Injection molding machine

Abstract

To increase versatility of molding targets by smoothly filling resin to mold cavities to expand the types of molding materials that can be injection molded, and to improve the quality of molded products by optimizing temperature control and control of mold closure pressure in the compression process to reduce the occurrence of molded product variation.SOLUTION: The injection filling process (S7) injection-fills the molding material Rm to the mold D by the injection device Mi in the mold clamping device Mc for which the mold clamping conditions including a predetermined mold gap Lg, a predetermined clamping force Pc, a predetermined back pressure Pb against the movable mold Dm, a predetermined mold closure pressure Pp, and a predetermined mold closure pressure adjustment condition T for the compressed state of the molding material Rm are set in advance. After the injection filling process (S7) is completed, the compression process (S11-S15) is performed based on the mold clamping conditions including the mold closure pressure adjustment condition T.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an injection molding machine that performs molding by injecting and filling a molding material into a mold clamped by a clamping device.

Background Art

[0002] Conventionally, as a molding method using an injection molding machine, a method of clamping a mold by applying a high-pressure clamping force to the mold is generally used. However, this general method increases energy consumption associated with applying a high-pressure clamping force, and is not necessarily a desirable method from the perspective of energy saving. For this reason, there is a demand for a molding method that clamps the mold by applying the minimum necessary clamping force while ensuring high quality and uniformity of the molded product. Already, the present applicant has proposed a new molding method that meets this demand in Patent Document 1.

[0003] The molding method of the injection molding machine disclosed in Patent Document 1 causes a predetermined mold gap to occur in the resin filled in the mold by a relative force relationship between a constant molding clamping force and a constant molding injection pressure at all times, and also causes natural compression by the molding clamping force even after the filling of the resin is completed, ensuring high quality of the molded product, simplifying the molding conditions and facilitating setting, shortening the molding cycle time, and further enhancing mass productivity and economy. Specifically, when performing molding by injecting and filling resin into a mold composed of a fixed mold and a movable mold clamped with a predetermined clamping force by a clamping device with an injection device, at least a clamping device that enables compression (natural compression) of the resin as the resin in the mold solidifies is used as the clamping device. A predetermined gap (mold gap) is caused to occur between the movable mold and the fixed mold during injection filling in advance, and the injection pressure (molding injection pressure) and the clamping force (molding clamping force) that enable good product molding are obtained and set. During production, the clamping device is clamped with the molding clamping force, and the molding injection pressure is set as the limit pressure. After driving the injection device to perform injection filling of the resin into the mold, the molded product is taken out after a predetermined cooling time has elapsed.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] International Publication WO2011 / 161899 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, the molding method of the injection molding machine in Patent Document 1 described above also had the following problems to be solved.

[0006] That is, when the molding material is a resin with low viscosity (high fluidity), there is no particular problem. However, when the molding material is a resin with low fluidity (high viscosity), a situation may occur where the resin filling into the mold cavity is not smoothly performed. As a result, there is a risk of molding defects due to resin shortage and the occurrence of variations (decrease in homogeneity) in the molded product. Depending on the combination of the low-fluidity resin and the mold cavity shape, there may also be a risk that molding (production) becomes difficult.

[0007] In particular, in the case of thermosetting resins, the flow resistance during injection filling increases and the molding cycle tends to be long. Therefore, compared with the case of high-fluidity resins, the injection filling speed into the mold is relatively low. As a result, it is easy for variations to occur in the resin curing speed near the gate and near the end far from the gate in the mold cavity. Since it cures due to the high temperature in the mold, there are difficulties in controlling the temperature of the mold, controlling the pressure with respect to the mold closing pressure in the compression process, and further, in grasping the behavior of the resin in the mold.

[0008] An object of the present invention is to provide an injection molding machine that solves the problems existing in such background art. [Means for Solving the Problems]

[0009] In order to solve the above-described problems, the injection molding machine M according to the present invention includes an injection device Mi that performs an injection filling process of injecting and filling a molding material Rm into a mold D having a predetermined mold gap Lg set between a movable mold Dm and a fixed mold Dc, a mold clamping device Mc that performs a compression process of pressurizing and compressing the mold D filled with the molding material Rm with a predetermined mold clamping pressure Pp, and a molding machine controller 2 that controls the injection device Mi and the mold clamping device Mc. When configuring the injection molding machine, a thermosetting resin material is applied to the molding material Rm, and mold clamping conditions having a predetermined mold gap Lg, a predetermined mold clamping force Pc, a predetermined back pressure Pb with respect to the movable mold Dm, and a predetermined mold closing pressure Pb are set for the mold clamping device Mc. At the same time, a molding machine controller 2 that sets mold clamping conditions having a predetermined mold closing pressure adjustment condition T for the compression state of the molding material using the size of the mold gap Lg, the size of the mold closing pressure Pp, or the viscosity Vr of the molding material Rm for the mold clamping device Mc, an injection device Mi that performs an injection filling process of injecting and filling the molding material Rm into the mold D of the mold clamping device Mc in which the mold clamping conditions Mc are set, a movable platen 5 that is supported by a tie bar mechanism portion 4 so as to be movable forward and backward and supports the movable mold Dm, a mold clamping platen 7 that is supported by the tie bar mechanism portion 4 so as to be movable forward and backward and incorporates a mold clamping drive mechanism portion 6 that clamps the movable mold Dm, and a chuck mechanism portion 8 that is provided integrally with the mold clamping platen 7 and can fix the mold clamping platen 7 at a predetermined position of the tie bar mechanism portion 4. The injection molding machine is characterized by including a mold clamping device Mc that performs a compression process based on mold clamping conditions having a mold closing pressure adjustment condition T for the mold D filled with the molding material Rm.

[0010] On the other hand, according to a preferred aspect of the invention, when configuring the injection molding machine M, the molding machine controller 2 can be provided on a display 2d that graphically displays the mold gap Lg, the mold closing pressure Pp, and the viscosity Vr by a graphic display portion 2dg. Further, the injection filling process can end when the movable mold Dm reaches a preset compression start position Xp. Furthermore, it is desirable to use a mold clamping cylinder 6c for the mold clamping drive mechanism portion 6 and connect a meter-out circuit 9 to the mold clamping cylinder 6c.

Effects of the Invention

[0011] According to the injection molding machine M according to the present invention as described above, the following remarkable effects can be obtained.

[0012] (1) Even if the molding material Rm has low fluidity (high viscosity), the resin flow path is widened by the mold gap Lg, and the resin can be smoothly filled into the cavity of the mold D. Therefore, it is possible to avoid the problem that molding (production) becomes difficult depending on the type of the molding material R, and it is possible to enhance the versatility of the molding target by expanding the types of the injection-moldable molding material R.

[0013] (2) Even in the molding of a thermosetting resin or the like in which the flow resistance during injection filling increases and the molding cycle tends to become long, it is possible to optimize the temperature control when heating the mold and the control of the mold closing pressure in the compression process. Therefore, it is possible to reduce the occurrence of molding defects due to resin shortage and the occurrence of variations in molded products, and to improve the quality of the molded products.

[0014] (3) Since the size of the mold gap Lg between the movable mold Dm and the fixed mold Dc is included as the compression state of the molding material Rm, the behavior of the compression state of the molding material Rm in the mold D caused by the difference in the size of the mold gap Lg can be grasped. Thereby, it is possible to optimize the mold closing pressure adjustment conditions T such as the compression timing associated with the mold gap Lg when setting.

[0015] (4) Since the size of the mold closing pressure Pp is included as the compression state of the molding material Rm, the behavior of the compression state of the molding material Rm in the mold D caused by the difference in the size of the mold closing pressure Pp can be grasped. Thereby, it is possible to optimize the mold closing pressure adjustment conditions T such as the compression timing associated with the mold closing pressure Pp.

[0016] (5) Since the magnitude of the viscosity of the molding material Rm is included as the compression state of the molding material Rm, the behavior of the compression state of the molding material Rm caused by the difference in the magnitude of the viscosity of the molding material Rm can be grasped. Thereby, it is possible to optimize the mold closing pressure adjustment conditions T such as the compression timing associated with the viscosity Vr of the molding material Rm.

[0017] (6) Since a thermosetting resin material is applied to the molding material Rm, it is possible to provide an injection molding machine M that is optimal for molded products using a low-fluidity molding material.

[0018] (7) The mold clamping device Mc is configured to include a movable platen 5 that is supported by the tie bar mechanism unit 4 so as to be movable forward and backward and supports the movable mold Dm, a mold clamping platen 7 that is supported by the tie bar mechanism unit 4 so as to be movable forward and backward and incorporates a mold clamping drive mechanism unit 6 for clamping the movable mold Dm, and a chuck mechanism unit 8 that is provided integrally with the mold clamping platen 7 and can fix the mold clamping platen 7 to a predetermined position of the tie bar mechanism unit 4. Therefore, the compression process by the mold clamping device Mc can be easily and surely implemented, and the ease of implementation and certainty can be ensured.

[0019] (8) In a preferred embodiment, if a display 2d is provided on the molding machine controller 2 and the graphic display unit 2dg of the display 2d graphically displays the mold gap Lg, the mold closing pressure Pp, and the viscosity Vr, the operator can grasp the mold gap Lg, the mold closing pressure Pp, and the viscosity Vr from the graphic display, so that the setting of the mold closing pressure adjustment condition T can be accurately and easily performed.

[0020] (9) In a preferred embodiment, if the injection filling process is terminated when the movable mold Dm reaches a preset compression start position Xp, a desired compression process can be performed on the resin Rd after the resin Rd is filled. Therefore, for example, it can be provided as an optimal injection molding machine also from the viewpoint of performing compression molding on molded products using a low-fluidity molding material or the like.

[0021] (10) In a preferred embodiment, if a mold clamping cylinder 6c is used in the mold clamping drive mechanism unit 6, a hydraulic circuit including the mold clamping cylinder 6c can be utilized, so that back pressure control on the resin Rd during injection filling becomes possible and the molding quality can be improved.

[0022] (11) In a preferred embodiment, by connecting the meter-out circuit 9 to the clamping cylinder 6c, a relatively simple hydraulic circuit 3 can be realized, which can be implemented easily and at low cost, and the back pressure control during molding can be performed easily and reliably.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0024] Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

[0025] First, the configuration of the injection molding machine M according to the present embodiment will be specifically described with reference to FIGS. 1 to 5.

[0026] In FIGS. 1 and 2, M is an injection molding machine, and includes an injection device Mi and a mold clamping device Mc installed on the upper surface of the machine base Mb.

[0027] The injection device Mi is installed on the machine base Mb so as to be movable forward and backward, and includes a heating cylinder 11 having an injection nozzle 11n at the front end and a hopper 11h at the rear end. A screw 12 is inserted into the heating cylinder 11, and a screw drive unit 13 is disposed at the rear end of the heating cylinder 11. The screw drive unit 13 includes an injection cylinder 14 incorporating a single-rod type injection ram 15, and a ram rod 15r protruding forward of the injection ram 15 is coupled to the rear end of the screw 12. Further, at the rear end of the injection ram 15, the shaft of a screw rotation motor (oil motor) 16 attached to the injection cylinder 14 is spline-coupled. Reference numeral 17 denotes an injection device moving cylinder that moves the injection device Mi forward and backward to perform nozzle touch on or release from the mold D.

[0028] The mold clamping device Mc basically includes a movable platen 5 that is supported by a tie bar mechanism portion 4 so as to be movable forward and backward and supports the movable mold Dm, and a mold clamping drive mechanism portion 6 that is supported by the tie bar mechanism portion 4 so as to be movable forward and backward and clamps the movable mold Dm, and a chuck mechanism portion 8 that is provided integrally with the mold clamping platen 7 and can fix the mold clamping platen 7 at a predetermined position of the tie bar mechanism portion 4.

[0029] More specifically, as shown in FIGS. 2 and 3, the upper surface of the machine base Mb is provided with a first fixed platen 21 and a second fixed platen 22 that are fixed at a distance from each other. Four parallel tie bars 4m... are respectively installed at the four corners between the first fixed platen 21 and the second fixed platen 22. Then, the movable platen 5 and the mold clamping platen 7 are supported by the respective tie bars 4m... so as to be slidably displaced. Thereby, the fixed mold Dc is supported by the front fixed platen 21, the movable mold Dm is supported by the movable platen 5, and the mold D is constituted by the fixed mold Dc and the movable mold Dm.

[0030] Also, as shown in FIG. 3, the mold clamping platen 7 incorporates a mold clamping drive mechanism section 6. The mold clamping drive mechanism section 6 is constituted by a single-rod type mold clamping cylinder 6c, and the tip of the mold clamping ram 6cr protruding forward is fixed to the back surface of the movable platen 5. Note that 23a and 23b indicate a pair of left and right single-rod type mold opening and closing cylinders installed between the rear fixed platen 22 and the movable platen 5.

[0031] Furthermore, a chuck mechanism section 8 is disposed on the back surface of the mold clamping platen 7 (on the side of the second fixed platen 22). The chuck mechanism section 8 is constituted by four chuck sections 8m corresponding to each tie bar 4m. In this case, as shown in FIG. 4, one tie bar 4m (the same applies to the other tie bars 4m) forms a ring-shaped concave groove portion 25s on the outer peripheral surface, and the concave groove portions 25s are provided at regular intervals along the axial direction. Note that the range where the concave groove portions 25s are provided is selected as the range where the chuck sections 8m function effectively in at least the entire moving range in the axial direction of the mold clamping platen 7.

[0032] One chuck section 8m (the same applies to the other chuck sections 8m) includes chuck half body sections (half nuts) 8mu and 8md divided into two parts vertically, and is configured to be able to chuck the tie bar 4m by sandwiching the tie bar 4m between the chuck half body sections 8mu and 8md. In the illustrated case, as shown in FIG. 4, an engaging portion 7r having a guide rail mechanism is provided on the back surface of the mold clamping platen 7, and the chuck half body sections 8mu and 8md are engaged with the engaging portion 7r so as to be able to move up and down, and are configured to be displaceable in opposite directions to each other by a link mechanism. Also, a chuck cylinder 24 is coupled to one chuck half body section 8mu to configure the chuck half body sections 8mu and 8md to be displaceable up and down, and ring-shaped protruding strip portions 25t that fit into the concave groove portions 25s provided on the outer peripheral surface of the tie bar 4m are formed on the inner peripheral surfaces of the chuck half body sections 8mu and 8md.

[0033] Accordingly, in FIG. 4, if the piston rod of the chuck cylinder 24 is projected, the positions of the chuck half bodies 8mu, 8md shown by the solid line cross-section, i.e., the chuck position Xs, are displaced. Thus, the rib portions 25t... and the groove portions 25s... are engaged to fix the mold clamping platen 7. On the other hand, if the piston rod of the chuck cylinder 24 is retracted, the positions of the chuck half bodies 8mu, 8md shown by the phantom line, i.e., the chuck release position Xr, are displaced. Thus, the rib portions 25t... and the groove portions 25s... are separated to allow the axial movement of the mold clamping platen 7. Note that the configuration of the chuck portion 8m illustrated is an example. For example, since there are four chuck portions 8m..., the inner peripheral surface of the chuck half body 8md... may be made flat, and the rib portions 25t... may be provided only on the inner peripheral surface of the chuck half body 8mu.... Basically, it can be replaced by various known mechanisms having the same function.

[0034] In this way, as the mold clamping device Mc, a movable platen 5 that is supported by the toggle mechanism portion 4 so as to be movable forward and backward and supports the movable mold Dm, a mold clamping platen 7 that is supported by the toggle mechanism portion 4 so as to be movable forward and backward and incorporates a mold clamping drive mechanism portion 6 (mold clamping cylinder 6c) for clamping the movable mold Dm, and a chuck mechanism portion 8 that is provided integrally with the mold clamping platen 7 and can fix the mold clamping platen 7 at a predetermined position of the toggle mechanism portion 4 are provided. Thus, the easiness and certainty of implementation can be ensured, such as easily and surely implementing the compression process by the mold clamping device Mc.

[0035] On the other hand, 3 is a hydraulic circuit, which mainly includes a variable displacement hydraulic pump 3p serving as a hydraulic drive source and a valve circuit 32 for performing various switching and controls, and also includes a meter-out circuit 9 connected to the mold clamping cylinder 6c. If the injection device Mi and the mold clamping device Mc are driven by the hydraulic circuit 3 including the hydraulic pump 3p, back pressure control based on hydraulic pressure can be utilized. In particular, back pressure control for the resin Rd during injection filling becomes possible, contributing to the improvement of the molding quality.

[0036] As shown in Fig. 3, the hydraulic pump 3p includes a pump section 35 and a servo motor 36 that rotationally drives the pump section 35. Note that 37 indicates a rotary encoder that detects the rotational speed of the servo motor 36. The pump section 35 incorporates a pump body 38 constituted by an inclined plate type piston pump. Therefore, the pump section 35 includes an inclined plate 42. If the inclination angle (swash plate angle) of the inclined plate 42 is increased, the stroke of the pump piston in the pump body 38 becomes larger, the discharge flow rate increases, and if the swash plate angle is decreased, the stroke of the pump piston becomes smaller and the discharge flow rate decreases. As a result, if the swash plate angle is set to a predetermined angle, it becomes possible to set a fixed discharge flow rate in which the discharge flow rate (maximum capacity) is fixed to a predetermined magnitude. A control cylinder 43 and a return spring 44 are attached to the inclined plate 42, and the control cylinder 43 is connected to the discharge port of the pump section 35 (pump body 38) via a switching valve (electromagnetic valve) 45. Thereby, the angle (swash plate angle) of the inclined plate 42 can be changed by controlling the control cylinder 43.

[0037] Also, the suction port of the pump section 35 is connected to an oil tank 39, and the discharge port is connected to the primary side of the valve circuit 32. The secondary side of the valve circuit 32 is connected to the above-described injection cylinder 14, screw rotation motor 16, injection device moving cylinder 17, mold clamping cylinder 6c, mold opening / closing cylinder 23a…, chuck cylinder 24…, and other various actuators such as an ejector cylinder (not shown). Therefore, the valve circuit 32 includes switching valves (electromagnetic valves) respectively connected to these actuators. Each switching valve is constituted by at least one or two or more valve components and necessary attached hydraulic components, etc., and at least has a switching function related to the supply, stop, and discharge of hydraulic oil for the above-described injection cylinder 14, screw rotation motor 16, injection device moving cylinder 17, mold clamping cylinder 6c, mold opening / closing cylinder 23a…, chuck cylinder 24…, and other various actuators such as an ejector cylinder (not shown). Thereby, if the rotational speed of the servo motor 36 is variably controlled, the discharge flow rate and discharge pressure of the variable displacement type hydraulic pump 31 can be varied.

[0038] Further, as shown in FIG. 3, an operating oil line 48 connected to the oil chamber (rear oil chamber) 6m of the clamping cylinder 6c is connected to the inflow side of the meter-out circuit 9, and the outflow side of this meter-out circuit 9 is connected to the oil tank 39. The meter-out circuit 9 includes check valves 51, 52, a direction control valve (electromagnetic valve) 53, and a relief valve (back pressure control valve) 54, and is configured to be connected as shown in FIG. 3.

[0039] Thereby, in the injection filling process, control of the clamping device Mc can be achieved only by back pressure control using the meter-out circuit 9. That is, due to the function of the meter-out circuit 9, the pressure of the resin Rd in the mold D is maintained at that pressure when it is below the set back pressure Pb [kN], and when it exceeds the back pressure Pb [kN], it is maintained at the back pressure Pb [kN] by the function of the relief valve 54.

[0040] In this way, by providing the meter-out circuit 9 connected to the clamping cylinder 6c, a relatively simple hydraulic circuit 3 can be realized, so that it can be implemented easily and at low cost, and there is an advantage that back pressure control during molding can be performed easily and reliably. Also, the injection device Mi and the clamping device Mc can be driven by a common hydraulic pump 3p. That is, it becomes possible to perform only back pressure control on the clamping device Mc during injection filling, and the driving force by the hydraulic pump becomes unnecessary. Therefore, the hydraulic pump on the clamping device Mc side of the two hydraulic pumps originally required on the injection device Mi side and the clamping device Mc side during injection filling becomes unnecessary, contributing to a significant cost reduction.

[0041] Reference numeral 2 denotes a molding machine controller. The molding machine controller 2 includes a controller main body 2m and a display 2d. The servo motor 36 described above is connected to a servo amplifier output port of the controller main body 2m, and the valve circuit 32 is connected to a control signal output port of the controller main body 2m. On the other hand, the encoder pulses obtained from the rotary encoder 37 are connected to the servo amplifier of the controller main body 2m. Reference numeral 55 denotes a pressure sensor that detects the hydraulic pressure connected to the primary side of the valve circuit 32, and the detection result of this pressure sensor 55 is provided to the controller main body 2m of the molding machine controller 2.

[0042] The controller main body 2m has a computer function incorporating hardware such as a CPU and an internal memory. Therefore, the internal memory includes a data memory that stores a control program (software) for executing various control processes (sequence control) and stores various types of data (databases). The control program includes a control program for realizing at least a part of the injection molding machine according to the present embodiment.

[0043] FIG. 1 shows the overall external configuration of the injection molding machine M. A display 2d attached to the molding machine controller 2 is attached to a side panel 61 standing near the middle of the injection molding machine M. The display 2d can perform various displays, and a touch panel is attached, and various setting operations and selection operations can be performed by this touch panel.

[0044] On this 2D display, as shown in the partial extraction screen diagram shown in FIG. 1, a graphic display section 2dg is displayed according to the present invention. By this graphic display section 2dg, at least the mold position (measured value) Xd, the mold closing pressure (measured value) Pp, and the viscosity (calculated value) Vr can be graphically displayed. As an example, in addition to these three operating physical quantities, the injection speed (measured value) Si, the injection pressure (set value) Pi, and the mold opening / closing speed (measured value) Sd are displayed. In addition, if necessary, various operating physical quantities (monitoring data) can be graphically displayed. Note that the viscosity (calculated value) Vr uses the differential value of the mold closing pressure Pp, that is, the pressure change ΔP per unit time.

[0045] In this way, by providing the display 2d in the molding machine controller 2 and displaying the graphic display section 2dg on this display 2d, the mold gap Lg, the mold closing pressure Pp, and the pressure difference ΔP (viscosity Vr) of the closing pressure Pp with respect to time are graphically displayed. Then, the operator can easily grasp the mold gap Lg, the mold closing pressure Pp, and the viscosity Vr from the graphic display, so that the setting of the mold closing pressure adjustment condition T such as the compression adjustment time Tc described later can be accurately and easily performed.

[0046] That is, by including the magnitude of the mold position Xd (the mold gap Lg between the movable mold Dm and the fixed mold Dc), the magnitude of the mold closing pressure Pp, and the magnitude of the viscosity Vr of the molding material Rm, the operator can visually and easily grasp at a glance the behavior of the compression state of the molding material Rm in the mold D caused by the difference in the magnitude of the mold gap Lg, the behavior of the compression state of the molding material Rm in the mold D caused by the difference in the magnitude of the mold closing pressure Pp, and the behavior of the compression state of the molding material Rm caused by the difference in the magnitude of the viscosity of the molding material Rm. That is, since the overall compression state of the molding material Rm from the start of the injection filling process to the end of the compression process can be easily grasped, the optimization of the mold closing pressure adjustment condition T such as the compression timing associated with these behaviors can be achieved.

[0047] Therefore, as shown in Fig. 1 (and Fig. 7), this graphic display unit 2dg includes an injection filling process from the start of injection to the end of injection, and a compression process (post-filling process) from the end of injection to before the molded product is taken out. In Fig. 1 (and Fig. 7), te indicates the time point when the injection filling process ends. From this time point te, the left area becomes the section of the injection filling process, and from this time point te, the right area becomes the section of the compression process (post-filling process). In both cases, the horizontal axis represents time t.

[0048] In addition, the display 2d can display various setting screens. Fig. 5 shows a part of the mold opening / closing screen Vm used in this embodiment. Since a "compression" switch 63 is provided on this mold opening / closing screen Vm, by turning on this "compression" switch 63, the setting screen Vs used in the injection molding machine according to this embodiment can be displayed in a window. This setting screen Vs includes an ON / OFF selection key 64 for compression, a standby position setting unit 65a for setting the standby position [mm] of the movable platen 5 before injection, a compression position setting unit 65b for setting the start position [mm] of compression, a mold clamping back pressure setting unit 65c for setting the mold clamping holding pressure (back pressure) [kN] during injection, a filling shortage time setting unit 65d for setting the filling shortage time Ts [seconds] when not shifting to the compression position, a compression adjustment time setting unit 65e for setting the compression adjustment time Tc [seconds], a primary mold closing pressure (compression pressure) Pp [kN] setting unit 65f for setting the mold closing pressure for the first compression, a secondary mold closing pressure (compression pressure) Pp [kN] setting unit 65g for setting the mold closing pressure for the second compression, and a switching time setting unit 65h for setting the switching time [s] to the second compression. Note that 66 indicates the "close" key of the setting screen Vs.

[0049] Next, an injection molding method using the injection molding machine M according to this embodiment will be sequentially described mainly with reference to Figs. 1, 7 - 12 according to the flowchart shown in Fig. 6.

[0050] In carrying out the injection molding method, first, setting processing is performed (step S1). In this setting processing, various normal molding conditions are set, and using the setting screen Vs shown in FIG. 5, the above-described various items related to the injection molding machine M according to the present embodiment are set.

[0051] Now, it is assumed that the mold clamping device Mc (movable mold Dm) is in the mold open position Xo shown in FIG. 8 (step S2). The mold open position Xo is a position where the chuck cylinder 24... is driven and controlled to switch the chuck portion 8m... to the chuck release position Xr, the mold clamping cylinder 6c is driven and controlled to move the movable platen 5 to the furthest retreat position (on the side of the second fixed platen 22), and the mold opening / closing cylinder 23a... is driven and controlled to move the movable platen 5 and the mold clamping platen 7 backward. In FIG. 8, 71 indicates an encoder for detecting the position of the mold clamping platen, and 72 indicates an encoder for detecting the position of the movable platen.

[0052] During production (during molding), the mold opening / closing cylinder 23a... is driven and controlled to move the movable platen 5 and the mold clamping platen 7 forward at high speed from the mold open position Xo to the chuck position Xc shown in FIG. 9. When the chuck position Xc is reached, the chuck cylinder 24... is driven and controlled to switch the chuck portion 8m... to the chuck position Xs and fix the mold clamping platen 7 to the tie bar 4m... (step S3). In FIG. 9, La indicates the moving stroke of the mold clamping platen 7 from the mold open position Xo to the chuck position Xc.

[0053] Next, the mold clamping cylinder 6c is driven and controlled to move the movable platen 5 forward, and the gap between the movable mold Dm and the fixed mold Dc is adjusted to set the movable mold Dm to the set standby position Xw shown in FIG. 10 (step S4). At this time, a set mold gap Lg is provided between the movable mold Dm and the fixed mold Dc. In FIG. 10, Lc indicates the moving stroke of the mold clamping ram 6cr during adjustment. Thereby, the preparation for starting injection on the mold clamping device Mc side is completed, and the direction control valve 53 of the meter-out circuit 9 is switched to the meter-out ON side (step S5).

[0054] On the other hand, in the injection device Mi, the screw 12 rotates by driving and controlling the screw rotation motor 16, and thereby, the molding material R supplied to the hopper 11h accumulates in front of the screw 12. Further, the injection device Mi moves forward to the nozzle touch position shown in FIG. 10 by driving and controlling the injection device moving cylinder 17. Thereby, the preparation for starting injection on the injection device Mi side is completed.

[0055] Note that, in particular, a low-fluidity molding material such as a thermosetting resin material can be applied to the molding material R. Thus, if a low-fluidity molding material is applied as the molding material R, it is possible to provide an injection molding machine M that can implement an optimal injection molding method for a molded product using a low-fluidity molding material.

[0056] When the above preparation for starting injection is completed, the injection cylinder 14 is driven and controlled to start injection of the molding material Rm (step S6). In this case, immediately before the start of injection, as described above, there is a mold gap Lg between the movable mold Dm and the fixed mold Dc, and the injection pressure is in a state of 0 and the mold clamping force is also in a state of 0. Therefore, the pressure difference before and after the movable platen 5 is 0 and in an equilibrium state, and the movable platen 5 is in a stopped state. Thus, the predetermined mold clamping force Pc in the mold clamping conditions of the present invention includes a state of 0, that is, a case where it is set to 0.

[0057] On the other hand, by the start of injection, the screw 12 advances, and the molding material Rm is filled into the cavity of the mold D, that is, the mold gap Lg between the movable mold Dm and the fixed mold Dc, through the injection nozzle 11n (step S7). In this case, a low-fluidity molding material is used as the molding material R, but since the initial mold clamping force is in a state of 0, the molding material Rm is injected and filled into the cavity of the mold D relatively smoothly. As the injection filling process progresses, the pressure of the resin Rd in the mold D rises, and since the mold clamping platen 7 is fixed in position by the chuck position Xs of the chuck portion 8m..., the movable platen 5 gradually retracts. At this time, by the function of the meter-out circuit 9, it is maintained at the set back pressure Pb [kN].

[0058] Then, as shown in FIG. 11, when the movable platen 5 reaches the set compression start position Xp, an end process for ending the injection filling process is performed (steps S8, S10). At this time, the screw 12 advances to the vicinity of the most forward position. In FIG. 11, Ls indicates the movement stroke of the screw 12 during injection filling, and Pb indicates the back pressure [kN] applied to the mold clamping ram 6cr. Therefore, in this case, the movable platen 5 reaching the compression start position Xp becomes the injection end condition.

[0059] In this way, if the injection filling process is ended by the movable mold Dm reaching the preset compression start position Xp, a desirable compression process can be performed on the resin Rd after the resin Rd is filled. Therefore, for example, it can be provided as an optimal injection molding machine also from the viewpoint of performing compression molding on a molded product using a low-fluidity molding material or the like.

[0060] When the injection filling process is completed, the compression process (primary compression process) is started (steps S11 (S13)). Note that there are a multi-pressure mode in which the mold clamping pressure (mold closing pressure) is set in multiple stages and a single-pressure mode in which a constant mold clamping pressure is used in the compression process.

[0061] FIG. 1 shows the case of a two-pressure mode by a primary mold clamping pressure (primary mold closing pressure) Ppsf in the primary compression process (first stage) and a secondary mold clamping pressure (secondary mold closing pressure) Ppss in the secondary compression process (second stage), and the explanatory diagram of FIG. 7 shows the case of a single-pressure mode by a constant mold clamping pressure (mold closing pressure).

[0062] Therefore, in the case of the single-pressure mode in FIG. 7, the compression adjustment time Tc is the adjustment time for changing the starting point at the beginning of the compression process, and in the case of the two-pressure mode in FIG. 1, it is the adjustment time for changing the switching point to the secondary compression process. Thus, the compression adjustment time Tc is not limited to changing at a specific time point, and may be changed at a plurality of time points if necessary, or the magnitude and duration of the mold closing pressure may be changed. Basically, the setting pattern of the mold closing pressure Pp including these can be arbitrarily changed. The change of this setting pattern becomes the mold closing pressure adjustment condition T. In the case of this embodiment, the compression adjustment time Tc becomes the mold closing pressure adjustment condition T.

[0063] The flowchart of FIG. 6 shows the case of the two-pressure mode. In FIG. 6, when the injection filling process ends, the timing process is started, and at the same time, the primary compression process is started with the set primary mold closing pressure [kN] (steps S12, S13). The compression process switches the meter-out circuit 9 to OFF and drives and controls the mold clamping cylinder 6c, and as shown in FIG. 12, the movable platen 5 is pressurized forward (toward the first fixed platen 21 side) with a predetermined pressure Pp. Then, based on the timing process, when the switching time [seconds] including the compression adjustment time Tc [seconds] set by the compression adjustment time setting unit 65e is reached, the primary compression process ends and the process is switched to the secondary compression process (secondary mold closing pressure) (steps S14, S15). Thereby, the secondary compression process is performed for a predetermined period. In FIG. 12, Lp indicates the compression amount by which the mold clamping ram 6cr is displaced by the pressure Pp. When the secondary compression process ends, mold opening is performed, and the ejector process for the molded product is performed (step S16). Further, when the next production continues, the same molding process is performed (steps S17, S2...).

[0064] By the way, the setting of the above-described compression adjustment time Tc is important. FIGS. 7(a)-(d) show characteristic diagrams for explaining the mold gap Xd, the mold closing pressure Pp, and the pressure difference ΔP (viscosity Vr) with respect to the time t of the mold closing pressure Pp, which are displayed on the graphic display unit 2dg of the display 2d provided in the injection molding machine M. Note that the compression process in FIG. 7 is the single-pressure mode described above.

[0065] Figure 7 shows the behavioral changes in the compression state of the molding material Rm when the compression adjustment time Tc is varied, that is, when the compression adjustment time Tc is set to "0" (dotted line Xdo) and when it is set to "Tcs" (solid line (Xds)). Now, in Figure 7(b), when the compression adjustment time Tc is set to "0", the mold gap Xd at the end of filling time te shows that, like the mold closing pressure characteristic line Ppo and the viscosity characteristic line Vro shown by the dotted line in Figures 7(c) and (d), the magnitudes of the mold closing pressure [kN] and viscosity [mPa·s] tend to rise immediately from the end of filling time te.

[0066] On the other hand, when the compression adjustment time Tc is set to the time "Tcs" as shown in Figure 7(b) for example, the mold gap Xd at the end of filling time te shows that, like the mold closing pressure characteristic line Pps and the viscosity characteristic line Vrs shown by the solid line in Figures 7(c) and (d), after the end of filling, in the interval of time t1 - t2, the mold closing pressure [kN] and viscosity [mPa·s] decrease and tend to rise again after time t2. In Figure 7(a), Si represents the injection speed, Pi represents the injection pressure, and Xs represents the screw position.

[0067] Figure 1 actually shows the graphic display unit 2dg when the compression adjustment time Tc is appropriately set. This figure is the case where there is a relatively small mold gap, that is, a mold gap Xd of about 5 [mm]. As is clear from this figure, after the end of filling, the viscosity Vr once decreases and then tends to rise again. Therefore, in this case, if the secondary mold closing pressure Ppss is set to the adjustment time Tcs, it can be made to approximately coincide with the rising timing of the viscosity Vr.

[0068] In this case, the setting of the compression adjustment time Tc may be set as an appropriate time value at the initial setting time by, for example, performing a trial molding in advance, or at the initial setting, "0" or an arbitrary provisional value may be set at the discretion of the operator, and each behavior may be confirmed on the graphic display unit 2dg during the molding process (production process), and then changed (updated) and set. In this way, since the viscosity of the molding material Rm can be easily and accurately confirmed by the graphic display unit 2dg, the setting of the optimized compression adjustment time Tc can be performed.

[0069] On the other hand, since a molding material with low fluidity is used as the molding material R, it is assumed that it may take time to reach the compression start position Xp in the injection filling process (step S7). In this case, when the set unfilled time Ts [seconds] has elapsed before reaching the compression start position Xp, the injection filling process is terminated even if the compression start position Xp is not reached (steps S9, S10). Therefore, when the unfilled time Ts has elapsed, a compression process for pressurizing the resin Rd in the mold D with the movable mold Dm is started (step S11). In this case, the elapse of the preset unfilled time (filling time) Ts from the start of the injection filling process is the injection end condition. Note that the processes after the compression process are the same as those in the case where the compression start position Xp described above is reached, and a primary compression process with the primary mold closing pressure, a secondary compression process with the secondary mold closing pressure, and an ejector process for the molded product are performed (steps S12 - S17).

[0070] In this way, if the injection filling process is terminated when the preset unfilled time Ts has elapsed from the start of the injection filling process, compression molding can be achieved by performing the compression process even when the compression start position Xp is not reached within the set unfilled time Ts due to factors such as the type of the low-fluidity molding material and the combination of the mold cavity shape. Therefore, molding defects due to resin shortage can be reduced, and the yield of the molded product can be increased.

[0071] Therefore, according to the injection molding machine M according to such an embodiment of the present invention, basically, a clamping condition including a predetermined mold gap Lg, a predetermined mold clamping force Pc, a predetermined back pressure Pb for the movable mold Dm, a predetermined mold closing pressure Pp, and a predetermined mold closing pressure adjustment condition T for the compression state of the molding material Rm is set. During molding, an injection filling step is performed in which the molding material Rm is injection filled into the mold D of the mold clamping device Mc with the clamping condition set by the injection device Mi. When the injection filling step is completed, a compression step is performed based on the clamping condition including the mold closing pressure adjustment condition T. Therefore, even if the molding material Rm has low fluidity (high viscosity), the resin can be smoothly filled into the cavity of the mold D. Thus, it is possible to avoid the problem that molding (production) becomes difficult depending on the type of the molding material R, and to enhance the versatility of the molding target by expanding the types of molding materials R that can be injection molded.

[0072] As described above, the preferred embodiments have been described in detail. However, the present invention is not limited to such embodiments, and can be arbitrarily changed, added, or deleted within the scope not departing from the gist of the present invention in terms of detailed configuration, shape, material, quantity, numerical value, etc.

[0073] For example, although the case where the mold gap Lg, the mold closing pressure Pp, and the viscosity Vr are directly and graphically displayed as they are has been shown, other graphic displays such as indirect or simplified displays are not excluded. On the other hand, although it is optimal for the injection device Mi and the mold clamping device Mc to be driven by a hydraulic circuit 3 including a hydraulic pump 3p, other drive sources and drive circuits are not excluded. Therefore, although it is desirable for the injection device Mi and the mold clamping device Mc to be driven by a common hydraulic pump 3p, it is not limited to this drive mode. Also, for the mold clamping drive mechanism section 6, while using a mold clamping cylinder 6c, it is desirable to connect a meter-out circuit 9 to this mold clamping cylinder 6c, but it can be replaced by other circuits that exhibit the same function.

Industrial Applicability

[0074] The injection molding machine according to the present invention can be used in various injection molding machines that plasticize various molding materials and perform molding by injecting and filling them into a mold.

Explanation of symbols

[0075] 2: Molding machine controller, 2d: Display, 2dg: Graphic display unit, 4: Tie-bar mechanism unit, 5: Moving platen, 6: Mold clamping drive mechanism unit, 6c: Mold clamping cylinder, 7: Mold clamping platen, 8: Chuck mechanism unit, 9: Meter-out circuit, (S7): Injection filling process, (S11 - S15): Compression process, M: Injection molding machine, Mi: Injection device, Mc: Mold clamping device, Rm: Resin material, D: Mold, Dm: Movable mold, Dc: Fixed mold, Lg: Mold gap, Pp: Mold closing pressure, Pc: Mold clamping force, Pb: Back pressure, T: Mold closing pressure adjustment condition, Vr: Viscosity, Xp: Compression start position

Claims

1. An injection molding machine comprising an injection device that performs an injection filling process of injecting and filling a molding material into a mold having a predetermined mold gap set between a movable mold and a fixed mold, a mold clamping device that performs a compression process of pressurizing and compressing the mold filled with the molding material with a predetermined mold closing pressure, and a molding machine controller that controls the injection device and the mold clamping device, wherein a thermosetting resin material is applied to the molding material, and a mold clamping condition having a predetermined mold gap, a predetermined mold clamping force, a predetermined back pressure on the movable mold, and a predetermined mold closing pressure is set for the mold clamping device, and a mold clamping condition having a predetermined mold closing pressure adjustment condition for the compression state of the molding material using the size of the mold gap, the size of the mold closing pressure, or the viscosity of the molding material is set for the mold clamping device; an injection device that performs an injection filling process of injecting and filling the molding material into the mold of the mold clamping device for which the mold clamping condition is set; a movable platen that is supported by a tie bar mechanism portion so as to be movable forward and backward and supports the movable mold, a mold clamping platen that is supported by the tie bar mechanism portion so as to be movable forward and backward and incorporates a mold clamping drive mechanism portion for clamping the movable mold, and a chuck mechanism portion that is provided integrally with the mold clamping platen and can fix the mold clamping platen to a predetermined position of the tie bar mechanism portion, and a mold clamping device that performs a compression process based on the mold clamping condition having the mold closing pressure adjustment condition on the mold filled with the molding material.

2. The injection molding machine according to claim 1, wherein the molding machine controller includes a display that graphically displays the mold gap, the mold closing pressure, and the viscosity on a graphic display unit.

3. The injection molding machine according to claim 1, wherein the injection filling process ends when the movable mold reaches a preset compression start position.

4. The injection molding machine according to claim 1, wherein the mold clamping drive mechanism portion includes a mold clamping cylinder.

5. The injection molding machine according to claim 4, further comprising a meter-out circuit connected to the mold clamping cylinder.

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