A powder coating stirring apparatus

Abstract

The utility model discloses a kind of powder coating stirring equipment, belong to powder coating production equipment technical field, including cavity and the stirring mechanism being set in it, the stirring mechanism includes driving motor and stirring shaft, the cavity is full-closed structure, and inert gas supply pipeline with control valve is connected;The stirring shaft is rotatably penetrated cavity and the output end connection of driving motor by magnetic coupling sealing element rotation;Spiral stirring vane is fixedly arranged on the stirring shaft, the pitch of the spiral stirring vane is non-equal distance setting, and it is composed by two spiral direction opposite blade segments, the helix angle of the spiral stirring vane linearly increases or decreases from one end to the other end of stirring shaft;At least one group of auxiliary stirring paddle is further fixed on the stirring shaft, and the auxiliary stirring paddle is located between the two blade segments of spiral stirring vane;Can effectively solve the problem of poor mixing quality of existing powder coating stirring equipment.

Description

Technical Field

[0001] This utility model relates to the technical field of powder coating production equipment, specifically to a powder coating mixing device. Background Technology

[0002] In the production of powder coatings, the mixing process is a crucial step. The quality of this process directly determines the consistency of the final product's color, gloss, and performance. Currently, commonly used mixing equipment mainly employs open or simply closed cavities, along with simple paddles or equidistant spiral belts as agitation mechanisms. While these common agitator blades can initially mix powder raw materials such as resins, pigments, fillers, and additives, the resulting flow field is singular, easily creating mixing dead zones. This is especially problematic for powder materials with large density differences and wide particle size distributions, leading to stratification or agglomeration, failing to meet high standards of uniformity.

[0003] In the production environment, the presence of oxygen and moisture can easily cause certain sensitive resins and additives to oxidize or clump due to moisture, which can seriously affect product quality. Furthermore, during the mixing process, friction between the powder and the mixing blades and the inner wall of the chamber generates heat. Simultaneously, due to electrostatic effects, the powder easily adheres to or clumps on the blades and inner wall, which not only reduces mixing efficiency but also increases cleaning difficulty and the possibility of batch-to-batch cross-contamination.

[0004] In view of the above problems, there is an urgent need for a new type of powder coating mixing equipment that can improve mixing uniformity, effectively prevent powder oxidation, and reduce powder adhesion. This would not only improve product quality but also simplify the production and maintenance process, reduce production costs, and meet the industry's higher requirements for efficient, stable production and high-quality materials. Utility Model Content

[0005] The purpose of this invention is to overcome the aforementioned technical difficulties and provide a powder coating mixing device that can improve mixing uniformity, effectively prevent powder oxidation, and reduce powder adhesion problems.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a powder coating mixing device, comprising a cavity and a mixing mechanism disposed therein, the mixing mechanism comprising a drive motor and a mixing shaft, the cavity being a fully enclosed structure and connected to an inert gas supply pipeline with a control valve; the mixing shaft rotatably passes through the cavity and is connected to the output end of the drive motor via a magnetic coupling seal; a spiral mixing blade is fixedly disposed on the mixing shaft, the pitch of the spiral mixing blade is non-equidistant and is composed of two segments with opposite spiral directions, the helix angle of the spiral mixing blade increases or decreases linearly from one end of the mixing shaft to the other end; at least one set of auxiliary mixing paddles is also fixedly disposed on the mixing shaft, the auxiliary mixing paddles being located between the two segments of the spiral mixing blades.

[0007] Furthermore, the edges of the spiral stirring blades are provided with several notches or serrated structures.

[0008] Furthermore, the auxiliary stirring paddle is one of a frame paddle, an anchor paddle, or a disc paddle.

[0009] Furthermore, a pressure sensor and a controller are connected to the inert gas supply pipeline. The controller is configured to control the opening and closing of the control valve based on the signal from the pressure sensor in order to maintain a slightly positive pressure state within the cavity.

[0010] Furthermore, the inner wall surface of the cavity is polished to a mirror finish, with a roughness Ra < 0.4 μm.

[0011] Furthermore, the bottom of the cavity is designed with a conical structure and is equipped with a pneumatic arch-breaking device.

[0012] The powder coating mixing device provided by this utility model has the following beneficial effects: This invention combines a composite stirring blade with non-equidistant, counter-spiraling blades and a linearly varying helix angle with an auxiliary stirring paddle located at a key position. Under the synergy of a fully enclosed inert gas protective environment, it generates strong multidimensional convection and shearing, effectively eliminating mixing dead zones, breaking up powder clumps, and ensuring uniform mixing. At the same time, the use of an inert gas supply pipeline reduces the risk of material oxidation and contamination. Thus, it effectively solves the problem of poor mixing quality in existing powder coating mixing equipment. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the powder coating mixing equipment of this utility model.

[0014] Figure 2 This is a schematic diagram of the spiral mixing blades of the powder coating mixing equipment of this utility model.

[0015] In the diagram, 1 is the cavity; 2 is the drive motor; 3 is the stirring shaft; 4 is the inert gas supply pipeline; 5 is the magnetic coupling seal; 6 is the spiral stirring blade; and 7 is the auxiliary stirring paddle. Detailed Implementation

[0016] The technical solution of this utility model will be clearly and completely described below with reference to specific embodiments. The described embodiments are merely some, not all, of these embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0017] like Figure 1-2 As shown, the present invention provides a powder coating mixing device, including a cavity 1 and a mixing mechanism disposed therein. The cavity 1 is a fully enclosed structure, and the entire inner wall surface of the cavity 1 is precision machined and polished to a mirror finish, making its roughness Ra < 0.4μm, thereby greatly reducing material adhesion. The bottom of the cavity 1 is set with a conical structure and is equipped with a pneumatic arch-breaking device, which is electrically connected to the drive motor 2 and connected to the controller. It is activated when discharging material, which can effectively shake off the attached material and significantly improve the discharge rate. The upper part of the cavity 1 is equipped with a feed valve and the lower part with a discharge valve. The feed valve at the upper part of the cavity 1 and the discharge valve at the lower part are both welded to the cavity 1 through standard flanges, and sealing gaskets are used between the flanges to ensure that there is no leakage at all interfaces.

[0018] The cavity 1 is connected to an inert gas supply pipeline 4 with a control valve, and the inert gas supply pipeline 4 is connected to a nitrogen source. For precise control, the inert gas supply pipeline 4 is equipped with a control valve and connected to a pressure sensor and a controller (not shown in the figure). The pressure sensor monitors the internal pressure of the cavity 1 in real time, and the controller compares this signal with a preset micro-positive pressure value and dynamically controls the opening and closing of the control valve to automatically maintain a stable micro-positive pressure within the cavity 1. This micro-positive pressure effectively prevents external air from seeping in, providing inert gas protection for the equipment from the source and preventing oxidation of materials during mixing.

[0019] The stirring mechanism includes a drive motor 2 and a stirring shaft 3. The stirring shaft 3 is rotatably connected to the output end of the drive motor 2 through the cavity 1 via a magnetic coupling seal 5. In this embodiment, the setting of the magnetic coupling seal 5 ensures the dynamic sealing of the stirring shaft 3 during rotation, thereby achieving leakage-free power transmission.

[0020] A spiral stirring blade 6 is fixedly mounted on the stirring shaft 3. The edges of the spiral stirring blade 6 are provided with several notches or serrated structures to enhance the ability to break up powder clumps. The pitch of the spiral stirring blade 6 is not equidistant and is composed of two segments with opposite spiral directions, that is, the spiral stirring blade 6 consists of a left-handed segment and a right-handed segment, and the pitches of the two segments are not equal. When the stirring shaft 3 rotates in one direction, the two segments of opposite spiral blades generate axial thrust in opposite directions on the material, forcing the material to form strong convection and mixing in the axial direction. At the same time, the helix angle of the spiral stirring blade 6 increases or decreases linearly from one end of the stirring shaft 3 to the other end, thereby forming different flow velocity zones and velocity gradients in the axial direction, generating strong shear force, efficiently breaking up clumps and dispersing trace components.

[0021] An auxiliary stirring paddle 7 is fixedly installed at the middle position of the two directional spiral blades 6. The auxiliary stirring paddle 7 is one of a frame paddle, an anchor paddle, or a disc paddle. In this embodiment, the auxiliary stirring paddle 7 is a frame paddle. The outer edge of the auxiliary stirring paddle 7 maintains a small gap with the inner wall of the cavity 1 to disperse the clumps that may be formed at the confluence of the two opposing flow streams and to scrape off any slight scale that may be attached to the wall.

[0022] Working principle: During operation, the powder coating raw material is added to chamber 1 and sealed. Inert gas (such as nitrogen) is introduced and drive motor 2 is started. The stirring shaft 3 drives the spiral stirring blades 6 and auxiliary stirring paddle 7 to rotate together. The two counter-rotating spiral blades force the material to form strong convective mixing in the axial direction, while the linearly changing spiral helix angle generates a velocity gradient in the radial direction, creating a strong shearing effect. The frame-type auxiliary stirring paddle 7, located at the center of convection, further breaks up clumps and scrapes the inner wall. The entire mixing process is carried out under the protection of a slight positive pressure of inert gas. After mixing is completed, the material is discharged from the bottom outlet with the assistance of gravity and a pneumatic arch-breaking device.

[0023] The applicant conducted a comparative experiment on the mixing quality. The experimental material was a mixture of 95% epoxy resin powder and 5% carbon black pigment (uneven mixing of this formula can easily lead to color variation). The experimental group used the stirring equipment described in the above embodiment of this utility model, while the control group used a conventional closed mixer with only a single-direction, equidistant spiral blade. The experimental method involved adding 50 kg of the above mixture to both devices and mixing for 15 minutes under the same conditions. After mixing, 10 samples (approximately 10 g each) were randomly selected from multiple locations including the top, middle, bottom, and edges of the chamber. Each sample was tested using a professional colorimeter. The degree of carbon black dispersion represented the mixing uniformity, and the results were expressed as color standard deviation (ΔE). The smaller the ΔE value, the more consistent the color of the sample and the higher the mixing uniformity. Simultaneously, the agglomeration rate (the percentage of agglomerates that failed to pass through an 80-mesh sieve) in the mixture was determined using a sieving method.

[0024] The test results are shown in the table below: detection indicators Experimental group (equipment of this invention) Control group (standard equipment) Color standard deviation (△E) 0.45 1.83 clumping rate 0.12% 0.85% Table 1 Comparison of Experimental Test Results Therefore, in terms of mixing uniformity, the color standard deviation (ΔE=0.45) of the product obtained by the equipment of this invention is much lower than that of the control group (ΔE=1.83). This indicates that the complex flow field generated by the composite stirring blades of this invention achieves ultimate dispersion of pigments in the resin matrix, effectively solving the problems of macroscopic segregation and microscopic agglomeration. Regarding agglomeration breaking capability, the agglomeration rate of the equipment of this invention (0.12%) is significantly lower than that of conventional equipment (0.85%), which is directly attributed to the strong shearing in the counter-spiral confluence zone and the breaking effect of the auxiliary stirring paddle. This invention achieves significant progress in mixing uniformity and agglomeration breaking capability through the synergistic effect of the composite stirring structure and the inert gas environment.

[0025] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

[0026] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A powder coating mixing device, comprising a cavity (1) and a mixing mechanism disposed therein, the mixing mechanism comprising a drive motor (2) and a mixing shaft (3), characterized in that: The cavity (1) is a fully enclosed structure and is connected to an inert gas supply pipeline (4) with a control valve; the stirring shaft (3) is rotatably connected to the output end of the drive motor (2) through the cavity (1) via a magnetic coupling seal (5); a spiral stirring blade (6) is fixedly provided on the stirring shaft (3), the pitch of the spiral stirring blade (6) is not equidistant and is composed of two blade segments with opposite spiral directions, and the spiral helix angle of the spiral stirring blade (6) increases or decreases linearly from one end of the stirring shaft (3) to the other end; at least one set of auxiliary stirring paddles (7) is also fixedly provided on the stirring shaft (3), and the auxiliary stirring paddles (7) are located between the two blade segments of the spiral stirring blade (6).

2. The powder paint mixing apparatus according to claim 1, characterized in that: The spiral stirring blade (6) has several notches or serrated edges on its blade edge.

3. The powder paint mixing apparatus according to claim 1, characterized in that: The auxiliary stirring paddle (7) is one of a frame paddle, an anchor paddle, or a disc paddle.

4. The powder coating mixing equipment according to claim 1, characterized in that: A pressure sensor and a controller are connected to the inert gas supply line (4). The controller is configured to control the opening and closing of the control valve according to the signal of the pressure sensor in order to maintain a slightly positive pressure state in the cavity (1).

5. The powder paint mixing apparatus of claim 1, wherein: The inner wall surface of the cavity (1) is polished to a mirror finish with a roughness Ra < 0.4 μm.

6. The powder paint mixing apparatus according to any one of claims 1 to 5, characterized in that: The bottom of the cavity (1) is set as a conical structure and is equipped with a pneumatic arch-breaking device.

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