Single screw sandwich injection device and process

Abstract

The invention discloses a single-screw sandwich injection device and process, comprising a barrel and a screw assembly, wherein a main blanking port and a secondary blanking port are provided on the barrel, and the screw assembly comprises a screw head, a check ring, a gasket, a shuttle valve and a screw body, wherein a plurality of external flow channels are circumferentially provided at the end of the screw head on one side of the check ring, and an inner hole which is communicated with the external flow channel and is opposite to the gasket is provided on the check ring; the screw body comprises a main plasticizing thread section, a main blanking section, an isolation section, a secondary plasticizing thread section and a secondary blanking section in sequence, an inner flow channel which passes through the screw body and the screw head in sequence is provided in the isolation section along the direction of the main blanking section, a feeding port which is communicated with the inner flow channel is obliquely provided on the isolation section, and a shuttle sliding chamber for the shuttle valve to slide inside to realize opening and closing of the inner flow channel is jointly provided at the end of the screw head and the end of the main plasticizing thread section, and the key points of the technical scheme are that the production of sandwich products is realized by the operation of a single screw, and the quality of sandwich products is guaranteed while the cost of sandwich injection is reduced.

Description

Technical Field

[0001] The invention relates to injection molding plasticizing equipment, in particular to a single-screw sandwich injection device and a process. Background Art

[0002] The existing sandwich injection requires two plasticizing systems to complete, the main purpose of which is to achieve the new packaging of the old injection molded products, realize the reuse of recycled plastics, and improve resource utilization. Without affecting the surface quality of plastic products, it can greatly save the manufacturing costs of injection molding manufacturers, and the market prospects are very broad.

[0003] However, the setting of two plasticizing systems, on the one hand, is complex to manufacture, which will lead to extremely high costs due to the difficulty of processing, and the large size has certain requirements on the floor space. On the other hand, sandwich injection has certain requirements on the synchronization of the two raw materials, but the two plasticizing systems are in a separate state, and it is difficult to achieve a certain injection synchronization. In order to ensure the quality of the sandwich injection product, it will increase the difficulty of synchronously injecting the two plasticizing systems to complete the sandwich injection. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a single-screw sandwich injection device and process, which can realize the production of sandwich products through the operation of a single screw, thereby reducing the cost of sandwich injection while ensuring the quality of the sandwich products.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A single-screw sandwich injection device comprises a hollow barrel and a screw assembly operating in the barrel, the barrel is provided with a main blanking port and a secondary blanking port, the screw assembly comprises a screw head, a check ring, a gasket, a shuttle valve, and a screw body, the check ring and the gasket are sleeved on the screw head in sequence, the outer circle of the gasket and the inner wall of the barrel body have a gap sufficient for molten plastic to pass through, a plurality of external flow channels are circumferentially provided at the end of the screw head on one side of the check ring, the check ring is provided with an inner hole communicating with the external flow channel and opposite to the gasket, and the end of the screw head on one side of the gasket is coaxially and tightly connected with the screw body thread;

[0007] The screw body includes a main plasticizing thread section, a main feeding section, an isolation section, a secondary plasticizing thread section, and a secondary feeding section in sequence. The main plasticizing thread section is located on one side of the screw head. The end of the secondary plasticizing thread section is provided with an inner flow channel that sequentially penetrates the screw body and the screw head along the isolation section direction, and the inner flow channel is coaxially arranged with the screw head. The end of the secondary plasticizing thread section is obliquely provided with a feeding port that communicates with the inner flow channel. The angles of the spiral edges on the main plasticizing thread section and the secondary plasticizing thread section are the same, and the inclination angle is the same as that of the feeding port. The end of the screw head and the end of the main plasticizing thread section are jointly provided with a shuttle sliding chamber for a shuttle valve to slide inside to realize the opening and closing of the inner flow channel.

[0008] With such arrangement, a main blanking port and an auxiliary blanking port are opened through the barrel, which correspond to the main blanking section and the auxiliary blanking section of the screw body respectively, and the screw body is divided into two front and rear sections for respective blanking. The outflow on the screw head and the inner flow channel opened inside the screw body form two output channels for conveying different plastics. The outer flow channel and the inner flow channel will eventually converge at the end of the screw head for synchronous sandwich injection. The whole process realizes sandwich injection through only one screw body, avoiding the setting of two plasticizing systems, reducing the cost of sandwich injection while ensuring the quality of sandwich products.

[0009] Further preferably, a slideway is symmetrically provided on the screw head along the circumferential direction, a sliding foot sliding in the slideway is provided at one end of the check ring, a trapezoidal platform is provided at the other end of the check ring to facilitate the flow of molten plastic, and the gasket is correspondingly provided with a trapezoidal groove matching the trapezoidal platform.

[0010] With such arrangement, through the matching arrangement of the slideway and the sliding foot and the matching arrangement of the trapezoidal platform and the trapezoidal groove, the check ring plays a limiting role in the process of sliding, preventing the rotational dislocation of the check ring, so that the inner hole in the check ring is always opposite to the outer flow channel, so that the outer flow channel can always receive the molten plastic from the main feeding section, thereby ensuring the quality of the sandwich injection product to a certain extent.

[0011] Further preferably, the shuttle slide chamber is provided with a shuttle valve sleeve at one end of the screw head, a sealing inner ring is provided at the other end of the shuttle slide chamber, and both ends of the shuttle valve are respectively provided with a protective ring and a sealing ring that match the shuttle valve sleeve and the sealing inner ring for sealing.

[0012] It is further preferred that: the protection ring and the sealing ring are both arranged to be inclined toward their axis, and the inclination directions are opposite, and the inclination angle of the sealing ring is between 45° and 60°.

[0013] Another object of the present invention is to provide a sandwich injection molding process corresponding to the above-mentioned single-screw sandwich injection device.

[0014] The above technical objectives of the present invention are achieved through the following technical solutions:

[0015] A single-screw sandwich injection molding process, in which the screw body is divided into a main plasticizing thread section and a secondary plasticizing thread section which are separated from each other, an outer flow channel is provided on the screw head to cooperate with the main plasticizing thread section to flow out molten plastic, and an inner flow channel is provided on the screw body and the screw head axis to cooperate with the secondary plasticizing thread section to flow out different molten plastics, and finally the two plastics converge at the end of the screw head to complete the sandwich injection.

[0016] In summary, the beneficial effects of the present invention compared with the prior art are as follows:

[0017] 1. For the injection production of sandwich products, it avoids the use of two plasticizing systems, and only uses one barrel and screw assembly to achieve sandwich injection, which is simple to operate and greatly reduces the space occupied by sandwich injection.

[0018] 2. The existing setting of two plasticizing systems is difficult to ensure the synchronous injection of two molten plastics, and has high requirements on the accuracy of the plasticizing equipment and the ability of the operators. The present invention sets the matching use of a barrel and a single screw assembly, and forms a double flow channel of molten plastic in the outer flow channel outside the screw assembly and the inner flow channel inside the screw assembly, which can improve the synchronization of sandwich injection, that is, ensure the quality of the sandwich product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the screw assembly in implementation 1;

[0020] Figure 2 For Example 1 Figure 1 A schematic diagram of the partial structure of one end of the middle screw head;

[0021] Figure 3 For Example 1 Figure 2 A cross-sectional view of

[0022] Figure 4 A partial cross-sectional view and a side view of the screw head in Example 1;

[0023] Figure 5 is a cross-sectional view of the screw body of Example 1;

[0024] Figure 6 For Example 1 Figure 5 Schematic diagram of some structures;

[0025] Figure 7 This is a schematic diagram of the structure of the shuttle valve in Example 1;

[0026] Figure 8 This is a schematic diagram of the pre-plastic state of the screw in Example 1;

[0027] Fig. 9 For Example 1 Figure 8 Schematic diagram of some structures;

[0028] Fig.10 It is a schematic diagram of the screw injection state of the embodiment.

[0029] Figure numerals: 1. screw assembly; 2. barrel; 21. main blanking port; 22. auxiliary blanking port; 3. screw head; 31. head; 32. cylindrical section A; 33. cylindrical section B; 34. cylindrical section C; 35. cylindrical section D; 36. outer flow channel; 37. inner flow channel; 38. slideway; 4. check ring; 41. slide foot; 42. trapezoidal platform; 5. gasket; 51. trapezoidal groove; 6. shuttle valve; 61. built-in flow channel; 62. protective ring; 63. sealing ring; 7. screw body; 71. main plasticizing thread section; 72. main blanking section; 73. isolation section; 74. auxiliary plasticizing thread section; 75. auxiliary blanking section; 8. feeding port; 9. shuttle slide chamber; 10. shuttle valve sleeve; 11. sealing inner ring; 12. connecting groove. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0031] Embodiment 1:

[0032] A single screw sandwich injection device, referring to Figure 1 and Figure 2 As shown, it includes a hollow barrel 2 (see Figure 7 ) and a screw assembly 1 operating in a barrel 2, the screw assembly 1 comprising a screw head 3, a check ring 4, a gasket 5, a shuttle valve 6, a screw body 7, the check ring 4 and the gasket 5 are sleeved on the screw head 3, and the screw head 3 is threadedly connected to the screw body 7.

[0033] Reference Figure 4 As shown, the screw head 3 includes a truncated cone-shaped head 31, a coaxial cylindrical segment A32, a cylindrical segment B33, a cylindrical segment C34, and a cylindrical segment D35 with decreasing radii in sequence. The cylindrical segment A32 is coaxially arranged with the head 31, and the radius of the cylindrical segment A32 is the same as the radius of the end of the head 31 with a larger diameter.

[0034] Reference Figure 2 As shown, the inner ring of the check ring 4 is slidably sleeved on the cylindrical segment B33, that is, it can slide on the cylindrical segment B33, and the outer ring of the check ring 4 abuts against the inner wall of the barrel 2 with a certain gap. This gap is small enough to prevent the molten plastic from passing through, but does not affect the rotation and reciprocating movement of the screw head 3 and the screw body 7.

[0035] Reference Figure 3As shown, the inner ring of the gasket 5 is sleeved on the cylindrical section C34 and is in a tight state with the cylindrical section C34. The gasket 5 is partially located on the cylindrical section D35. The outer ring radius of the gasket 5 is smaller than the inner ring radius of the barrel 2, that is, there is a certain distance between the outer ring of the gasket 5 and the inner wall of the barrel 2, and this distance is enough for the molten plastic to pass through. The main thing is that when the check ring 4 is tightly pressed against the cylindrical section A32, there is a certain distance between the check ring 4 and the gasket 5, and a trapezoidal platform 42 is provided at the end of the check ring 4 on one side of the gasket 5 to facilitate the molten plastic to flow down. The trapezoidal platform 42 is in a truncated cone shape inclined toward the middle. A part of the trapezoidal platform 42 is on the cylindrical section B33 and a part is within the range of the cylindrical section C34. The gasket 5 is correspondingly provided with a trapezoidal groove 51 that matches the trapezoidal platform 42. When the trapezoidal platform 42 is tightly pressed against the trapezoidal groove 51, there is a certain distance between the check ring 4 and the cylindrical section A32.

[0036] Reference Figure 2 and Figure 3 As shown, a slideway 38 extending along the axial direction is provided at the end of the cylindrical segment A32 on one side of the check ring 4, and the slideway 38 is provided on the outer circle of the cylindrical segment A32. The slideway 38 does not penetrate the other end of the cylindrical segment A32, and the cylindrical segment A32 is provided with four slideways 38 at equal intervals along its circumference. The number of the slideways 38 is not limited to four. The end of the check ring 4 on one side of the cylindrical segment A32 is provided with a sliding foot 41 that cooperates with the slideway 38, and the sliding foot 41 can slide in the slideway 38 along the axial direction of the cylindrical segment A32.

[0037] A plurality of outer flow channels 36 are circumferentially provided at the end of the screw head 3 on one side of the check ring 4 (the head 31 and the cylindrical section A32). The outer flow channels 36 and the slideways 38 are staggered. In this embodiment, four outer flow channels 36 are provided, and the four outer flow channels 36 are circumferentially arranged at equal intervals. A plurality of inner holes (not shown in the figure) passing through both ends are provided in the check ring 4, and the plurality of inner holes are respectively communicated with the plurality of outer flow channels 36. That is, when the check ring 4 is pressed against the cylindrical section A32, the molten plastic enters between the cylindrical section A32 and the gasket 5, and then enters the inner hole of the check ring 4 and the outer flow channel 36 in turn, so that the molten plastic enters the front end of the screw head 3.

[0038] Reference Figure 5 and Figure 6As shown, the screw body 7 includes a main plasticizing thread segment 71, a main feeding segment 72, an isolation segment 73, a secondary plasticizing thread segment 74, and a secondary feeding segment 75 in sequence. The various parts of the screw body 7 are integrally formed. One end of the main plasticizing thread segment 71 is connected to the main feeding segment 72, and the other end is threadedly connected to the cylindrical segment D35 of the screw head 3, that is, a connecting groove 12 for inserting the cylindrical segment D35 is provided at the end of the main plasticizing thread segment 71, and the connecting groove 12 is circumferentially provided with an internal thread, and an external thread matching the internal thread is provided on the outer circle of the cylindrical segment D35, and a main feeding port 21 and a secondary feeding port 22 corresponding to the main feeding segment 72 and the secondary feeding segment 75 are respectively provided on the barrel 2.

[0039] Among them, an inner flow channel 37 is provided in the isolation section 73 along the direction of the main feeding section 72, which sequentially penetrates the screw body 7 and the screw head 3. The inner flow channel 37 is cylindrical and is coaxially arranged with the screw head 3 and the screw body 7. A feeding port 8 communicating with the inner flow channel 37 is provided on the surface of the isolation section 73, which is inclined toward the axial direction. The main thing is that the spiral edge angles on the main plasticizing thread section 71 and the auxiliary plasticizing thread section 74 are the same, and the inclination angle with the feeding port 8 is the same, both of which are β.

[0040] The end of the screw head 3 and the end of the main plasticizing thread section 71 are jointly provided with a shuttle chamber 9 for the shuttle valve 6 to slide inside to realize the opening and closing of the inner flow channel 37. The cavity opened in the screw head 3 is only the inclined part of the end of the shuttle chamber 9. The shuttle chambers 9 are coaxially opened with the connecting groove 12 and the inner flow channel 37, and the shuttle chambers 9 are communicated with the connecting groove 12 and the inner flow channel 37. The diameter of the shuttle chamber 9 is smaller than the diameter of the connecting groove 12. It is worth noting that the shuttle chamber 9 is located on the inner flow channel 37, that is, the inner flow channel 37 is divided into two sections.

[0041] The shuttle sliding chamber 9 is provided with a shuttle valve 6 sheath at one end of the screw head 3 (see Figure 4 ), the other end of the shuttle chamber 9 is provided with a sealing inner ring 11 (see Figure 6 ), the shuttle valve 6 sleeve and the sealing inner ring 11 are respectively installed on the screw head 3 and the main plasticizing thread section 71; at the same time, refer to Figure 7 As shown, the two ends of the shuttle valve 6 are respectively provided with a protective ring 62 and a sealing ring 63 which are matched with the shuttle valve 6 sheath and the sealing inner ring 11 for sealing. The protective ring 62 and the sealing ring 63 are both inclined toward their axis, and the inclination directions of the protective ring 62 and the sealing ring 63 are opposite. Figure 7 It can be seen that the protection ring 62 and the sealing ring 63 are in an outwardly convex and inclined state, whereby the shuttle valve 6 sleeve and the sealing inner ring 11 are respectively recessed and inclined toward the screw head 3 and the main plasticizing thread section 71, Figure 4 and Figure 7 , the inclination angles of the shuttle valve 6 sheath and the protection ring 62 are the same, that is, the angle θ in the figure, and the inclination angle of the sealing ring 63 is between 45° and 60°, that is, Figure 7The angle α in .

[0042] Working principle:

[0043] When pre-molding in a single screw sandwich injection unit, refer to Figure 8 and Fig. 9 Schematic diagram of the pre-plastic state, different plastic particles enter the main and auxiliary feeding sections 75 of the screw body 7 from the main and auxiliary feeding ports 22 of the barrel 2 respectively, the screw body 7 is driven to rotate by an oil motor or an electric motor, and the plastics are plasticized in the main and auxiliary plasticizing thread sections 74 respectively. Due to the shearing of the main and auxiliary plasticizing thread sections 74 and the heating of the external heater, the granular plastics are gradually melted into molten plastics in the main and auxiliary plasticizing thread sections 74 respectively, and under the spiral conveying effect of the screw body 7, the plastics are conveyed from the rear ends of the main and auxiliary plasticizing thread sections 74 to the front ends respectively.

[0044] For the granular plastic entering from the main blanking port 21, the molten plastic in the main plasticizing threaded section 71 passes forward through the outer circle of the gasket 5, pushing the check ring 4 to move forward, so that the check ring 4 is tightly pressed against the cylindrical section A32, allowing the molten plastic to pass through the inner hole of the check ring 4 into the outer flow channel 36 of the screw head 3 and into the front end of the barrel 2, thereby realizing the injection of a single plastic.

[0045] Due to the isolation effect of the isolation section 73 on the screw body 7, the molten plastics in the main plasticizing thread section 71 and the auxiliary plasticizing thread section 74 will not be mixed. The molten plastic in the auxiliary plasticizing thread section 74 will enter the feed port 8, and then enter the inner flow channel 37, and push the shuttle valve 6 to move forward. The protective ring 62 of the shuttle valve 6 is attached to the shuttle valve 6 of the screw head 3. The molten plastic enters the inner flow channel 37 of the screw head 3 from the built-in flow channel 61 on the shuttle valve 6, and also enters the front end of the barrel 2 to complete the injection of the second plastic.

[0046] Due to the pre-plasticizing effect, the screw body 7 retreats, the front end of the barrel 2 stores material, and the two molten plastics reach the front end of the barrel 2 at the same time. Therefore, the plastic passing through the main plasticizing thread section 71 is on the outside, and the plastic passing through the auxiliary plasticizing thread section 74 is on the inside, completing the sandwich injection of the two plastics.

[0047] When pre-plasticization is completed and the injection state is entered, refer to Fig.10 Schematic diagram of injection state, the screw body 7 is driven by a cylinder or a motor to push the plastic forward. Due to the reaction force, the plastic pushes the check ring 4 and the shuttle valve 6 to move backward. The trapezoidal platform 42 of the check ring 4 sticks to the trapezoidal groove 51 of the gasket 5. Because the inclination angles are exactly the same and the gap between the check ring 4 and the barrel 2 is small enough, the plastic is prevented from moving backward;

[0048] At the same time, the sealing ring 63 of the shuttle valve 6 fits the sealing inner ring 11, and since the angles of the two are exactly the same, the plastic retreat channel is also cut off. Therefore, under the thrust of the screw, the two molten plastics are kept in an inner and outer enclosed state, and the barrel 2 is pushed out into the mold, thereby realizing the production of plastic sandwich products.

[0049] Embodiment 2:

[0050] According to the sandwich injection device developed according to Example 1, a single-screw sandwich injection molding process is provided. The screw body 7 is divided into a main plasticizing thread section 71 and a secondary plasticizing thread section 74 which are separated from each other. An outer flow channel 36 is opened on the screw head 3 to cooperate with the main plasticizing thread section 71 to flow out molten plastic. An inner flow channel 37 is opened on the axis of the screw body 7 and the screw head 3 to cooperate with the secondary plasticizing thread section 74 to flow out different molten plastics. Finally, the two plastics converge at the end of the screw head 3 to complete the sandwich injection.

[0051] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A single-screw sandwich injection device, comprising a hollow barrel (2) and a screw assembly (1) operating in the barrel (2), wherein the barrel (2) is provided with a main blanking port (21) and a secondary blanking port (22), wherein: The screw assembly (1) comprises a screw head (3), a check ring (4), a gasket (5), a shuttle valve (6), and a screw body (7). The check ring (4) and the gasket (5) are sleeved on the screw head (3) in sequence. There is a gap between the outer circle of the gasket (5) and the inner wall of the barrel (2) body for molten plastic to pass through. A plurality of external flow channels (36) are circumferentially provided at the end of the screw head (3) on one side of the check ring (4). The check ring (4) is provided with an inner hole which is communicated with the external flow channels (36) and is opposite to the gasket (5). The end of the screw head (3) on one side of the gasket (5) is coaxially and tightly connected to the screw body (7) by thread. The screw body (7) comprises a main plasticizing thread section (71), a main material discharge section (72), an isolation section (73), a secondary plasticizing thread section (74), and a secondary material discharge section (75) in sequence. The main plasticizing thread section (71) is located on one side of the screw head (3). The end of the main plasticizing thread section (71) is provided with a connecting groove (12) for inserting the screw head (3). The end of the secondary plasticizing thread section (74) is provided with an inner flow groove (12) that sequentially penetrates the screw body (7) and the screw head (3) along the direction of the isolation section (73). The inner flow channel (37) is coaxially arranged with the screw head (3); the end of the auxiliary plasticizing thread segment (74) is obliquely provided with a feed port (8) communicating with the inner flow channel (37); the spiral edges of the main plasticizing thread segment (71) and the auxiliary plasticizing thread segment (74) have the same angle and the same inclination angle as the feed port (8); the ends of the screw head (3) and the main plasticizing thread segment (71) are jointly provided with a shuttle sliding chamber (9) for a shuttle valve (6) to slide inside to realize the opening and closing of the inner flow channel (37).

2. A single screw sandwich injection device according to claim 1, characterized in that: The screw head (3) is provided with a slideway (38) symmetrically along the circumferential direction, one end of the check ring (4) is provided with a sliding foot (41) that slides in the slideway (38), the other end of the check ring (4) is provided with a trapezoidal platform (42) that facilitates the flow of molten plastic, and the gasket (5) is correspondingly provided with a trapezoidal groove (51) that matches the trapezoidal platform (42).

3. A single screw sandwich injection device according to claim 1 or 2, characterized in that: The shuttle valve (6) sleeve is provided at one end of the shuttle sliding chamber (9) on the screw head (3), and a sealing inner ring (11) is provided at the other end of the shuttle sliding chamber (9). Both ends of the shuttle valve (6) are respectively provided with a protective ring (62) and a sealing ring (63) which are matched with the shuttle valve (6) sleeve and the sealing inner ring (11) and are used for sealing.

4. A single screw sandwich injection device according to claim 3, characterized in that: The protection ring (62) and the sealing ring (63) are both arranged to be inclined toward their axis and in opposite directions, and the inclination angle of the sealing ring (63) is between 45° and 60°.

5. The sandwich injection process of the single screw sandwich injection device according to any one of claims 1 to 4, characterized in that: The screw body (7) is divided into a main plasticizing thread section (71) and a secondary plasticizing thread section (74) which are separated from each other. An outer flow channel (36) is provided on the screw head (3) to cooperate with the main plasticizing thread section (71) to flow out molten plastic. An inner flow channel (37) is provided at the axis of the screw body (7) and the screw head (3) to cooperate with the secondary plasticizing thread section (74) to flow out different molten plastics. Finally, the two plastics merge at the end of the screw head (3) to complete sandwich injection.

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