A micro-foaming injection melt mixing device

Abstract

The present application relates to the technical field of plastic molding machines, and in particular to a micro-foaming injection melt mixing device: comprising a barrel, a screw, a connecting pipe, a control valve, a supercritical fluid injection mixing part, a melt pump, a static mixer and a one-way valve, wherein the screw is arranged in the barrel in a rotating and reciprocating structural form, a melt inlet and a melt outlet are sequentially provided on the front end side wall of the barrel, and the melt inlet and the melt outlet are sequentially connected through the connecting pipe, the control valve, the supercritical fluid injection mixing part, the melt pump, the static mixer and the one-way valve; a cut-off ring is slidably arranged in the barrel between the melt inlet and the melt outlet, and the cut-off ring is fixedly sleeved on the screw; the melt in the barrel is drawn out and mixed with the supercritical fluid, and a polymer / supercritical fluid homogeneous system is formed through the joint action of various components, thereby avoiding the current situation that the mixing in the barrel is uneven and requires a more complex structure to achieve, and the present invention is easy to maintain.

Description

Technical Field

[0001] The present application relates to the technical field of plastic molding machines, and in particular to a micro-foaming injection melt mixing device. Background Art

[0002] Micro-foam injection molding is a special process of injection molding. It is to inject supercritical fluid such as CO2 or N2 into molten melt such as PP, PE through a high-pressure injection device. The melt mixed with supercritical fluid is then injected into the mold cavity. After the pressure is released, tiny bubbles are formed, thereby reducing the weight of the product, reducing internal stress, and reducing product deformation.

[0003] There are currently two ways to inject supercritical fluid into the melt:

[0004] The first method is to directly add supercritical fluid to a specific position outside the barrel and inject it intermittently through an external specific device. The structure is relatively complex, and this method cannot ensure the uniformity of the foam size, and the mixing effect of the supercritical fluid and the melt is poor;

[0005] The second method is to set an air channel in the screw, and set a number of micropores connected to the air channel on the circumferential surface of the homogenizing section. The supercritical gas in the air channel is discharged through the micropores to mix with the melt, solving the problem of uniform foaming size. However, this method is to inject supercritical fluid into the rotating screw, which requires a set of complex structures to meet its airtightness requirements, and then use the screw itself to rotate for mixing; although it has a certain effect, the effect is not ideal, and it is difficult to maintain, and it cannot meet the needs of high-quality products. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a micro-foaming injection melt mixing device, which solves the technical problem that the supercritical fluid and the melt are mixed unevenly, resulting in uneven foaming in the product, which has a significant impact on the product quality and performance. In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A micro-foaming injection melt mixing device comprises a barrel, a screw, a connecting pipe, a control valve, a supercritical fluid injection mixing part, a melt pump, a static mixer and a one-way valve. The screw is arranged in the barrel in a rotating and reciprocating structural form. A melt inlet and a melt outlet are sequentially opened on the front end side wall of the barrel. The melt inlet and the melt outlet are connected in sequence through the connecting pipe, the control valve, the supercritical fluid injection mixing part, the melt pump, the static mixer and the one-way valve. A cut-off ring is slidably arranged in the barrel between the melt inlet and the melt outlet, and the cut-off ring is fixedly sleeved on the screw.

[0008] Furthermore, the supercritical fluid injection mixing part includes an injection block, a flow channel is provided in the injection block, an injection port A connected to the flow channel is provided on the side wall of the injection block, and a mixing cap for uniformly dispersing the supercritical gas into the melt is provided in the flow channel.

[0009] Furthermore, the mixing cap is loosely fitted with the flow channel in a sliding manner and can control the opening and closing of the injection port A. A sealing ring is provided at one end of the injection port A close to the flow channel.

[0010] Furthermore, the mixing cap includes a cap body and a cap body in a hollow ring structure, the cap body and the cap body are connected in a fixed manner, the outer wall of the cap body is gap-matched with the side wall of the flow channel, and an injection port B matching the injection port A is opened on the outer wall of the cap body; a number of injection ports are evenly opened on the inner wall of the cap body; and a number of through holes are evenly arranged on the cap body.

[0011] Furthermore, the injection port is arranged obliquely along the melt flow direction; and a plurality of injection ports are arranged in a spiral circumferential direction along the inner wall of the cap body.

[0012] Furthermore, a slider is symmetrically arranged on the upper part of the outer wall of the body in a fixed manner, a sliding groove for the slider to slide is opened on the side wall of the flow channel, and a spring is connected between the slider and the upper wall or lower wall of the sliding groove.

[0013] The beneficial effects of the present invention are:

[0014] By arranging a connecting pipe, a control valve, a supercritical fluid injection mixing part, a melt pump, a static mixer and a one-way valve on the front end side wall of the barrel, the melt in the barrel is drawn out and mixed with the supercritical fluid, and a polymer / supercritical fluid homogeneous system is formed through the joint action of various components, thereby avoiding the current situation that the mixing in the barrel is uneven and requires a relatively complex structure to achieve. In addition, the present invention is easy to maintain and does not require the main body of the equipment to be disassembled.

[0015] Since a mixing cap is arranged in the flow channel in the injection block, the supercritical fluid is refined through the injection port on the inner wall of the cap body and then evenly dispersed into the melt, which can ensure uniform bubble diameters. The injection port 10 has an inclined structure and a plurality of injection ports are arranged in a spiral along the inner wall of the cap body 92, so that the supercritical melt and the melt can be combined into a swirl flow, and the combination effect is better. The mixture is squeezed through the through hole on the cap body again to produce a confluence, so that it is fully mixed. The mixing cap can also control the closing and opening of the injection port A, and the two are linked to each other. The existing intermittent injection structure is replaced by a simple structure, which simplifies the equipment, saves money, and can also avoid some common airtightness problems of the intermittent injection structure.

[0016] The mixture is meshed and pressurized by the melt pump. Under the combined action of the thrust of the screw 2 and the pressure of the melt pump 6, the melt is sucked into a branch on one side, and the mixture can be further homogenized through gear meshing, thus killing two birds with one stone. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention;

[0018] Figure 2 It is a schematic diagram of the opening control valve and a partial cross-sectional structure of the present invention;

[0019] Figure 3 It is a schematic diagram of a partial cross-sectional structure of a closing control valve of the present invention;

[0020] Figure 4 The structure of the present invention Figure 3 A is shown in the enlarged structural diagram;

[0021] Figure 5 It is a schematic diagram of the cross-sectional structure of the mixing cap of the present invention.

[0022] In the figure:

[0023] 1. Barrel, 2. Screw, 3. Connecting pipe, 4. Control valve, 5. Supercritical fluid injection mixing part, 51. Injection block, 52. Runner, 53. Injection port A, 54. Sealing ring, 6. Melt pump, 7. Static mixer, 8. One-way valve, 9. Mixing cap, 91. Cap body, 92. Cap body, 93. Injection port B, 10. Injection port, 11. Melt inlet, 12. Melt outlet, 13. Cut-off ring, 14. Through hole, 15. Slider, 16. Slide groove, 17. Spring. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention will now be further described in detail with reference to the accompanying drawings and the following examples so that the public can better understand the implementation method of the present invention. The specific implementation scheme of the present invention is as follows:

[0025] A micro-foaming injection melt mixing device, characterized in that it includes a barrel 1, a screw 2, a connecting pipe 3, a control valve 4, a supercritical fluid injection mixing part 5, a melt pump 6, a static mixer 7 and a one-way valve 8, the screw 2 is arranged in the barrel 1 in a rotating and reciprocating structural form, the front end side wall of the barrel 1 is sequentially provided with a melt inlet 11 and a melt outlet 12, the melt inlet 11 and the melt outlet 12 are sequentially connected through the connecting pipe 3, the control valve 4, the supercritical fluid injection mixing part 5, the melt pump 6, the static mixer 7 and the one-way valve 8, the connecting pipe 3 is connected to the side wall of the barrel 1 at the melt inlet 11 by bolts, and the one-way valve 8 is connected to the side wall of the barrel 1 at the melt outlet 12 by bolts. When the device fails, it can be repaired by removing the bolts at the two locations, and there is no need to disassemble the device itself, which simplifies the maintenance method; a cut-off ring 13 is slidably provided in the barrel 1 between the melt inlet 11 and the melt outlet 12, and the cut-off ring 13 is fixedly sleeved on the screw 2, so that the melt can enter the bypass on one side of the barrel 1 and can also prevent the mixture from flowing back.

[0026] The supercritical fluid injection mixing part 5 includes an injection block 51, a flow channel 52 for the melt to pass through is provided in the injection block 51, an injection port A53 connected to the flow channel 52 is provided on the side wall of the injection block 51, a mixing cap 9 for uniformly dispersing the supercritical gas into the melt is provided in the flow channel 52, the mixing cap 9 and the flow channel 52 are gap-matched in a sliding manner, and the opening and closing of the injection port A53 can be controlled, the mixing cap 9 includes a cap body 91 and a cap body 92 in a hollow circular ring structure, the cap body 92 and the cap body 91 are connected in a fixed manner, the outer wall of the cap body is gap-matched with the side wall of the flow channel 52, and the outer wall of the cap body is provided with a gap that is connected to the injection port A53. The injection port B93 matched with 53, the upper part of the outer wall of the cap body 92 is symmetrically provided with a slider 15 in a fixed manner, and a slide groove 16 for the slider 15 to slide is opened on the side wall of the flow channel 52, and a spring 17 is connected between the slider 15 and the upper wall or lower wall of the slide groove 16; the melt flows in the flow channel 52 under the combined action of the thrust of the screw 2 and the pressure of the melt pump 6, thereby pushing the mixing cap 9 to overcome the force of the spring 17 and move along the flow direction of the melt, thereby aligning the injection port B93 with the injection port A53; a sealing ring 54 is provided at one end of the injection port A53 close to the flow channel 52 to prevent the supercritical fluid from directly entering the flow channel 52.

[0027] A plurality of injection ports 10 are evenly arranged on the inner wall of the cap body 92, and the supercritical fluid is finely and evenly sprayed into the melt through the injection ports 10. The injection ports 10 are arranged to form an inclined structure along the flow direction of the melt, and a plurality of injection ports 10 are arranged in a circumferential spiral along the inner wall of the cap body 92. With this structural form, the supercritical fluid sprayed from the injection ports 10 moves along the inner wall of the cap body 92 to form a vortex, which is easier to combine with the melt. A plurality of through holes 14 are evenly arranged on the cap body 91, and the mixture is squeezed through the confluence of the through holes 14, so that the mixture is better homogenized.

[0028] The working principle and working process of the present invention are as follows: Figure 2 As shown, the control valve 4 is opened, and the cut-off ring 13 is located on the left side of the melt inlet 11. Due to the rotation thrust of the screw 2 and the pressure of the melt pump 6, the melt enters the connecting pipe 3 from the melt inlet 11, and then enters the supercritical fluid injection mixing part 5 through the connecting pipe 3 through the control valve 4. At this time, the melt pushes the mixing cap 9 to overcome the tension or pressure of the spring 17 to move, and then the injection port B93 is aligned with the injection port A53, so that the supercritical fluid is injected into the inside of the cap body 92, and the supercritical fluid inside the cap body 92 is ejected through the injection port 10 to mix with the melt. The supercritical fluid and the melt pass through the through hole 14 and are squeezed again to have a higher degree of homogenization. The mixture continues to pass through the melt pump 6, and is pressurized by the meshing of gears in the melt pump 6, and further passes through the static mixer 7, so that the melt that was not mixed with the supercritical fluid at the beginning is mixed to form a polymer / supercritical fluid homogeneous system as a whole, and then enters the barrel 1 on the left side of the cut-off ring 13 through the one-way valve 8 through the melt outlet 12.

[0029] like Figure 3 As shown, the control valve 4 is closed, the melt stops flowing, and the mixing cap 9 is no longer subjected to the thrust of the melt flow, so the spring 17 resets the mixing cap 9 and blocks the injection port A53 with the side wall of the cap body 92; the screw 2 is pushed to rotate toward the left nozzle, and the one-way valve 8 is closed to protect the melt pump from being damaged under high pressure, and the mixture is ejected by the thrust of the screw 2.

[0030] In the description of the present invention, it should be understood that the terms "center", "upper", "lower", "left", "right", "front", "back", "lower left", "upper right", "outer", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Although the present invention has been described according to a limited number of embodiments, those skilled in the art, with the benefit of the above description, should understand that other embodiments can be conceived within the scope of the invention described thereby.

Claims

1. A micro-foaming injection melt mixing device, characterized in that: The invention comprises a barrel (1), a screw (2), a connecting pipe (3), a control valve (4), a supercritical fluid injection mixing section (5), a melt pump (6), a static mixer (7) and a one-way valve (8). The screw (2) is arranged in the barrel (1) in a rotating and reciprocating structural form. A melt inlet (11) and a melt outlet (12) are sequentially provided on the front end side wall of the barrel (1). The melt inlet (11) and the melt outlet (12) are connected in sequence through the connecting pipe (3), the control valve (4), the supercritical fluid injection mixing section (5), the melt pump (6), the static mixer (7) and the one-way valve (8). A cut-off ring (13) is slidably arranged in the barrel (1) between the melt inlet (11) and the melt outlet (12). The cut-off ring (13) is fixedly sleeved on the screw (2).

2. A micro-foaming injection melt mixing device according to claim 1, characterized in that: The supercritical fluid injection and mixing section (5) comprises an injection block (51), a flow channel (52) is provided in the injection block (51), an injection port A (53) connected to the flow channel (52) is provided on the side wall of the injection block (51), and a mixing cap (9) for uniformly dispersing the supercritical fluid into the melt is provided in the flow channel (52).

3. A micro-foaming injection melt mixing device according to claim 2, characterized in that: The mixing cap (9) is loosely fitted with the flow channel (52) in a sliding manner and is capable of controlling the opening and closing of the injection port A (53). A sealing ring (54) is provided at one end of the injection port A (53) close to the flow channel (52).

4. A micro-foaming injection melt mixing device according to claim 2 or 3, characterized in that: The mixing cap (9) comprises a cap body (91) and a cap body (92) in a hollow ring structure. The cap body (92) and the cap body (91) are connected in a fixed manner. The outer wall of the cap body (92) is gap-matched with the side wall of the flow channel (52), and an injection port B (93) matching with the injection port A (53) is provided on the outer wall of the cap body (92); a plurality of injection ports (10) are evenly provided on the inner wall of the cap body (92); and a plurality of through holes (14) are evenly provided on the cap body (91).

5. A micro-foaming injection melt mixing device according to claim 4, characterized in that: The injection port (10) is arranged obliquely along the melt flow direction; and a plurality of injection ports (10) are arranged in a spiral direction along the inner wall of the cap body (92).

6. A micro-foaming injection melt mixing device according to claim 4, characterized in that: Slide blocks (15) are symmetrically arranged on the upper part of the outer wall of the cap body (92) in a fixed manner, and a slide groove (16) for the slide blocks (15) to slide is provided on the side wall of the flow channel (52), and a spring (17) is connected between the slide block (15) and the upper wall or the lower wall of the slide groove (16).

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