a vulcanizing machine for molding instead of steam hot pressing, which ensures stability during the preparation process, enables precision parts processing, and reduces input costs.

[0052] The plugging process of this invention does not require workshop investment, reduces infrastructure investment, eliminates safety hazards, improves production efficiency, expands the precision processing methods of expandable polystyrene, and most importantly, can ensure the production of high-precision foamed parts. It has a promotional effect in the processing of precision parts from expandable polystyrene.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A foaming molding process for plugging screws, characterized in that, The plugging screw foaming molding process includes: Step S1: Spread expandable polystyrene granules in an iron tray, and place the iron tray in an oven for pre-foaming; the oven is heated at 40℃ for 3 hours, and then heated to 70℃ and kept at that temperature for 10 minutes. Step S2: Heat the vulcanizing machine, control the temperature of the upper mold to 130±10℃, and the temperature of the lower mold to be 10℃ lower than that of the upper mold; Step S3: Weigh a fixed amount of pre-foamed material granules, pour them into the mold and lock the mold; lock the mold and vibrate it to make the material granules fill the cavity evenly; after the mold vibrates the material granules, the mold is covered with an insulation sleeve and then sent into the vulcanizing machine; Step S4: Adjust the mold so that the small end of the plug is facing down and the large end is facing up, and place it into the vulcanizing machine. The vulcanizing machine closes the mold and heats and keeps the mold warm for 3 minutes. Step S5: Turn the mold over so that the small end of the plug is facing up and the large end is facing down, and then put it into the vulcanizing machine. After the vulcanizing machine closes the mold, heat and keep it warm for 3 minutes. Step S6: Remove the mold and let it cool, then remove the plug and dry it.

2. The plugging screw foaming molding process according to claim 1, characterized in that, The mold is a four-cavity mold, and the mold is edge-locking.

3. The plugging screw foaming molding process according to claim 1, characterized in that, In step S3, the material particles are weighed using an electronic scale with a sensitivity of 0.01g.

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