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CN-116635202-B - Injection molding apparatus and method for reducing velocity increase of flow fronts during injection molding

CN116635202BCN 116635202 BCN116635202 BCN 116635202BCN-116635202-B

Abstract

The present disclosure relates to an injection molding device (1), the injection molding device (1) comprising at least a first mold plate, the first mold plate comprising a first injection inlet (3) and a second injection inlet (5), the first injection inlet (3) being arranged in fluid connection with a first gate (4) leading into a mold cavity (2), the second injection inlet (5) being arranged in fluid connection with a second gate (6) leading into the mold cavity (2). The first and second injection inlets (3, 5) are arranged to open in sequence. The second gate (6) comprises a first gate volume (11) which opens into the cavity (2). The second gate (6) is further provided with a second gate volume (12) to allow injection material to flow into the second gate volume (12) at the same time as the first gate volume (11) and thereafter into the cavity (2). The present disclosure also relates to a method for reducing the velocity increase of a flow front (10) during injection molding.

Inventors

  • E. ANDRE

Assignees

  • 宁波吉利汽车研究开发有限公司
  • 浙江吉利控股集团有限公司

Dates

Publication Date
20260508
Application Date
20211125
Priority Date
20201216

Claims (8)

  1. 1. Injection molding device (1), the injection molding device (1) comprising at least a first mold plate, the first mold plate comprising a first injection inlet (3) and a second injection inlet (5), the first injection inlet (3) being arranged in fluid connection with a first gate (4) opening into a mold cavity (2), the second injection inlet (5) being arranged in fluid connection with a second gate (6) opening into the mold cavity (2), wherein the first injection inlet (3) and the second injection inlet (5) are arranged to be opened in sequence, and the first injection inlet (3) is opened before the second injection inlet (5), wherein the second gate (6) comprises a first gate volume (11) opening into the mold cavity (2), characterized in that the second gate (6) is further provided with a second gate volume (12) to allow injection material to flow into the second gate volume (12) simultaneously with the first gate volume (11) and thereafter into the mold cavity (2), wherein the second gate (6) is extended from the second gate (2) by the first gate volume (14), and the second gate (6) comprises a throttle valve (13) opening into the first increasing volume (14).
  2. 2. Injection molding apparatus (1) according to claim 1, wherein the second gate volume (12) is further provided by a second increased volume extending from the second injection inlet (5) in a second direction different from the first direction.
  3. 3. Injection molding apparatus (1) according to claim 2, wherein the first increased volume and/or the second increased volume is in the shape of one or more of a cuboid, an ellipsoid, a parallelepiped, a cylinder.
  4. 4. Injection molding apparatus (1) according to claim 1, wherein the throttle valve (13) has a cross-sectional area between about 1/4 to 3/4 of the cross-sectional area of the second gate volume (12), wherein the throttle valve (13) connects the first gate volume (11) and the second gate volume (12).
  5. 5. Injection molding apparatus (1) according to any one of the preceding claims, wherein the size of the second gate volume (12) is a function of the distance between the first injection inlet (3) and the second injection inlet (5).
  6. 6. A method for reducing a velocity increase of a flow front (10) during injection molding, wherein an injection molding device (1) comprises at least a first mold plate comprising a first injection inlet (3) and a second injection inlet (5), the first injection inlet (3) being arranged in fluid connection with a first gate (4) opening into a mold cavity (2), the second injection inlet (5) being arranged in fluid connection with a second gate (6) opening into the mold cavity (2), wherein the first injection inlet (3) and the second injection inlet (5) are arranged to open in sequence, and the first injection inlet (3) is opened before the second injection inlet (5), wherein the second gate (6) comprises a first gate volume (11) opening into the mold cavity (2), wherein the method comprises: Providing the second gate (6) with a second gate volume (12) to allow injection material to flow into the second gate volume (12) simultaneously with the first gate volume (11) and thereafter into the cavity (2), thereby reducing the velocity of the injection flow from the second gate (6) in the cavity (2), -Providing the second gate volume (12) by providing a first increasing volume (14) extending in a first direction from the second injection inlet (5), and -Providing said second gate (6) with a throttle valve (13) opening into said first increasing volume (14).
  7. 7. The method according to claim 6, wherein the method comprises: -providing the second gate volume (12) also by providing a second increased volume extending from the second injection inlet (5) in a second direction different from the first direction.
  8. 8. The method of claim 7, wherein the method comprises: -providing said first increased volume and/or said second increased volume with the shape of one or more of a cuboid, an ellipsoid, a parallelepiped, a cylinder.

Description

Injection molding apparatus and method for reducing velocity increase of flow fronts during injection molding Technical Field The present disclosure relates to an injection molding apparatus and a method for reducing a velocity increase of a flow front during injection molding. Background Injection molding is a well known plastic molding technique that is used to mold plastic parts of many shapes and sizes. When injection molding large parts, today's injection molding apparatus use several inlets that open in sequence, with the injection of liquid plastic usually beginning in the middle of the part. When the second inlet is open during the filling phase, the flow front of the injected liquid plastic associated with the second inlet experiences a velocity increase. Such a speed increase is undesirable because it affects the final quality of the injection molded part. Excessive speed variations on the flow front will result in visible surface deformations on the painted part. One way to solve this problem is to use stepwise open portals (see link https// www.synventive.com/products/active-gate-control. Aspx). However, these portals are expensive and take a significant amount of time to install. Thus, there is a need for improvements in previously known methods of addressing the velocity increase of the flow front during injection molding. Disclosure of Invention It is an object of the present disclosure to provide an injection molding apparatus and method capable of solving the mentioned problems. This object is achieved by an injection molding device according to claim 1 and a method according to claim 8. The dependent claims provide advantageous exemplary embodiments. The present disclosure relates to an injection molding apparatus including at least a first mold plate. The first mold plate includes a first injection inlet arranged to be in fluid connection with a first gate opening into the cavity and a second injection inlet arranged to be in fluid connection with a second gate opening into the cavity. The first injection inlet and the second injection inlet are arranged to be opened sequentially, and the first injection inlet is opened before the second injection inlet. The second gate includes a first gate volume that opens into the cavity. The second gate is also provided with a second gate volume to allow the injection material to flow into the second gate volume at the same time as the first gate volume and thereafter into the cavity, thereby reducing the velocity of the injection flow from the second gate in the cavity. By adding a second gate volume to the second gate, in addition to the already existing first gate volume into the cavity, the added volume can be used as a shock absorber (buffer device) for the injected liquid plastic. The velocity increase on the flow front of the injected material from the second gate is reduced, and in some cases reduced all the way to zero. While the injection molding apparatus according to the present disclosure is most beneficial during the filling phase, it has been shown that improvements are also provided during the pressure retention phase. Another advantage of an injection molding apparatus according to the present disclosure is that a second gate volume can be added to an existing injection molding apparatus. Even if the cost is increased compared to if the second gate volume were to be increased during design of the injection molding apparatus, the cost would still be significantly lower than if a step-wise opening inlet was used. The second gate volume may be provided by a first increased volume extending in the first direction from the second injection inlet. The second gate volume may take a variety of forms and, in the case of the least complex form, extends in a first direction, for example in a direction away from the direction in which the second gate opens into the cavity. The second gate volume may also be provided by a second increased volume extending from the second injection inlet in a second direction different from the first direction. The second gate volume may extend in a second direction different from the first direction if the second gate volume cannot be generated sufficiently large to meet the need in such a way that the extension in only the first direction increases the second gate volume. The second direction may be perpendicular to the first direction and extend in a direction that is horizontal or perpendicular with respect to the extension of the first direction. Alternatively, the second direction may extend in a direction at an angle less than or greater than 90 ° to the first direction. The second gate volume may also extend in positive and negative second directions, and one example may be that the second gate volume is substantially T-shaped. The first increased volume and/or the second increased volume may be in the shape of one or more of a cuboid, an ellipsoid, a parallelepiped, a cylinder. The first increased volume