JP4893220B2 - Resin multilayer injection molding method and resin multilayer injection molding apparatus - Google Patents

Description

  The present invention relates to a resin multilayer injection molding method and a resin multilayer injection molding apparatus in which at least two kinds of resin molding materials are injection molded into a multilayer structure.

In recent years, resin molded products used for automobile parts and home appliances have their molds at the same time as molding in order to increase the decorativeness and diversity, or to reduce the cost by omitting the steps during the molding process. Molding with a resin molding material as a multilayer structure has been implemented. That is,
(1) In order to enhance the decorativeness and diversity of the molded product, for example, a laminate formed with a structure in which a resin layer having a soft feeling or a colored resin layer having a high-class feeling is laminated on the surface of the molded product .
(2) Sandwich molding in which the inside of a resin molded product is filled with a recycled material or a resin material containing a reinforcing material in order to effectively use the recycled material and reinforce the molded product. Such a method has been proposed.

  In these molding methods, when the resin molding material to be the first layer is injected and filled into the mold cavity, the mold cavity volume is enlarged when the resin molding material to be the second layer is injected and filled. Done. As the mold clamping mechanism used in these molding methods, a direct pressure type having a hydraulic mold clamping cylinder in which the expansion control of the mold cavity volume is relatively easy is adopted. (See Patent Document 1)

By the way, in these molding methods, the amount of expansion of the mold cavity volume is an important factor affecting the thickness and dimensions of the molded product, and is required to be controlled with high accuracy and high reproducibility. However, in the molding method using such a conventional direct pressure type mold clamping mechanism, the control accuracy of the hydraulic cylinder varies due to the compressibility of the hydraulic oil and the change in viscosity due to a temperature change.
Further, since the cylinder stroke is long, the control response is low. Furthermore, since the control amount of the cylinder stroke and the movement amount of the mold are one-to-one, there is a problem that when the multilayer injection molding is performed due to the low position control characteristics, it is impossible to obtain a molded product with a high thickness of the molded product. was there.

For this reason, there is disclosed a mold platen position control method for a toggle type mold clamping device that improves the control accuracy by performing the backward movement control of the movable platen with a cross head that performs a movement larger than the reverse amount of the movable platen.
According to this method, the distance between the movable platen and the fixed platen can be kept constant with high accuracy. (See Patent Document 2)

However, the molding method in which the toggle mechanism is bent using the conventional toggle type mold clamping device to enlarge the mold cavity volume still has the following problems.
That is, after the injection molding of the second layer resin molding material, the toggle mechanism is driven to open the mold, the mold cavity volume is enlarged, and the second layer molding resin material filling space is secured. In this toggle mechanism, when the injection filling pressure of the second layer acts on the movable mold surface, it is not possible to obtain a sufficient holding force necessary to hold and resist the movable platen position. For this reason, when the filling pressure is applied to the movable mold surface, there is a problem that the movable platen retreats, the mold cavity volume is further enlarged, and the thickness accuracy of the molded product cannot be maintained.

JP 54-86550 A JP-A-8-309779

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to improve mold cavity volume expansion position control in mold cavity volume expansion control using a toggle type mold clamping mechanism. Another object of the present invention is to provide a resin multilayer injection molding method and a resin multilayer injection molding apparatus for obtaining a resin molded article having a desired multilayer structure.

  In order to achieve the above object, a resin multilayer injection molding method according to claim 1 of the present invention is a mold using an injection device for injecting and filling at least two kinds of resin molding materials into a mold cavity, and a toggle mechanism. A resin multi-layer injection molding method for obtaining a multi-layer molded product by using a mold clamping device for opening and closing and mold clamping, and molding by molding a first layer resin molding material into a mold cavity Later, the movable platen is moved backward to enlarge the mold cavity to form a secondary cavity between the first layer of the resin molding material and the mold cavity surface, and the second layer is formed in the formed secondary cavity. When the resin molding material is injected and filled, the secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then the movable plate is locked with the toggle mechanism in a predetermined mold. Until reaching the cavity expansion position After retracting the toggle mechanism drives the thickness adjustment mechanism, and performs to advance the movable platen to the locking state of the toggle mechanism drives the toggle mechanism.

  According to a second aspect of the present invention, there is provided a resin multi-layer injection molding method comprising: an injection device for injecting and filling at least two types of resin molding materials into a mold cavity; and a mold opening / closing and mold clamping using a toggle mechanism. A resin multi-layer injection molding method for obtaining a multi-layer molded article using a mold clamping device, wherein after molding a resin molding material of a first layer into a mold cavity by injection, The mold cavity is enlarged to form a secondary cavity between the first layer resin molding material and the mold cavity surface, and the second layer resin molding material is placed inside the first layer resin molding material. In injection filling, the secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then the movable platen is in a predetermined mold cavity enlarged position in the locked state of the toggle mechanism. Drive the mold thickness adjustment mechanism until After retracting the glue mechanism, and performs to advance the movable platen to the locking state of the toggle mechanism drives the toggle mechanism.

  According to a third aspect of the present invention, there is provided a resin multi-layer injection molding method according to the first or second aspect of the present invention, wherein after the second layer resin molding material is injected and filled, the movable plate moves backward. Toggle mechanism by driving the mold thickness adjusting mechanism until the mold clamping force setting position at the time of filling the first layer resin is filled between the start of mold opening for taking out the multilayer molded product and the start of mold closing in the next cycle It is characterized by advancing.

  The multilayer injection molding method for resin according to claim 4 of the present invention is the invention according to any one of claims 1 to 3, wherein the first layer and / or the second layer is a physical foaming agent or a chemical foaming agent. A resin molding material containing a foaming agent such as the above, wherein after the injection filling of the first layer and / or the second layer, the toggle mechanism is driven to retract the movable plate to a predetermined foaming position. .

  In order to achieve the above object, a multilayer injection molding apparatus for resin according to claim 5 of the present invention is a mold using an injection apparatus for injecting and filling at least two types of resin molding materials into a mold cavity, and a toggle mechanism. A resin multi-layer injection molding apparatus for obtaining a multi-layer molded product, which is molded by injection-filling a first-layer resin molding material into a mold cavity. Later, the movable platen is moved backward to enlarge the mold cavity to form a secondary cavity between the first layer of the resin molding material and the mold cavity surface, and the second layer is formed in the formed secondary cavity. When the resin molding material is injected and filled, the secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then the movable plate is locked with the toggle mechanism in a predetermined mold. Until reaching the cavity expansion position After retracting the toggle mechanism drives the thickness adjustment mechanism, characterized by being configured to advance the movable platen to the locking state of the toggle mechanism drives the toggle mechanism.

  In order to achieve the above object, a multilayer injection molding apparatus for resin according to claim 6 of the present invention is a mold using an injection apparatus for injecting and filling at least two types of resin molding materials into a mold cavity, and a toggle mechanism. A resin multi-layer injection molding apparatus for obtaining a multi-layer molded product, which is molded by injection-filling a first-layer resin molding material into a mold cavity. Later, the movable platen is moved backward to enlarge the mold cavity to form a secondary cavity between the first layer resin molding material and the mold cavity surface, and within the first layer resin molding material. When the second layer of resin molding material is injected and filled, the secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then the movable platen is in the locked state of the toggle mechanism. Becomes a predetermined mold cavity expansion position In after retracting the toggle mechanism drives the mold thickness adjustment mechanism, characterized by being configured to advance the movable platen to the locking state of the toggle mechanism drives the toggle mechanism.

  According to a seventh aspect of the present invention, there is provided the resin multilayer injection molding apparatus according to the fifth or sixth aspect, wherein the mold thickness adjusting mechanism is inserted through the four corners on the back surface of the link housing of the mold clamping device. The four axes are configured to be driven synchronously or individually by driving means provided on each tie bar nut screwed to the tie bar.

  The multilayer injection molding apparatus for resin according to claim 8 of the present invention is the invention according to any one of claims 5 to 7, wherein the first layer and / or the second layer are foamed materials such as a physical foaming agent and a chemical foaming agent. A resin molding material containing an agent, wherein the movable platen is moved back to a predetermined foaming position by driving a toggle mechanism after injection filling of the first layer and / or the second layer. To do.

  In the resin multilayer injection molding method according to claim 1, after the first layer resin molding material is injected and filled into the mold cavity, the second layer resin molding material is closed with the toggle mechanism locked. Since injection filling is performed in the formed secondary cavity, the resin filling pressure does not act on the crosshead of the toggle mechanism even when the resin filling force of the second layer acts on the movable mold surface. Is pushed back and the secondary cavity does not further expand, so that the thickness accuracy of the molded product can be maintained and the molded product will not be defective.

In the resin multilayer injection molding method according to claim 2, after the first layer of the resin molding material is injected and filled into the mold cavity, the toggle mechanism is closed in a locked state to form a secondary cavity, Since the resin molding material of the second layer is injected and filled into the resin molding material of the first layer, even if the resin charging pressure of the second layer acts on the movable mold surface, the resin filling force is not applied to the crosshead of the toggle mechanism. Therefore, the toggle mechanism is not pushed back and the secondary cavity does not further expand, so that the thickness accuracy of the molded product can be maintained and no defect occurs in the molded product.
In the resin multi-layer injection molding method according to the third aspect, the mold thickness adjusting mechanism is driven to start the toggle mechanism between the start of mold opening after completion of cooling of the molded product and the start of mold closing in the next cycle. Since it is moved to a predetermined molding position, the molding cycle time is not extended.

  In the resin multilayer injection molding method according to claim 4, since the foaming agent is included in the first layer and / or the second layer resin molding material, the laminated molded product having the foam layer, the inside, the outside, or the inside It is possible to obtain a sandwich molded product in which the outside is foamed. The expansion of the mold cavity volume in foaming uses the magnification characteristics of the toggle mechanism, and the relationship between the cross head and the movable plate detected when the mold clamping device at the mold touch point is moved in the mold opening direction. Is stored as position data, and the position of the movable platen is controlled based on the stored position data. According to this method, it is possible to obtain a multi-layer injection-molded product having a foam layer having a desired expansion ratio and cell diameter.

  In the resin multilayer injection molding apparatus according to claim 5, after the first layer of the resin molding material is injected and filled in the mold cavity, the second layer of the resin molding material is closed with the toggle mechanism locked. Since it is configured to inject and fill the formed secondary cavity, the resin filling force does not act on the crosshead of the toggle mechanism even when the resin filling pressure of the second layer acts on the movable mold surface. Since the toggle mechanism is pushed back and the secondary cavity does not further expand, the thickness accuracy of the molded product can be maintained, and no defect occurs in the molded product.

  In the multilayer injection molding apparatus for resin according to claim 6, after the first layer of the resin molding material is injected and filled into the mold cavity, the toggle mechanism is closed in a locked state to form a secondary cavity, Since the resin molding material of the second layer is injected and filled inside the resin molding material of the first layer, even if the resin filling pressure of the second layer acts on the movable mold surface, the resin is applied to the crosshead of the toggle mechanism. The filling force does not act, and therefore, the toggle mechanism is pushed back and the secondary cavity does not further expand, so that the thickness accuracy of the molded product can be maintained and the molded product will not be defective.

In the resin multi-layer injection molding apparatus according to the seventh aspect, the mold thickness adjusting mechanism is inserted into the four corners of the back side of the link housing of the mold clamping apparatus and is driven by driving means provided on each of the tie bar nuts screwed to the tie bar. Since the axes are driven synchronously or individually, the movable platen parallelism adjustment, movable platen position adjustment that matches the mold parallelism, fine clamping force adjustment, mold cavity volume expansion position Can be finely adjusted with high accuracy and high reproducibility.

  In the multilayer injection molding apparatus for resin according to claim 8, a multilayer injection molded product in which the first layer is foamed using a resin molding material containing a foaming agent in the first layer resin, and either the first layer or the second layer is used. In addition, a multilayer injection molded product in which a foam layer and a foam layer are laminated can be obtained using a resin molding material containing a foaming agent.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
1 to 9 relate to the best mode for carrying out the present invention, FIG. 1 is an overall conceptual diagram of a resin multilayer injection molding apparatus according to an embodiment of the present invention, and FIG. 2 conceptually shows a mold thickness adjusting mechanism. It is a conceptual drawing. FIG. 3 is a flowchart showing a molding operation procedure, FIG. 4 is a flowchart showing a molding operation procedure for foaming a second-layer resin molding material, FIG. 5 is a process explanatory diagram for explaining the outline of the molding process, and FIG. It is process explanatory drawing explaining the outline of the molding process which foams the resin molding material of this.
FIG. 7 is an overall conceptual diagram of a multilayer injection molding apparatus for resin showing another embodiment, FIG. 8 is a process explanatory view for explaining the outline of a molding process according to another embodiment, and FIG. 9 is a second layer of another embodiment. It is process explanatory drawing explaining the outline of the molding process which foams a resin molding material.

  As shown in FIG. 1, an injection molding apparatus 100 according to the present invention includes a mold clamping device 110, an injection device 120, a control device 130 that controls the mold clamping device 110 and the injection device 120, and a mold 30. Yes. As shown in FIG. 1, the mold 30 includes a fixed mold 31 and a movable mold 32, and the fixed mold 31 and the movable mold 32 have a half-push structure and are fitted in a fitting portion, and in a fitted state. The cavity surface formed on the fixed mold 31 and the cavity surface formed on the movable mold 32 are combined to form the mold cavity 32. The fitting portion of the half-push structure is formed over the entire circumference of the mold, and even if the volume of the mold cavity 33 is increased after injection filling, the resin molding material filled in the mold cavity 33 is the mold 30. To prevent leakage. Reference numeral 34 denotes a secondary cavity formed by injecting and filling the first layer of resin molding material and then retracting the movable mold 32.

A mold clamping device 110 shown in FIG. 1 includes a link driving mechanism 18 having a fixed mold 12, a movable mold 13, and an electric servo motor 22 as driving sources, a toggle mechanism 16 driven by the link driving mechanism 18, and an electric servo motor 22. The movable platen 13 is guided by a tie bar 21 installed between the fixed platen 12 and the link housing 11 and can be moved forward and backward together with the movable die 32 by the toggle mechanism 16. ing.
A stroke sensor 24 as a position sensor for detecting the position of the crosshead 17 is attached to the crosshead drive shaft 23 of the link drive mechanism 18 provided in the mold clamping device 110. The position of the head 17 can be accurately detected.

  In the present embodiment, the stroke sensor 24 is arranged as a position sensor for detecting the position of the crosshead 17. However, the position sensor for detecting the position of the crosshead 17 is not limited to this. Of course, a method of detecting by a sensor built in the electric servo motor 22 may be used.

  Further, the mold clamping device 110 includes a mold clamping force sensor 25 at one end of the tie bar 21 on the fixed platen side as a sensor for detecting the mold clamping force, and the mold clamping force detection sensor 25 detects the extension amount of the tie bar 21. Thus, the mold clamping force is detected. Further, the injection molding apparatus 100 is arranged such that the movable platen position sensor 26 detects the position of the movable platen 13 as a mold opening / closing stroke sensor for detecting the mold opening / closing stroke. The opening / closing stroke of the mold 30 is detected. The detection signals from these detectors are received, and the mold opening / closing is controlled by the output signal of the mold clamping control unit.

The mold clamping device 110 includes a mold thickness adjusting mechanism 19 for attaching the molds 30 having different thicknesses. The toggle mechanism 16 can be moved forward and backward by rotationally driving a tie bar nut 27 that is inserted into the link housing 11 by the driving means 29 and screwed into the tie bar 21. Further, the mold clamping force can be set by driving the mold thickness adjusting mechanism 19.
Reference numeral 28 denotes a die height position sensor that detects the die height position by detecting the amount of movement of the link housing 11 that moves together with the toggle mechanism 16 by the mold thickness adjusting mechanism 19, and can accurately detect the die height position.

The toggle mechanism 16 in the present embodiment is a 5-bar double toggle type having 5 link nodes, and has a method of controlling the movement of the movable platen 13 and the mold clamping force by operating the cross head 17 in the mold opening / closing direction. A four-section double toggle mechanism with four link sections may be used.
Further, in the present embodiment, the electric servo motor 22 as shown in FIG. 1 is used as the driving means for the crosshead 17, but the present invention is not limited to the present embodiment applicable to the present invention, and the driving means for the crosshead 17 is hydraulic. A cylinder or the like may be applied to the present invention. The mold clamping device 110 is placed on a machine base (not shown).

Next, the configuration of the injection device 120 used in the embodiment of the present invention will be described.
The injection device 120 shown in FIG. 1 includes a first injection unit 41 that supplies a first layer of resin molding material into a mold cavity 33 and a second injection unit 42 that supplies a second layer of resin molding material. , Each injection unit is equipped with a barrel and a screw having a flight, a hopper for supplying a resin molding material into the barrel, a screw moving means for moving the screw back and forth, and a screw rotation drive for rotating the screw Means are provided.
The first injection unit 41 and the second injection unit 42 have shut-off valves 43 and 44 that open and close the resin flow path.

  The first injection unit 41 and the second injection unit 42 are configured such that a pellet-shaped resin molding material is supplied from the hopper into the barrel when the screw is rotated by a screw rotating means. The pellet-shaped resin molding material is heated by a heater attached to the barrel, melted by being subjected to a kneading compression action by the rotation of the screw, and sent to the front of the screw. The molten resin sent to the front of the screw is injected and filled into the mold cavity through the nozzles through the shut-off valves 43 and 44 attached to the tip of the barrel by the screw advanced by the screw moving means.

The first injection unit 41 supplies molten resin into the mold cavity from the axial direction of the injection molding apparatus 100 of the fixed mold 31 and the second injection unit 42 supplies the mold cavity from the direction intersecting with the axis of the injection molding apparatus 100 of the fixed mold 31. It is the composition to do. The resin molding materials for the first layer and the second layer are general-purpose thermoplastic resins such as polyethylene (PE), polypropylene (PP), and ABS resin, polycarbonate (PC), polyacetal (POM), polyamide (nylon), etc. General-purpose engineering plastics can be used. It is also useful to use these recycled materials as the core material for sandwich molding.
Moreover, although the screw moving means and the screw rotating means of the injection apparatus 100 in this embodiment are driven by an electric servo motor, the embodiment applicable to the present invention is not limited to this embodiment, and drives a hydraulic cylinder and a hydraulic motor. It may be a moving and rotating means as a source.

  The control device 130 used in the present embodiment includes a mold clamping control unit 71 that controls the mold clamping device 110, a mold clamping condition setting unit that sets the mold clamping conditions, and an injection control unit 72 that controls the injection device 130. And an injection condition setting device for setting injection conditions.

The mold thickness adjustment 19 shown in FIG. 2 has four tie bars including a drive means 29 that uses an electric servomotor that drives and rotates a tie bar nut 27 screwed into a tie bar 21 inserted through four corners on the back of the link housing 11. 21 is provided in each. Reference numeral 22 denotes an electric servo motor which is a drive unit of the link drive mechanism 18 that drives the toggle mechanism 16.
The amount of movement of the link housing 11 that is moved by the mold thickness adjusting mechanism 19 is detected by the above-described die height position sensor 28 that detects the die height position. In this embodiment, the four tie bars 21 are each provided with driving means for driving the tie bar nuts 27 independently, and the four axes are driven synchronously or individually. However, the two tie bars are paired, Alternatively, the four tie bars 21 may be driven as a set by one driving means.

  The operation of the injection molding apparatus 100 configured as described above will be described. FIG. 3 is a flowchart showing a molding operation procedure, FIG. 4 is a flowchart showing a molding operation procedure for foaming a second-layer resin molding material, FIG. 5 is a process explanatory diagram for explaining the outline of the molding process, and FIG. It is process explanatory drawing explaining the outline of the molding process which foams the resin molding material of this.

The molding operation procedure is performed according to the following procedure as shown in FIGS.
(A) A mold closing operation is performed based on the crosshead position setting value (S1) previously set by the mold clamping condition setting device. After the detection signal of the stroke sensor 24 reaches the set value (S1), the electric servo motor 22 is controlled so as to hold the set value (S1) to perform position holding control (the toggle mechanism is in the mechanical lock state).
(B) The shutoff valve 43 of the first injection unit 41 is opened, and the first layer of molten resin is injected and filled into the mold cavity 33. After the first layer of molten resin is injected and filled and the pressure holding is completed, the shutoff valve 43 is closed, and then cooling is performed for a predetermined time set according to the cooling and solidification state of the first layer resin.

(C) After detecting that the cooling of the first layer resin has been completed, the mold opening operation is performed based on the crosshead position (S2) set by the mold clamping condition setting device, and the movable platen 13 is moved backward to clamp the mold. Release power. After the detection signal of the stroke sensor 24 reaches the set value (S2), the electric servo motor 22 is controlled so as to hold the set value (S2) to perform position holding control (the toggle mechanism is in a bent state).
(D) After detecting that the mold clamping force has been released and the detection signal of the stroke sensor 24 has reached the set value (S2), the die height is retracted based on the die height position set value (S12) set by the mold clamping condition setter. By operating, the movable platen 13 is moved backward to enlarge the volume of the mold cavity 33, and a secondary cavity 34 is formed between the first layer resin surface and the movable cavity surface. After the detection signal of the die height position sensor 28 reaches the set value (S12), the drive means 29 is controlled so as to hold the set value (S12) and the position holding control is performed (the toggle mechanism is in the bent state).

(E) After detecting that the predetermined die height position (S12) has been reached, the mold closing operation is performed based on the crosshead position (S3) set by the mold clamping condition setting device to advance the movable platen 13. After the detection signal of the stroke sensor 24 reaches the set value (S3), the electric servo motor 22 is controlled so as to hold the set value (S3) to perform position holding control (the toggle mechanism is in the mechanical lock state).
(F) The shutoff valve 44 of the second injection unit 42 is opened, and the second layer of molten resin is injected and filled into the secondary cavity 34. After the second layer of molten resin is injected and filled and the pressure holding is completed, the shutoff valve 44 is closed, and then cooling is performed for a predetermined time set according to the cooling and solidification state of the second layer resin.

(G) After detecting that the cooling of the second layer resin has been completed, the movable platen 13 is moved backward by performing a mold opening operation based on the mold opening position setting value set by the mold clamping condition setting device. After the detection signal of the stroke sensor 24 reaches the set value, the electric servomotor 22 is controlled so as to hold the mold open position, and position holding control is performed (the toggle mechanism is in a bent state). Next, the molded product is extruded from the mold 30 and taken out of the injection molding machine.
(H) After the completion of mold opening is detected, the extrusion operation of the molded product is performed, and the die height advance operation is performed based on the die height position setting value (S11) set by the mold clamping condition setting device, and the mold clamping condition setting device The toggle mechanism 16 is advanced to a position where the mold clamping force set in step 1 is obtained. After the detection signal of the die height position sensor 28 reaches the set value (S11), the drive means 29 is controlled to hold the set value (S11), position holding control is performed, and a start signal for the next molding is waited.

Next, a molding operation procedure for foaming the second layer resin after injection filling will be described with reference to FIGS. In this procedure, the procedure from (a) to (e) is the same as the procedure shown in FIG. 3 and FIG. 5 described above.
(F) The shut-off valve 44 of the second injection unit 42 is opened, and a second layer of molten resin to be a foam layer is injected and filled into the secondary cavity 34. After the injection and filling of the second layer of molten resin is completed, the shut-off valve 44 is closed, and then a skin layer is formed on the secondary cavity contact surface of the second layer resin, which is set according to the formation state of the skin layer The mold clamping state is maintained for a predetermined time (t1).
(G) After the skin layer is formed on the secondary cavity contact surface of the second layer, the movable platen 13 is moved backward by performing the mold opening operation based on the crosshead position (S4) set by the mold clamping condition setting device. The volume of the secondary cavity 34 is increased. Then, the second layer resin is foamed in the enlarged cavity. After the detection signal of the stroke sensor 24 reaches the set value (S4), the electric servo motor 22 is controlled so as to hold the set value (S4) until a predetermined cooling time to perform position holding control (the toggle mechanism is Bent state).

(H) After detecting that the cooling of the second layer is completed, the mold opening operation is performed based on the mold opening position setting value set by the mold clamping condition setting device, and the movable platen 13 is moved backward. After the detection signal of the stroke sensor 24 reaches the set value, the electric servomotor 22 is controlled so as to hold the mold open position, and position holding control is performed (the toggle mechanism is in a bent state). Next, the molded product is extruded from the mold 30 and taken out of the injection molding machine.
(I) After detecting the completion of mold opening, an extrusion operation of the molded product is performed, and a die height advancement operation is performed based on the die height position setting value (S11) set by the mold clamping condition setting device to set the mold clamping condition setting device. The toggle mechanism 16 is advanced to a position where the mold clamping force set in step 1 is obtained. After the detection signal of the die height position sensor 28 reaches the set value (S11), the drive means 29 is controlled to hold the set value (S11), position holding control is performed, and a start signal for the next molding is waited.

Here, in the expansion operation of the mold cavity volume for foaming (FIG. 6G), the movable plate with respect to the movement stroke of the crosshead 17 immediately before the movable mold 32 comes into contact with the fixed mold 31 (mold touch). The 13 movement strokes have a ratio of about 10: 1. In addition, the moving speed of the movable plate 13 with respect to the moving speed of the crosshead 19 is approximately 10 to 1. In other words, in the mold clamping apparatus provided with the toggle mechanism 16, if the position of the crosshead 17 is controlled, the movable platen 13 is controlled with an accuracy of about 10 times the crosshead position accuracy. Position control can be performed. And even with a molded product that could not be molded by the injection foam molding method and the injection foam molding device that expands the mold cavity volume of the conventional mold and foams the resin, the foaming magnification, the bubble diameter, and the thickness of the molded product are highly accurate. It is possible to obtain a multilayer injection molded product having a dense surface layer and little variation in foaming ratio and bubble size.
Further, the secondary cavity is formed between the surface of the first layer resin and the movable cavity surface, but the embodiment applicable to the present invention is not limited to this example, and the surface of the first layer resin and the fixed mold The structure formed between cavity surfaces may be sufficient.

FIG. 7 is an overall conceptual diagram of a multilayer injection molding apparatus for resin showing another embodiment, FIG. 8 is a process explanatory view for explaining the outline of a molding process according to another embodiment, and FIG. 9 is a second layer of another embodiment. It is process explanatory drawing explaining the outline of the molding process which foams a resin molding material.
The difference between the injection molding apparatus 200 shown in FIG. 7 and the injection molding apparatus 100 shown in FIG. 1 will be described. Similar to the first injection unit 51, the second injection unit 52 of the injection molding apparatus 200 is arranged in communication with the back surface of the stationary platen 12 via the injection nozzle 56 in the axial direction of the injection molding apparatus 200. Two types of molten resin are supplied to the cavities 33 and 34 of the mold 60 by switching the shut-off valve 55 attached to the mold 60. The basic configurations of the mold 60, the mold clamping device 110, and the control device 230 are the same as those shown in FIG.

The operation of the injection molding apparatus 200 configured as described above will be described. The molding operation procedure is performed according to the following procedure as shown in FIG. In addition, the flowchart which shows the shaping | molding operation | movement procedure of FIG. 7 was abbreviate | omitted. This is because the step of refilling the first layer of resin after the second layer of molten resin is injected and filled in the cavity is added to the operation flow described above. This is because it can be easily understood from the process explanatory diagram described in the above.
(A) A mold closing operation is performed based on the crosshead position setting value (S1) previously set by the mold clamping condition setting device. After the detection signal of the stroke sensor 24 reaches the set value (S1), the electric servo motor 22 is controlled so as to hold the set value (S1) to perform position holding control (the toggle mechanism is in the mechanical lock state).
(B) The shut-off valve 53 of the first injection unit 51 is opened and the shut-off valve 55 in the injection nozzle 56 is switched to inject and fill the first layer of molten resin as a base material into the mold cavity 33. After the injection and filling of the first layer of molten resin is completed, the shutoff valve 53 is closed and the shutoff valve 55 in the injection nozzle 56 is switched to the injection and filling direction of the second layer of resin, and then the base resin is cooled and solidified. Cooling is performed for a predetermined time set according to the state.

(C) After detecting that the cooling of the base resin has been completed, the mold opening operation is performed based on the crosshead position (S2) set by the mold clamping condition setting device, and the movable platen 13 is moved backward to apply the mold clamping force. release. After the detection signal of the stroke sensor 24 reaches the set value (S2), the electric servo motor 22 is controlled so as to hold the set value (S2) to perform position holding control (the toggle mechanism is in a bent state).
(D) After detecting that the mold clamping force has been released and the detection signal of the stroke sensor 24 has reached the set value (S2), the die height is retracted based on the die height position set value (S12) set by the mold clamping condition setter. By operating, the movable platen 13 is moved backward to enlarge the volume of the mold cavity 33, and a secondary cavity 34 is formed between the first layer resin surface and the movable cavity surface. After the detection signal of the die height position sensor 28 reaches the set value (S12), the drive means 29 is controlled so as to hold the set value (S12) and the position holding control is performed (the toggle mechanism is in the bent state).

(E) After detecting that the predetermined die height position (S12) has been reached, the mold closing operation is performed based on the crosshead position (S3) set by the mold clamping condition setting device to advance the movable platen 13. After the detection signal of the stroke sensor 24 reaches the set value (S3), the electric servo motor 22 is controlled so as to hold the set value (S3) to perform position holding control (the toggle mechanism is in the mechanical lock state).
(F) The shut-off valve 54 of the second injection unit 52 is opened, and the second layer of molten resin as a core material is injected and filled into the base resin. After the injection and filling of the second layer of molten resin is completed, the shutoff valve 54 is closed and the shutoff valve 55 in the injection nozzle 56 is switched to the injection and filling direction of the first layer of resin.
(G) Next, before the second layer resin as the core material is solidified, the first injection unit 51 is driven to fill an appropriate amount of the first layer molten resin to remove traces of the core material filling on the surface of the molded product. To do. And by this filling operation, the molten resin in the resin flow path from the shut-off valve 55 to the nozzle tip is replaced with the first layer resin, and the first layer resin and the second layer resin may be mixed in the next molding. Absent. Cooling is performed for a predetermined time set according to the cooling and solidification state of the core material.

(H) After detecting that the cooling of the core material is completed, the mold opening operation is performed based on the mold opening position setting value set by the mold clamping condition setting device, and the movable platen 13 is moved backward. After the detection signal of the stroke sensor 24 reaches the set value, the electric servomotor 22 is controlled so as to hold the mold open position, and position holding control is performed (the toggle mechanism is in a bent state). Next, the molded product is extruded from the mold 30 and taken out of the injection molding machine.
(I) After detecting the completion of mold opening, an extrusion operation of the molded product is performed, and a die height advancement operation is performed based on the die height position setting value (S11) set by the mold clamping condition setting device to set the mold clamping condition setting device. The toggle mechanism 16 is advanced to a position where the mold clamping force set in step 1 is obtained. After the detection signal of the die height position sensor 28 reaches the set value (S11), the drive means 29 is controlled to hold the set value (S11), position holding control is performed, and a start signal for the next molding is waited.

Next, a molding procedure for foaming the second-layer resin molding material in another embodiment will be described with reference to FIG. In this procedure, the procedure from (a) to (e) is the same as that shown in FIG. 8 described above, and here, the procedure (f) and after will be described.
(F) The shut-off valve 54 of the second injection unit 52 is opened, and a molten resin containing a second-layer foaming agent serving as a core material is injected and filled into the first-layer base resin. After the injection filling of the second layer of molten resin is completed, the shutoff valve 54 is closed and the shutoff valve 55 in the injection nozzle 56 is switched to the resin charging direction of the first layer.
(G) Next, before the resin of the second layer is foamed or solidified, the first injection unit 51 is driven to fill with an appropriate amount of the molten resin of the first layer to remove traces of filling of the core material on the surface of the molded product. And by this filling operation, the molten resin in the resin flow path from the shut-off valve 55 to the nozzle tip is replaced with the first layer resin, and the first layer resin and the second layer resin may be mixed in the next molding. Absent. A predetermined time clamping force set according to the bubble nucleus formation state of the core material and the cooling and solidification state of the first layer resin is maintained.

(H) After the first layer of molten resin is refilled and a predetermined mold clamping holding time has elapsed, the mold opening operation is performed based on the crosshead position (S4) set by the mold clamping condition setting device, and the movable platen 13 Is retracted to increase the volume of the secondary cavity. Then, the second layer resin is foamed in the enlarged cavity. After the detection signal of the stroke sensor 24 reaches the set value (S4), the electric servo motor 22 is controlled so as to hold the set value (S4) until a predetermined cooling time to perform position holding control (the toggle mechanism is Bent state).
(I) After detecting that the cooling of the foamed layer is completed, the mold opening operation is performed based on the mold opening position setting value set by the mold clamping condition setting device, and the movable platen 13 is moved backward. After the detection signal of the stroke sensor 24 reaches the set value, the electric servomotor 22 is controlled so as to hold the mold open position, and position holding control is performed (the toggle mechanism is in a bent state). Next, the molded product is extruded from the mold 30 and taken out of the injection molding machine.
(J) After the completion of mold opening is detected, the molded product is pushed out, and the die height advancement operation is performed based on the die height position setting value (S11) set by the mold clamping condition setting device to set the mold clamping condition setting device. The toggle mechanism 16 is advanced to a position where the mold clamping force set in step 1 is obtained. After the detection signal of the die height position sensor 28 reaches the set value (S11), the drive means 29 is controlled to hold the set value (S11), position holding control is performed, and a start signal for the next molding is waited.

  In the present invention, as shown in FIGS. 5, 6, 8 and 9 (c) to (e), the secondary cavity is formed by driving the toggle mechanism 16 of the mold clamping device 110 to release the mold clamping force. (C) Next, after the mold thickness adjusting mechanism 19 is retracted until the movable platen 13 is in a locked state of the toggle mechanism 16 until it reaches a predetermined mold cavity enlargement position (S12) (d), the toggle mechanism 16 is driven. The movable platen 13 is moved forward until the toggle mechanism 16 is locked (e). For example, after the mold clamping force is released (c), the mold thickness adjusting mechanism 19 is synchronized with the retreating operation. Alternatively, the toggle mechanism 16 may be driven to advance the movable platen 13 and the toggle mechanism 16 may be locked when a predetermined mold cavity position (S12) is detected. In this case, since the steps (d) and (e) of the molding process are performed simultaneously, the process time is shortened.

  As is apparent from the above description, in the present invention, the second layer resin molding material is formed by injection-filling the first layer resin molding material and then closing the mold with the toggle mechanism locked. Since the next cavity is injected and filled, even if the resin filling pressure of the second layer acts on the movable platen, the resin filling force does not act on the crosshead of the toggle mechanism. Therefore, since the toggle mechanism is not pushed back and the mold cavity is not further expanded, the thickness accuracy of the molded product can be maintained, and a desired multilayer injection molded product can be obtained without the occurrence of molding defects.

Also, after injection-filling the first-layer resin molding material, the toggle mechanism is closed in a locked state to form a secondary cavity, and the second-layer resin molding material is placed inside the first-layer resin molding material. Since injection filling is performed, the resin filling force does not act on the crosshead of the toggle mechanism even if the resin filling pressure of the second layer acts on the movable platen. Therefore, since the toggle mechanism is not pushed back and the mold cavity is not further expanded, the thickness accuracy of the molded product can be maintained, and a desired multilayer injection molded product can be obtained without the occurrence of molding defects.
Since the mold thickness adjustment mechanism is driven and the toggle mechanism is moved to the mold clamping force setting position for the first layer molding between the start of the mold opening process after completion of cooling and the start of mold closing of the next cycle, Does not extend the molding cycle time.

In the embodiment of the present invention, the resin molding material of the first layer is injected and filled into the mold cavity at a predetermined crosshead position setting value (S1) at which the toggle mechanism is in the locking state. A low pressure mold clamping state in which the position setting value is set to an arbitrary intermediate position of a predetermined crosshead position setting value (S1) in which the toggle mechanism is in a locking state from a mold touch point in which the toggle mechanism is in a bent state, or a mold touch It is possible to apply a mold open holding state method in which a predetermined gap is provided from a point and a movable cross is placed at a predetermined crosshead position.
In this case, a configuration in which the toggle mechanism is driven after the injection molding of the first layer of the resin molding material to obtain the cross head position setting value (S1) is preferable.

Furthermore, since the resin molding material for the second layer uses a material containing a foaming agent, it is possible to obtain a multilayer injection molded product having a foamed layer or a sandwich molded product in which the inside is foamed. The expansion of the mold cavity volume in foaming uses the magnification characteristics of the toggle mechanism, and the crosshead position detected when the movable platen of the mold clamping device at the mold touch point is moved in the mold opening direction. Control based on the data of the board position. According to this method, it is possible to obtain a foamed multilayer injection molded product having a desired foaming ratio and cell diameter.
In addition, using a resin molding material containing a foaming agent in the first layer resin, using a multilayer injection molded product in which the first layer is foamed, and using a resin molding material containing both the first layer and the second layer a foaming agent, A multilayer injection molded product in which a foam layer and a foam layer are laminated can be obtained. In the embodiment of the present invention, the foaming operation is configured such that the movable platen is moved backward by one step up to the predetermined foaming mold opening position (S4). The structure which reverse | retreats a board may be sufficient.

1 is an overall conceptual diagram of a multilayer injection molding apparatus for resin according to an embodiment of the present invention. 3 is a conceptual diagram conceptually showing a mold thickness adjusting mechanism. It is a flowchart which shows a shaping | molding operation | movement procedure. It is a flowchart which shows the shaping | molding operation | movement procedure which foams the resin molding material of the 2nd layer. It is process explanatory drawing explaining the outline of a formation process. It is process explanatory drawing explaining the outline of the molding process which foams the resin molding material of the 2nd layer. It is a whole conceptual diagram of the multilayer injection molding apparatus of resin which shows other embodiment. It is process explanatory drawing explaining the outline of the shaping | molding process by other embodiment. It is process explanatory drawing explaining the outline of the molding process which foams the 2nd layer resin molding material of other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Link housing 12 Fixed board 13 Movable board 16 Toggle mechanism 17 Cross head 18 Link drive mechanism 19 Mold thickness adjustment mechanism 21 Tie bar 22 Electric servo motor 23 Cross head drive shaft 24 Stroke sensor 25 Mold clamping force sensor 26 Movable board position sensor 27 Tie bar Nut 28 Die height position sensor 29 Driving means 30, 60 Mold 31, 61 Fixed mold 32, 62 Movable mold 33 Mold cavity 34 Secondary cavity 41, 51 First injection unit 42, 52 Second injection unit 43, 44, 53 , 54, 55 Shut-off valve 56 Injection nozzle 71 Mold clamping control unit 72 Injection control unit 100, 200 Injection molding device 110 Mold clamping device 120, 220 Injection device 130, 230 Control device S1 Cross head position (1st layer clamping completed) Setting value)
S2 Cross head position (Clamping force release setting value)
S3 Cross head position (2nd layer clamping completion set value)
S4 Cross head position (foaming mold opening setting value)
S11 Die height position (1st layer molding setting position)
S12 Die height position (2nd layer molding setting position)
t1 Second layer cooling time

Claims (8)

Multilayer of resin to obtain a multilayer molded product by using an injection device for injecting and filling at least two types of resin molding materials into a mold cavity and a mold clamping device for opening and closing the mold and clamping using a toggle mechanism An injection molding method,
After the first layer of the resin molding material is injected and filled into the mold cavity, the movable plate is retracted to enlarge the mold cavity, and between the first layer of the resin molding material and the mold cavity surface. When forming a secondary cavity and injecting and filling the second layer resin molding material into the formed secondary cavity,
The secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then adjusting the mold thickness until the movable platen reaches the predetermined mold cavity enlarged position in the locked state of the toggle mechanism. A resin multi-layer injection molding method comprising: driving a mechanism to retract the toggle mechanism and then driving the toggle mechanism to advance the movable platen to a locking state of the toggle mechanism. Multilayer of resin to obtain a multilayer molded product by using an injection device for injecting and filling at least two types of resin molding materials into a mold cavity and a mold clamping device for opening and closing the mold and clamping using a toggle mechanism An injection molding method,
After the first layer of the resin molding material is injected and filled into the mold cavity, the movable plate is retracted to enlarge the mold cavity, and between the first layer of the resin molding material and the mold cavity surface. When forming the secondary cavity and injecting and filling the resin molding material of the second layer into the resin molding material of the first layer,
The secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then adjusting the mold thickness until the movable platen reaches the predetermined mold cavity enlarged position in the locked state of the toggle mechanism. A resin multi-layer injection molding method comprising: driving a mechanism to retract the toggle mechanism and then driving the toggle mechanism to advance the movable platen to a locking state of the toggle mechanism.   After injection filling the resin molding material of the second layer, the first layer of resin filling is performed between the start of mold opening for taking out the multilayer molded product after the movable plate moves backward and the start of mold closing of the next cycle. 3. The resin multilayer injection molding method according to claim 1, wherein the mold thickness adjusting mechanism is driven until the mold clamping force setting position is reached to advance the toggle mechanism.   The first layer and / or the second layer is a resin molding material containing a foaming agent such as a physical foaming agent or a chemical foaming agent, and the toggle mechanism is driven after the injection filling of the first layer and / or the second layer. 4. The resin multilayer injection molding method according to claim 1, wherein the movable platen is retracted to a predetermined foaming position. A resin multilayer having an injection device for injecting and filling at least two types of resin molding materials into a mold cavity, and a mold clamping device for opening and closing the mold and clamping using a toggle mechanism. An injection molding device,
After the first layer of the resin molding material is injected and filled into the mold cavity, the movable plate is retracted to enlarge the mold cavity, and between the first layer of the resin molding material and the mold cavity surface. When forming a secondary cavity and injecting and filling the second layer resin molding material into the formed secondary cavity,
The secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then adjusting the mold thickness until the movable platen reaches the predetermined mold cavity enlarged position in the locked state of the toggle mechanism. A resin multilayer injection molding apparatus configured to drive the mechanism to retract the toggle mechanism, and then drive the toggle mechanism to advance the movable platen to the locking state of the toggle mechanism. A resin multilayer having an injection device for injecting and filling at least two types of resin molding materials into a mold cavity, and a mold clamping device for opening and closing the mold and clamping using a toggle mechanism. An injection molding device,
After the first layer of the resin molding material is injected and filled into the mold cavity, the movable plate is retracted to enlarge the mold cavity, and between the first layer of the resin molding material and the mold cavity surface. When forming the secondary cavity and injecting and filling the resin molding material of the second layer into the resin molding material of the first layer,
The secondary cavity is formed by driving the toggle mechanism of the mold clamping device to release the mold clamping force, and then adjusting the mold thickness until the movable platen reaches the predetermined mold cavity enlarged position in the locked state of the toggle mechanism. A resin multilayer injection molding apparatus configured to drive the mechanism to retract the toggle mechanism, and then drive the toggle mechanism to advance the movable platen to the locking state of the toggle mechanism.   The mold thickness adjusting mechanism is configured such that the four axes are driven synchronously or individually by driving means provided in each of the tie bar nuts that are inserted through the four corners of the back surface of the link housing of the mold clamping device and screwed into the tie bar A multilayer injection molding apparatus for resin according to claim 5 or 6.   The first layer and / or the second layer is a resin molding material containing a foaming agent such as a physical foaming agent or a chemical foaming agent, and the toggle mechanism is driven after the injection filling of the first layer and / or the second layer. 8. The resin multilayer injection molding apparatus according to claim 5, wherein the movable platen is configured to be retracted to a predetermined foaming position.

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