A melt injection unit and injection mold

Abstract

A melt injection unit and injection mold, belonging to the field of injection molding technology, includes a nozzle structure, a valve needle, a heating structure, and a valve needle drive structure. The nozzle structure has an injection port for melt to flow out. The valve needle enters the nozzle structure and is adapted to the injection port. The valve needle drive structure is connected to the valve needle and is used to drive the valve needle to move, thereby opening and closing the injection port of the nozzle structure. The heating structure provides heat to the nozzle structure to keep the melt inside the nozzle structure in a molten state. By setting a guide structure inside the nozzle structure, the reciprocating movement of the valve needle is guided, keeping the valve needle coaxial with the nozzle structure. This reduces the impact of processing errors or actual process temperature deviations on the coaxiality of the valve needle and nozzle structure; furthermore, it reduces wear between the valve needle and the cold mold runner, thereby improving mold life and improving the yield and quality of the products.

Description

Technical Field

[0001] This invention belongs to the field of injection molding technology, specifically relating to a melt injection unit and an injection mold. Background Technology

[0002] Injection molding, also known as injection molding, is a molding method that combines injection and molding. The advantages of injection molding include high production speed and efficiency, automated operation, a wide variety of designs and shapes (from simple to complex), and sizes ranging from large to small. It also produces dimensionally accurate products, facilitates product updates and replacements, and can create complex shapes. Injection molding is suitable for mass production and molding processes involving complex shapes.

[0003] An existing injection mold features a needle valve type nozzle structure, as shown in Chinese patent document No. 202123110167.8. This needle valve type nozzle structure includes a mold cavity plate, a hot runner plate, a back plate, a cold mold, a needle valve assembly, a drive assembly, and a heat insulation sleeve. The needle valve assembly further includes a bushing and a needle valve. The bushing is disposed within the hot runner plate, with one end connected to the sprue seat and the other end connected to the drive assembly. The needle valve passes through the sprue seat, nozzle, and bushing. The bushing and needle valve, the sprue seat and needle valve, and the nozzle and needle valve cooperate to form an injection flow channel. The drive assembly pushes the needle valve to reciprocate axially within the nozzle, thereby pushing the material in the injection flow channel into the discharge chamber, completing the injection molding. During operation, this nozzle structure requires that the cold mold, nozzle, and needle valve maintain a coaxial arrangement. However, in the existing technology, the nozzle structure is difficult to achieve theoretical coaxiality due to processing errors or deviations between the actual process temperature and the design process temperature. This makes it easy for a certain degree of coaxiality deviation to occur between the cold mold, the nozzle, and the needle valve. During the reciprocating motion of the needle valve, it will cause wear on the injection port of the cold mold, leading to damage to the cold mold. This, in turn, will result in defects such as flash and peeling at the gate of the product, affecting the yield and quality of the product. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a melt injection unit and an injection mold.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A melt injection unit includes a nozzle structure, a valve needle, a heating structure, and a valve needle drive structure. The nozzle structure has an injection port for melt to flow out. The valve needle enters the nozzle structure and is adapted to the injection port. The valve needle drive structure is connected to the valve needle and is used to drive the valve needle to move to open and close the injection port of the nozzle structure. The heating structure provides heat to the nozzle structure to keep the melt inside the nozzle structure in a molten state. The nozzle structure has a guide structure with a guide hole for the valve needle to pass through and be guided coaxially.

[0007] In this invention, the nozzle structure includes a nozzle, a nozzle base, and a hollow channel penetrating the nozzle structure. The hollow channel and a portion of the outer surface of the valve needle together define a melt channel. The nozzle has a glue inlet communicating with the hollow channel and a connecting part for connecting the nozzle base at both ends. The nozzle base has an installation end for defining the melt channel inlet and a connecting end for cooperating with the connecting part at both ends.

[0008] In this invention, the guide structure is disposed between the mounting end and the connecting end, the guide structure is located within the melt channel, and the guide structure has a guide hole coaxial with the melt channel, a through hole for defining part of the melt channel, and a support rib located between the through holes.

[0009] In this invention, the guide structure has multiple through holes arranged around the outer periphery of the guide hole, and the through holes are rotationally symmetrical about the central axis of the guide structure.

[0010] In this invention, a first arc transition section is provided at the end of the through hole facing the melt channel inlet, and the first arc transition section is used to guide the melt into the through hole; a second arc transition section is provided at the end of the through hole facing the dispensing port, and the second arc transition section is used to guide the melt out of the through hole.

[0011] In this invention, the connecting part and the connecting end are mutually adapted stepped structures. After the connecting part and the connecting end are connected, they have inner surfaces of the same diameter at the joint. The inner surfaces of the connecting part and the connecting end are tightly joined, making the inner surfaces at this position continuous. However, there is a gap at the joint of the outer surfaces of the connecting part and the connecting end, making the outer surfaces at the joint of the connecting part and the connecting end disconnected.

[0012] In this invention, the melt channel includes an inlet section, a first transition section, a guide section, a second transition section, a horizontal flow section, a third transition section, and a nozzle section that are connected in sequence.

[0013] In this invention, the flow cross-sectional areas of the inlet section, the first transition section, and the guide section are all greater than the flow cross-sectional area of ​​the advection section; the flow cross-sectional areas of the guide section and the inlet section are equal.

[0014] In this invention, the nozzle base is a structure formed by welding the nozzle sleeve, guide block and nozzle insert into one piece, or the nozzle base is manufactured by additive manufacturing technology.

[0015] Based on the melt injection unit provided by the present invention, the present invention also provides an injection mold, including a cold half mold and a hot half mold, wherein the cold half mold defines at least one molding cavity, the hot half mold includes a runner and at least one melt injection unit as described above, the melt injection unit is adapted to the molding cavity, the injection port of the melt injection unit is connected to the molding cavity through the sprue, and the melt channel of the melt injection unit is connected to the runner.

[0016] The beneficial effects of this invention are: by setting a guide structure inside the nozzle structure, the reciprocating movement of the valve needle is guided by the guide structure, so that the valve needle is kept coaxial with the nozzle structure, reducing the influence of machining errors or actual process temperature deviations on the coaxiality of the valve needle and nozzle structure; thereby reducing the wear between the valve needle and the cold half-mold sprue, thereby improving the mold life, and at the same time improving the yield and quality of the products. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the melt injection unit in this embodiment;

[0018] Figure 2 This is a schematic diagram of the nozzle structure in this embodiment;

[0019] Figure 3 This is a schematic diagram of the melt channel structure in this embodiment;

[0020] Figure 4 This is a schematic diagram of the nozzle structure in this embodiment;

[0021] Figure 5 This embodiment presents a schematic diagram of the nozzle base structure.

[0022] Figure 6 This is a schematic diagram of the guide block in this embodiment;

[0023] Figure 7 This is a schematic diagram of the nozzle cover structure in this embodiment;

[0024] Figure 8 This is a schematic diagram of the valve needle in this embodiment;

[0025] Figure 9 This is a schematic diagram of the injection mold in this embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0027] like Figures 1 to 8 As shown, this embodiment discloses a melt injection unit, including a nozzle structure 1, a valve needle 2, a heating structure 3, and a valve needle drive structure 4. The nozzle structure 1 has a filling port 111 for melt to flow out. The valve needle 2 enters the nozzle structure 1 and is connected to the filling port 111. The valve needle drive structure 4 is connected to the valve needle 2 and is used to drive the valve needle 2 to move, thereby opening and closing the filling port 111 of the nozzle structure 1. The heating structure 3 is fitted outside the nozzle structure 1 and is used to provide heat to the nozzle structure 1, keeping the melt inside the nozzle structure 1 in a molten state. The nozzle structure 1 has a guide structure 5, in which a guide hole 511 is provided for the valve needle 2 to pass through and be guided coaxially. The nozzle structure 1 includes a nozzle 11, a nozzle base 12, and a hollow channel 13 penetrating the nozzle structure 1. The hollow channel 13 and a portion of the outer surface of the valve needle 2 together define a melt channel 14. The nozzle 11 has a glue inlet 111 communicating with the hollow channel 13 and a connecting part 112 for connecting the nozzle base 12 at both ends. The nozzle base 12 has an installation end 121 for defining the inlet of the melt channel 14 and a connecting end 122 for cooperating with the connecting part 112 at both ends. A guide structure 5 is disposed between the installation end 121 and the connecting end 122. The guide structure 5 is located inside the melt channel 14 and has a guide hole 511 coaxial with the melt channel 14, a through hole 512 for defining a portion of the melt channel 14, and a support rib 513 located between the through holes 512. The nozzle 11 and the nozzle base 12 are connected by a connecting part 112 and a connecting end 122. The valve needle 2 is inserted into the nozzle structure 1 through the hollow channel 13 to form a melt channel 14 for melt flow. The valve needle 2 passes through the guide hole 511 of the guide structure 5. The valve needle 2 is adapted to the guide hole 511. The guide hole 511 guides the reciprocating movement of the valve needle 2, ensuring the coaxiality of the valve needle 2 with the hollow channel 13 during reciprocating movement. This avoids wear on the injection port 111 of the nozzle 11 and the sprue 61 of the cold half mold 6 during the reciprocating movement of the valve needle 2, effectively extending the service life of the mold and ensuring the yield and quality of the products.

[0028] In a preferred embodiment, the guide structure 5 has a plurality of through holes 512 arranged around the outer periphery of the guide hole 511, and the through holes 512 are rotationally symmetrical about the central axis of the guide structure 5. A first arc transition section 123 is provided at the end of the through hole 512 facing the inlet of the melt channel 14, which guides the melt into the through hole 512. A second arc transition section 124 is provided at the end of the through hole 512 facing the dispensing port 111, which guides the melt out of the through hole 512 and also has a pressurizing effect.

[0029] In a preferred embodiment, the connecting portion 112 and the connecting end 122 are connected by a threaded connection. The connecting portion 112 and the connecting end 122 are mutually adaptable stepped structures. After the connecting portion 112 and the connecting end 122 are connected, they have inner and outer surfaces of the same diameter at the contact point. The inner surfaces of the connecting portion 112 and the connecting end 122 are tightly engaged, making the inner surface at this position continuous, thereby making the melt channel 14 defined by this part continuous. However, there is a gap at the contact point of the outer surfaces of the connecting portion 112 and the connecting end 122, thereby making the outer surface at the contact point of the connecting portion 112 and the connecting end 122 disconnected. Even when the connecting portion 112 and the connecting end 122 are screwed together, the length of the screw-in portion is longer than the length of the outer portion, thereby ensuring that when the connecting portion 112 and the connecting end 122 are fully engaged and tightened, a tightly engaged contact surface can be formed at the contact point of the inner surfaces.

[0030] In this embodiment, the melt channel 14 includes an inlet section 141, a first transition section 142, a guide section 143, a second transition section 144, a horizontal flow section 145, a third transition section 146, and a nozzle section 11, which are connected in sequence. The inlet section 141 is composed of one or more sequentially connected hollow cylindrical channels. If the inlet section 141 is composed of multiple sequentially connected hollow cylindrical channels, adjacent hollow cylindrical channels are connected by a hollow frustum channel. The first transition section 142 is composed of a hollow frustum channel, and its guide section 143 is connected to it. The guide section 143 is defined by a through hole 512 of the guide structure 5. The second transition section 144 is composed of a hollow frustum channel, and its larger end is connected to the guide section 143. The horizontal flow section 145 is composed of one or more sequentially connected hollow cylindrical channels. If it is composed of multiple connected hollow cylindrical channels, adjacent hollow cylindrical channels are connected by a hollow frustum channel. The third transition section 146 is composed of a hollow frustum-shaped channel, and its larger end connects to the horizontal flow section 145. The nozzle 11 section is cylindrical, and its diameter is the same as the diameter of the functional section 22 of the valve needle 2. The flow cross-sectional areas of the inlet section 141, the first transition section 142, and the guide section 143 are all larger than the flow cross-sectional area of ​​the horizontal flow section 145. Preferably, the flow cross-sectional areas of the guide section 143 and the inlet section 141 are substantially equal or equal. The first contact surface formed at the junction of the first transition section 142 and the guide section 143, and the second contact surface formed at the junction of the second transition section 144 and the guide section 143, have outer radii equal to the outer radius of the first contact surface, the outer radius of the second contact surface, and the outer radius of the through hole 512.

[0031] In a preferred embodiment, the nozzle base 12 is integrally formed by welding the nozzle sleeve 15, guide block 51, and nozzle insert 16, or the nozzle base 12 is manufactured using additive manufacturing technology. During maintenance and use, both sides of the guide block 51 are always in close contact with the nozzle sleeve 15 and nozzle insert 16, and the position of the guide block 51 will not shift. Therefore, problems such as melt or even fine melt entering the gaps on both sides of the guide block 51 due to changes in the position of the guide block 51, causing the guide block 51 to become eccentric and affecting its positioning and guiding function, and aggravating wear between the valve needle 2, the guide block 51, and the injection port 111, are not encountered in the melt injection unit, thus ensuring a long service life for the melt injection unit.

[0032] In a preferred embodiment, the nozzle sleeve 15 has a receiving cavity 151 and defines an inlet section 141 and a first transition section 142. A guide block 51 defines a guide structure 5, and a guide hole 511 is provided along the central axis of the guide block 51. The nozzle insert 16 defines at least a connecting end 122 and a second transition section 144; the nozzle insert 16 and the guide block 51 are mounted in the receiving cavity 151, one end face of the guide block 51 contacts the bottom of the receiving cavity 151, the outer periphery of the guide block 51 contacts a portion of the sidewall of the receiving cavity 151, and one end of the second transition section 144 of the nozzle insert 16 abuts against the other end face of the guide block 51; the nozzle insert 16 also defines a partial advection section 145.

[0033] In a preferred embodiment, the valve needle 2 includes a drive section 21, a functional section 22, a tapered section 23, and a mating section 24 connected in sequence. The drive section 21 is used to connect with the valve needle drive structure 4; the functional section 22 is used to connect with the hollow channel 13 to define the melt channel 14; the tapered section 23 is used to guide the functional section 22 into the injection port 111, the diameter of the large end of the tapered section 23 is equal to the diameter of the functional section 22, and the diameter of the small end of the tapered section 23 is equal to the diameter of the mating section 24; the mating section 24 is used to connect with the sprue 61 of the cold mold half 6.

[0034] like Figure 9 As shown, based on the melt injection unit disclosed in the above embodiment, this embodiment also discloses an injection mold, including a cold half mold 6 and a hot half mold 7. The cold half mold 6 defines at least one molding cavity. The hot half mold 7 includes a runner and at least one melt injection unit as described above. The melt injection unit is adapted to the molding cavity. The injection port 111 of the melt injection unit is connected to the molding cavity through the sprue port 61. The melt channel 14 of the melt injection unit is connected to the runner.

[0035] The above are merely preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by essentially the same means is within the protection scope of the present invention.

Claims

1. A melt injection unit, comprising a nozzle structure, a valve needle, a heating structure, and a valve needle driving structure, wherein the nozzle structure has an injection port for melt to flow out, the valve needle enters the nozzle structure and is adapted to the injection port, the valve needle driving structure is connected to the valve needle, the valve needle driving structure is used to drive the valve needle to move to open and close the injection port of the nozzle structure, and the heating structure is used to provide heat to the nozzle structure, characterized in that: The nozzle structure is provided with a guide structure, and the guide structure has a guide hole for the valve needle to pass through and be guided in a coaxial manner. The nozzle structure includes a hollow channel penetrating the nozzle structure, and the hollow channel and a portion of the outer surface of the valve needle jointly define a melt channel; the melt channel includes an inlet section, a first transition section, a guide section, a second transition section, a horizontal flow section, a third transition section, and a nozzle section connected in sequence; the flow cross-sectional area of ​​the inlet section, the first transition section, and the guide section is larger than the flow cross-sectional area of ​​the horizontal flow section; the flow cross-sectional area of ​​the guide section is equal to that of the inlet section; the first transition section is formed by a hollow frustum-shaped channel, and the first transition section is connected to the guide section; the second transition section is formed by a hollow frustum-shaped channel, and the larger end of the second transition section is connected to the guide section.

2. The melt injection unit according to claim 1, characterized in that: The nozzle structure includes a nozzle and a nozzle base. The nozzle has a glue inlet at both ends that communicates with the hollow channel and a connecting part for connecting to the nozzle base. The nozzle base has an installation end for defining the melt channel inlet and a connecting end for cooperating with the connecting part.

3. The melt injection unit according to claim 2, characterized in that: The guide structure is disposed between the mounting end and the connecting end, and is located within the melt channel. The guide structure has a guide hole coaxial with the melt channel, a through hole for defining part of the melt channel, and a support rib located between the through holes.

4. The melt injection unit according to claim 3, characterized in that: The guide structure has multiple through holes arranged around the outer periphery of the guide hole, and the through holes are rotationally symmetrical about the central axis of the guide structure.

5. A melt injection unit according to claim 3, characterized in that: The end of the through hole facing the melt channel inlet is provided with a first arc transition section, which is used to guide the melt into the through hole; the end of the through hole facing the dispensing port is provided with a second arc transition section, which is used to guide the melt out of the through hole.

6. A melt injection unit according to claim 2, characterized in that: The connecting part and the connecting end are mutually adapted stepped structures. After the connecting part and the connecting end are connected, they have inner surfaces of the same diameter at the joint. The inner surfaces of the connecting part and the connecting end are tightly joined, making the inner surfaces of the connecting part and the connecting end continuous. However, there is a gap at the joint of the outer surfaces of the connecting part and the connecting end, making the outer surfaces of the connecting part and the connecting end disconnected.

7. A melt injection unit according to claim 2, characterized in that: The nozzle base is a structure formed by welding the nozzle sleeve, guide block and nozzle insert into one piece, or the nozzle base is manufactured by additive manufacturing technology.

8. An injection mold comprising a cold mold half and a hot mold half, wherein the cold mold half defines at least one molding cavity, characterized in that: The hot semi-mold includes a runner and at least one melt injection unit as described in any one of claims 1-7. The melt injection unit is adapted to the molding cavity. The injection port of the melt injection unit is connected to the molding cavity through the sprue. The melt channel of the melt injection unit is connected to the runner.

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