PLA in-mold crystallization injection mold

Abstract

The utility model provides a PLA (polylactic acid) in-mold crystallization injection mold which comprises an upper mold, a lower mold and a plurality of forming cavities, a mounting cavity is formed in the upper mold, a shunting seat is arranged in the mounting cavity, and an air heat insulation area is formed between the outer wall of the shunting seat and the inner wall of the mounting cavity; a feeding hole is formed in the upper end of the flow dividing base, a discharging hole is formed in the bottom of the flow dividing base, the discharging hole is communicated with the feeding hole through a flow dividing channel, and a first electric heater used for heating raw materials in the flow dividing channel is arranged on the side wall of the flow dividing base; a hot nozzle is arranged at the lower end of the flow dividing base, a valve hole is formed in the hot nozzle, the valve hole is coaxial with the discharging hole and communicated with the forming cavity, an air cylinder coaxial with the hot nozzle is vertically arranged at the upper end of the flow dividing base, and the output end of the air cylinder is connected with a valve needle in the valve hole and used for controlling the discharging end of the valve hole to be communicated or blocked with the forming cavity. The PLA in-mold crystallization injection mold disclosed by the utility model is compact in structure, capable of accurately controlling the crystallization process of PLA, high in injection molding efficiency and good in effect.

Description

Technical Field

[0001] The utility model relates to a mold, in particular to a PLA in-mold crystallization injection mold. Background Art

[0002] Polylactic acid, also known as polylactide, abbreviated as PLA in English, belongs to the polyester family. It is a polymer obtained by polymerization with lactic acid as the main raw material. The raw material source is sufficient and renewable. It has good biodegradability and environmentally friendly characteristics, so it is an ideal green polymer material. Polylactic acid can remain stable at room temperature and has good mechanical properties. It can eventually degrade into water and carbon dioxide under composting conditions without polluting the environment. Using polylactic acid to replace plastic is one of the most effective ways to reduce pollution and protect the environment.

[0003] The PLA injection mold in the prior art usually has only one liquid inlet channel. When multiple products need to be molded, multiple branch channels are processed in the mold, so that the feed channel branches into multiple branch channels in the mold and enters the cavity in sequence. The processing is inconvenient, the manufacturing cost is high, and it is difficult to control the crystallization of PLA, which affects the injection molding quality. Utility Model Content

[0004] Technical issues to be solved

[0005] The technical problem to be solved by the utility model is to provide a PLA in-mold crystallization injection mold which has a compact structure, low production cost, can form multiple products at the same time, and can effectively control the crystallization process.

[0006] Technical solutions to the problem

[0007] The utility model provides a PLA in-mold crystallization injection mold, which comprises an upper mold, a lower mold and a plurality of molding cavities arranged between the upper mold and the lower mold, wherein a mounting cavity 20 is formed in the upper mold, a shunt seat 6 is arranged in the mounting cavity 20, a gap is provided between the outer wall of the shunt seat 6 and the inner wall of the mounting cavity 20 and an air heat insulation zone is formed; a feed hole 601 is provided at the upper end of the shunt seat 6, the feed hole 601 is communicated with the sprue sleeve 5 on the upper mold and is used for feeding, and discharge holes 601 are provided at the bottom of the shunt seat 6, which are the same in number and correspond to the molding cavities one by one 2. The discharge hole 602 is connected with the feed hole 601 through the diverter channel 60, and the side wall of the diverter seat 6 is provided with a first electric heater 7 for heating the raw material in the diverter channel 60; a hot nozzle 91 is provided at the lower end of the diverter seat 6, and a valve hole is formed in the hot nozzle 91, and the valve hole is coaxial with the discharge hole 602 and connected with the molding cavity, and a cylinder 8 coaxial with the hot nozzle is vertically provided at the upper end of the diverter seat 6, and the output end of the cylinder 8 is connected with the valve needle 92 in the valve hole and is used to control the connection or blocking of the discharge end of the valve hole with the molding cavity.

[0008] Furthermore, there are multiple molding cavities that are evenly distributed circumferentially, and the discharge hole 602 is arranged directly above the molding cavity.

[0009] Furthermore, medium flow channels for cooling are provided in the upper mold and the lower mold.

[0010] Furthermore, the diverter seat 6 includes a main seat body, the feed hole 601 is opened on the main seat body, the side wall of the main seat body is circumferentially evenly distributed with sub-seat bodies with the same number as the molding cavity, and the discharge hole 602 and the first electric heater 7 are arranged on the sub-seat body.

[0011] Furthermore, the upper and lower ends of the sub-base body are provided with mounting grooves, and the first electric heater 7 is installed in the mounting grooves.

[0012] Furthermore, the first electric heater 7 is elliptical, racetrack-shaped or rectangular, and its length direction is parallel to the length direction of the branch channel 60 .

[0013] Furthermore, the upper die is provided with a mounting opening with an open upper end, and the cylinder is installed in the mounting opening.

[0014] Furthermore, a hole body 603 coaxial with the discharge hole 602 is provided at the upper end of the diverter seat 6, and the hole body 603 is a stepped hole. A support block 81 is provided in the hole body, and the top surface of the support block 81 is higher than the top surface of the diverter seat and forms an upper supporting surface, and an axial hole for accommodating the output shaft of the cylinder 8 to pass through is provided on the upper supporting surface.

[0015] Furthermore, the upper mold includes a first template 2 and a second template 3 installed on the lower surface of the first template 2. The lower bottom surface of the first template 2 and / or the upper surface of the second template 3 are concave inward to form the installation cavity. The bottom surface of the installation cavity is provided with a hot nozzle installation hole for installing a hot nozzle 91. The hot nozzle 91 is provided with a second electric heater, and there is a gap between the outer wall of the hot nozzle 91 and the inner wall of the hot nozzle installation hole.

[0016] Furthermore, a positioning portion for positioning is provided between the diverter seat 6 and the mounting cavity.

[0017] Beneficial Effects

[0018] The PLA in-mold crystallization injection mold of the utility model adopts a multi-cavity structure, can realize the simultaneous molding of multiple products, and has high production efficiency; adopts a split structure, is easy to process, has low manufacturing cost, and has high precision; a diverter seat is provided, can realize fast and uniform diversion, has good diversion effect, and has high product quality; an air insulation layer is provided, has a simple and compact structure, greatly reduces the contact area between the diverter seat and the mold, reduces thermal bridges, improves the temperature control efficiency and effect of the diverter channel, and has high injection molding quality; adopts a sub-seat body structure setting, can reduce the contact area between two adjacent sub-seat bodies, reduce the influence of thermal bridges, and improve the temperature control efficiency and effect of the diverter channel; a hidden cylinder structure setting has a compact structure, no convex structure, high safety in use, and long service life; the PLA in-mold crystallization injection mold of the utility model has a compact structure, can accurately control the crystallization process of PLA, and has high injection molding efficiency and good effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of the PLA in-mold crystallization injection mold of the utility model;

[0020] Figure 2 It is a cross-sectional view of the PLA in-mold crystallization injection mold of the utility model;

[0021] Figure 3 It is a schematic diagram of the installation of the manifold seat of the PLA in-mold crystallization injection mold of the utility model;

[0022] Figure 4 It is a schematic diagram of the exploded structure of the PLA in-mold crystallization injection mold of the utility model;

[0023] Figure 5 It is a cross-sectional view of the upper mold of the PLA in-mold crystallization injection mold of the utility model;

[0024] Figure 6 It is a partial enlarged view of the upper mold of the PLA in-mold crystallization injection mold of the utility model;

[0025] Figure 7 This is a schematic diagram of the installation of the first electric heater of the PLA in-mold crystallization injection mold of the utility model;

[0026] Figure 8 It is a structural schematic diagram of the manifold seat of the PLA in-mold crystallization injection mold of the utility model;

[0027] Fig. 9 It is a transverse cross-sectional view of the manifold seat of the PLA in-mold crystallization injection mold of the utility model. DETAILED DESCRIPTION

[0028] The following is a detailed description of the embodiments of the present utility model in conjunction with the accompanying drawings.

[0029] See also Figure 1-Figure 9The utility model provides a PLA in-mold crystallization injection mold, including an upper mold and a lower mold 4, a plurality of molding cavities are arranged between the upper mold and the lower mold, and a plurality of products can be molded simultaneously. A sprue bushing 5 is arranged on the top surface of the upper mold for connecting with an injection molding machine and realizing feeding. The plurality of molding cavities are evenly distributed circumferentially with the sprue bushing 5 as the axis. In this embodiment, there are four molding cavities.

[0030] A mounting cavity 20 is formed in the upper mold, and the mounting cavity is located at the upper end of the molding cavity. Specifically, the upper mold includes a first template 2 and a second template 3. The second template 3 is fitted and installed on the lower surface of the first template 2. The lower bottom surface of the first template 2 or the upper surface of the second template 3 is concave inward, thereby forming the above-mentioned mounting cavity 20. A diverter seat 6 is fixed in the mounting cavity 20. The thickness of the diverter seat 6 is less than the depth of the mounting cavity. There is a gap between the outer wall of the diverter seat 6 and the inner wall of the mounting cavity 20, thereby forming an air insulation zone. Specifically, there are gaps between the upper surface of the diverter seat 6 and the upper surface of the mounting cavity, between the lower surface of the diverter seat 6 and the lower surface of the mounting cavity, and between the side wall (side) of the diverter seat and the side wall of the mounting cavity, which avoids (reduces) the direct contact between the diverter seat 6 and the upper mold to generate a thermal bridge, and avoids heat transfer between the diverter seat and the upper mold, so as to quickly and accurately control the temperature of the diverter seat (flow channel) to accurately control the crystallization process of PLA.

[0031] A positioning portion is provided between the diverter seat 6 and the mounting cavity. The positioning portion may be a positioning protrusion, a positioning groove or a positioning pin, and is used to radially position the diverter seat to ensure the position accuracy of the feed hole and the discharge hole.

[0032] A feed hole 601 is provided at the upper end of the diverter seat 6, and the feed hole 601 is arranged at the center of the diverter seat, and is connected (jointed) with the gate sleeve 5 on the upper mold for feeding. A discharge hole 602 is provided at the bottom of the diverter seat 6. The number of the discharge holes 602 is the same as the number of molding cavities, and they correspond one to one, that is, one discharge hole 602 corresponds to one molding cavity, and is located directly above the molding cavity. Each discharge hole 602 is connected to the feed hole 601 through a diverter channel 60. At the same time, a first electric heater 7 is provided on the side wall of the diverter seat 6. The first electric heater 7 is used to heat the raw material in the diverter channel 60, that is, to control the feed temperature. Specifically, the diverter seat 6 includes a main seat body, the feed hole 601 is provided on the top surface of the main seat body, and sub-seat bodies are evenly distributed circumferentially on the side wall of the main seat body. The number of the seat body and the molding cavity is the same. In the present embodiment, the sub-seat body is a rectangular parallelepiped and is integrally formed with the main seat body. The two adjacent sub-seat bodies are not connected to avoid mutual influence, thereby improving the temperature control efficiency of the branch channel; the discharge hole 602 is arranged on the bottom surface of the sub-seat body, and the branch channel is arranged in the sub-seat body. In the present embodiment, the first electric heater 7 is arranged on the side wall of the sub-seat body. Specifically, an installation groove 62 is opened at the upper end and the lower end of the sub-seat body, and the first electric heater 7 is installed in the installation groove. In the present embodiment, the first electric heater is formed by bending a strip of metal. The first electric heater 7 is elliptical, runway-shaped or rectangular, and its length direction is parallel to the length direction of the branch channel 60, which can realize rapid and uniform heating of the branch channel; in the present embodiment, the branch seat is cross-shaped, that is, it has four sub-seat bodies.

[0033] A plurality of wire pressing plates are arranged in the installation cavity, which are used to fix the wires of the first electric heater so that the wires fit the inner wall of the installation cavity to avoid contact with the shunt seat and cause safety hazards; at the same time, holes are arranged on the side walls of the installation cavity for threading the wires and for dissipating heat in the installation area.

[0034] A hot nozzle 91 is provided at the lower end of the diverter seat 6. Specifically, the number of hot nozzles 91 is the same as that of the molding cavities and is installed at the lower end of the sub-seat body. The hot nozzle is a cylindrical structure. A valve hole is formed in the hot nozzle 91. The valve hole is coaxial with the discharge hole 602. The upper end is connected with the discharge hole, and the lower end is connected with the molding cavity. A valve needle 92 is provided in the valve hole. The axial movement of the valve needle controls the opening or closing of the discharge end of the hot nozzle and the connection or blocking with the molding cavity. A cylinder is provided at the upper end of the diverter seat 6. The cylinder is vertically arranged and coaxial with the hot nozzle. The output end of the cylinder 8 is connected to the valve needle 92 for controlling the axial movement of the valve needle, thereby controlling the connection or blocking between the discharge end of the valve hole and the molding cavity. A hole body 603 is provided at the upper end of the diverter seat 6 The hole body 603 is coaxial with the discharge hole 602, which is a stepped hole. A cylindrical support block 81 is arranged in the hole body. The top surface of the support block 81 is higher than the top surface of the diverter seat, forming an upper support surface for contacting with the top surface of the mounting cavity, thereby supporting the diverter seat. At the same time, an axial hole is opened on the upper support surface, which is coaxial with the discharge hole and can accommodate the output shaft of the cylinder 8 to pass through, so as to achieve connection with the valve needle; in this embodiment, an installation opening with an open upper end is opened on the upper mold (first template), and the cross-section of the installation opening is the center of a circle, which can just accommodate the insertion of the cylinder, and the cylinder is fixed in the installation opening by bolts; at the same time, an upper base plate 1 is installed on the top surface of the first template, and the upper base plate 1 is used to support and protect the cylinder.

[0035] A hot nozzle mounting hole is provided on the bottom surface of the mounting cavity, and the hot nozzle mounting hole is used to install a hot nozzle 91. A second electric heater is provided on the hot nozzle 91 for heating the raw material in the valve hole. At the same time, there is a gap between the outer wall of the hot nozzle 91 and the inner wall of the hot nozzle mounting hole, forming another air insulation zone to avoid heat transfer with the mold; in this embodiment, the hot nozzle mounting hole is a stepped hole, and an annular protrusion is provided on the upper side wall of the hot nozzle. The outer diameter of the annular protrusion is the same as the aperture of the large hole at the upper end of the stepped hole, that is, it can just accommodate the insertion of the annular protrusion, thereby realizing radial positioning of the hot nozzle, and the lower end of the annular protrusion contacts the step surface of the large hole of the stepped hole, thereby realizing axial support, and the top surface of the hot nozzle is higher than the bottom surface of the mounting cavity, thereby realizing support for the diverter seat, thereby forming a gap between the lower bottom surface of the diverter seat and the lower bottom surface of the mounting cavity.

[0036] Medium flow channels are provided in the upper mold and the lower mold, and the medium flow channels are used for cooling to control the internal temperature, thereby controlling the crystallization process of PLA and improving the injection molding quality.

[0037] The PLA in-mold crystallization injection mold of the utility model adopts a multi-cavity structure, can realize the simultaneous molding of multiple products, and has high production efficiency; adopts a split structure, is easy to process, has low manufacturing cost, and has high precision; a diverter seat is provided, can realize fast and uniform diversion, has good diversion effect, and has high product quality; an air insulation layer is provided, has a simple and compact structure, greatly reduces the contact area between the diverter seat and the mold, reduces thermal bridges, improves the temperature control efficiency and effect of the diverter channel, and has high injection molding quality; adopts a sub-seat body structure setting, can reduce the contact area between two adjacent sub-seat bodies, reduce the influence of thermal bridges, and improve the temperature control efficiency and effect of the diverter channel; a hidden cylinder structure setting has a compact structure, no convex structure, high safety in use, and long service life; the PLA in-mold crystallization injection mold of the utility model has a compact structure, can accurately control the crystallization process of PLA, and has high injection molding efficiency and good effect.

[0038] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A PLA in-mold crystallization injection mold, characterized in that: The invention comprises an upper die, a lower die and a plurality of molding cavities arranged between the upper die and the lower die, wherein an installation cavity is formed in the upper die, a diverter seat is arranged in the installation cavity, a gap is provided between the outer wall of the diverter seat and the inner wall of the installation cavity and an air heat insulation zone is formed; a feed hole is provided at the upper end of the diverter seat, the feed hole is connected with the gate sleeve on the upper die and is used for feeding, discharge holes which are the same in number as the molding cavities and correspond to each other in one to one are provided at the bottom of the diverter seat, the discharge holes are connected with the feed holes through a diverter channel, a first electric heater for heating the raw material in the diverter channel is provided on the side wall of the diverter seat; a hot nozzle is provided at the lower end of the diverter seat, a valve hole is formed in the hot nozzle, the valve hole is coaxial with the discharge hole and is connected with the molding cavity, a cylinder which is coaxial with the hot nozzle is vertically arranged at the upper end of the diverter seat, the output end of the cylinder is connected with the valve needle in the valve hole and is used to control the connection or blocking between the discharge end of the valve hole and the molding cavity.

2. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: There are multiple molding cavities that are evenly distributed in the circumferential direction, and the discharge holes are arranged directly above the molding cavities.

3. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: The upper mold and the lower mold are provided with medium flow channels for cooling.

4. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: The diverter seat includes a main seat body, the feed hole is opened on the main seat body, the side wall of the main seat body is circumferentially evenly distributed with sub-seat bodies with the same number as the molding cavity, and the discharge hole and the first electric heater are arranged on the sub-seat body.

5. The PLA in-mold crystallization injection mold according to claim 4, characterized in that: The upper end and the lower end of the sub-base body are provided with mounting grooves, and the first electric heater is mounted in the mounting grooves.

6. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: The first electric heater is elliptical, racetrack or rectangular, and its length direction is parallel to the length direction of the branch channel.

7. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: The upper die is provided with a mounting opening with an open upper end, and the cylinder is mounted in the mounting opening.

8. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: A hole body coaxial with the discharge hole is provided at the upper end of the diverter seat, and the hole body is a stepped hole. A support block is provided in the hole body, and the top surface of the support block is higher than the top surface of the diverter seat and forms an upper support surface. An axial hole for the output shaft of the cylinder to pass through is provided on the upper support surface.

9. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: The upper mold includes a first template and a second template installed on the lower surface of the first template. The lower bottom surface of the first template and / or the upper surface of the second template are concave inward to form the installation cavity. The bottom surface of the installation cavity is provided with a hot nozzle installation hole for installing a hot nozzle. The hot nozzle is provided with a second electric heater, and there is a gap between the outer wall of the hot nozzle and the inner wall of the hot nozzle installation hole.

10. The PLA in-mold crystallization injection mold according to claim 1, characterized in that: A positioning portion for positioning is provided between the diverter seat and the mounting cavity.

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