Sequentially injected multi-component shuttle-stack injection molding

Abstract: A method of cyclic injection molding is provided in which a first multi-component plastic product 125 and a second multi-component plastic product 123a are molded in an injection molding apparatus defining a right adjustable mold cavity 129,134 and a left adjustable mold cavity 119,132. In the method the adjustment of the mold cavities, injection of plastic material, and solidification of the plastic material are arranged such as to provide a highly efficient and highly controllable method of shuttle stack injection molding of multi-component plastic products.

Description: The present invention generally pertains to a method and an apparatus for multi-cavity injection molding of plastic products and is particularly directed to a highly efficient and highly controllable method and an apparatus for shuttle stack injection molding of multi-component plastic products. Heretofore shuttle stack injection molding of multi-component plastic products was either carried out so that only two products were produced in each injection molding cycle, as described in United States Patent No. 4,935,184, with the resulting low efficiency, or alternatively so that at least two mold cavities were filled at the same time by the same injection unit, giving rise to unbalanced filling of the cavities. The present invention enables production of four or more products in each production cycle while the filling of each cavity may be separate and therefore may be fully controlled. The present invention provides a method of cyclic injection molding a multi-component product in an injection molding system comprising a mold positioning system, a first injection system and a second injection system, and a left molding block, a right molding block and an intermediate molding block located between the left and the right molding blocks, said blocks being disposed for axial movement in respect to each other, the left molding block defining a first left general mold cavity part and the intermediate molding block defining a first left gated mold cavity part and a second left gated mold cavity part, the right molding block defining a first right general mold cavity part and the intermediate molding block defining a first right gated mold cavity part and a second right gated mold cavity part, the intermediate molding block defining a first runner system and a second runner system connected to said gated mold parts, the method comprising the steps of: (a) combining by the mold positioning system said molding blocks so that the first left general mold cavity part is connected with the first left gated mold cavity part to form a first left mold cavity, (b) injecting by the first injection system via the first runner system a first fluid plastic material into the first left mold cavity, and solidifying the material to produce a first left plastic component, (c) separating by the mold positioning system the right and intermediate molding blocks, (d) combining by the mold positioning system said molding blocks so that the first right general mold cavity part is connected with the first right gated mold cavity part to form a first right mold cavity, (e) injecting by the first injection system via the first runner system first fluid plastic material into the first right mold cavity, and solidifying the material to produce a first right plastic component, (f) separating by the mold positioning system the left and intermediate molding blocks, retaining the first left plastic component on the first left general mold cavity part, (g) combining by the mold positioning system said molding blocks so that the first left general mold cavity part is connected with the second left gated mold cavity part to form a second left mold cavity, which encompasses said first left plastic component, (h) injecting by the second injection system via the second runner system a second fluid plastic material into the second left mold cavity so that the second fluid plastic is united with the first left plastic component and solidifying the material to mold a first left multi-component plastic product, (i) separating by the mold positioning system the right and intermediate molding blocks, retaining the first right plastic component on the first right general mold cavity part, (j) combing by the mold positioning system said molding blocks so that the first right general mold cavity part is connected with the second right gated mold cavity part to form a second right mold cavity, which encompasses said first right plastic component, (k) injecting by the second injection system via the second runner system second fluid plastic material into the second right mold cavity so that the second fluid plastic is united with the first right plastic component and solidifying the material to mold a first right multi-component plastic product, (l) separating by the mold positioning system the left and intermediate molding blocks, to eject the first left product molded in step (h), wherein step (c) comprises the step of (m) ejecting a first right product molded in step (k) of the preceding molding cycle. In a preferred embodiment, wherein additional the left molding block defines at least one second left general mold cavity part and the right molding block defines at least one second right general mold cavity part, the method additionally comprising the steps of: wherein step (g) comprises the step of (n) combining by the mold positioning system said molding blocks so that one of said at least one second left general mold cavity part is connected with the first left gated mold cavity part to form a third left mold cavity, wherein step (h) comprises the step of (o) injecting by the first injection system via the first runner system first fluid plastic material into the third left mold cavity, and solidifying the material to produce a second left plastic component, wherein step (i) comprises the step of (p) separating by the mold positioning system the right and intermediate molding blocks, wherein step (j) comprises the step of (q) combining by the mold positioning system said molding blocks so that one of said at least one second right general mold cavity part is connected with the first right gated mold cavity part to form a third right mold cavity, wherein step (k) comprises the step of (r) injecting by the first injection system via the first runner system first fluid plastic material into said third right mold cavity, and solidifying the material to produce a second right plastic component, wherein step (l) comprises the step of (s) separating by the mold positioning system the left and intermediate molding blocks, retaining the second left plastic component on said second left general mold cavity part, wherein step (a) of the following cycle comprises the step of (t) combining by the mold positioning system said molding blocks so that any one of said at least one left general mold cavity part is connected with the second left gated mold cavity part to form a fourth left mold cavity, which encompasses said second left plastic component, wherein step (b) of the following cycle comprises the step of (u) injecting by the second injection system via the second runner system second fluid plastic material into the fourth left mold cavity so that the second fluid plastic is united with the second left plastic component and solidifying the material to mold a second left multi-component plastic product, wherein step (c) of the following cycle comprises the step of (v) separating by the mold positioning system the right and intermediate molding blocks, retaining the second right plastic component on any one of said at least one right general mold cavity part, wherein step (d) of the following cycle comprises the step of (w) combining by the mold positioning system said molding blocks so that any one of said at least one right general mold cavity part is connected with the second right gated mold cavity part to form a fourth right mold cavity, which encompasses said second right plastic component, wherein step (e) of the following cycle comprises the step of (x) injecting by the second injection system via the second runner system second fluid plastic material into the fourth right mold cavity so that the second fluid plastic is united with the second right plastic component and solidifying the material to mold a second right multi-component plastic product, wherein step (f) of the following cycle comprises the step of (y) separating by the mold positioning system the left and intermediate molding blocks, to eject the second left product molded in step (u), wherein step (p) comprises the step of (z) ejecting a second right product molded in step (e). Additional features of the present invention are described in relation to the description of the preferred embodiments. Figures 1 through 8 show within a cycle four chronological top sectional views of an injection molding system used for operating the cyclical method of the invention. Referring to Figures 1 through 8 showing an injection molding system being a standard injection molding machine with two independent standard injection units 101,102. The injection molding system comprises a mold positioning system 103 being a standard clamping unit and a left and a right locking means 117,118 for locking the left molding block 104 together with the intermediate molding block 105 or for locking the right molding block 106 together with the intermediate molding block 105 respectively. A left molding block 104, a right molding block 106, and an intermediate molding block 105, located between the left and the right molding blocks 104,106 are disposed for axial movement in respect to each other. The left molding block 104 defines a first left general mold cavity part 107, a second left general mold cavity part 115 and the intermediate molding block 105 defines a first left gated mold cavity part 108 and a second left gated mold cavity part 109. The right molding block 106 defines a first right general mold cavity part 110, a second right general mold cavity part 116 and the intermediate molding block defines a first right gated mold cavity part 111 and a second right gated mold cavity part 112. The intermediate molding block 105 defines a first runner system 113 connected to the first left gated mold cavity part and the first right gated mold cavity part 108,111 and further defines a second runner system 114 connected to the second left gated mold cavity part and the second right gated mold cavity part 109,112. The method comprises the following steps: Figure 1. Combining by the mold positioning system 103 the molding blocks 104,105,106 so that the first left general mold cavity part 107 is connected with the first left gated mold cavity part 108 to form a first left mold cavity 119 and so that the second left general mold cavity part 115 is connected with the second left gated mold cavity part 109 to form a fourth left mold cavity 120, which encompasses a left plastic component 121 formed in the previous production cycle. Injecting by the first injection system 101 via the first runner system 113 a first fluid plastic material into the first left mold cavity 119, and solidifying the material to produce a first left plastic component 122 and approximately at the same time injecting by the second injection system 102 via the second runner system 114 a second fluid plastic material into the fourth left mold cavity 120, so that the second fluid plastic is united with the second left plastic component 121, and solidifying the material to mold a second left multi-component plastic product 123. Figure 2. While locking together the left and intermediate molding blocks 104,105 and by the left locking means 117, separating by the mold positioning system 103 the right and intermediate molding blocks 106,105 and retaining a second right plastic component 124 formed in the previous cycle on the second right general mold cavity part 116, and ejecting a first right product 125 molded in the previous production cycle. Rotating revolvable section 127 of the right molding block 106 pivoting around the centre axis 128 of the injection molding system by a right rotational means, not shown, and combining by the mold positioning system 103 molding blocks 104,105,106 so that the first right general mold cavity part 110 is connected with the first right gated mold cavity 111 to form a first right mold cavity 129, and so that the second right general mold cavity part 116 is connected with the second right gated mold cavity part 112 to form a fourth right mold cavity 130, which encompasses the second right plastic component 124. Figure 3. Injecting by the first injection system 101 via the first runner system 113 first fluid plastic material into the first right mold cavity 129, and solidifying the material to produce a first right plastic component 124a and approximately at the same time injecting by the second injection system 102 via the second runner system 114 second fluid plastic material into the fourth right mold cavity 130 so that the second fluid plastic is united with the second right plastic component 124 and solidifying the material to mold a second right multi-component plastic product 125a. Figure 4. While locking together the right and intermediate molding blocks 106,105 by the right locking means 118, separating by the mold positioning system 103 the left and intermediate molding blocks 104,105 and retaining the first left plastic component 122 on the first left general mold cavity part 107, and ejecting the second left product 123. Rotating revolvable section 126 of the left molding block 104 pivoting around the centre axis 128 of the injection molding by the mold positioning system 103 molding blocks 104,105,106 so that the first left general mold cavity part 107 is connected with the second left gated mold cavity part 109 to form a second left mold cavity 132 which encompasses the first left plastic component 122, and so that the second left general mold cavity part 115 is connected with the first left gated mold cavity part 108 to form a third left mold cavity 131. Figure 5. Injecting by the first injection system 101 via the first runner system 113 fluid plastic material into the third left mold cavity 131, and solidifying the material to produce a second left plastic component 122a and approximately at the same time injecting by the second injection system 102 via the second runner system 114 a second fluid plastic material into the second left mold cavity 132, so that the second fluid plastic is united with the first left plastic component 122 and solidifying the material to mold a first left multi-component plastic product 123a. Figure 6. While locking together the left and intermediate molding blocks 104,105 by the left locking means 117, separating by the mold positioning system 103 the right and intermediate molding blocks 106,105 and retaining the first right plastic component 124a on the first right general mold cavity part 110, and ejecting second right product 125a. Rotating revolvable section 127 of the right molding block 106 pivoting around the centre axis 128 of the injection molding system by a right rotational means, not shown, and combining by the mold positioning system 103 molding blocks 104,105,106 so that the second right general mold cavity part 116 is connected with the first right gated mold cavity part 111 to form a third right mold cavity 133, and so that the first right general mold cavity part 110 is connected with the second right gated mold cavity part 112 to form a second right mold cavity 134, which encompasses the first right plastic component 124a. Figure 7. Injecting by the first injection system 101 via the first runner system 113 first fluid plastic material into the third right mold cavity 133, and solidifying the material to produce a second right plastic component 124b and approximately at the same time injecting by the second injection system 102 via the second runner system 114 second fluid plastic material into the second right mold cavity 134 so that the second fluid plastic is united with the first right plastic component 124a and solidifying the material to mold a first right multi-component plastic product 125b. Figure 8. While locking together the right and intermediate molding blocks 106,105 by the right locking means 118, separating by the mold positioning system 103 to the left and intermediate molding blocks 104,105 and retaining the second left plastic component 122a on the second left general mold cavity part 115, and ejecting the first left product123a. Rotating revolvable section 126 of the left molding block 104 pivoting around the centre axis 128 of the injection molding system by a left rotational means, not shown, and combining by the mold positioning system 103 molding blocks 104,105,106 to obtain the same mold position as described in the beginning of the production cycle. While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather a exemplifications of the preferred embodiment thereof. Many other variations are possible. There may be more than two injection units used and more than three molding blocks, with one more injection unit and one more molding block, three component products may be made. With two more injection units and two more molding blocks, four component products may be made. The molding blocks may be operated in such a fashion that two stack-molds are disposed for axial movement in respect to each other. The injection units may be placed in many different constellations, vertically, horizontally, along the machine axis or perpendicular thereto, or different angles altogether. When using a standard injection molding machine for the method of the invention, the injection units will normally have to be separated from the intermediate molding block at some period of the production cycle, but it is possible to operate the invention with the injection units attached to the intermediate molding block. If it is necessary to apply hold pressure during a period when an injection unit is detached from the intermediate molding block, it is possible to apply hold pressure to a runner system by constricting the runner system and applying alternative hold pressure by a piston means. The opening and closing periods may be different from the preferred embodiment, it is, for example, possible for the left side to open two or three times every time the right side opens once. It is possible to produce a different product in the left side and the right side, as, for example, a container and a lid both needing two barrier materials for such properties as moisture, oxygen, carbon dioxide, solutions, and air, for products such as foods, carbonated drinks, paints and vacuumated blood tubes. The runner systems may consist of forked or unconnected sections or sections separated by valves of many types. It may be useful to include a controlled valve near or at the gate to each product, although this feature is optional. To start up the system without such valves, either double material is injected the first time or a previously produced product is inserted in half of the mold cavities. There may be any convenient amount of general mold cavity parts which in turn is exposed to the gated mold cavity parts. If, for example, there are three general and two gate mold cavity parts, the extra general mold cavity part may be used as a separate station for printing or in line blow molding or the like.

Claims: A Method of cyclic injection molding a multi-component product in an injection molding system comprising a mold positioning system (103), a first injection system (101) and a second injection system (102), and a left molding block (104), a right molding block (106) and an intermediate molding block (105) located between the left and the right molding blocks, said blocks being disposed for axial movement in respect to each other, the left molding block defining a first left general mold cavity part (107) and the intermediate molding block defining a first left gated mold cavity part (108) and a second left gated mold cavity part (109), the right molding block defining a first right general mold cavity part (110) and the intermediate molding block defining a first right gated mold cavity part (111) and a second right gated mold cavity part (112), the intermediate molding block defining a first runner system (113) and a second runner system (114) connected to said gated mold parts, the method comprising the steps of: (a) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that the first left general mold cavity part (107) is connected with the first left gated mold cavity part (108) to form a first left mold cavity (119), (b) injecting by the first injection system (101) via the first runner system (113) a first fluid plastic material into the first left mold cavity (119), and solidifying the material to produce a first left plastic component (122), (c) separating by the mold positioning system (103) the right and intermediate molding blocks (106, 105), (d) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that the first right general mold cavity part (110) is connected with the first right gated mold cavity part (111) to form a first right mold cavity (129), (e) injecting by the first injection system (101) via the first runner system (113) first fluid plastic material into the first right mold cavity (129), and solidifying the material to produce a first right plastic component (124a), (f) separating by the mold positioning system (103) the left and intermediate molding blocks (104, 105), retaining the first left plastic component (122) on the first left general mold cavity part (107), (g) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that the first left general mold cavity part (107) is connected with the second left gated mold cavity part (109) to form a second left mold cavity (132), which encompasses said first left plastic component (122), (h) injecting by the second injection system (102) via the second runner system (114) a second fluid plastic material into the second left mold cavity (132) so that the second fluid plastic is united with the first left plastic component (122) and solidifying the material to mold a first left multi-component plastic product (123a), (i) separating by the mold positioning system (103) the right and intermediate molding blocks (106, 105), retaining the first right plastic component (124a) on the first right general mold cavity part (110), (j) combing by the mold positioning system (103) said molding blocks (104, 105, 106) so that the first right general mold cavity part (110) is connected with the second right gated mold cavity part (112) to form a second right mold cavity (134), which encompasses said first right plastic component (124a), (k) injecting by the second injection system (102) via the second runner system (114) second fluid plastic material into the second right mold cavity (134) so that the second fluid plastic is united with the first right plastic component (124a) and solidifying the material to mold a first right multi-component plastic product (125b), (l) separating by the mold positioning system (103) the left and intermediate molding blocks (104, 105), to eject the first left product (123a) molded in step (h), wherein step (c) comprises the step of (m) ejecting a first right product (125) molded in step (k) of the preceding molding cycle. A method according to claim 1, wherein the left molding block (104) defines at least one second left general mold cavity part (115) and the right molding block (106) defines at least one second right general mold cavity part (116), and comprising the steps of: wherein step (g) comprises the step of (n) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that one of said at least one second left general mold cavity part (115) is connected with the first left gated mold cavity part (108) to form a third left mold cavity (131), wherein step (h) comprises the step of (o) injecting by the first injection system (101) via the first runner system (113) first fluid plastic material into the third left mold cavity (131), and solidifying the material to produce a second left plastic component (122a), wherein step (i) comprises the step of (p) separating by the mold positioning system (103) the right and intermediate molding blocks (106, 105), wherein step (j) comprises the step of (q) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that one of said at least one second right general mold cavity part (116) is connected with the first right gated mold cavity part (111) to form a third right mold cavity (133), wherein step (k) comprises the step of (r) injecting by the first injection system (101) via the first runner system (113) first fluid plastic material into said third right mold cavity (133), and solidifying the material to produce a second right plastic component (124b), wherein step (I) comprises the step of (s) separating by the mold positioning system (103) the left and intermediate molding blocks (104, 105), retaining the second left plastic component (122a) on said second left general mold cavity part (115), wherein step (a) of the following cycle comprises the step of (t) combining by the mold positioning system (103) said molding blocks so that any one of said at least one left general mold cavity part (107, 115) is connected with the second left gated mold cavity part (108) to form a fourth left mold cavity (120), which encompasses said second left plastic component (121), wherein step (b) of the following cycle comprises the step of (u) injecting by the second injection system (102) via the second runner system (114) second fluid plastic material into the fourth left mold cavity (120) so that the second fluid plastic is united with the second left plastic component (121) and solidifying the material to mold a second left multi-component plastic product (123), wherein step (c) of the following cycle comprises the step of (v) separating by the mold positioning system (103) the right and intermediate molding blocks (106, 105), retaining the second right plastic component (124) on any one of said at least one right general mold cavity part (110, 116), wherein step (d) of the following cycle comprises the step of (w) combining by the mold positioning system (103) said molding blocks (104, 105, 106) so that any one of said at least one right general mold cavity part (110, 116) is connected with the second right gated mold cavity part (112) to form a fourth right mold cavity (130), which encompasses said second right plastic component (124), wherein step (e) of the following cycle comprises the step of (x) injecting by the second injection system (102) via the second runner system (114) second fluid plastic material into the fourth right mold cavity (130) so that the second fluid plastic is united with the second right plastic component (124) and solidifying the material to mold a second right multi-component plastic product (125a), wherein step (f) of the following cycle comprises the step of (y) separating by the mold positioning system (103) the left and intermediate molding blocks (104, 105), to eject the second left product (123) molded in step (u), wherein step (p) comprises the step of (z) ejecting a second right product (125a) molded in step (e). A method according to claim 2, wherein the method utilizes only one second left general mold cavity part (115) and the method utilizes only one second right general mold cavity part (116). An injection molding apparatus for cyclic injection molding a multi-component product comprising a mold positioning system (103), a first injection system (101) and a second injection system (102), and a left molding block (104), a right molding block (106) and an intermediate molding block (105) located between the left and the right molding blocks, said blocks being disposed for axial movement in respect to each other, the left molding block defining a first left general mold cavity part (107) and the intermediate molding block defining a first left gated mold cavity part (108) and a second left gated mold cavity part (109), the right molding block defining a first right general mold cavity part (110) and the intermediate molding block defining a first right gated mold cavity part (111) and a second right gated mold cavity part (112), the injection molding apparatus comprising: a mold positioning system (103) for combining said molding blocks (104, 105, 106) so that the first left general mold cavity part (107) is connected with the first left gated mold cavity part (108) to form a first left mold cavity (119), the first injection system (101) comprising means for injecting a first fluid plastic material into the first left mold cavity (119), to produce a left plastic component (122, 122a), the mold positioning system (103) comprising means for separating the right and intermediate molding blocks (106, 105), means for ejecting a right multi-component plastic product (125, 125a), the mold positioning system (103) comprising means for combining said molding blocks (104, 105, 106) so that the first right general mold cavity part (110) is connected with the first right gated mold cavity part (111) to form a first right mold cavity (129), the first injection system (101) comprising means for injecting first fluid plastic material into the first right mold cavity (129) to produce a right plastic component (124, 124a), the mold positioning system (103) comprising means for separating the left and intermediate molding blocks (104, 105), means for retaining said left plastic component (122, 122a) on the first left general mold cavity part (107), the mold positioning system (103) comprising means for combining said molding blocks (104, 105, 106) so that the first left general mold cavity part (107) is connected with the second left gated mold cavity part (109) to form a second left mold cavity (132), so that the second left mold cavity (132) may encompass said left plastic component (122, 122a), the second injection system (102) comprising means for injecting second fluid plastic material into the second left mold cavity (132) so that the second fluid plastic may be united with said left plastic component (122, 122a), to mold a left multi-component plastic product (123, 123a), means for retaining said right plastic component (124, 124a) on the first right general mold cavity part (110), when the mold positioning system (103) separates the right and intermediate molding blocks (106, 105), the mold positioning system (103) comprising means for combining said molding blocks (104, 105, 106) so that the first right general mold cavity part (110) is connected with the second right gated mold cavity part (112) to form a second right mold cavity (134), so that the second right mold cavity may encompass said right plastic component (124, 124a), the second injection system (102) comprising means for injecting second fluid plastic material into the second right mold cavity (134) so that the second fluid plastic may be united with said right plastic component (124, 124a) to mold a right multi-component plastic product (125b), means for ejecting the left multi-component plastic product (123, 123a), when the mold positioning system (103) separates the left and intermediate molding blocks (104, 105).

Inventors: SORENSEN JENS OLE, SORENSEN, JENS OLE
Applicants: SORENSEN JENS OLE, SORENSEN, JENS OLE
Application year: 1990
Main classification: B29C45
IPC codes: B29C45