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CN-116963892-B - Injection nozzle

CN116963892BCN 116963892 BCN116963892 BCN 116963892BCN-116963892-B

Abstract

The present disclosure relates to an injection nozzle (1) suitable for injection molding of thermoplastic materials, in particular polyolefin materials, the injection nozzle (1) comprising a housing (2), the housing (2) comprising a sleeve-shaped 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) forming part of a melt channel (6). In the central channel (5), a needle part (7) is arranged 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 closed in a sealing manner by the front end (10) of the needle part (7). A spacer (11) is arranged between the rear section (3) and the front section (4), defining the overall length of the housing (2) in the axial direction (z).

Inventors

  • Sven Sprller

Assignees

  • 奥托曼纳股份有限公司

Dates

Publication Date
20260512
Application Date
20220315
Priority Date
20210317

Claims (19)

  1. 1. Injection nozzle (1) suitable for injection molding of thermoplastic materials, the injection nozzle (1) comprising: a. A housing (2) comprising a sleeve-shaped 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) forming part of a melt channel (6), in the central channel (5) a needle part (7) being arranged to be movable in the axial direction (z) between a retracted open position and an extended closed position, in which closed position a gate (8) at a nozzle head (9) of the front section (4) is closed in a sealing manner by a front end (10) of the needle part (7), wherein B. A spacer (11) is arranged between the rear section (3) and the front section (4), defining the overall length of the housing (2) in the axial direction (z); c. The injection nozzle (1) comprises a needle part centring device (14), the needle part centring device (14) being adapted to centre the needle part (7) in a radial direction when the needle part (7) is moved between the open position and the closed position during operation, wherein I. The pin part centering device (14) is arranged in the axial direction (z) between the spacer (11) and the gate (8), and/or The pin component centering device (14) is designed as a separate element which is inserted into the front section (4) of the housing (2) opposite the gate (8).
  2. 2. Injection nozzle (1) according to claim 1, wherein the spacer (11) comprises a ring and/or a bushing and/or a washer.
  3. 3. Injection nozzle (1) according to claim 1, wherein the needle part centring device (14) is arranged in a recess (15) of the front section (4).
  4. 4. An injection nozzle (1) according to claim 3, wherein the needle part centring means (14) is sandwiched between a shoulder (16) of the recess (15) and the spacer (11).
  5. 5. Injection nozzle (1) according to any of the preceding claims 1 to 4, wherein the needle part centring means (14) is annular.
  6. 6. Injection nozzle (1) according to any of the preceding claims 1 to 4, wherein the needle part centring means (14) comprises at least one fin (17), which fin (17) extends in a radial direction and comprises an inner guiding surface (18), which guiding surface (18) centers the needle part (7) in a radial direction during operation.
  7. 7. An injection nozzle (1) according to claim 3, wherein the needle part centring means comprise at least two fins (17) spaced apart from each other in the circumferential direction.
  8. 8. Injection nozzle (1) according to any of the preceding claims 1 to 4, wherein the nozzle head (9) of the front section (4) in combination with the front end (10) of the needle part (7) forms a shaped profile (12) for embedding into a cavity profile (13) during operation.
  9. 9. Injection nozzle (1) according to claim 8, wherein the length of the spacer (11) in the axial direction (z) is configured to compensate for thermal expansion of the housing (2) in the axial direction (z) such that the molding profile (12) is adjustably embedded in the cavity profile (13) with respect to a thermoplastic material specific operating temperature.
  10. 10. Injection nozzle (1) according to claim 9, wherein the molding contour (12) is embedded in a flush manner in a cavity contour (13).
  11. 11. Injection nozzle (1) according to any one of the preceding claims 1 to 4, wherein the spacer (11) comprises a rear sealing surface (19) and a front sealing surface (20) in the mounted position, the rear sealing surface (19) and front sealing surface (20) cooperating with the front section (4) and the rear section (3) to prevent leakage of molten thermoplastic material from the central channel (5).
  12. 12. Injection nozzle (1) according to any one of the preceding claims 1 to 4, wherein the rear section (3) comprises an external thread (21) and the front section (4) comprises an internal thread (22), the internal thread (22) engaging with the external thread (21) in the mounted position for interconnecting the front section (4) and the rear section (3).
  13. 13. Injection nozzle (1) according to any of the preceding claims 1 to 4, wherein the spacer (11) is arranged in the central channel (5) and forms part of the melt channel (6).
  14. 14. Injection nozzle (1) according to any of the preceding claims 1 to 4, wherein the spacer (11) and/or the needle part centring means (14) comprise an engagement profile for engagement with a corresponding tool for removal or replacement.
  15. 15. Injection nozzle (1) according to any one of the preceding claims 1 to 4, wherein the front section (4) comprises an outer part (30) and a nozzle head element (28).
  16. 16. Injection nozzle (1) according to claim 15, wherein the nozzle head element (28) is interconnected with the outer part (30) from the inside or from the outside.
  17. 17. Injection nozzle (1) according to claim 1, wherein the thermoplastic material is a polyolefin material.
  18. 18. An injection molding tool (23) for injection molding of thermoplastic material, the injection molding tool (23) comprising: a. at least one cavity (24), said cavity (24) having a cavity contour (13) at least partially defining a plastic part formed therein from a molten thermoplastic material, and B. Injection nozzle (1) according to at least 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 part of the cavity profile (13).
  19. 19. The injection molding tool (23) according to claim 18, wherein the thermoplastic material is a polyolefin material.

Description

Injection nozzle Technical Field The present invention relates to the field of injection nozzles for injection molding of thermoplastic materials, in particular polyolefins. Background EP0873841A2 published by Mold Masters limited in 1998 relates to a valve gated injection molding apparatus having a valve member with a cylindrical front end. The integral insert mounted at the front end of the nozzle has a gate and positioning vanes extending inwardly from an outer body into a central opening leading to the gate. The inner surface of the vane is mounted around the forward end of the reciprocating valve pin to guide and very accurately position it in alignment with the gate. Very precisely maintaining the leading end of the reciprocating valve pin in alignment with the gate, making it cylindrical rather than tapered, creates a cleaner gate mark. EP1990175A1 published by Mold Masters limited at 11 in 2008 relates to an injection molding apparatus comprising a valve-gated nozzle with a nozzle tip assembly and a valve pin slidably disposed therein. The nozzle head assembly includes a nozzle liner having a first valve pin guide portion, a valve pin guide having a second valve pin guide portion upstream of the first valve pin guide portion, and a transfer seal having an aperture for receiving the nozzle liner and the valve pin guide therein. The transfer seal bore includes alignment surfaces surrounding the nozzle liner 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. Inglass (co) corporation, published in 2017, month 4, DE102016219833A1, relates to a nozzle end of an injection molding machine (injector). The injection molding machine includes a tip and a ring nut each having a distal end, one of which is configured to connect with a gate of a molding cavity, which mates with a shutter end of a valve pin of the injection molding machine, and which has a total thickness in cross section that is equal to or less than a thickness of a cross section of the shutter end of the valve pin. Disclosure of Invention Injection nozzles for injection molding thermoplastic materials, in particular polyolefin materials, are arranged during operation in expensive and precisely manufactured molding tools in order to inject molten thermoplastic material into the cavities of the molding tools. The cavity having a cavity profile defines the shape of the plastic part formed therein from the injected molten plastic material after solidification. In order to precisely eject the molten material, the nozzles are fluidly interconnected to the mold cavity by gates that are openable and closable by a movable pin member of the respective nozzle. In order to avoid wear of the forming tool, each gate is formed as part of the nozzle head facing the cavity, and the maintenance or replacement costs of the nozzle are lower compared to the forming tool in case of gate damage. In order to be able to produce high-quality plastic parts with almost no discernable injection marks from the gate through which the molten material is injected into the mold cavity, the nozzle should form a horizontal or slightly concave surface with the mold cavity during operation. The injection nozzle is therefore preferably designed to take into account thermal expansion and thus achieve good alignment with the mould cavity during operation. A preferred variant of the injection nozzle according to the present disclosure comprises a housing which is particularly suitable for mounting in a corresponding injection moulding tool. The housing comprises a sleeve-shaped rear section and a coaxially arranged sleeve-shaped front section, which surrounds a central channel extending in the axial direction. In the central passage, a needle member is arranged to be movable in the axial direction between a retracted open position and an extended closed position in which a gate at the nozzle head of the front section is closed in a sealing manner by the front end of the needle member. A spacer is arranged between the rear section and the front section defining the total length of the nozzle in the axial direction. The spacers are preferably designed to be exchangeable, so that the total length of the housing can be adjusted by exchanging and/or adjusting the spacers to spacers of different lengths in the axial direction. The spacer may be in the form of multiple parts. By having an adjustable total length of the nozzle, thermal expansion of the nozzle during operation can be predicted and/or compensated for. This allows the use of nozzles mounted in the same injection molding tool to handle different thermoplastic materials requiring different operating temperatures. The spacer comprises a ring and/or a bushing and/or a washer etc. depending on the application. Typically, the spacer