Injection nozzle
By designing an adjustable injection nozzle structure, the problems of nozzle wear and thermal expansion were solved, enabling efficient and low-cost thermoplastic material molding and ensuring the production of high-quality plastic parts.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- OTTOMANN GMBH
- Filing Date
- 2022-03-15
- Publication Date
- 2026-05-12
AI Technical Summary
Existing injection nozzles are prone to wear during the molding of thermoplastic materials, leading to damage to the molding tools, high repair or replacement costs, and difficulty in adapting to the needs of different thermoplastic materials at different operating temperatures.
An injection nozzle has been designed, comprising a sleeve-shaped front section and a rear section. Through an adjustable spacer and a needle component centering device, the nozzle can achieve precise alignment with the cavity and thermal expansion compensation, reducing wear and supporting the molding requirements of different materials.
It improves the service life of injection nozzles, reduces maintenance costs, ensures high-quality molding of plastic parts, and adapts to the operating temperatures of different thermoplastic materials.
Smart Images
Figure CN116963892B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of injection nozzles for injection molding of thermoplastic materials, particularly polyolefins. Background Technology
[0002] Mold Masters Ltd.'s EP0873841A2, published in 1998, relates to a valve-gated injection molding apparatus featuring a valve member with a cylindrical front end. An integral insert mounted at the nozzle tip has a gate and locating blades extending inward from an outer body into a central opening leading to the gate. The inner surface of the blades is fitted around the tip of a reciprocating valve needle to guide and precisely position it aligned with the gate. Maintaining the tip of the reciprocating valve needle precisely aligned with the gate, making it cylindrical rather than conical, produces cleaner gate marks.
[0003] Mold Masters Ltd. disclosed EP1990175A1 in November 2008, relating to an injection molding apparatus comprising a valve-gated nozzle with a nozzle head assembly and a valve pin slidably disposed therein. The nozzle head assembly includes a nozzle bushing having a first valve pin guide portion, a valve pin guide having a second valve pin guide portion located upstream of the first valve pin guide portion, and a transfer seal having an orifice for receiving the nozzle bushing and the valve pin guide therein. The transfer seal orifice includes alignment surfaces surrounding the nozzle bushing and the valve pin guide to align the first and second valve pin guide portions with the mold gate, such that the valve pin is precisely aligned during operation. The transfer seal also includes means for connecting the nozzle head assembly to the nozzle body.
[0004] In Glass AG, in April 2017, published DE102016219833A1, which relates to a nozzle end of an injection molding machine. The injection molding machine includes a tip and an annular nut, each having a distal end, one of which is configured to connect to a gate of a molding cavity, engages with an open / close end of a valve needle of the injection molding machine, and has a total thickness in cross-section equal to or less than the thickness of the cross-section of the open / close end of the valve needle. Summary of the Invention
[0005] Injection nozzles for injection molding thermoplastic materials, particularly polyolefins, are arranged within expensive and precision-manufactured molding tools during operation to inject molten thermoplastic material into the cavity of the molding tool. The cavity, having a cavity profile, defines the shape of the plastic part formed therein after solidification by the injected molten plastic material. To accurately eject the molten material, the nozzle is fluidly interconnected with the cavity via a gate, which can be opened and closed by a movable needle component of the respective nozzle. To avoid wear on the molding tool, each gate is formed as part of the nozzle head facing the cavity; nozzle repair or replacement costs are lower compared to molding tools with damaged gates. To produce high-quality plastic parts with virtually undetectable injection marks originating from the gate into the cavity, the nozzle should form a horizontal or slightly concave surface with the cavity during operation. Therefore, injection nozzles are preferably designed to account for thermal expansion and thus achieve good alignment with the cavity during operation.
[0006] A preferred variation of the injection nozzle according to this disclosure includes a housing, particularly suitable for mounting in a corresponding injection molding tool. The housing includes a cylindrical rear section and a coaxially arranged sleeve-shaped front section surrounding a central channel extending in an axial direction. In the central channel, a needle member is arranged axially movable between a retracted open position and an extended closed position, in which the gate at the nozzle head of the front section is sealed shut by the front end of the needle member. A spacer is arranged between the rear and front sections, defining the total axial length of the nozzle.
[0007] The spacer is preferably designed to be replaceable, such that the overall length of the housing can be adjusted by replacing and / or adjusting the spacer to different lengths in the axial direction. The spacer can be multi-part. By having an adjustable overall nozzle length, the thermal expansion of the nozzle during operation can be predicted and / or compensated. This allows for the processing of different thermoplastic materials requiring different operating temperatures using nozzles mounted in the same injection molding tool.
[0008] Depending on the application, the spacer includes a ring and / or a bushing and / or a washer, etc. Typically, the spacer is at least partially made of a rigid material, such as metal, particularly steel. The thermal coefficient of the spacer is preferably similar to that of the housing, particularly the front section, such that the expansion of the spacer is similar to the thermal expansion of the material used for the housing.
[0009] In a preferred variation, the nozzle head of the front segment is combined with the front end of the needle component to form a molding profile for embedding into a cavity profile during operation. As previously mentioned, the cavity profile at least partially defines the manufactured plastic part, particularly its external shape. The gate here is formed by the nozzle head of the front segment. Because the gate is integrated into the nozzle head, it can be easily replaced in case of wear, for example, caused by the needle component. The nozzle head is typically integrally formed with the front segment; however, a separate nozzle head or nozzle head assembly is also possible. Thus, the front segment can be a multi-part design if appropriate. For example, the front segment includes an external component and a separate nozzle head element, which is detachably connected to the external component, particularly by a fixing device. This allows, for example, replacement of only the nozzle head element of the nozzle in case of wear, rather than replacing the entire front segment. Furthermore, depending on the specific cavity profile, the nozzle head element can be selected to combine with the needle component to form a matching molding profile, while the external component can be generic and independent of this. According to the design, the fixing device includes a flange that, in the assembled state, is axially arranged at the nozzle head element between the spacer and the inwardly projecting part of the external component. The nozzle head element can be connected to the external component from either the inside or the outside. Good results can be obtained when it is inserted from the rear section into the external component opposite the nozzle head.
[0010] In the closed position, the tip of the needle component is preferably flush with the nozzle head of the front section. This avoids undesirable injection marks on the plastic part caused by any axial displacement of the tip of the needle component relative to the nozzle head.
[0011] When the axial length of the spacer is configurable to compensate for the axial thermal expansion of the assembled housing and nozzle, good results can be obtained, allowing the molding profile to be fitted into the cavity profile in an adjustable manner, particularly flush, with respect to a specific operating temperature of a thermoplastic material. In some variations, the total length of the housing can be configured by the length of the spacer, such that the molding profile extends beyond the cavity profile into the cavity. If required, this even allows the manufacture of plastic parts with a slightly recessed shape in the injection mark area. The spacer typically allows compensation for the thermal expansion effects of a particular application. Furthermore, the axial position of the molding profile can be adjusted to compensate for the thermal expansion of the housing. It should be noted that the axial position of the tip of the needle component in the closed position is also typically configurable. The spacer can be a multi-part design, allowing its axial length to be increased by adding additional parts or decreased by removing parts. In other embodiments, the length of the spacer can be configured by a cutting process such as grinding.
[0012] To further reduce wear on the gate and the needle component, the nozzle includes a needle component centering device. In some variations, the needle component centering device includes at least one channel for the melt to pass through it. The needle component centering device is typically arranged axially between the spacer and the gate to center the needle component radially during operation as it moves between the open and closed positions. This allows the needle component to remain centered, if suitable. Preferably, the needle component centering device is arranged close to the nozzle head, particularly adjacent to the nozzle tip. Here, the needle component centering device may be arranged in a recess in the front section. This eliminates the predetermined center of needle component wear during operation, for example, through the tapered portion of the central channel, when moving between the open and closed positions.
[0013] In some variations, the needle centering device is designed as a separate element inserted into the front section of the housing opposite the gate. This allows the needle centering device to be removed, for example, if replacement is required. In turn, this reduces manufacturing effort and associated costs because the needle centering device can be machined in a separate (optimized) cutting process. However, the needle centering device and the front section can also be manufactured as a single component, for example, by additive manufacturing. The needle centering device is preferably annular. This allows for a coaxial arrangement with the central channel within the central channel, wherein the outer surface of the annular needle centering device is supported by the central channel of the front section during operation.
[0014] To avoid any undesirable misalignment of the needle component centering device relative to the central channel, the needle component centering device is preferably sandwiched between a shoulder of the recess and the spacer. The shoulder is typically formed as a radially inwardly extending circumferential protrusion. The recess is preferably located near the nozzle head of the front section, making it possible to permanently center the needle component in the axial direction using the needle component centering device. This further improves the radial alignment of the needle component's tip relative to the gate.
[0015] The needle component centering device typically includes at least one fin extending in the radial direction. The fin usually extends substantially straight relative to the axial direction; however, it may also extend in a curved manner about a central axis in the axial direction. Typically, the at least one fin includes an internal guide surface that centers the needle component in a radially centered position during operation. Preferably, the guide surface is substantially parallel to the needle component, minimizing wear in the event of direct contact between the needle component and the guide surface. To achieve this, when the needle component has, for example, a circular cross-section, the guide surface has a corresponding curvature at least in a region. To reduce the flow resistance of the molten plastic material through the needle component guiding device, the at least one fin may include a tapered edge in the axial direction.
[0016] Good performance is possible when the needle component centering device comprises at least two fins, particularly three fins spaced apart from each other in the circumferential direction. The respective guide surfaces of the fins provide circumferential support in the radial direction for the needle component, which is movably arranged in the axial direction between them. Typically, the guide device has rotational symmetry about the axial direction. In the case of three fins, the fins are preferably arranged circumferentially spaced apart from each other.
[0017] Alternatively or additionally, the needle component centering device includes an inner ring and an outer ring spaced apart from each other by at least one bridging member. The inner ring may include a guide surface facing the needle component and having a corresponding curvature. Typically, one to four bridging members support the inner ring relative to the outer ring.
[0018] The spacer and / or the guide may include an engagement profile for engaging with a corresponding tool for removal or replacement. Due to the typically small tolerances of these components, removal is generally not possible without damaging the spacer, the needle assembly centering device, and other components of the nozzle, especially after use. The engagement profile allows for the precise application of force (linear in the axial direction and / or torque about the axial direction) to remove the spacer and / or the guide, particularly from the central channel. The engagement profile may be formed as a thread or a polygonal profile, such as a hexagon. Typically, the engagement profile is arranged at the rearward-facing ends of the spacer and the needle assembly guide.
[0019] If appropriate, the rear section includes an external thread, and the front section includes an internal thread, which engages with the external thread in the mounting position for connecting the front and rear sections to each other. Preferably, the front section is detachable from the rear section, particularly by loosening the threads between them. Preferably, the spacer includes a rear sealing surface and a front sealing surface located in the mounting position, which mate with the front and rear sections to prevent leakage of molten thermoplastic material from the central channel. Depending on the application, the spacer is arranged in the central channel and forms part of the melt channel. This prevents leakage from the central channel. Furthermore, the spacer also prevents unwanted flow of molten plastic material between the internal and external threads of the front and rear sections.
[0020] A first variation of the injection molding tool according to this disclosure for injection molding thermoplastic materials, particularly polyolefin materials, includes at least one cavity having a cavity profile that at least partially defines a plastic part formed therein by molten thermoplastic material. The injection molding tool further includes at least one injection nozzle, as described above, arranged adjacent to the cavity for supplying molten thermoplastic material to the cavity, the injection nozzle forming at least a portion of the cavity profile.
[0021] It should be understood that the foregoing general description and the following detailed description present embodiments and are intended to provide an overview or framework for understanding the nature and features of this disclosure. The accompanying drawings are included to provide a further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles and operation of the disclosed concepts. Attached Figure Description
[0022] The disclosure described herein will be more fully understood from the detailed description and accompanying drawings given below, which should not be construed as limiting the disclosure described in the appended claims. The drawings show:
[0023] Figure 1 Partial sectional and perspective views of a first variation of an injection nozzle according to this disclosure are shown;
[0024] Figure 2 The box K is shown. Figure 1 Detailed view of the first variation;
[0025] Figure 3 An exploded diagram of the first variation is shown;
[0026] Figure 4 A cross-sectional view of a first variation of an injection molding tool according to the present disclosure is shown, including a second variation of an injection nozzle according to the present disclosure;
[0027] Figure 5 The box T shows the diagram. Figure 4 Detailed view;
[0028] Figure 6 A second variation of the nozzle according to this disclosure is shown; and
[0029] Figure 7 It shows Figure 6 The second variation is a cross-sectional view along the section line UU. Detailed Implementation
[0030] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, which show some, but not all, of the features. In fact, the embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Wherever possible, similar reference numerals will be used to refer to similar parts or components.
[0031] Figure 1 Partial cross-sectional and perspective views of a first variation of nozzle 1 according to this disclosure are shown. Figure 2 The box K is shown. Figure 1 A detailed view of the first variation.
[0032] Figure 3 An exploded view of the first variation of the injection nozzle 1 is shown. Figure 4 A cross-sectional view of a first variation of the injection molding tool 23 according to the present disclosure is shown, including a second variation of the injection nozzle 1 according to the present disclosure. Figure 5 It shows Figure 4 The detailed view shown in box P. Figure 6 A second variation of nozzle 1 according to this disclosure is shown. Figure 7 It shows Figure 6 The second variation is a cross-sectional view along the section line UU.
[0033] A first variation of the injection nozzle 1 includes a housing 1 adapted for mounting in a corresponding injection molding tool 23 adjacent to a cavity 24, such as... Figure 4 As shown. Figures 1 to 3 As shown, the housing typically includes a cylindrical rear section 3 and a coaxially arranged sleeve-shaped front section 4, the sleeve-shaped front section 4 surrounding a central channel 5 extending in the axial direction z and forming part of a melt channel 6. The central channel 5 is preferably fluidly interconnected with a melt channel 6 of the injection molding tool at the rear section 3.
[0034] In the central channel 5, a needle component 7 is configured to move along the axial direction z between a retracted open position and an extended closed position, in which the gate 8 located at the nozzle head 9 of the front section 4 is sealed shut by the front end 10 of the needle component 7. This... Figure 1 and Figure 2 This is most evident in the middle. Here, the nozzle head is integrally formed with the front section 4 of the nozzle, thereby allowing heat to be well distributed from the heating element 25, which is arranged at least partially around the housing 2, to the nozzle head 9.
[0035] A spacer 11 is typically disposed between the rear section 3 and the front section 4, defining the total length of the nozzle 1 in the axial direction z. In a first variation of the nozzle 1, such as... Figure 3 As shown, the spacer 11 is formed as a bushing disposed in the central channel 5 of the housing 2. The spacer 11 is at least partially made of tool steel. The spacer 11 typically includes a rear sealing surface 19 and a front sealing surface 20 located in the mounting position, which interact with the front section 4 and the rear section 3, respectively, to prevent molten thermoplastic material from leaking from the central channel 5. Figure 5 As shown, in a variation of the bushing-type spacer 11, a front sealing surface 19 and a rear sealing surface 20 are arranged at the end face of the bushing 11. During operation, the front sealing surface 20 presses against a corresponding surface of the front section 4 in the axial direction z. Similarly, the rear sealing surface 19 presses against a corresponding surface of the rear section 3. The spacer 11 is preferably disposed in the central channel 5, which extends in the axial direction z between the needle component centering device 14 and the rear section 3 and forms part of the melt channel 6.
[0036] like Figure 2 As shown, the nozzle head 9 of the front section 4 combines with the front end 10 of the needle component 7 to form a molding profile 12, which is embedded in a cavity profile 13 during operation. Figure 5As shown. The length of the spacer 11 in the axial direction z is adjustable, especially because the spacer 11 is designed to be interchangeable with a spacer 11 of a different length.
[0037] As described above, the injection nozzle 1 preferably includes a needle component centering device 14, which includes at least one channel for the melt to pass through. The needle component centering device 14 is arranged between the gate 8 at the front section 4 and the spacer 11, and is used to center the needle component 7 in the radial direction when the needle component 7 moves between the open and closed positions during operation. Figure 5 As shown. In the illustrated variation, the needle component centering device 14 is formed as a single annular component comprising three fins 17, each fin 17 extending radially inward. Each fin typically includes a guide surface 18 for axially guiding the needle component 7 and thereby centering the needle component 7 in a radial direction. Figure 2 and Figure 5 As shown, the needle component centering device 14 is preferably arranged in the recess 15 of the front section 4 of the nozzle head 9 near the nozzle 1 in the central channel 5. The recess 15 includes a rounded shoulder 16 for supporting the needle component centering device 14 in the axial direction z when pressed in the axial direction by the spacer 11 during operation.
[0038] like Figure 3 As shown, the rear section 3 may include an external thread 21, and the front section 4 may include a corresponding internal thread 22 for engaging the external thread 21, to connect the front section 4 to the rear section 3. Typically, the front section 4 is detachably connected to the rear section 3; however, a fixed interconnection is also conceivable.
[0039] Figure 4 A cross-sectional view of an injection molding tool 23 is shown, the tool including an injection nozzle 1 according to the present disclosure. The injection molding tool 23 includes at least one cavity 24 having a cavity profile 13 defining the shape of a plastic part formed therein from molten thermoplastic material. The injection molding tool 23 also includes at least one injection nozzle 1, as previously described, arranged adjacent to the cavity 24 for supplying molten thermoplastic material to the cavity via a melt channel 6. Figure 5 As shown, the injection nozzle 1 forms at least a portion of the cavity profile 13.
[0040] Optionally, the bushing 26 is arranged to at least partially surround the nozzle head 9 of the nozzle 1. The bushing includes a notch on its outer side forming part of a cooling channel 27 for cooling the bushing 26. The cooling channel is typically interconnected with the cooling circuit (not shown) of the injection molding tool 23.
[0041] like Figure 6 and Figure 7 As shown, a second variation of the nozzle 1 has a multi-part front section 4. The front section 4 includes an outer part 30 and a separate nozzle head element 28, which is detachably connected to the outer part 30. In the second variation shown, the nozzle head element 28 is connected to the outer part 30 via a retaining device 29 formed as a flange 29. The flange 29 is arranged in the axial direction z between the outer part 30 and the needle component centering device 14. Furthermore, the flange 29, as a shoulder 15, engages with the outer part 30 to form the recess 15, to receive and support the needle component centering device 14 relative to the spacer 11 and thus relative to the rear section 3. To remove the nozzle head element 28 from the outer part 30, the outer part is unscrewed from the rear section 3.
[0042] More precisely, the terms used in this specification are descriptive rather than limiting, and it should be understood that changes may be made without departing from the scope of this disclosure.
[0043] Parts list
[0044] 1. Injection nozzle 18. Guide surface (needle component centering device)
[0045] 2. Housing (injection nozzle) 19. Rear sealing surface (spacer)
[0046] 3 Rear section (housing) 20 Front sealing surface (spacer)
[0047] 4. Front section (housing) 21. External thread (rear section)
[0048] 5. Central channel 22 internal thread (front section)
[0049] 6 Melt Channels 23 Injection Molding Tools 7-pin component with 24 cavities (injection molding tool)
[0050] 8 gates, 25 heating elements 9. Nozzle head (front section) 26. Bushing (cooling)
[0051] 10 Front end (pin component) 27 Cooling channels
[0052] 11 spacers 28 nozzle head elements 12. Molding profile; 29. Fixing device (flange, nozzle head element). 13 Cavity Profile 30 External Components
[0053] 14-pin component centering device
[0054] 15. Concave section (front part)
[0055] 16. Shoulder area (indentation)
[0056] 17. Fins (Needle component centering device)
Claims
1. An injection nozzle (1) suitable for injection molding of thermoplastic materials, the injection nozzle (1) comprising: a. A housing (2) comprising a cylindrical rear section (3) and a coaxially arranged sleeve-shaped front section (4), the sleeve-shaped front section (4) surrounding a central channel (5) extending in an axial direction (z) and forming part of a melt channel (6); in the central channel (5), a needle component (7) is arranged to be movable in the axial direction (z) between a retracted open position and an extended closed position, in which the gate (8) at the nozzle head (9) of the front section (4) is sealed by the front end (10) of the needle component (7); wherein b. A spacer (11) is arranged between the rear section (3) and the front section (4), defining the total length of the housing (2) in the axial direction (z); c. The injection nozzle (1) includes a needle component centering device (14), which is used to center the needle component (7) in the radial direction when the needle component (7) moves between the open position and the closed position during operation; wherein i. The needle component centering device (14) is arranged axially (z) between the spacer (11) and the gate (8); and / or ii. The needle component centering device (14) is designed as a separate element inserted into the front section (4) of the housing (2) opposite to the gate (8).
2. The injection nozzle (1) according to claim 1, wherein, The spacer (11) includes a ring and / or a bushing and / or a washer.
3. The injection nozzle (1) according to claim 1, wherein, The needle component centering device (14) is disposed in a recess (15) of the front section (4).
4. The injection nozzle (1) according to claim 3, wherein, The needle component centering device (14) is sandwiched between a shoulder (16) of the recess (15) and the spacer (11).
5. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The needle component centering device (14) is annular.
6. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The needle component centering device (14) includes at least one fin (17) that extends in a radial direction and includes an internal guide surface (18) that centers the needle component (7) in a radial direction during operation.
7. The injection nozzle (1) according to claim 3, wherein, The needle component centering device includes at least two fins (17) spaced apart from each other in the circumferential direction.
8. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The nozzle head (9) of the front section (4) is combined with the front end (10) of the needle component (7) to form a molding profile (12) for embedding into the cavity profile (13) during operation.
9. The injection nozzle (1) according to claim 8, wherein, The length of the spacer (11) in the axial direction (z) is configured to compensate for the thermal expansion of the housing (2) in the axial direction (z), such that the molding profile (12) is adjustablely embedded in the cavity profile (13) relative to a specific operating temperature of a thermoplastic material.
10. The injection nozzle (1) according to claim 9, wherein, The molding profile (12) is flush-fitted into the cavity profile (13).
11. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The spacer (11) includes a rear sealing surface (19) and a front sealing surface (20) located at the installation position. The rear sealing surface (19) and the front sealing surface (20) cooperate with the front section (4) and the rear section (3) to prevent molten thermoplastic material from leaking from the central channel (5).
12. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The rear section (3) includes an external thread (21), and the front section (4) includes an internal thread (22), which engages with the external thread (21) in the installation position for connecting the front section (4) and the rear section (3) to each other.
13. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The spacer (11) is arranged in the central channel (5) and forms part of the melt channel (6).
14. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The spacer (11) and / or the needle centering device (14) includes an engagement profile for engaging with a corresponding tool for removal or replacement.
15. The injection nozzle (1) according to any one of claims 1 to 4, wherein, The front section (4) includes an external component (30) and a nozzle head element (28).
16. The injection nozzle (1) according to claim 15, wherein, The nozzle head element (28) is connected to the external component (30) from the inside or from the outside.
17. The injection nozzle (1) according to claim 1, wherein, The thermoplastic material is a polyolefin material.
18. An injection molding tool (23) for injection molding of thermoplastic materials, said injection molding tool (23) comprising: a. At least one cavity (24), said cavity (24) having a cavity profile (13) that at least partially defines a plastic part formed therein by molten thermoplastic material, and b. At least one injection nozzle (1) according to any one of claims 1 to 15, the injection nozzle (1) being arranged adjacent to the cavity (24) for supplying molten thermoplastic material to the cavity, the injection nozzle (1) forming at least a portion of the cavity profile (13).
19. The injection molding tool (23) according to claim 18, wherein, The thermoplastic material is a polyolefin material.