Micro-foaming injection molding process and micro-foaming injection molding floor sweeping robot shell

Abstract

The invention discloses a micro-foaming injection molding process applied to a sweeping robot and a micro-foaming injection molding sweeping robot shell, the micro-foaming injection molding process comprises the following steps: B1, providing molds including a first mold and a second mold, the first mold and the second mold being used for combining to form a closed cavity, a through liquid injection channel is formed in the first mold and / or the second mold, and the liquid injection channel is communicated with the cavity; b2, combining the first mold and the second mold to form a cavity with the volume of V1; b3, a micro-foaming injection molding machine, a foaming agent and a polymer are provided, the foaming agent is evenly mixed into the molten polymer through the micro-foaming injection molding machine, and an injection molding melt is obtained; b4, the injection molding melt is injected into the cavity through the liquid injection channel; b5, standing to foam the injection molding melt; b6, the mold is adjusted before the injection molding melt is thoroughly cured, so that the size of the cavity is reduced to V2, and V1 is larger than V2; and B7, the shape of the mold is kept till the injection molding melt is thoroughly cured.

Description

Technical Field

[0001] The present invention relates to the field of injection molding processing, and particularly to a microcellular injection molding process applied to a floor cleaning robot and a microcellular injection molded housing of a floor cleaning robot. Background Art

[0002] Injection molding is an industrial manufacturing process that injects molten polymers into a closed mold cavity under high temperature and pressure and forms a preset shape after cooling and solidifying. Its technical principle is based on the fluidity of thermoplastic or thermosetting materials in the molten state. By precisely controlling the temperature, pressure, and mold structure, products with stable dimensions and complex structures can be efficiently produced. This technology is widely used in fields such as consumer electronics, automotive parts, and the outer shells of household appliances, and has significant advantages such as high production efficiency, excellent repeat accuracy, and wide material adaptability. However, due to the high material density of traditional injection molded products, there are inherent defects such as large weight, concentrated internal stress, and high shrinkage deformation rate. Especially in application scenarios that require a balance between lightweight and mechanical properties, performance breakthroughs need to be achieved through process innovation.

[0003] In order to improve the above defects, the microcellular injection molding technology emerged. By uniformly dispersing physical or chemical blowing agents in the polymer melt and using rapid pressure release or thermal decomposition to form a micron-level closed-cell structure, the material density can be reduced, the impact resistance can be improved, and the internal stress can be relieved. Such a microporous structure can disperse the stress concentration under external loads and effectively inhibit crack propagation, especially suitable for the lightweight design of thin-walled or complex geometric components.

[0004] However, while reducing the density, the microcellular injection molding process inevitably leads to the deterioration of the surface quality of the product, specifically manifested as an increase in surface roughness, a decrease in glossiness, and an increase in micro-porosity caused by the exposure of micropores. In scenarios such as floor cleaning robots that need to frequently contact dust, grease, or humid environments, the surface micropores are prone to becoming channels for pollutant penetration, leading to problems such as accelerated material corrosion, internal dirt accumulation, and difficult sanitation cleaning, severely restricting the application of this technology in high-end products. Summary of the Invention

[0005] An object of the present invention is to provide a microcellular injection molding process applied to a floor cleaning robot and a microcellular injection molded housing of a floor cleaning robot, aiming to solve the technical problem of poor surface quality of products produced by the microcellular injection molding process.

[0006] To achieve the above object, the present invention provides a microcellular injection molding process for a floor cleaning robot. The microcellular injection molding process is applicable to a microcellular injection molding device, which includes a mold assembly and a microcellular injection molding machine. The mold assembly includes a first mold and a second mold. The first mold and the second mold are combined to form a closed cavity with a volume of V1. A through liquid injection channel is formed on the first mold and / or the second mold, and the liquid injection channel is communicated with the cavity. The microcellular injection molding process includes the following steps: B1. Using the microcellular injection molding machine to uniformly mix a foaming agent into a molten polymer to obtain an injection melt; B2. Injecting the injection melt into the cavity through the liquid injection channel; B3. Standing still to make the injection melt foam; B4. Adjusting the mold before the injection melt is completely cured so that the volume of the cavity is reduced to V2, where V1 > V2; B5. Maintaining the shape of the mold until the injection melt is completely cured to form an injection molded part; B6. Taking out the injection molded part from the mold.

[0007] According to an embodiment of the present invention, the outer surface of the first mold is a stretched body, and the second mold is formed with a receiving groove that cooperates with the outer surface of the first mold. The first mold is inserted into the receiving groove so that the first mold and the second mold are combined to form a closed cavity.

[0008] According to an embodiment of the present invention, one side surface of the first mold and / or the second mold close to the cavity is movable.

[0009] According to an embodiment of the present invention, the polymer includes fibers with a weight percentage of 3% to 40%.

[0010] According to an embodiment of the present invention, the fibers are one or more of glass fibers, carbon fibers, aramid fibers, and natural fibers, and / or the length of the fibers is L, where L satisfies the relationship: 80 μm ≤ L ≤ 500 μm.

[0011] According to an embodiment of the present invention, the polymer includes an ultraviolet absorber with a weight percentage of 0.1% to 2% and a light stabilizer with a weight percentage of 0.05% to 1%; or, the polymer includes carbon black with a weight percentage of 1% to 5%.

[0012] According to an embodiment of the present invention, after step B2, it further includes: B21: Adjusting the volume of the cavity to V3 so that the internal pressure of the injection melt is constant throughout step B2, where V1 and V3 satisfy the relationship: V1 ≤ 1% * V3.

[0013] According to an embodiment of the present invention, after step B2, it further includes: B21: Adjusting the volume of the cavity so that the volume of the cavity after the injection melt is input in place is V3; before step B3, it further includes: B31: Adjusting the volume of the cavity to V4, where V4 > V3.

[0014] According to an embodiment of the present invention, the second mold is used to form the appearance surface of the floor sweeping robot, and the first mold is used to form the working surface of the floor sweeping robot. A through liquid injection channel is formed on the first mold, and a through pressure relief channel is formed on the second mold, and the liquid injection channel and the pressure relief channel are respectively communicated with the cavity; step B2 includes: injecting the injection melt into the cavity through the liquid injection channel, and there is an air mass between the injection melt and the second mold, and the air mass is communicated with the pressure relief channel; step B3 includes: completely discharging the air mass through the pressure relief channel, and standing still to make the injection melt foam.

[0015] The present invention also provides a micro-foaming injection molded floor sweeping robot housing, which is produced by using the micro-foaming injection molding process for floor sweeping robots described in any one of the above.

[0016] The beneficial effects of the present invention are as follows: The micro-foaming injection molding process for floor sweeping robots provided by the present invention includes the following steps: B1. Provide a mold, the mold includes a first mold and a second mold, the first mold and the second mold are used to combine to form a closed cavity, and a through liquid injection channel is formed on the first mold and / or the second mold, and the liquid injection channel is communicated with the cavity; B2. Combine the first mold and the second mold to form a cavity with a volume of V1; B3. Provide a micro-foaming injection molding machine, a foaming agent and a polymer, and use the micro-foaming injection molding machine to uniformly mix the foaming agent into the molten polymer to obtain an injection melt; B4. Inject the injection melt into the cavity through the liquid injection channel; B5. Stand still to make the injection melt foam; B6. Adjust the mold before the injection melt is completely cured so that the volume of the cavity is adjusted to V2, V1>V2; B7. Keep the shape of the mold until the injection melt is completely cured.

[0017] The present invention dynamically compresses the volume of the mold cavity after the injection melt foams and before it is completely cured, and utilizes the viscosity characteristics formed by the melt in the foaming stage to realize the differential regulation of the surface layer and the internal structure. When the volume of the cavity suddenly shrinks, the surface melt is extruded by the mold and undergoes densification flow, and the microporous structure is compressed or even closed. However, due to the relatively slow conduction of pressure by the injection melt in the internal region, it maintains its original shape and still retains the closed-cell micro-structure formed by foaming. Thus, a gradient distribution of "dense surface - internal foaming" is formed. Its essence is to synchronously achieve the goals of surface strengthening and lightweighting in a single molding through the coupling of process timing and material rheological behavior.

[0018] Based on the above principle, this process effectively balances the contradiction between microcellular injection molding lightweight and surface quality. The surface densification significantly reduces the risk of pore exposure, enhances the barrier ability against external pollutants such as dust and grease, and at the same time improves the surface hardness and scratch resistance, meeting the stringent requirements of the cleaning and wear resistance of the shell of the sweeping robot; the internal foaming structure realizes weight reduction and stress dispersion through uniformly distributed closed cells, taking into account the overall mechanical properties. In addition, this process does not rely on coatings or secondary processing, and can achieve structural optimization through dynamic cavity adjustment of the mold, reducing production costs while avoiding the problem of limited application scenarios caused by surface defects in traditional microcellular processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0020] Figure 1 is a schematic flow chart of a microcellular injection molding process applied to a sweeping robot provided by an embodiment of the present invention; Figure 2 is a schematic flow chart of a microcellular injection molding process applied to a sweeping robot provided by another embodiment of the present invention; Figure 3 is a schematic flow chart of a microcellular injection molding process applied to a sweeping robot provided by still another embodiment of the present invention.

[0021] Explanation of the reference numerals in the drawings: 1, first mold; 2, second mold; 3, cavity; 4, liquid injection channel; 5, injection melt; 6, pressure relief channel; 7, air mass; 8, microcellular injection molding machine. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] Currently, in order to address the problems brought by the micro pores in the microcellular process, the prior art usually relies on surface coatings or secondary processing to improve the micro pore defects. However, these solutions often lead to an increase in production costs and may offset the lightweight advantages brought by the microcellular technology. Please refer to Figure 1 as shown,Figure 1 It is a schematic flow chart of a micro-foaming injection molding process applied to a floor cleaning robot provided by an embodiment of the present invention. To solve the above technical problems, an embodiment of the present invention discloses a micro-foaming injection molding process applied to a floor cleaning robot. The micro-foaming injection molding process is applicable to a micro-foaming injection molding device. The micro-foaming injection molding device includes a mold assembly and a micro-foaming injection molding machine 8. The mold assembly includes a first mold 1 and a second mold 2. The first mold 1 and the second mold 2 are combined to form a closed cavity 3 with a volume of V1. A through liquid injection channel 4 is formed on the first mold 1 and / or the second mold 2, and the liquid injection channel 4 is communicated with the cavity 3. The micro-foaming injection molding process includes the following steps: B1. Use the micro-foaming injection molding machine 8 to uniformly mix the foaming agent into the molten polymer to obtain an injection molding melt 5; B2. Inject the injection molding melt 5 into the cavity 3 through the liquid injection channel 4; B3. Let it stand still to make the injection molding melt 5 foam; B4. Adjust the mold before the injection molding melt 5 is completely cured, so that the volume of the cavity 3 is reduced to V2, where V1 > V2; B5. Keep the shape of the mold until the injection molding melt 5 is completely cured to form an injection molded part; B6. Take out the injection molded part from the mold.

[0024] In this embodiment, by precisely controlling the timing relationship between the foaming and curing of the injection molding melt 5, the mold cavity 3 is dynamically compressed after the melt foams and before it is completely cured. Utilizing the high viscosity characteristics formed by the rapid cooling of the surface melt and the fluidity difference of the internal melt, the gradient design of the material structure is realized. When the volume of the cavity 3 suddenly decreases, the surface melt is in contact with the mold, and the micropores are squeezed and closed to form a non-porous dense layer; while the compression force received by the internal melt is attenuated by the flow resistance of the injection molding melt 5, and the surface pressure cannot be fully transmitted to the core area, so that the microporous structure formed by the foaming of the internal area is retained. Utilize the relatively high viscosity of the injection molding melt 5 before curing to realize the spatial distribution characteristics of the pressure gradient. Through the process coordination of foaming first and then compressing in a single molding, a "dense shell layer - porous core layer" composite structure is constructed inside the material, realizing lightweight and surface function strengthening simultaneously.

[0025] It should be understood that the complete curing referred to in this application means that the injection molding melt 5 completely loses its fluidity and becomes a solid. Analyzed from the data, when the temperature of the injection molding melt 5 is lower than its softening temperature, it can be regarded as completely cured. It can also be controlled according to the reference curing time and molding hardness provided by the raw material supplier. For example, standing for 100% - 120% of the reference curing time is regarded as completely cured, or the hardness after demolding reaches 90% of the reference molding hardness is regarded as completely cured.

[0026] Compared with the prior art, the microcellular injection molding process provided in this embodiment for a floor cleaning robot breaks through the mutually exclusive problem between lightweight and surface quality in traditional microcellular injection molding. The dense surface layer not only significantly reduces the risk of contamination penetration caused by pore exposure, but also improves surface hardness and scratch resistance, meeting the requirements of the floor cleaning robot's housing for frequent contact with complex environments; while the internal closed-cell structure reduces weight and disperses stress through uniformly distributed micropores, maintaining the impact resistance and dimensional stability of the overall structure. In addition, the process directly realizes structural optimization through dynamic cavity adjustment of the mold, without relying on secondary processing or additional functional layers, which not only simplifies the production process and reduces costs, but also avoids the weakening of mechanical properties and application scenario limitations caused by surface roughness or open pores in the traditional process.

[0027] It should be noted that there are obvious differences between this embodiment and the technical solution in the prior art that controls the filling pressure to make the injection melt 5 not fully foam, specifically: in the incomplete foaming control process of the prior art, the pore size in the whole product is reduced and the density is decreased, and this change exists uniformly in the whole product. While increasing the surface strength, the internal density also increases, significantly weakening the low-density advantage of the microcellular injection molding process. However, the compression in this embodiment is limited to the surface of the product, and a large number of microbubbles still remain inside, which enables the microcellular injection molding process of this embodiment to produce products with a smaller density under the same surface quality requirements.

[0028] It should be understood that the control of the shrinkage cavity area in this embodiment is closely related to the viscosity of the injection melt 5. To a certain extent, the smaller the viscosity of the injection melt 5, the greater the compression on its surface will be transmitted to other parts; while the greater the viscosity of the injection melt 5, the more the compression on its surface will be confined to the product surface layer. That is, the later the timing of step B6, the smaller the influence on the internal pores of the product, but correspondingly, the closer the injection melt 5 is to solidification, the greater the resistance to cavity 3 adjustment, the greater the difficulty of pore closure, and when the solidification progresses to a certain extent, the pressure on the product surface is more likely to be transmitted to the center of the product, resulting in product deterioration. Therefore, the specific volume adjustment ratio, the deformed area of the cavity 3, and the adjustment timing should all be specifically adjusted according to actual situations such as the actual foaming agent, polymer composition, and injection temperature.

[0029] According to an embodiment of the present invention, the outer surface of the first mold 1 is a stretched body, and the second mold 2 is formed with a receiving groove that cooperates with the outer surface of the first mold 1. The first mold 1 is inserted into the receiving groove so that the first mold 1 and the second mold 2 are combined to form a closed cavity 3.

[0030] This embodiment provides a specific implementation of the variable cavity 3. By designing the outer surface of the first mold 1 as a stretched body such as a columnar or prismatic shape, a highly adaptable sliding sealing interface is formed with the accommodating groove of the second mold 2. During the dynamic compression process, the continuous regular surface of the stretched body closely adheres to the inner wall of the accommodating groove. Through the geometric characteristic of surface contact rather than line contact, the microscopic gap generated during relative movement is significantly reduced, thereby effectively suppressing melt leakage or pressure dissipation during the volume adjustment stage of the cavity 3. At the same time, the through-type design of the liquid injection channel 4 allows the melt to be uniformly filled along the axial direction of the mold, avoiding local pressure fluctuations caused by lateral diversion and ensuring the stability of the melt flow field during the foaming and compression stages. This structure provides a reliable guarantee for the precise dynamic regulation of the volume of the cavity 3 through the collaborative optimization of geometric sealing and fluid path.

[0031] According to an embodiment of the present invention, one or both of the first mold 1 and the second mold 2 are movable on the surface close to the cavity 3.

[0032] This embodiment provides another specific implementation of the variable cavity 3. By designing the side surface of the cavity 3 of at least one of the first mold 1 or the second mold 2 as a movable structure, such as a flexible mold in the form of an airbag, its deformation ability is used to directly regulate the volume of the cavity 3. When the size of the cavity 3 needs to be adjusted, the surface of the first mold 1 or the second mold 2 is advanced into the cavity 3, applying a uniform pressure to the foaming melt to cause the collapse of the pores on the product surface. The technical solution of this embodiment realizes a wider compression ratio adjustment range while simplifying the traditional cavity adjustment mechanism through a rigid-flexible coupled dynamic response mechanism of the mold, and is particularly suitable for the molding of products with complex curved surfaces or gradually changing wall thicknesses.

[0033] According to an embodiment of the present invention, the polymer includes fibers with a weight percentage of 3% to 40%.

[0034] This embodiment forms a fiber-reinforced composite modification mechanism by adding fibers to the polymer and combining the microcellular injection molding process, which is specifically manifested as follows: the fibers form a rigid network skeleton in the melt, restricting the excessive expansion of pores during the foaming process, refining the pore size and improving the distribution uniformity. The interface between the fibers and the polymer can induce heterogeneous nucleation and also increase the pore density. Moreover, the strength loss caused by microcellular foaming is effectively compensated by the high modulus characteristic of the fibers, and the axial orientation of the fibers can specifically enhance the tensile and bending strengths of the product.

[0035] In addition, from the perspective of the molding process, the doping of fiber materials can also optimize the melt rheological process. Especially in the injection molding process of static foaming, the fibers increase the melt viscosity, inhibit the escape of the decomposed gas of the foaming agent, and cooperate with the high-shear mixing of the injection molding machine to ensure the uniform dispersion of the gas-liquid two-phase. At the same time, the high-viscosity melt reduces turbulence during the mold filling stage and reduces the risk of cell coalescence and rupture. In addition, the incorporation of fibers can also enhance dimensional stability. The coefficient of thermal expansion of the fibers is significantly lower than that of the matrix resin. By restricting the anisotropy of the cooling shrinkage of the foamed product, warpage deformation is reduced, which is especially suitable for thin-walled or high-precision structural parts.

[0036] Too much fiber content will lead to the deterioration of melt fluidity, the increase of product brittleness and the distortion of cell structure, while too little fiber content is difficult to compensate for the strength loss caused by micro-foaming and weaken the lightweight synergistic effect. When the fiber content accounts for 3% to 40% of the polymer by weight, better bubble dispersion effects can be achieved.

[0037] Furthermore, the fiber is one or more of glass fiber, carbon fiber, aramid fiber and natural fiber, and / or, the length of the fiber is L, and L satisfies the relational expression: 80μm ≤ L ≤ 500μm.

[0038] The length of the fiber has an obvious influence on the performance of the injection molded product. The longer the fiber, the better the strengthening effect, but the more prone it is to breakage. The shorter the fiber, the more uniform the dispersion, and the relatively lower requirements for the injection molding equipment. In this embodiment, the fiber length is 80 - 500μm. Through its full wetting with the melt due to its high specific surface area, at least the following two effects are achieved. On the one hand, the short fibers are easily oriented in the shear flow field, forming an interlaced barrier with the escape path of the decomposed gas of the foaming agent, inhibiting cell coalescence and improving the distribution uniformity. At the same time, the interfacial stress concentration points between the fiber ends and the matrix can induce the passivation of microcracks and delay the fatigue failure of the product. On the other hand, the short fibers avoid the deterioration of melt fluidity caused by the entanglement of long fibers under the limited length, and maintain effective stress transfer through the critical aspect ratio, so that the fiber strengthening efficiency and the lightweight foaming reach a balance.

[0039] According to an embodiment of the present invention, the polymer includes an ultraviolet absorber with a weight ratio of 0.1% to 2% and a light stabilizer with a weight ratio of 0.05% to 1%; or, the polymer includes carbon black with a weight ratio of 1% to 5%.

[0040] With the progress of technology and additional requirements for the functions of floor cleaning robots, some floor cleaning robots are equipped with an ultraviolet disinfection function. Undoubtedly, ultraviolet rays will accelerate the aging of the injection-molded housing, thereby affecting the service life of the floor cleaning robot itself. In this embodiment, two light stabilization solutions are adopted to solve the problem of housing aging caused by ultraviolet rays: for transparent or light-colored components such as sensor covers, 0.1%-2% ultraviolet absorber is added in combination with 0.05%-1% light stabilizer. Through the molecular-level energy conversion mechanism, such as the combination of benzotriazole absorbers and hindered amine HALS stabilizers, the transmittance of ultraviolet rays can be significantly reduced, and it has good compatibility with the micro-foaming process; for the black housing, 1%-5% carbon black can be directly introduced to achieve full-band ultraviolet shielding, and at the same time, it has the function of a foaming nucleating agent. In addition, the cost of carbon black is relatively low, more cost-effective, and is especially suitable for the manufacture of the housing of floor cleaning robots that need to balance functionality, weather resistance, and economy.

[0041] According to an embodiment of the present invention, after step B2, it further includes: B21: adjusting the volume of the cavity 3 to V3 so that the internal pressure of the injection melt 5 remains constant throughout step B2, where V1 and V3 satisfy the relationship: V1 ≤ 1% * V3.

[0042] In this embodiment, through the dynamic adjustment of the volume of the cavity 3 and the coordinated control of the injection process of the injection melt 5, precise pressure stabilization of the internal pressure during the melt filling stage is achieved: when the original volume V1 of the cavity 3 is limited to not exceed 1% of V3, the air remaining in the original cavity 3 can be ignored relative to the total amount of the injection melt 5. The cavity 3 essentially constitutes a quasi-constant pressure container with an expandable volume, and its volume is compensated in real time as the melt injection amount increases to achieve pressure-stabilized injection molding. This technical feature effectively inhibits the premature activation and escape of the foaming agent during the filling stage, strictly limits the foaming process to the controlled expansion stage after demolding, thereby reducing the standard deviation of the cell diameter distribution and improving the uniformity of the cell structure. At the same time, it avoids the defect of the melt front jet flow caused by local overpressure, improves the cell closure rate of the thin-walled housing, and ensures the qualified rate of the finished product.

[0043] It should be understood that step B4 includes reducing the volume of the cavity 3 to V2, that is, V2 and V3 satisfy the relationship: V2 < V3.

[0044] Please refer to Figure 2 shown in Figure 2 which is a schematic flow chart of a micro-foaming injection molding process applied to a floor cleaning robot provided by another embodiment of the present invention.

[0045] According to an embodiment of the present invention, after step B2, it further includes: B21: adjusting the volume of the cavity 3 so that the volume of the cavity 3 after the injection melt 5 is input in place is V3; before step B3, it further includes: B31: adjusting the volume of the cavity 3 to V4, where V4 > V3.

[0046] It should be understood that the injection melt 5 input in place in this embodiment means that the actual input amount of the injection melt 5 in the cavity 3 reaches the preset volume, and the injection melt 5 injected into the cavity 3 is sufficient to form a preset part after solidification. In addition, step B4 includes reducing the volume of the cavity 3 to V2, that is, V2 and V4 satisfy the relationship: V2 < V4.

[0047] In this embodiment, in step B4, the injection melt 5 is injected into the cavity 3 through the liquid injection channel 4 to make its volume reach V3. After the filling is completed, in step B5, the volume of the cavity 3 is actively adjusted to V4, and the internal pressure of the melt is reduced by volume expansion, so as to accurately trigger the foaming behavior of the foaming agent. This staged volume control mechanism decouples the filling and foaming processes: in the filling stage, a constant internal pressure is maintained to ensure that the melt completely fills the cavity 3 and no pores are generated, while in the foaming stage, the internal pressure of the melt is reduced below the foaming critical pressure by the controllable expansion of the cavity 3, thereby avoiding the interference of the melt flow shear force on pore nucleation during the mold filling stage, ensuring that foaming only occurs in the static melt under uniform thermodynamic conditions, thus significantly improving the uniformity of the pore distribution and the interfacial bonding strength, and at the same time avoiding defects such as pore tearing and insufficient foaming at the melt front caused by the simultaneous mold filling and foaming in the traditional process.

[0048] Please refer to Figure 3 as shown in Figure 3 is a schematic flow chart of a microcellular injection molding process applied to a floor cleaning robot provided by another embodiment of the present invention.

[0049] According to an embodiment of the present invention, the second mold 2 is used to form the appearance surface of the floor cleaning robot, the first mold 1 is used to form the working surface of the floor cleaning robot, a through liquid injection channel 4 is formed on the first mold 1, a through pressure relief channel 6 is formed on the second mold 2, and the liquid injection channel 4 and the pressure relief channel 6 are respectively communicated with the cavity 3; step B2 includes: injecting the injection melt 5 into the cavity 3 through the liquid injection channel 4, there is an air mass 7 between the injection melt 5 and the second mold 2, and the air mass 7 is communicated with the pressure relief channel 6; step B3 includes: completely discharging the air mass 7 through the pressure relief channel 6 and standing still to make the injection melt 5 foam.

[0050] In this embodiment, through the partition design of the first mold 1 and the second mold 2 and the directional discharge control mechanism of the air mass 7, the regional differential control of the foaming behavior is realized: when the air mass 7 on the second mold 2 side is discharged through the pressure relief channel 6, the internal pressure gradient in the cavity 3 causes the foaming to start preferentially from the appearance surface area of the molded product, that is, the second mold 2 side, while the injection melt 5 in the working surface area is subjected to the compression effect brought by the foaming on the opposite side, and the activation energy threshold of the foaming agent inside it is increased, resulting in a foaming inhibition effect. This technical feature enables the floor cleaning robot housing to form a gradient foaming structure, keeps the working surface in a high-density state due to melt compression, and further improves the surface quality.

[0051] The present invention also provides a micro-foamed injection molded housing for a floor sweeping robot, which is produced by using the micro-foamed injection molding process for a floor sweeping robot according to any one of the above.

[0052] Since the micro-foamed injection molded housing for a floor sweeping robot provided in this embodiment is produced by using the micro-foamed injection molding process for a floor sweeping robot according to any one of the above, therefore, the micro-foamed injection molded housing for a floor sweeping robot in this embodiment also has the technical effects of the above embodiments, that is, on the premise of maintaining the low density advantage of the internal micro-foaming, the quality of the surface layer area is significantly increased, and the isolation effect on dust and grease during the actual operation of the floor sweeping robot is optimized.

[0053] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, then the directional indication also changes accordingly.

[0054] It should also be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be a central element at the same time. When an element is referred to as "connected" to another element, it can be directly connected to the other element or can also be indirectly connected to the other element through a central element.

[0055] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those skilled in the art can implement it. When the combination of technical solutions appears to be contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0056] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the description and drawings of the present invention under the design concept of the present invention, or direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A micro-foaming injection molding process applied to a floor cleaning robot, characterized in that, The micro-foaming injection molding process is applicable to a micro-foaming injection molding device, which includes a mold assembly and a micro-foaming injection molding machine. The mold assembly includes a first mold and a second mold. The first mold and the second mold are combined to form a closed cavity with a volume of V1. A through liquid injection channel is formed on the first mold and / or the second mold, and the liquid injection channel is communicated with the cavity. The micro-foaming injection molding process includes the following steps: B1. Use the micro-foaming injection molding machine to uniformly mix a foaming agent into the molten polymer to obtain an injection molding melt; B2. Inject the injection molding melt into the cavity through the liquid injection channel; B3. Let it stand still to allow the injection molding melt to foam; B4. Before the injection molding melt is completely cured, adjust the mold so that the volume of the cavity is reduced to V2, where V1 > V2; B5. Keep the shape of the mold until the injection molding melt is completely cured to form an injection molded part; B6. Take out the injection molded part from the mold.

2. The micro-foaming injection molding process applied to the floor cleaning robot according to claim 1, wherein The outer surface of the first mold is a stretched body, and the second mold is formed with a receiving groove that cooperates with the outer surface of the first mold. The first mold is inserted into the receiving groove so that the first mold and the second mold are combined to form the closed cavity.

3. The micro-foaming injection molding process applied to the floor sweeping robot according to claim 1, characterized in that, One side surface of the first mold and / or the second mold close to the cavity is movable.

4. The micro-foaming injection molding process applied to a floor cleaning robot according to claim 1, characterized in that, The polymer includes fibers with a weight ratio of 3% to 40%.

5. The micro-foaming injection molding process applied to a floor cleaning robot according to claim 4, wherein, The fibers are one or more of glass fibers, carbon fibers, aramid fibers, and natural fibers, and / or The length of the fiber is L, and L satisfies the relationship: 80 μm ≤ L ≤ 500 μm.

6. The micro-foaming injection molding process applied to a floor cleaning robot according to claim 1, characterized in that, The polymer includes an ultraviolet absorber with a weight ratio of 0.1% to 2% and a light stabilizer with a weight ratio of 0.05% to 1%; or The polymer includes carbon black with a weight ratio of 1% to 5%.

7. The micro-foaming injection molding process applied to a floor cleaning robot according to any one of claims 1-6, characterized in that, After step B2, it further includes: B21: Adjust the volume of the cavity to V3 so that the internal pressure of the injection molding melt is constant throughout step B2, where V1 and V3 satisfy the relationship: V1 ≤ 1% * V3.

8. The micro-foaming injection molding process applied to a floor sweeping robot according to any one of claims 1-6, characterized in that, After step B2, it further includes: B21: Adjust the volume of the cavity so that the volume of the cavity after the injection molding melt is input in place is V3; Before step B3, it further includes: B31: Adjust the volume of the cavity to V4, where V4 > V3.

9. The microcellular injection molding process applied to a floor cleaning robot according to any one of claims 1-6, characterized in that The second mold is used to form the outer surface of a floor cleaning robot, and the first mold is used to form the working surface of the floor cleaning robot. A through liquid injection channel is formed on the first mold, and a through pressure relief channel is formed on the second mold, and the liquid injection channel and the pressure relief channel are respectively communicated with the cavity; Step B2 includes: Inject the injection molding melt into the cavity through the liquid injection channel. There is an air mass between the injection molding melt and the second mold, and the air mass is communicated with the pressure relief channel; Step B3 includes: Completely discharge the air mass through the pressure relief channel, and let it stand still to allow the injection molding melt to foam.

10. A micro-foaming injection molded housing for a floor cleaning robot, characterized in that, It is produced by using the micro-foaming injection molding process for a floor cleaning robot according to any one of claims 1 to 9.

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