Injection molding machine

Abstract

To provide an injection molding machine that can quickly and easily determine molding conditions for achieving a desired expansion ratio.SOLUTION: An injection molding machine includes: a clamping device that opens, closes, and clamps a mold; an injection device that injects molten resin containing gas into a cavity of the clamped mold; an input device that accepts input operations from an operator; and a control device that controls the clamping device and the injection device based on information input through the input device. When a ratio of resin or a foam layer in a molded product is updated through the input device, the control device calculates a correction stroke based on a reference stroke of a screw and the ratio required to inject molten resin equivalent to a volume of the cavity, and advances the screw within a heating cylinder by the correction stroke, thereby foaming the injected molten resin within the cavity.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an injection molding machine capable of foam molding. [Background technology]

[0002] Conventionally, injection molding machines capable of so-called "foam molding" have been known, in which a molded article having a foam layer (voids) inside the molded article is formed by injecting a molten resin containing a gas into a mold (see, for example, Patent Documents 1 to 3).

[0003] In foam molding, in order to balance the rigidity and lightness of the molded product, an adjustment process to adjust the expansion ratio (the ratio of the foam layer to the volume of the molded product) must be carried out prior to mass production of the molded product. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 57-069024 [Patent Document 2] Japanese Patent Application Publication No. 61-239917 [Patent Document 3] Japanese Patent Application Publication No. 05-147091 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional adjustment process, the expansion ratio is generally adjusted by comparing the weight of prototype molded products while changing the injection stroke. However, this method has the problem that it takes a long time and experience to determine the molding conditions to achieve the desired expansion ratio.

[0006] The present invention has been made to solve the problems of the prior art, and its object is to provide an injection molding machine that can quickly and easily determine molding conditions for achieving a desired expansion ratio. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides an injection molding machine comprising a clamping device that opens, closes, and clamps a mold, an injection device that injects molten resin containing gas into the cavity of the clamped mold, an input device that accepts input operations from an operator, and a control device that controls the clamping device and the injection device based on information input through the input device, wherein the injection device comprises a heating cylinder whose tip is connected to the clamped mold, and a screw that moves back and forth inside the heating cylinder, and when the ratio of resin or foam layer in the molded product is updated through the input device, the control device calculates a correction stroke based on the ratio and the reference stroke of the screw required to inject the molten resin equivalent to the volume of the cavity, and advances the screw by the correction stroke within the heating cylinder, thereby foaming the injected molten resin in the cavity. [Effects of the Invention]

[0008] According to the present invention, molding conditions for achieving a desired expansion ratio can be determined quickly and simply. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of an injection molding machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the main parts of a mold clamping device, an injection device, and a foaming agent supply device. [Figure 3] FIG. 2 is a hardware block diagram of the injection molding machine. [Figure 4] 4 is a flowchart of a molding condition update process according to the first embodiment. [Figure 5]10 is an example of a molding condition update screen according to the first embodiment. [Figure 6] 10 is another example of the molding condition update screen according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing the relationship between the forward limit, the backward limit, the metering completion position, and the injection completion position. [Figure 8] 4 is a flowchart of a fully automatic molding process according to the first embodiment. [Figure 9] 10 is a flowchart of a molding condition update process according to the second embodiment. [Figure 10] 10 is a flowchart of a semi-automatic molding process according to a second embodiment. [Figure 11] 13 is a screen example of a molding condition update screen according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An injection molding machine 10 according to the present invention will be described below with reference to the drawings. The injection molding machine 10 is a device that injects a measured amount of molten resin into a mold to form a molded product. The injection molding machine 10 is also a device capable of so-called "foam molding," which involves injecting molten resin containing gas into the cavity of a mold to form a molded product having a foam layer (void) inside.

[0011] [Configuration of injection molding machine 10] Fig. 1 is a side view of an injection molding machine 10 according to this embodiment. Fig. 2 is an enlarged view of essential parts of a mold clamping unit 20, an injection unit 30, and a foaming agent supplying unit 40. Fig. 3 is a hardware block diagram of the injection molding machine 10. As shown in Figs. 1 to 3, the injection molding machine 10 mainly comprises a mold clamping unit 20, an injection unit 30, a foaming agent supplying unit 40, and a control device 60.

[0012] The mold clamping device 20 opens, closes, and clamps the mold 21. Specifically, the mold clamping device 20 mainly includes a fixed die plate 23 that supports a fixed-side mold 22, and a movable die plate 25 that supports a movable-side mold 24. The fixed-side mold 22 and the movable-side mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the injection molding machine 10.

[0013] The movable die plate 25 moves left and right along the tie bars 27 as the driving force of the die opening / closing motor 28 is transmitted through the toggle link mechanism 26. When the movable die plate 25 moves leftward, the fixed-side die 22 and the movable-side die 24 move apart. On the other hand, when the movable die plate 25 moves rightward, the fixed-side die 22 and the movable-side die 24 come into contact with each other, forming a cavity C (internal space) inside the die 21. Then, when pressure is further applied in a direction that moves the movable die plate 25 rightward, the fixed-side die 22 and the movable-side die 24 are clamped.

[0014] The injection unit 30 plasticizes, measures, and injects the molding material (resin). The injection unit 30 according to this embodiment is disposed horizontally apart from the mold clamping unit 20 (to the right of the mold clamping unit 20). The injection unit 30 mainly includes a heating cylinder 31, a screw 32, a hopper 33, and a hopper block 34.

[0015] The heating cylinder 31 is a cylindrical member that extends in the left-right direction of the injection molding machine 10. The heating cylinder 31 mainly includes a resin passage 35 and a nozzle 36. In addition, a band heater that heats the heating cylinder 31 is attached to the outer circumferential surface of the heating cylinder 31.

[0016] The resin passage 35 is a cylindrical space extending in the axial direction (longitudinal direction) inside the heating cylinder 31. The resin passage 35 communicates with the outside of the heating cylinder 31 (cavity C of the mold 21) through a nozzle 36 provided at the tip (front end) of the heating cylinder 31. In other words, the resin passage 35 is a space extending from the nozzle 36 along the axial direction.

[0017] The screw 32 is a cylindrical member. A spiral groove is formed on the outer circumferential surface of the screw 32. The screw 32 is housed in the internal space of the heating cylinder 31 in a state in which it can move left and right (hereinafter referred to as "forward and backward") and rotate in the injection molding machine 10. The screw 32 moves forward and backward when the driving force of the injection motor 37 is transmitted thereto, and rotates when the driving force of the metering motor 38 is transmitted thereto.

[0018] More specifically, when the injection motor 37 is rotated forward, the screw 32 moves (advances) toward the tip of the heating cylinder 31 (i.e., the nozzle 36). On the other hand, when the injection motor 37 is rotated backward, the screw 32 moves (retreats) toward the base end of the heating cylinder 31 (i.e., the side opposite the nozzle 36). Hereinafter, within the range that the tip position of the screw 32 can reach within the heating cylinder 31, the position closest to the nozzle 36 will be referred to as the "forward limit," and the position farthest from the nozzle 36 will be referred to as the "rear limit." Furthermore, the terms "forward rotation" and "reverse rotation" of the injection motor 37 do not specify an absolute direction of rotation, but merely specify a relative relationship (i.e., forward rotation and reverse rotation are rotations in opposite directions).

[0019] The hopper 33 is a funnel-shaped member that stores the raw molding material. The hopper block 34 is a member that supports the heating cylinder 31 and the hopper 33. The hopper 33 is connected to a resin passage 35 through the hopper block 34 at a portion of the heating cylinder 31 closer to the base end than the tip end. The molding material stored in the hopper 33 is supplied to the resin passage 35 of the heating cylinder 31 through an opening provided at the bottom end. The molding material used in this injection molding machine 10 is, for example, so-called "pellets" that are formed into a cylindrical shape.

[0020] In the injection device 30, the screw 32 moves backward while rotating by rotating the injection motor 37 in the reverse direction and rotating the metering motor 38. As a result, pellets supplied through the hopper 33 are plasticized and filled (metered) into the resin passage 35 ahead of the screw 32. In addition, in the injection device 30, the injection motor 37 rotates forward to move the screw 32 forward. As a result, the plasticized resin ahead of the screw 32 is injected into the cavity of the mold 21 through the nozzle 36.

[0021] Furthermore, the nozzle 36 is equipped with a shutoff valve (on-off valve) 39. The shutoff valve 39 is disposed in the passage of the molten resin inside the nozzle 36. The shutoff valve 39 is an electromagnetic valve that can be switched between an open position that opens the passage and a closed position that closes the passage under the control of the control device 60. That is, when the shutoff valve 39 is in the open position, the molten resin inside the resin passage 35 can be injected (discharged) through the nozzle 36. On the other hand, when the shutoff valve 39 is in the closed position, the molten resin inside the resin passage 35 does not leak out of the nozzle 36.

[0022] The foaming agent supplying device 40 is a device that supplies a gas (e.g., carbon dioxide gas, nitrogen gas) serving as a physical foaming agent to the resin passage 35 of the heating cylinder 31. More specifically, the foaming agent supplying device 40 supplies the gas to the molten resin that has been plasticized and measured by the screw 32. The foaming agent supplying device 40 according to this embodiment includes a gas cylinder 41 that stores the gas, and an injection device 42 that converts the gas stored in the gas cylinder 41 into a supercritical state and injects it into the resin passage 35. As a result, the molten resin containing the gas is metered into a region of the heating cylinder 31 ahead of the screw 32. Note that, instead of the foaming agent supplying device 40, a granular physical foaming agent may be supplied to the injection molding machine 10 through a hopper 33.

[0023] [Configuration of control device 60] As shown in Fig. 3, the control device 60 includes a CPU (Central Processing Unit) 61 and a memory 62. The memory 62 is configured, for example, with a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The control device 60 realizes the processing described below by having the CPU 61 read and execute program code stored in the ROM or HDD. The RAM is used as a work area when the CPU 61 executes the program.

[0024] However, the specific configuration of the control device 60 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0025] The control device 60 controls the overall operation of the injection molding machine 10. More specifically, the control device 60 controls the mold opening / closing motor 28, the injection motor 37, the metering motor 38, the shutoff valve 39, and the injection device 42 based on various signals output from a rotary encoder 64, a load cell 65 (pressure sensor), and a display / input device 67.

[0026] The mold opening / closing motor 28, the injection motor 37, and the metering motor 38 are servo motors that generate driving forces to open and close the mold 21, to move the screw 32 back and forth, and to rotate the screw 32, for example, under the control of a servo amplifier (not shown).

[0027] The rotary encoder 64 is a sensor that detects the speed and tip position of the screw 32. More specifically, the rotary encoder 64 outputs pulse signals corresponding to the rotation of the injection motor 37 to the control device 60. The control device 60 then determines the speed of the screw 32 based on the number of pulse signals output per unit time. The control device 60 also determines the tip position of the screw 32 based on the cumulative value of the pulse signals.

[0028] The load cell 65 is a sensor that detects the pressure applied to the screw 32. More specifically, the load cell 65 outputs a pressure signal (voltage value) corresponding to the pressure applied to the screw 32 to the control device 60. Then, the control device 60 identifies the pressure applied to the screw 32 based on the pressure signal output from the load cell 65.

[0029] Furthermore, a display input device 67 is connected to the control device 60. The display input device 67 is a user interface that includes a display (display device) that displays various information to be notified to the operator, and buttons, switches, dials, etc. (input devices) that accept input operations by the operator. The display input device 67 may also include a touch panel superimposed on the display. The display input device 67 accepts input operations by the operator and outputs an input signal corresponding to the accepted input operation to the control device 60.

[0030] [Molding conditions] The memory 62 stores molding conditions. The molding conditions are operating conditions of the injection molding machine 10 that executes the fully automatic molding process and the semi-automatic molding process described below. The molding conditions include, for example, at least a metering completion position, an injection completion position, and an expansion ratio. However, the molding conditions may further include an injection speed, an injection pressure, a heating temperature, and the like. The control device 60 stores molding conditions inputted, for example, via a molding condition update screen described later with reference to FIGS. 5 and 6, in the memory 62.

[0031] The metering completion position is the position of the screw 32 when a predetermined amount of molten resin has been metered into the region forward of the screw 32 of the heating cylinder 31. The injection completion position is the position of the screw 32 when the injection of the metered molten resin into the cavity C is completed. The expansion ratio is a value representing the ratio of the volume of the resin injected into the cavity C before and after foaming. The expansion ratio is a value (%) of 100 or more. The expansion ratio is an example of the ratio of the resin or foam layer in the molded product.

[0032] As shown in Fig. 8, the metering completion position P3 and the injection completion position P4 are located between the forward movement limit P1 and the backward movement limit P2. That is, the metering completion position P3 is a position forward of the backward movement limit P2 and rearward of the injection completion position P4. The injection completion position P4 is a position rearward of the forward movement limit P1 and forward of the metering completion position P3. The metering completion position P3 and the injection completion position P4 are specified by the length from the forward movement limit P1 toward the rear.

[0033] The distance between the metering completion position P3 and the injection completion position P4 is the injection stroke of the screw 32 required to inject a predetermined amount of molten resin into the cavity C. The amount of molten resin injected into the cavity C in one injection process corresponds to the value obtained by multiplying the area of ​​the cross section of the heating cylinder 31 (the cross section perpendicular to the forward / backward direction of the screw 32) by the injection stroke.

[0034] The injection stroke required to inject molten resin equivalent to the volume of cavity C into cavity C is defined as the reference stroke L0. The injection strokes corrected according to the foaming ratio are defined as corrected strokes L1 and L2. In this embodiment, the reference stroke L0 is 50 mm. The corrected strokes L1 and L2 are shorter than the reference stroke L0.

[0035] [First embodiment] The processing of the control device 60 according to the first embodiment will be described with reference to Figures 4 to 8. The control device 60 asynchronously and in parallel executes the molding condition update processing shown in Figure 4 and the fully automatic molding processing shown in Figure 8. In other words, the control device 60 can execute the molding condition update processing at any timing while the fully automatic molding processing is being executed.

[0036] [Molding condition update process] FIG. 4 is a flowchart of the molding condition update process according to the first embodiment. FIG. 5 is an example of a molding condition update screen according to the first embodiment. FIG. 6 is another example of a molding condition update screen according to the first embodiment. FIG. 7 is a diagram showing the relationship between the forward limit P1, the backward limit P2, the metering completion positions P3, P5, P6, and the injection completion position P4. The molding condition update process is a process for updating molding conditions in accordance with the operator's operation on the display input device 67. The control device 60 executes the molding condition update process shown in FIG. 4 at the timing instructed by the operator via the display input device 67.

[0037] First, the control device 60 displays the molding condition update screen shown in Fig. 5(A) on the display / input device 67 (S11). The molding condition update screen is a screen that allows the operator to update the molding conditions (especially the foaming ratio). As shown in Fig. 5(A), for example, the molding condition update screen includes text boxes for receiving input of the reference value and set value of the metering completion position, the reference value and set value of the injection completion position, and the set value of the foaming ratio, a display area for displaying the calculation results of the metering completion position, the injection completion position, and the foaming ratio, a "reference setting" icon, a "calculation" icon, and an "update" icon.

[0038] The reference positions are the metering completion position and injection completion position when the foaming ratio is 100%. In other words, the distance between the reference position of the metering completion position and the reference position of the injection completion position is the reference stroke L0. When the reference position of the metering completion position (= 60 mm) and the reference position of the injection completion position (= 10 mm) are input and the [Set Reference] icon is selected, the control device 60 stores this distance (= 50 mm) in the memory 62 as the reference stroke L0.

[0039] Furthermore, when a set value of the foaming ratio is input and the [Calculate] icon is selected (S12: Calculate), the control device 60 calculates the correction stroke by dividing the reference stroke L0 by the input foaming ratio. Then, the control device 60 moves at least one of the metering completion position P3 and the injection completion position P4 to make the forward distance of the screw 32 coincide with the correction stroke (S13 to S18).

[0040] For example, when the foaming ratio is set to 200% (changed from 100% to 200%), the control device 60 divides the reference stroke L0 (= 50 mm) by the new foaming ratio (= 200%) to calculate the correction stroke L1 (= 25 mm). Then, when the foaming ratio after the change (= 200%) is greater than the foaming ratio before the change (= 100%) (S13: Yes), the control device 60 fixes the injection completion position P4 (= 10 mm) and advances the current metering completion position P3 (= 60 mm) to a new metering completion position P5 (= 35 mm) (S14). The distance between the injection completion position P4 and the new metering completion position P5 becomes the correction stroke L1.

[0041] Next, as shown in Fig. 5(B), the control device 60 displays the new metering completion position P5 (= 35 mm), injection completion position P4 (= 10 mm), and new foaming ratio (= 200%) in the calculation result column of the molding condition update screen (S11). Next, when the [Update] icon is selected (S12: Update), the control device 60 stores the metering completion position P5 (= 35 mm), injection completion position P4 (= 10 mm), and foaming ratio (= 200%) displayed in the calculation result column in the memory 62 as updated molding conditions, and ends the molding condition update process. However, it is assumed that the molding conditions before the update are still stored in the memory 62.

[0042] Furthermore, when the foaming ratio is set to 125% (changed from 200% to 125%), the control device 60 divides the reference stroke L0 (= 50 mm) by the new foaming ratio (= 125%) to calculate the corrected stroke L2 (= 40 mm). Next, since the foaming ratio has decreased (S13: No), the control device 60 determines whether the new injection completion position will move forward of the advance limit P1 if the metering completion position P5 (= 35 mm) is fixed and the injection completion position P4 (= 10 mm) is advanced (S15).

[0043] Next, when the control device 60 determines that the new injection completion position does not exceed the forward limit P1 (S15: No), it advances the injection completion position (S16). The distance between the new injection completion position and the metering completion position P5 becomes the correction stroke. Then, the control device 60 executes the processing from step S11 onwards again.

[0044] However, in the above example, since it is necessary to advance the injection completion position P4 by 15 mm to achieve the correction stroke L2 (= 40 mm), the new injection completion position will move forward from the advance limit P1 (S15: Yes). Therefore, the control device 60 determines whether the new metering completion position will move rearward from the retreat limit P2 when the injection completion position P4 (= 10 mm) is fixed and the metering completion position P5 (= 35 mm) is retreated (S17).

[0045] Next, if the control device 60 determines that the new metering completion position P6 (= 50 mm) does not exceed the retraction limit P2 (S17: No), it retracts the current metering completion position P5 (= 35 mm) to the new metering completion position P6 (= 50 mm) (S18). The distance between the injection completion position P4 and the new metering completion position P6 becomes the correction stroke L2. Then, the control device 60 executes the processing from step S11 onwards again. On the other hand, if the control device 60 determines that advancing the injection completion position will exceed the advancement limit P1 and retracting the metering completion position will exceed the retraction limit P2 (S15: Yes & S17: Yes), it notifies the user that the input setting value is not achievable (S19) and executes the processing from step S11 onwards again.

[0046] [Fully automated molding process] 8 is a flowchart of the fully automatic molding process according to the first embodiment. The fully automatic molding process is a process in which a molten resin containing gas is injected into the cavity C of the clamped mold 21 to form a molded article having a foam layer, and the process is automatically repeated. The control device 60 starts the fully automatic molding process in response to a molding instruction being input through the display input device 67, for example. The molding instruction includes the number of molded articles to be molded.

[0047] At the start of the fully automatic molding process, the mold 21 is opened, the shutoff valve 39 is switched to the closed position, and the molten resin to be injected next is metered into the space ahead of the screw 32 of the heating cylinder 31 (i.e., the screw 32 is positioned at the metering completion position P3).The molding conditions are also set as follows: metering completion position P3 = 60 mm, injection completion position P4 = 10 mm, and foaming ratio = 100%.

[0048] First, the control device 60 closes and clamps the mold 21 by rotating the mold opening / closing motor 28 (S21). As a result, a cavity C is formed in the mold 21. The processing of step S11 is an example of a mold clamping process.

[0049] Next, after the mold clamping process (S21) is completed, the control device 60 switches the shutoff valve 39 to the open position and rotates the injection motor 37 forward to move the screw 32 forward from the metering completion position P3 to the injection completion position P4 (S23). As a result, the molten resin metered into the region in front of the screw 32 in the heating cylinder 31 is injected into the cavity C of the mold 21. The processes of step S23 and steps S25 and S26, which will be described later, are an example of an injection process.

[0050] Next, after the injection process (S23, S25, S26) is completed, the control device 60 switches the shutoff valve 39 to the closed position, moves the screw 32 backward from the injection completion position P4 to the metering completion position P3 while rotating, and supplies gas into the heating cylinder 31 by the injector 42 (S28). As a result, the pellets supplied to the heating cylinder 31 through the hopper 33 are plasticized, and molten resin containing gas is metered into the space ahead of the screw 32 in the heating cylinder 31. The processes of step S28 and step S29, which will be described later, are an example of a metering process for metering the molten resin to be injected in the next injection process.

[0051] After the injection process (S23, S25, S26) is completed, the control device 60 rotates the mold opening / closing motor 28 to open the mold 21, and causes the robot arm to remove the molded product from the opened mold 21 (S30). The process of step S30 is an example of a removal process. The weighing process (S28) and the removal process (S30) may be performed in the order shown in FIG. 8, in the reverse order, or in parallel.

[0052] Next, after the weighing process (S28, S29) and the removal process (S30) are completed, the control device 60 determines whether the number of molded articles specified in the molding instruction has been molded (S31). If the control device 60 determines that not all molded articles have been molded yet (S31: No), it executes the processes from step S21 onwards again. In other words, the control device 60 repeatedly executes the processes from step S21 to S30 until the number of molded articles specified in the molding instruction has been molded (S31: No). If the control device 60 determines that the number of molded articles specified in the molding instruction has been molded (S31: Yes), it ends the fully automatic molding process.

[0053] As described above, the molding condition update process may be executed in parallel with the fully automatic molding process. Therefore, after the mold clamping process (S21) is completed, the control device 60 determines whether the molding conditions have been updated since the previous measurement process (S28, S29) (S22). Furthermore, if the control device 60 determines that the molding conditions have been updated (S22: Yes), it determines whether the measurement completion position has changed between the molding conditions before and after the update (S24).

[0054] If the control device 60 determines that the molding conditions have not been updated (S22: No), it executes the injection process under the existing molding conditions (S23). If the control device 60 determines that the molding conditions have been updated and the metering completion position has not been changed (S22: Yes & S24: No), it executes the injection process under the updated molding conditions (S25). That is, the control device 60 advances the screw 32 from the current position (= metering completion position) to the changed injection completion position. If the control device 60 determines that the molding conditions have been updated and the metering completion position has been changed (S22: Yes & S24: Yes), it executes the injection process under the molding conditions before the update (S26).

[0055] Next, after the injection process (S23, S25) is completed, the control device 60 determines whether the metering completion position has been changed since the previous metering process (S28, S29) (S27). If the control device 60 determines that the metering completion position has not been changed (S27: No), the control device 60 retracts the screw 32 to the existing metering completion position, thereby metering the molten resin to be injected in the next injection process (S28). If the control device 60 determines that the metering completion position has been changed (S27: Yes), the control device 60 retracts the screw 32 to a new metering completion position, thereby metering the molten resin to be injected in the next injection process (S29). Furthermore, if the control device 60 has executed the process of step S26, the control device 60 omits the determination of step S27 and executes the process of step S29.

[0056] [Effects of the first embodiment] According to the first embodiment, the injection stroke is corrected simply by updating the foaming ratio via the display / input device 67. As a result, molding conditions for achieving a desired foaming ratio can be determined quickly and easily. The ratio of the resin or foam layer in the molded product is not limited to the foaming ratio, but may be the ratio of the resin in the molded product. In this case, the corrected stroke can be calculated by multiplying the reference stroke by the ratio of the resin.

[0057] Furthermore, according to the first embodiment, when the foaming ratio increases, the injection completion position is fixed and the metering completion position is advanced. This minimizes the amount of molten resin remaining in the region ahead of the screw 32 of the heating cylinder 31 after the injection process is completed. As a result, the residence time of the molten resin in the heating cylinder 31 can be prevented from becoming too long, thereby stabilizing the quality of the molded product.

[0058] Furthermore, according to the first embodiment, when the foaming ratio decreases and the injection completion position does not exceed the forward limit, the injection completion position is advanced. This eliminates the need for re-metering to move the screw 32 to a new metering completion position, thereby reducing the amount of resin to be purged and preventing the cycle time from becoming longer.

[0059] Furthermore, according to the first embodiment, if the metering completion position is changed (S22: Yes & S24: Yes) after the metering process (S28, S29) is executed, the molded product is molded under the molding conditions before the update, and then the new molding conditions are applied. This eliminates the need to purge the molten resin that has already been metered, thereby reducing the loss of molding material.

[0060] Whether to move the metering completion position or the injection completion position to achieve the correction strokes L1 and L2 is not limited to the variations of steps S13 to S18 in Fig. 4. As another example, if the foaming ratio is changed between the metering process (S28, S29) and the next injection process (S23, S25, S26), the injection completion position may always be moved. As yet another example, if the foaming ratio is changed between the injection process (S23, S25, S26) and the metering process (S28, S29), the metering completion position may always be moved.

[0061] [Second embodiment] The processing of the control device 60 according to the second embodiment will be described with reference to Figures 9 and 10. Note that a detailed description of the points in common with the first embodiment will be omitted, and the description will focus on the points of difference.

[0062] [Molding condition update process] 9 is a flowchart of the molding condition update process according to the second embodiment. The molding condition update process according to the second embodiment is different from the first embodiment in that steps S11 to S19 are the same as those in the first embodiment, but steps S41 to S43 are added.

[0063] When the [Update] icon is selected (S12: Update), the control device 60 determines whether or not the measurement completion position has been changed in steps S13 to S18 (S41). Next, when the control device 60 determines that the measurement completion position has been changed (S41: Yes), it prompts the operator to select whether or not to perform purging and re-measurement via the display / input device 67 (S42), as shown in Fig. 6(B), for example.

[0064] Then, when the operator selects to perform purging and re-metering (S42: Yes), the control device 60 advances the screw 32 to the advance limit P1 ("PURGE" in FIG. 7), discharges the molten resin filled in the resin passage 35 to the outside, and re-meters the molten resin by rotating the screw 32 and retracting it to a new metering completion position P5 (S43). On the other hand, when the operator selects not to perform purging and re-metering (S42: No), the control device 60 ends the molding condition update process without executing the process of step S43. Furthermore, when the control device 60 determines that the metering completion position has not been changed (S41: No), it ends the molding condition update process without executing the processes of steps S41 to S42.

[0065] [Semi-automatic molding process] 10 is a flowchart of semi-automatic molding processing according to the second embodiment. The semi-automatic molding processing differs from the fully automatic molding processing in that the operation of the injection molding machine 10 is temporarily stopped each time a molded product is molded, and the injection molding machine 10 resumes operation when the operator inputs a command to mold the next molded product. The semi-automatic molding processing shares the processes of steps S21 to S26 and S28 to S30 with the fully automatic molding processing, but differs from the fully automatic molding processing in that step S27 is omitted and steps S51 to S55 are added.

[0066] After causing the robot arm to remove the molded product (S30), the control device 60 temporarily suspends the operation of the injection molding machine 10. The operator opens the safety door (not shown) of the injection molding machine 10 and obtains the molded product removed by the robot arm. Next, the control device 60 waits until the operator inputs an instruction to update the molding conditions (S51), end the semi-automatic molding process (S52), or continue injection molding (S53).

[0067] Then, when the control device 60 receives an instruction to update the molding conditions through the display / input device 67 (S51: Yes), it executes the molding condition update process shown in Fig. 9 (S54). Furthermore, when the control device 60 receives an instruction to end the semi-automatic molding process (for example, by operating a key) (S52: Yes), it ends the semi-automatic molding process. Furthermore, when the control device 60 receives an instruction to continue injection molding (for example, by closing a safety door) (S53: Yes), it executes the processes from step S21 onwards again.

[0068] Furthermore, if the control device 60 determines that the metering completion position has been changed in the most recent step S54 (S24: Yes), it determines whether or not purging and re-metering (S43) have been performed (S55). If the control device 60 determines that purging and re-metering have been performed (S55: Yes), it executes the process of step S25. On the other hand, if the control device 60 determines that purging and re-metering have not been performed (S55: No), it executes the process of step S26.

[0069] [Effects of the second embodiment] According to the second embodiment, when the metering completion position is changed in the molding condition update process (S41: Yes), purging and re-metering are executed, so that the updated molding conditions can be immediately reflected. Also, the operator is allowed to select whether to execute purging and re-metering (S42), and if purging and re-metering are not executed, the molding process is executed under the molding conditions before the update (S55: No → S26), so that the operator can select whether to immediately reflect the molding conditions or to reduce loss of molding material.

[0070] It is also possible to omit step S42 and perform purge and re-measurement whenever the metering completion position is changed. The molding condition update process shown in FIG. 9 can also be applied to the first embodiment. In this case, the fully automatic molding process adds the process of step S55. Furthermore, the molding condition update process shown in FIG. 4 can also be applied to the second embodiment. In this case, the semi-automatic molding process omits the process of step S55.

[0071] [Third embodiment] The molding condition update process according to the third embodiment will be described with reference to Fig. 11. Fig. 11 is an example of a molding condition update screen according to the third embodiment. Note that detailed description of the commonalities with the first and second embodiments will be omitted, and the description will focus on the differences. The molding condition update process according to the third embodiment differs from the first and second embodiments in that it sets one of the metering completion position and the injection completion position, and the foaming ratio.

[0072] 11(A), for example, when the set values ​​of the metering completion position (=50 mm) and the foaming ratio (=200%) are input and the [Calculate] icon is selected (S12: Calculate), the control device 60 calculates a correction stroke (=25 mm) by dividing the reference stroke L0 (=50 mm) by the foaming ratio (=200%). Next, the control device 60 calculates a new injection completion position (=25 mm) by subtracting the correction stroke (=25 mm) from the set metering completion position (=50 mm). Then, the control device 60 displays the set metering completion position and foaming ratio, and the calculated injection completion position in the calculation result column of the molding condition update screen (S11). On the other hand, when the new injection completion position exceeds the forward limit P1 (S15: Yes), a notification is issued to reset the molding conditions (S19).

[0073] 11(B), for example, when the set values ​​of the injection completion value (=5 mm) and the foaming ratio (=200%) are input and the [Calculate] icon is selected (S12: Calculate), the control device 60 calculates a correction stroke (=25 mm) by dividing the reference stroke L0 (=50 mm) by the foaming ratio (=200%). Next, the control device 60 calculates a new metering completion position (=30 mm) by adding the correction stroke (=25 mm) to the set injection completion position (=5 mm). Then, the control device 60 displays the set injection completion position and foaming ratio, as well as the calculated lightening completion position, in the calculation result column of the molding condition update screen (S11). On the other hand, when the new metering completion position exceeds the retract limit P2 (S17: Yes), a notification is issued to reset the molding conditions (S19).

[0074] According to the third embodiment, since the operator is allowed to set either the metering completion position or the injection completion position in addition to the foaming ratio, it becomes easier for the operator to achieve the molding conditions he or she desires.

[0075] The above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the present invention. [Explanation of symbols]

[0076] 10... injection molding machine, 20... mold clamping device, 21... mold, 22... fixed side mold, 23... fixed die plate, 24... movable side mold, 25... movable die plate, 26... toggle link mechanism, 27... tie bar, 28... mold opening / closing motor, 30... injection device, 31... heating cylinder, 32... screw, 33... hopper, 34... hopper block, 35... resin passage, 36... nozzle, 37... injection motor, 38... metering motor, 39... shut-off valve, 40... blowing agent supply device, 41... gas cylinder, 42... spray device, 60... control device, 61... CPU, 62... memory, 64... rotary encoder, 65... load cell, 67... display / input device

Claims

1. a mold clamping device that opens, closes, and clamps the mold; an injection device that injects a molten resin containing gas into a cavity of the clamped mold; an input device that accepts input operations by an operator; a control device that controls the mold clamping device and the injection device based on information input through the input device, The injection device a heating cylinder whose tip communicates with the clamped mold; a screw that moves back and forth inside the heating cylinder, The control device When the ratio of the resin or foam layer in the molded product is updated through the input device, a correction stroke is calculated based on the reference stroke of the screw required to inject the molten resin corresponding to the volume of the cavity and the ratio; an injection molding machine, characterized in that the injected molten resin is foamed in the cavity by advancing the screw by the corrected stroke within the heating cylinder.

2. the ratio is the expansion ratio of the gas in the cavity, 2. The injection molding machine according to claim 1, wherein the control device calculates the corrected stroke by dividing the reference stroke by the foaming ratio.

3. 3. The injection molding machine according to claim 2, wherein the control device moves at least one of a metering completion position of the screw when metering of the molten resin is completed to a region of the heating cylinder forward of the screw and an injection completion position of the screw when injection of the molten resin into the cavity is completed, in order to match the forward distance of the screw to the correction stroke.

4. The control device an injection process in which the screw is advanced to the injection completion position to inject the molten resin into the cavity of the clamped mold; a measuring process in which the screw is retracted to the metering completion position while rotating, and the molten resin to be injected in the next injection process is measured into a region of the heating cylinder forward of the screw; 4. The injection molding machine according to claim 3, wherein the injection completion position is moved when the foaming ratio is changed between the measurement process and the next injection process.

5. 4. The injection molding machine according to claim 3, wherein the control device advances the metering completion position when an input operation to increase the foaming ratio is received through the input device.

6. The control device When an input operation to decrease the foaming ratio is received through the input device, it is determined whether or not the advancement limit of the heating cylinder will be exceeded if the injection completion position is advanced; When it is determined that the advance limit is not exceeded, the injection completion position is advanced; 4. The injection molding machine according to claim 3, wherein the metering completion position is moved backward when it is determined that the forward limit has been exceeded.

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