JP4523372B2 - Manufacturing method and manufacturing apparatus for resin molded product - Google Patents

Description

  The present invention relates to a resin molding technique.

  As a method for producing a resin molded product, injection molding is widely used in which a molten resin is filled in a cavity formed in a mold and foamed to produce a resin molded product. Methods for foaming the molten resin in the cavity include chemical foaming in which a foaming agent is mixed with the molten resin and supercritical gas foaming in which carbon dioxide or nitrogen gas in a supercritical state is dissolved in the molten resin and foamed. Proposed. Supercritical gas foaming is more suitable for fine foaming than chemical foaming, and is excellent in reducing weight, sinking, and warping of members that require strength. In addition, since the fluidity of the molten resin is improved and low-pressure molding is possible, it is possible to perform batch molding of a plurality of parts, thin parts, and downsizing of a molding machine. Furthermore, the cooling time by the endothermic absorption of the supercritical gas can shorten the time for cooling the molten resin, and the molding cycle can be shortened.

  In injection molding in which a molten resin is foamed to produce a resin molded product, the strength of the molded product depends on the foaming rate of the bubble cells. Therefore, a technique for adjusting the foaming rate of the bubble cell has been proposed. For example, Patent Document 1 proposes a technique for producing a fine foam having a three-dimensional structure in which a foam layer and a non-foam layer are mixed. Patent Document 2 proposes a technique for improving the strength by reducing the foaming rate by changing the volume of the cavity at a portion where strength is required, and solidifying the portion.

JP-A-9-85788 JP 2002-67111 A

  Here, the foaming rate of the bubble cell depends on the internal pressure of the molten resin in the cavity. That is, when the internal pressure of the molten resin is high, the foaming rate is low, and the resin molded product is made more solid. Conversely, when the internal pressure of the molten resin is low, the foaming rate is high. Therefore, for example, when it is desired to make the foaming rate of the resin molded product uniform, it is desirable to make the internal pressure of the molten resin in the cavity uniform. However, the internal pressure of the molten resin tends to decrease in proportion to the distance of the molten resin flow path from the molten resin introduction portion (gate portion) into the cavity. That is, the internal pressure of the molten resin increases near the introduction portion and decreases as the distance from the introduction portion increases.

  For this reason, the bubble cell becomes small in the vicinity of the introduction portion, but the bubble cell becomes large on the end portion side of the flow path, and it is difficult to make the foaming rate uniform. In particular, when supercritical gas foaming is used, it is desirable to increase the distance of the flow path of the molten resin by taking advantage of the high fluidity of the molten resin. Is difficult to homogenize, and the advantages of supercritical gas foaming cannot be fully utilized. In addition, for example, in the case where it is desired to locally change the foaming rate of the resin molded product, such as when solidifying a plurality of locations of the resin molded product to the same extent and increasing the foaming rate to the same extent at other locations, According to the distance of the flow path, the foaming rate for each part to be solidified is not uniform.

  Therefore, an object of the present invention is to correct a change in the foaming rate of the bubble cell due to the length of the flow path of the molten resin, and to arbitrarily control the foaming rate of the bubble cell.

  According to the present invention, in a method for producing a resin molded product, a molten resin is filled into a cavity formed in a mold and foamed to produce a resin molded product, and the molten resin is filled into the cavity. And a moving step of moving a plurality of movable wall bodies that are movably provided so as to partially change the volume in the cavity. The predetermined moving wall body is moved from the initial position to the position of the molding surface of the resin molded product in a predetermined movement order, and the moving order is from the introduction part of the molten resin into the cavity to the moving wall body. There is provided a method for producing a resin molded product, which is set according to the distance of the flow path of the molten resin.

  According to the present invention, when moving the moving wall body from the initial position to the position of the molding surface of the resin molded product, the moving order is set according to the distance of the flow path of the molten resin. The movement of the moving wall body locally affects the internal pressure of the molten resin in the cavity, but the timing of the change of the internal pressure changes depending on the movement order of the moving wall body. Growth can be suppressed or promoted. Therefore, by setting the movement order according to the distance of the flow path of the molten resin, the change in the foaming rate of the bubble cell due to the length of the flow distance is corrected, and the foaming rate of the bubble cell is arbitrarily controlled. For example, the foaming rate of the resin molded product can be made uniform as a whole or locally different.

  In the present invention, when the moving wall body is moved in the direction of reducing the volume in the cavity, it is desirable to move the moving wall body from the moving wall body on the longer side. When the moving wall body is moved in a direction to reduce the volume in the cavity, that is, when the foaming rate of the bubble cell is suppressed, the moving wall body is melted by moving the moving wall body from the end side of the flow path. On the end side of the flow path where the internal pressure of the resin tends to be low, the internal pressure is increased early to delay the growth of the bubble cells, and the targeted foaming rate can be obtained.

  In the present invention, when the moving wall body is moved in the direction of expanding the volume in the cavity, it is desirable to move the moving wall body from the moving wall body on the short side. When the moving wall body is moved in the direction of expanding the volume in the cavity, that is, when the foaming rate of the bubble cell is promoted, the moving wall body is moved from the introduction portion side to On the introduction part side where the internal pressure tends to be high, the internal pressure is lowered early to accelerate the growth of the bubble cell, and the targeted foaming rate is obtained.

  Moreover, in this invention, the moving order of each said moving wall body may be set according to the said distance and the foaming rate made into the objective in each site | part of the said resin molded product. With this configuration, different foaming rates can be obtained favorably at each part of the resin molded product.

  In this case, the moving wall body corresponding to the part with the smaller foaming rate is moved in the direction of reducing the volume in the cavity, and the moving wall body corresponding to the part with the larger foaming rate is used. It is desirable to move it first. With this configuration, a partially solidified resin molded product can be obtained.

  In this case, it is desirable that the moving wall body corresponding to the portion with the higher foaming rate is moved in the direction of expanding the volume in the cavity. With this configuration, a resin molded product having a foamed portion with a partly higher foaming rate can be obtained.

  Further, in this case, the resin molding in which the foaming rate has a first foaming rate and a second foaming rate that is larger than the first foaming rate, and the second foaming rate is set. Parts of the product may be positioned on both sides of the part of the resin molded product in which the first foaming rate is set. With this configuration, since the solid part with the first foaming rate set is made more solid, the solid part is sandwiched between the foaming part with the higher foaming rate and the second foaming rate is set. Deformation of the entire warp or the like can be effectively prevented.

  In the present invention, it is desirable that an inert gas in a supercritical state is dissolved in the molten resin. The present invention is particularly suitable for supercritical gas foaming in which the flow path of the molten resin is long.

  Further, according to the present invention, in a resin molded product manufacturing apparatus for manufacturing a resin molded product, a molten resin is filled in a cavity formed in a mold and foamed to form an inner wall of the cavity, A plurality of movable wall bodies movably provided so as to partially change the volume in the cavity; drive means for moving each of the movable wall bodies; and control means for controlling the drive means. The control means is configured to cause the predetermined moving wall body to move from an initial position to a position of the molding surface of the resin molded product in a predetermined movement order after filling the cavity with the molten resin. And the order of movement is set according to the distance of the flow path of the molten resin from the molten resin introduction portion into the cavity to the moving wall body Manufacturing Location is provided.

  According to the present invention, when moving the moving wall body from the initial position to the position of the molding surface of the resin molded product, the moving order is set according to the distance of the flow path of the molten resin. The movement of the moving wall body locally affects the internal pressure of the molten resin in the cavity, but the timing of the change of the internal pressure changes depending on the movement order of the moving wall body. Growth can be suppressed or promoted. Therefore, by setting the movement order according to the distance of the flow path of the molten resin, the change in the foaming rate of the bubble cell due to the length of the flow distance is corrected, and the foaming rate of the bubble cell is arbitrarily controlled. For example, the foaming rate of the resin molded product can be made uniform as a whole or locally different.

  In the present invention, when the moving wall body is moved in the direction of reducing the volume in the cavity, it is desirable to move the moving wall body from the moving wall body on the longer side. When the moving wall body is moved in a direction to reduce the volume in the cavity, that is, when the foaming rate of the bubble cell is suppressed, the moving wall body is melted by moving the moving wall body from the end side of the flow path. On the end side of the flow path where the internal pressure of the resin tends to be low, the internal pressure is increased early to delay the growth of the bubble cells, and the targeted foaming rate can be obtained.

  In the present invention, when the moving wall body is moved in the direction of expanding the volume in the cavity, it is desirable to move the moving wall body from the moving wall body on the short side. When the moving wall body is moved in the direction of expanding the volume in the cavity, that is, when the foaming rate of the bubble cell is promoted, the moving wall body is moved from the introduction portion side to On the introduction part side where the internal pressure tends to be high, the internal pressure is lowered early to accelerate the growth of the bubble cell, and the targeted foaming rate is obtained.

  As described above, according to the present invention, the change in the foaming rate of the bubble cell due to the length of the flow path of the molten resin can be corrected, and the foaming rate of the bubble cell can be arbitrarily controlled.

<Device configuration>
FIG. 1A is a system diagram of a resin molded product manufacturing apparatus A according to an embodiment of the present invention. The manufacturing apparatus A is an injection molding machine that employs supercritical gas foaming, but the present invention is also applicable to an injection molding machine that employs chemical foaming. The manufacturing apparatus A includes an injection apparatus 100, a mold clamping apparatus 200, and a supercritical gas generation apparatus 300. The injection device 100 includes a hopper 101 into which a resin material that is a raw material of a resin molded product is charged, a screw cylinder 102 that performs transfer, compression, kneading, melting, measurement, and the like of the resin material charged into the hopper 101, and a screw cylinder 102 And a nozzle 103 for injecting the molten resin in the screw cylinder 102 into the mold in the mold clamping device 200. Such a configuration of the injection device 100 may be the same as that of a known injection device.

  The supercritical gas generator 300 is a device that changes a gas such as carbon dioxide gas or nitrogen gas filled in the cylinder 301 to an inert gas in a supercritical state. The supercritical gas generated by the supercritical gas generator 300 is introduced into the screw cylinder 102 via the injection device 302 and is dissolved in the molten resin in the screw cylinder 102. The molten resin in which the supercritical gas is melted is injected into a mold described later in the mold clamping device 200.

  Next, the mold structure housed in the mold clamping device 200 will be described. FIG. 1B is a schematic view of a mold structure B of the manufacturing apparatus A. The mold structure B includes a fixed mold 10 and a movable mold 11. The movable mold 11 is configured to be movable as a whole by an actuator (not shown), and the mold 10 is clamped or divided.

  A cavity 16 is formed in the molds 10 and 11. The mold 10 is formed with a gate portion 10a serving as an introduction portion for the molten resin injected from the nozzle 103, and the molten resin is filled into the cavity 16 from the gate portion 10a. In this embodiment, it is assumed that a rectangular parallelepiped plate-like member is molded as a resin molded product by the manufacturing apparatus A, and the cavity 16 forms a rectangular parallelepiped filling space.

  Next, the mold 11 forms a plurality of inner walls of the cavity 16 in a substantially hollow main body having an open right end in the same figure, and is movably provided so as to partially change the volume in the cavity 16. The movable wall bodies 111a to 111k (hereinafter collectively referred to as the movable wall body 111) are disposed. In the present embodiment, each movable wall 111 has a rectangular parallelepiped shape, and constitutes a wall that defines the left side of the molded surface of the resin molded product. In FIG. 1B, a broken line L1 indicates the position of the molding surface of the resin molded product defined by the movable wall body 111. In the present embodiment, all the wall bodies that define the left side surface of the resin molded product are configured by the movable wall body 111, but it goes without saying that a part of the wall bodies may be fixed walls.

  Each moving wall 111 has rods 12a to 12k (hereinafter collectively referred to as rod 12) and cylinders 13a to 13k (hereinafter collectively referred to as cylinder 13) as driving means for individually moving them. Are provided respectively. In the present embodiment, the hydraulic actuator is used as the driving means for moving the movable wall 111, but the present invention is not limited to this, and it goes without saying that other driving means such as a driving mechanism using a motor may be used. .

  Each rod 12 has one end connected to the corresponding moving wall 111, and the other end is provided with a piston 12 'as shown in FIG. 1 (c). The cylinder 13 has a hollow cylindrical shape and is housed so that the piston 12 ′ can reciprocate in the internal space. The rod 12 passes through one end surface of the cylinder 13. The cylinder 13 is provided with oil passages 131 and 132. When hydraulic oil is supplied from the oil passage 131 into the cylinder 13 and discharged from the oil passage 132, the piston 12 'moves to the right in FIG. The corresponding moving wall 111 moves in the right direction in FIG. Further, when hydraulic oil is supplied from the oil passage 132 into the cylinder 13 and discharged from the oil passage 131, the piston 12 'moves to the left in the figure, and the corresponding moving wall body 111 in FIG. It will move to the left. The volume of the cavity 16 can be partially changed by moving the movable wall 111 in this manner.

  Supply and discharge of hydraulic fluid in the oil passages 131 and 132 of each cylinder 13 are switched by the control valve 14. The control valve 14 is, for example, an electromagnetic valve, and is provided for each hydraulic actuator. Switching of the control valve 14 is performed by the control unit 15. The control unit 15 is a sequence circuit that sequentially switches the control valve 14 or a control circuit that includes a CPU, a RAM, a ROM, an interface, and the like.

<Manufacturing method>
Next, a method for manufacturing a resin molded product using the manufacturing apparatus A will be described. Although the gate portion 10a can be set at an arbitrary position, in the present embodiment, as shown in FIG. 1B, the gate portion 10a is provided substantially at the center of the cavity 16, so that the flow path of the molten resin is From the center to both ends. Therefore, the moving wall body 111f has the shortest distance of the flow path of the molten resin from the gate portion 10a, and the moving wall bodies 111a and 111k have the longest distance. For this reason, for example, when the molten resin is filled into the cavity 16 and solidified with the arrangement of the movable wall bodies 111 shown in FIG. 1B (similar to the prior art), on both ends of the cavity 16. The internal pressure of the molten resin is low, the bubble cell is large, the internal pressure of the molten resin is high at the center, the bubble cell is small, and the bubble cell is not uniformly foamed.

  Therefore, in this embodiment, when moving each moving wall body 111 from the initial position to the position (line L1) of the molding surface of the resin molded product, the moving order is from the gate portion 10a to each moving wall body 111. It is set according to the distance of the flow path of the molten resin. By adopting such a setting method, the moving order of the moving wall body 111 can locally affect the internal pressure of the molten resin in the cavity 16 to suppress or promote the growth of bubble cells.

  Therefore, by setting the movement order according to the distance of the flow path of the molten resin, the change in the foaming rate of the bubble cell due to the length of the flow distance is corrected, and the foaming rate of the bubble cell is arbitrarily controlled. Can be possible. Hereinafter, a specific example of the movement of each moving wall body 111 will be described. Here, the case where the foaming rate of a bubble cell is equalized in each site | part of a resin molded product is demonstrated.

  FIGS. 2A to 2C are diagrams showing an example of movement of each moving wall body 111 in the case where the foaming rate of the bubble cells is made uniform in each part of the resin molded product. FIG. 2A is a diagram illustrating a process of filling the cavity 16 with molten resin from the gate portion 10a. In the figure, each moving wall 111 is located at the initial position. Specifically, the movable wall bodies 111e to 111g arranged in the vicinity of the gate portion 10a are located at the position (line L1) of the molding surface of the resin molded product, and in this example, these movable wall bodies 111e to 111g. 111g does not move. The other moving wall bodies 111a to 111d and 111h to 111k are positioned as initial positions at positions where the local volume of the corresponding cavity 16 is expanded from the original volume according to the distance from the gate portion 10a. .

  First, the movable walls 111c and 111d and 111h and 111i are located at positions (line L2) that are separated from each other in the direction in which the local volume of the cavity 16 is expanded, rather than the position (line L1) of the molding surface of the resin molded product. ing. Further, the movable walls 111a and 111b and 111j and 111k on the end side of the flow path are further separated in the direction of expanding the local volume of the cavity 16 than the position (line L1) of the molding surface of the resin molded product. It is located at the position (line L3).

  After performing the filling step of filling the cavity 16 with the molten resin as shown in FIG. 2 (a) with the respective moving wall bodies 111 arranged at the initial positions in this way, the moving wall bodies 111a to 111d and 111h are filled. To 111k are moved in a predetermined order. In the case of the example in FIG. 2, the movable walls 111a to 111d and 111h to 111k are moved to the position (line L1) of the molding surface of the resin molded product. This is the case. In this case, it is moved from the moving wall body on the side where the distance of the flow path from the gate portion 10a is long. That is, first, as shown in FIG. 2 (b), the movable walls 111a and 111b and 111j and 111k are moved to the position (line L1) of the molding surface of the resin molded product. By doing so, the internal pressure of the molten resin at both ends in the cavity 16 can be increased early, bubble growth can be delayed, and foaming of the bubble cell can be suppressed.

  That is, as described above, the internal pressure of the molten resin tends to decrease at both ends of the cavity 16 away from the gate portion 10a. However, the movable walls 111a and 111b and 111j and 111k on the both ends are resin-molded first. It moves to the position of the molding surface of the product (line L1), and by increasing the internal pressure of the molten resin at both ends of the cavity 16 first, the foaming of the bubble cell is delayed and suppressed. It is possible to obtain the foaming rate of the bubble cell and the uniform foaming rate. In this embodiment, the moving wall bodies 111a and 111b and 111j and 111k are moved simultaneously. For example, the moving wall bodies 111a and 111k may be moved individually in the order of the moving wall bodies 111b and 111j. (This is the same in other cases described later).

  Next, as shown in FIG. 2C, the movable walls 111c and 111d and 111h and 111i are moved to the position (line L1) of the molding surface of the resin molded product. The portions in the cavity 16 corresponding to the moving walls 111c and 111d and 111h and 111i have a higher internal pressure of the molten resin than the portions corresponding to the moving walls 111a and 111b and 111j and 111k, but more than the central portion of the cavity 16. Also lower. Therefore, by moving the moving walls 111c and 111d and 111h and 111i next to the moving walls 111a and 111b and 111j and 111k, the growth of the bubble cell is delayed and the internal pressure of the molten resin in the entire cavity 16 is increased. Can be made uniform. Thus, by moving each movable wall body 111 in a predetermined order, a resin molded product in which the foaming rate of the bubble cells is made uniform can be obtained. In particular, by sequentially moving each moving wall 111, the growth of the bubble cell is made uniform as a whole, and each moving wall 111 can be moved without delay with respect to the progress of resin cooling. A molded product can be obtained. Also, the foaming of the molten resin can employ chemical foaming, but it is suitable for the supercritical gas foaming that allows a longer flow path of the molten resin and enables finer foaming.

  Next, FIGS. 3A to 3C are diagrams showing another example of movement of each movable wall body 111 in the case where the foaming ratio of the bubble cell is made uniform at each part of the resin molded product. In the example of FIG. 2, the moving wall body 111 is moved in the direction of reducing the volume of the cavity 16, but in this example, it is moved in the direction of enlargement.

  FIG. 3A is a diagram showing a process of filling the cavity 16 with molten resin from the gate portion 10a. In the figure, each moving wall 111 is located at the initial position. Specifically, in the case of this example, the moving wall bodies 111a and 111b and 111j and 111k located on both ends of the cavity 16 are located at the molding surface position (line L1) of the resin molded product, and these movements The walls 111a and 111b and 111j and 111k do not move. The other moving walls 111c to 111i are positioned as initial positions at positions where the local volume of the corresponding cavity 16 is reduced from the original volume according to the distance from the gate portion 10a.

  First, the movable walls 111c and 111d and 111h and 111i are located at positions (line L4) that are separated in the direction of reducing the local volume of the cavity 16 from the position (line L1) of the molding surface of the resin molded product. ing. Further, the movable wall bodies 111e to 111g located in the vicinity of the gate portion 10a are further spaced apart (line) in the direction of reducing the local volume of the cavity 16 than the position (line L1) of the molding surface of the resin molded product. L5).

  After performing the filling step of filling the molten resin into the cavity 16 as shown in FIG. 3A with the respective moving wall bodies 111 arranged at the initial positions in this manner, the moving wall bodies 111c to 111i are set to the predetermined positions. The moving process of moving in this order is performed. In the case of the example in FIG. 3, the movable walls 111c to 111i are moved to the position (line L1) of the molding surface of the resin molded product. In this case, the volume in the cavity 16 is moved in the expanding direction. . In this case, it is moved from the moving wall body on the side where the distance of the flow path from the gate portion 10a is short. That is, first, as shown in FIG. 3B, the moving wall bodies 111e to 111g are moved to the position (line L1) of the molding surface of the resin molded product. By doing so, the internal pressure of the molten resin in the central portion in the cavity 16 can be reduced early, the growth of the bubble cell can be accelerated, and the foaming of the bubble cell can be promoted.

  That is, as described above, the internal pressure of the molten resin tends to be higher than that at both ends in the central portion of the cavity 16 close to the gate portion 10a, but the movable walls 111e to 111g on the central portion side are first molded with resin. The cell is moved to the position (line L1) of the molding surface of the product, the internal pressure of the molten resin at the central portion side of the cavity 16 is first lowered, and the bubble cell growth is accelerated by promoting the bubble cell growth. The foaming rate and uniform foaming rate of the bubble cells at both ends of 16 can be obtained.

  Next, as shown in FIG.3 (c), the movable wall bodies 111c and 111d and 111h and 111i are moved to the position (line L1) of the molding surface of a resin molded product. The portions in the cavity 16 corresponding to the moving walls 111c and 111d and 111h and 111i have a higher internal pressure of the molten resin than the portions corresponding to the moving walls 111a and 111b and 111j and 111k, but more than the central portion of the cavity 16. Also lower. Therefore, by moving the moving wall bodies 111c and 111d and 111h and 111i next to the moving wall bodies 111e to 111g, the internal pressure of the molten resin in the entire cavity 16 can be made uniform.

  Next, FIGS. 4A to 4C are diagrams showing still another example of movement of each moving wall body 111 in the case where the foaming ratio of the bubble cell is made uniform at each part of the resin molded product. In the example of FIG. 2, the moving wall body 111 is moved in the direction of reducing the volume of the cavity 16, and in the example of FIG. 3, the moving wall body 111 is moved in the direction of increasing the volume of the cavity 16. The moving wall body 111 is moved as shown in FIG. 2, and another part of the moving wall body 111 is moved as shown in FIG.

  FIG. 4A is a diagram showing a process of filling the cavity 16 with molten resin from the gate portion 10a. In the figure, each moving wall 111 is located at the initial position. Specifically, in the case of this example, the movable wall bodies 111d and 111h positioned at the intermediate position between the center portion and both end portions of the cavity 16 are positioned at the position (line L1) of the molding surface of the resin molded product. The moving wall bodies 111d and 111h do not move. The moving wall bodies 111a to 111c and 111i to 111k on both ends of the cavity 16 are positioned as initial positions at positions (line L6) at which the local volume of the corresponding cavity 16 is expanded from the original volume. Further, the moving wall bodies 111e to 111g on the center side of the cavity 16 are positioned as initial positions at positions (line L7) where the local volume of the corresponding cavity 16 is reduced from the original volume.

  After performing the filling step of filling the molten resin into the cavity 16 as shown in FIG. 4A in the state where the movable wall bodies 111 are arranged at the initial positions in this way, the movable wall bodies 111a to 111c and 111e are performed. Through 111g and 111i through 111k are moved in a predetermined order. In the case of the example in FIG. 4, any of the moving wall bodies 111 a to 111 c and 111 i to 111 k and the moving wall bodies 111 e to 111 g may be moved first, but moved from the side that suppresses foaming of bubble cells. Is preferable. Therefore, in the present embodiment, first, as shown in FIG. 4B, the movable wall bodies 111a to 111c and 111i to 111k are moved to the position (line L1) of the molding surface of the resin molded product. By so doing, foaming of the bubble cells can be suppressed on both end sides of the cavity 16. In this case, since the volume in the cavity 16 is moved in the direction of reducing, the moving wall bodies 111a and 111k → 111b and 111j → 111c and 111i are used when moved individually.

  Next, as shown in FIG.4 (c), the movable wall bodies 111e thru | or 111g are moved to the position (line L1) of the molding surface of a resin molded product. By so doing, foaming of the bubble cell can be promoted on the central portion side of the cavity 16. In this case, since the volume in the cavity 16 is moved in the direction of enlarging, when moving individually, the moving walls 111f → 111e and 111g. As in this example, even if some of the moving wall bodies 111 are moved so as to reduce the volume of the cavity 16 and other part of the moving wall bodies 111 are moved so as to enlarge the volume of the cavity 16, The internal pressure of the molten resin in the cavity 16 is made uniform, and the growth of the bubble cell is delayed at a portion far from the gate portion 10a, while it can be accelerated at a close portion, and the foaming rate of the entire resin molded product is made uniform. be able to.

  Next, the case where a different foaming rate is set in each part of the resin molded product will be described. Fig.5 (a) is a figure which shows roughly the foaming degree of each site | part of the resin molded product made into the objective of this example. In FIG. 5 (a), the parts b, d, f, h, j are solid parts having a lower foaming rate, and the parts a, c, e, g, i, k are foaming parts having a higher foaming rate. Foamed portions a, c, e, g, i, and k are located on both sides of the portions b, d, f, h, and j. In this resin molded product, since the solid portion is sandwiched between the foamed portions, deformation such as warpage of the entire resin molded product can be effectively prevented. In other words, since there are foamed parts on both sides of the solid part, which is likely to be deformed due to cooling shrinkage of the molten resin, the foamed part follows the deformation of the solid part, and the deformation is divided between the solid parts. As a whole, the resin molded product is a resin molded product with less deformation such as warpage.

  In this way, when setting different foaming rates in each part of the resin molded product, in addition to the distance of the flow path, the moving order of the movable wall bodies 111 is set according to the foaming rate in each part of the resin molded product. Set. By doing so, a different foaming rate can be obtained favorably in each part of the resin molded product. In the case of this embodiment, each part a thru | or k of the resin molded product shown to Fig.5 (a) respond | corresponds to the movable wall bodies 111a thru | or 111k, respectively.

  In the case of the present embodiment, the movable wall bodies 111b, 111d, 111f, 111h, 111j corresponding to the portion (solid portion) with a smaller foaming rate are moved in the direction of reducing the volume in the cavity 16, and The movable wall bodies 111a, 111c, 111e, 111g, 111i, and 111k corresponding to the portion (foamed portion) with a higher foaming rate are moved before. With this configuration, a partially solidified resin molded product can be obtained. In addition, the movable wall bodies 111a, 111c, 111e, 111g, 111i, and 111k corresponding to the foamed portion are moved in a direction in which the volume in the cavity 16 is enlarged. With this configuration, a resin molded product having a foamed portion with a partly higher foaming rate can be obtained.

  FIGS. 5B to 5D are diagrams showing examples of movement of the movable wall bodies 111 when the resin molded product shown in FIG. 5A is molded. In the example of FIGS. 5B to 5D, as described above, the moving wall bodies 111b, 111d, 111f, 111h, and 111j are moved in the direction of reducing the volume of the cavity 16, and the moving wall body 111a in the expanding direction. , 111c, 111e, 111g, 111i, and 111k are moved. FIG. 5B is a diagram illustrating a process of filling the cavity 16 with molten resin from the gate portion 10a.

  In the figure, each moving wall 111 is located at the initial position. Specifically, in this example, the moving walls 111b, 111d, 111f, 111h, and 111j corresponding to the solid portions b, d, f, h, and j have the local volume of the corresponding cavity 16 as the original volume. It is located as an initial position at a position (line L8) to be further enlarged. Moreover, the movable wall bodies 111a, 111c, 111e, 111g, 111i, and 111k corresponding to the foamed portions a, c, e, g, i, and k reduce the local volume of the corresponding cavity 16 from the original volume. The initial position is located at the position (line L9).

  After performing the filling process in which the molten resin is filled into the cavity 16 as shown in FIG. 5B in a state where the movable wall bodies 111 are arranged at the initial positions in this way, the movable wall bodies 111 are placed in a predetermined order. The moving process of moving is performed. Here, first, as shown in FIG. 5 (c), the movable walls 111b, 111d, 111f, 111h, 111j corresponding to the solid portions b, d, f, h, j are positioned on the molding surface of the resin molded product. Move to (line L1). At this time, the movement order is set as moving wall bodies 111b and 111j → 111d and 111h → 111f from both ends of the cavity 16 according to the distance of the flow path from the gate portion 10a as indicated by numerals in FIG. By doing so, uniform foaming of the bubble cells can be obtained between the solid portions.

  Next, as shown in FIG. 5 (d), the movable walls 111a, 111c, 111e, 111g, 111i, and 111k corresponding to the foamed portions a, c, e, g, i, and k are formed on the molding surface of the resin molded product. To the position (line L1). At this time, as indicated by numerals in the figure, the moving order is set as moving walls 111e and 111g → 111c and 111i → 111a and 111k from the center of the cavity 16 according to the distance of the flow path from the gate 10a. By carrying out like this, the uniform foaming of a bubble cell can be obtained between each foaming part part.

  Next, another example is given and demonstrated about the case where a different foaming rate is set in each site | part of a resin molded product. Fig.6 (a) is a figure which shows roughly the foaming degree of each site | part of the resin molded product made into the objective of this example. In FIG. 6 (a), the resin molded product has a lower foaming rate at the center side, the higher the foaming rate as it reaches the both end sides, the lowest foaming rate at the part f, and the parts a and k. Has the highest foaming rate.

  As described above, when the molten resin is filled into the cavity 16 and solidified, the internal pressure of the molten resin is low at both ends of the cavity 16, the bubble cell is large, the internal pressure of the molten resin is high at the center, and the bubbles Since the cell becomes small, even when the movable wall body 111 is initially arranged at the position of the molded product of the resin molded product and is not moved as it is, the foaming rate is lower in the central part, and the foaming rate becomes higher as it reaches both ends. A resin molded product is obtained, but with this, the foaming rate cannot be arbitrarily controlled. In this example, it is possible to mold a resin molded product having a lower foaming rate at the central portion of the resin molded product and a higher foaming rate at both ends than when the movable wall 111 is not moved in this manner.

  Also in the case of this example, in addition to the distance of the flow path, the moving order of the moving walls 111 is set according to the foaming rate at each part of the resin molded product. By doing so, a different foaming rate can be obtained favorably in each part of the resin molded product. In the case of this example, each part a thru | or k of the resin molded product shown to Fig.6 (a) respond | corresponds to the movable wall bodies 111a thru | or 111k, respectively.

  In the case of this example, the moving wall bodies 111d to 111h corresponding to the part with the smaller foaming rate are moved in the direction of reducing the volume in the cavity 16, and the moving wall body 111a corresponding to the part with the higher foaming rate is used. Through 111c and 111i through 111k are moved in the direction of enlarging the volume in the cavity 16. In order to increase the foaming rate at both ends of the resin molded product, the moving walls 111a to 111c and 111i to 111k are moved first to promote the growth of the bubble cells.

  FIGS. 6B to 6D are diagrams showing an example of movement of each moving wall body 111 when the resin molded product shown in FIG. 6A is molded. FIG. 6B is a diagram showing a process of filling the molten resin into the cavity 16 from the gate portion 10a.

  In the figure, each moving wall 111 is located at the initial position. Specifically, in the case of this example, the movable wall bodies 111a to 111c and 111i to 111k corresponding to the portions a to c and i to k on both ends of the resin molded product have a local volume of the corresponding cavity 16. It is positioned as an initial position at a position (line L11) to be reduced from the original volume. Further, the movable wall bodies 111d to 111h corresponding to the portions d to h on the center side of the resin molded product are initially positioned at positions (line L10) at which the local volume of the corresponding cavity 16 is expanded from the original volume. Is located as.

  After performing the filling process in which the molten resin is filled into the cavity 16 as shown in FIG. 6B in a state where the movable wall bodies 111 are arranged at the initial positions as described above, the movable wall bodies 111 are placed in a predetermined order. The moving process of moving is performed. Here, first, as shown in FIG. 6 (c), the movable walls 111a to 111c and 111i to 111k corresponding to the portions a to c and i to k on both ends of the resin molded product are molded into the resin molded product. Move to surface position (line L1). By moving these simultaneously, the foaming rate is increased in the order of the parts a → b → c (k → j → i).

  Next, as shown in FIG. 6D, the movable wall bodies 111d to 111h corresponding to the portions d to h on the center side of the resin molded product are moved to the position (line L1) of the molding surface of the resin molded product. . By moving these simultaneously, the foaming rate becomes higher in the order of the part d → e → f (h → g → f). By doing in this way, as shown to Fig.6 (a), the foaming rate is lower in a center part, and the resin molded product from which a foaming rate becomes higher as it reaches both ends is obtained.

  Next, the case where a different foaming rate is set in each part of the resin molded product will be described with another example. FIG. 7A is a view schematically showing the degree of foaming at each part of the resin molded product targeted in this example. In FIG. 7 (a), in the resin molded product, first, a certain range (parts d to h) on the center side is more average than the remaining ranges (parts a to c and i to k) on both ends. In particular, the foaming rate is high. Further, in a certain range (parts d to h) on the center side, the foaming rate is high near both ends (d → e → f and h → g → f in order), and the remaining portions on both ends are further increased. Even within the range (parts a to c and i to k), the foaming rate is high near the both ends (a → b → c, k → j → i in order).

  Also in the case of this example, in addition to the distance of the flow path, the moving order of the moving walls 111 is set according to the foaming rate at each part of the resin molded product. By doing so, a different foaming rate can be obtained favorably in each part of the resin molded product. In the case of this example, each part a thru | or k of the resin molded product shown to Fig.7 (a) respond | corresponds to the movable wall bodies 111a thru | or 111k, respectively.

  In the case of this example, the moving wall bodies 111a to 111c and 111i to 111k corresponding to ranges (parts a to c and i to k) having a smaller foam rate on average are directions in which the volume in the cavity 16 is reduced. The moving wall bodies 111d to 111h corresponding to the range where the foaming rate is higher on average (parts d to h) are moved in the direction in which the volume in the cavity 16 is enlarged. In order to reduce the foaming rate in the regions at both ends of the resin molded product, the movable walls 111a to 111c and 111i to 111k are moved first to suppress the growth of the bubble cells.

  FIGS. 7B to 7D are diagrams showing an example of movement of each movable wall 111 when the resin molded product shown in FIG. 7A is molded. FIG. 7B is a diagram showing a process of filling the cavity 16 with molten resin from the gate portion 10a.

  In the figure, each moving wall 111 is located at the initial position. Specifically, in the case of this example, the movable wall bodies 111a to 111c and 111i to 111k corresponding to the portions a to c and i to k on both ends of the resin molded product have a local volume of the corresponding cavity 16. It is positioned as an initial position at a position (line L12) where the original volume is expanded. Further, the movable wall bodies 111d to 111h corresponding to the portions d to h on the center side of the resin molded product are initially positioned at a position (line L13) for reducing the local volume of the corresponding cavity 16 from the original volume. Is located as.

  After performing the filling process of filling the molten resin into the cavity 16 as shown in FIG. 7B in the state where the movable wall bodies 111 are arranged at the initial positions in this way, the movable wall bodies 111 are arranged in a predetermined order. The moving process of moving is performed. Here, first, as shown in FIG. 7 (c), the movable walls 111a to 111c and 111i to 111k corresponding to the portions a to c and i to k on both ends of the resin molded product are molded into the resin molded product. Move to surface position (line L1). Thereby, it is possible to lower the foaming rate on average than the region (parts d to h) on the center side. Further, by simultaneously moving the moving wall bodies 111a to 111c and 111i to 111k, the foaming rate is increased in the order of parts a → b → c (k → j → i).

  Next, as shown in FIG. 7 (d), the movable wall bodies 111d to 111h corresponding to the portions d to h on the center side of the resin molded product are moved to the position (line L1) of the molding surface of the resin molded product. . By moving these simultaneously, the foaming rate becomes higher in the order of the part d → e → f (h → g → f). By doing in this way, the resin molded product by which the foaming rate was controlled as shown to Fig.7 (a) can be obtained.

(A) is the system diagram of the manufacturing apparatus A of the resin molded product which concerns on one Embodiment of this invention, (b) is the schematic of the metal mold | die structure B of the manufacturing apparatus A, (c) is the structural diagram of a hydraulic actuator. . (A) thru | or (c) is a figure which shows the example of a movement of each moving wall body 111 in the case of equalizing the foaming rate of a bubble cell in each site | part of a resin molded product. (A) thru | or (c) is a figure which shows the other movement example of each moving wall body 111 in the case of equalizing the foaming rate of a bubble cell in each site | part of a resin molded product. (A) thru | or (c) is a figure which shows the further another example of a movement of each moving wall body 111 in the case of equalizing the foaming rate of a bubble cell in each site | part of a resin molded product. (A) is a figure which shows roughly the foaming degree of each site | part of the resin molded product which can be shape | molded by embodiment of this invention, (b) thru | or (d) shape | mold the resin molded product shown to Fig.5 (a). It is a figure which shows the example of a movement of each moving wall body 111 in the case of doing. (A) is a figure which shows roughly the foaming degree of each site | part of the other resin molded product which can be shape | molded by embodiment of this invention, (b) thru | or (d) are the resin molded products shown to Fig.6 (a). It is a figure which shows the example of a movement of each moving wall body 111 in the case of shape | molding. (A) is a figure which shows roughly the foaming degree of each site | part of still another resin molded product which can be shape | molded by embodiment of this invention, (b) thru | or (d) are the resin molding shown in FIG. 7 (a). It is a figure which shows the example of a movement of each moving wall body 111 in the case of shape | molding goods.

Explanation of symbols

10, 11 Mold 111a-111k Moving wall 12a-12k Rod (driving means)
13a to 13k cylinder (drive means)
15 Control unit 16 Cavity

Claims (11)

In a resin molded product manufacturing method for manufacturing a resin molded product by filling a molten resin into a cavity formed in a mold and foaming it,
A filling step of filling the cavity with the molten resin;
Moving the plurality of moving wall bodies configured to move so as to partially change the volume inside the cavity, and forming an inner wall of the cavity; and
In the moving step,
Moving the predetermined movable wall body from the initial position to the position of the molding surface of the resin molded product in a predetermined movement order;
The method of manufacturing a resin molded product, wherein the moving order is set according to a distance of a flow path of the molten resin from the molten resin introduction part into the cavity to the moving wall body .   2. The resin molded product according to claim 1, wherein when the moving wall body is moved in a direction of reducing the volume in the cavity, the moving wall body is moved from the moving wall body on the longer side. Production method.   2. The resin molded product according to claim 1, wherein when the moving wall body is moved in a direction in which the volume in the cavity is increased, the moving wall body is moved from the moving wall body on the short side. Production method.   The moving order of each said moving wall body is set according to the said distance and the foaming rate made into the objective in each site | part of the said resin molded product, The Claim 1 thru | or 3 characterized by the above-mentioned. Manufacturing method for resin molded products.   The moving wall body corresponding to the part with the lower foaming rate is moved in the direction of reducing the volume in the cavity and moved before the moving wall body corresponding to the part with the higher foaming rate. The method for producing a resin molded product according to claim 4, wherein:   6. The method for manufacturing a resin molded product according to claim 5, wherein the moving wall body corresponding to a portion having a higher foaming rate is moved in a direction in which the volume in the cavity is enlarged. The foaming rate has a first foaming rate and a second foaming rate greater than the first foaming rate,
The part of the resin molded product in which the second foaming rate is set is located on both sides of the part of the resin molded product in which the first foaming rate is set. The manufacturing method of the resin molded product in any one.   The method for producing a resin molded product according to any one of claims 1 to 7, wherein an inert gas in a supercritical state is dissolved in the molten resin. In a resin molded product manufacturing apparatus for manufacturing a resin molded product by filling a molten resin into a cavity formed in a mold and foaming it,
A plurality of movable wall bodies configured to constitute an inner wall of the cavity and to be movable so as to partially change a volume in the cavity;
Driving means for moving each of the moving wall bodies;
Control means for controlling the drive means;
With
The control means includes
After the molten resin is filled into the cavity, the driving unit is controlled so that the predetermined moving wall body moves from the initial position to the position of the molding surface of the resin molded product in a predetermined movement order,
The apparatus for producing a resin molded product, wherein the moving order is set according to a distance of a flow path of the molten resin from the molten resin introduction portion into the cavity to the moving wall body .   10. The resin molded product according to claim 9, wherein when the moving wall body is moved in a direction of reducing the volume in the cavity, the moving wall body is moved from the moving wall body on the longer side. Manufacturing equipment.   10. The resin molded product according to claim 9, wherein when the moving wall body is moved in a direction in which the volume in the cavity is enlarged, the moving wall body is moved from the moving wall body on the short side. Manufacturing equipment.

Images