Injection molding method and injection molding machine

Abstract

The present invention is provided with a molding machine controller (2) having: a zero point setting control function unit (Fs) that sets a mold closing position (Xz) to a zero point (Po) by moving a movable mold (Dm) located at a mold opening position (Xo) forward to the mold closing position (Xz) by means of a mold closing device (Mc); a mold gap setting control function unit (Fg) that sets the mold gap (Lg) by moving the movable mold (Dm) back from the zero point (Po) by a stroke amount (Lgs) corresponding to the mold gap (Lg) to be set; and an injection / filling control function unit (Fi) that injects and fills the molding material (R) into the mold (D) in which the mold gap (Lg) is set.

Description

Technical Field

[0001] The present invention relates to an injection molding method and an injection molding machine for molding by injecting and filling a molding material into a mold in which a predetermined mold gap is provided between a movable mold and a fixed mold. Background Art

[0002] Conventionally, the following injection molding machine (injection molding method) has been known from, for example, the injection molding machine described in Patent Document 1 proposed by the present applicant: A molding material is injected and filled into a mold in which a predetermined mold gap is provided between a movable mold and a fixed mold by a clamping device, and molding is performed.

[0003] The injection molding machine described in Patent Document 1 has a function of molding by a specific molding method. In this specific molding method, a molding injection pressure and a molding clamping force are obtained and set such that a predetermined gap (parting opening) is generated between the movable mold and the fixed mold of the mold during injection filling and a qualified product can be molded. Then, the clamping device is clamped with the molding clamping force, and an injection device that sets the molding injection pressure to the limit pressure is driven to inject and fill the resin into the mold. Further, in this injection molding machine, a unit for detecting the parting opening (mold gap) is constituted by a position detector, and this position detector detects the relative position between the movable mold and the fixed mold by being attached to the mold.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-22842 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, the conventional injection molding machine (injection molding method), typified by the injection molding machine of Patent Document 1 described above, still has the following problems to be solved.

[0009] First, in such an injection molding machine, a molding material, that is, a fluidized molten resin, is injected and filled into a mold in a state where a minute mold gap is provided. Therefore, the accuracy of the set mold gap directly affects the molding quality. Conventionally, when setting this mold gap, setting has been performed using a position sensor such as a position detector attached to the mold or an encoder provided near the mold as in Patent Document 1. Therefore, it is easily affected by the temperature of the molding machine and the mold. In particular, when molding using a thermosetting resin material as the molding material, the mold temperature is set to about 160°C to 180°C. Therefore, the mold is liable to undergo metal expansion, and there is a problem that the mold gap cannot be set with high precision. As a result, there is a difficulty in easily reducing the quality and homogeneity of the molded product.

[0010] Second, a position detector or a position sensor, which is an accessory part (special part) of the mold, needs to be attached to the mold itself or in its vicinity. Therefore, it is disadvantageous in terms of cost and maintenance. In addition, a control system with high control precision is required, and temperature correction processing of detection data and the like are needed. As a result, the structure of the control system becomes complicated, and it is easy to cause an increase in the cost of control. As a result, there is still room for further improvement from the viewpoint of reducing the number of parts and achieving cost reduction.

[0011] An object of the present invention is to provide an injection molding method and an injection molding machine that solve the problems existing in such background art.

[0012] Means for Solving the Problem

[0013] To solve the above problems, the injection molding method of the present invention uses an injection device Mi to inject and fill a molding material R into a mold D in which a predetermined mold gap Lg is provided between a movable mold Dm and a fixed mold Dc by means of a mold clamping device Mc, and at this time, it is characterized in that the closed mold position Xz is set as a zero point Po by moving the movable mold Dm located at the open mold position Xo forward to the closed mold position Xz by using the mold clamping device Mc (S2 to S8), the mold gap Lg is set by moving the movable mold Dm backward from this zero point Po by a stroke amount Lgs corresponding to the mold gap Lg to be set (S9 to S11), and then, an injection filling process of injecting and filling the molding material R into the mold D in which the mold gap Lg is set is performed (S12 to S14).

[0014] Moreover, to solve the above problems, the injection molding machine M of the present invention is configured to have a molding machine controller 2, and the molding machine controller 2 performs the following control: using an injection device Mi to inject and fill a molding material R into a mold D in which a predetermined mold gap Lg is provided between a movable mold Dm and a fixed mold Dc by means of a mold clamping device Mc. At this time, it is characterized in that the molding machine controller 2 has: a zero point setting control function unit Fs that sets the closed mold position Xz as a zero point Po by moving the movable mold Dm located at the open mold position Xo forward to the closed mold position Xz by using the mold clamping device Mc; a mold gap setting control function unit Fg that sets the mold gap Lg by moving the movable mold Dm backward from this zero point Po by a stroke amount Lgs corresponding to the mold gap Lg to be set; and an injection filling control function unit Fi that injects and fills the molding material R into the mold D in which the mold gap Lg is set.

[0015] On the other hand, according to a preferred embodiment of the invention, the setting of the die gap Lg is preferably carried out at each injection in the molding cycle, and the molding material R is preferably a thermosetting resin material. Also, it may be that after the injection filling process of the molding material R into the die D, a compression process (S15 to S17) for pressing the movable die D is carried out. On the other hand, it may be that the mold clamping device Mc is configured to include: a movable platen 5, which is supported by the tie bar mechanism portion 4 so as to be movable forward and backward, and the movable platen 5 supports the movable die Dm; a mold clamping platen 7, which is supported by the tie bar mechanism portion 4 so as to be movable forward and backward, and the mold clamping platen 7 is internally provided with a mold clamping drive mechanism portion 6, and the mold clamping drive mechanism portion 6 clamps the movable die Dm; and a clamping mechanism portion 8, which is integrally provided on the mold clamping platen 7 and can fix the mold clamping platen 7 at a specified position of the tie bar mechanism portion 4. Also, it may be that the die gap setting control function portion Fg uses an encoder E2, and the encoder E2 detects the stroke amount Lgs of the backward movement of the movable die Dm. Also, it may be that the molding machine controller 2 is provided with a compression control function portion Fp, and the compression control function portion Fp presses the movable die Dm after the injection filling process of the injection filling control function portion Fi to carry out a compression process.

[0016] Advantages of the Invention

[0017] According to such an injection molding method and an injection molding machine M of the present invention, the following remarkable effects are achieved.

[0018] (1) By using the mold clamping device Mc to move the movable die Dm located at the open mold position Xo forward to the closed mold position Xz and setting the closed mold position Xz as the zero point Po, and by moving the movable die Dm backward from this zero point Po by a stroke amount Lgs corresponding to the die gap Lg to be set to set the die gap Lg, and then carrying out an injection filling process (S13) of injecting the molding material R into the die D with the die gap Lg set, even when injecting and filling the die D in a state where a minute die gap Lg is set, the die gap Lg can be set with high precision and more accurately, and the quality and homogeneity of the molded product can be improved dramatically.

[0019] (2) There is no need to attach a position detector or a position sensor, which is an accessory part (special part) of the die D, to the die D itself or in its vicinity, so the low cost and maintainability can be improved. Moreover, there is no need for a control system that requires high control precision, and there is no need for a processing function such as temperature correction processing of the detection data, so cost reduction for die control including simplification of the control system can be achieved.

[0020] (3) According to a preferred method, as long as the mold gap Lg is set during each injection in the molding cycle, the deviation of the mold gap Lg generated between injections can be avoided. Therefore, from the perspective of ensuring molding quality and homogeneity, it can be implemented as the most preferred method.

[0021] (4) According to a preferred method, if the molding material R is a thermosetting resin material, even when the mold temperature is set to about 160°C to 180°C, the mold gap Lg can be set with high precision without being affected by the metal expansion of the mold D. Therefore, it can be provided as the best injection molding method (injection molding machine M) for molded products using thermosetting resin materials such as phenolic resin.

[0022] (5) According to a preferred method, when implementing the injection molding method, as long as after the injection filling process (S13) of the molding material R into the mold D, the movable mold Dm is pressurized by the compression control function unit Fp to perform the compression process (S15, S16, S17), the accurate injection filling amount of the molding material R can be compressed. Therefore, from the perspective of performing high-quality and highly homogeneous compression molding, it can also be provided as the best injection molding method.

[0023] (6) According to a preferred method, as long as the mold clamping device Mc is configured to have: a movable disk 5, which is supported by the tie rod mechanism part 4 to be movable forward and backward, and the movable disk 5 supports the movable mold Dm; a mold clamping disk 7, which is supported by the tie rod mechanism part 4 to be movable forward and backward, and the mold clamping disk 7 is internally provided with a mold clamping drive mechanism part 6, and the mold clamping drive mechanism part 6 performs the mold clamping of the movable mold Dm; and a clamping mechanism part 8, which is integrally provided on the mold clamping disk 7 and can fix the mold clamping disk 7 at a specified position of the tie rod mechanism part 4, the injection molding method of the present invention can be easily and reliably implemented, and the ease of implementation and the reliability of implementation can be ensured.

[0024] (7) According to a preferred method, as long as the mold gap setting control function unit Fg uses the encoder E2 that detects the stroke amount Lgs of the backward movement of the movable mold Dm, the mold gap Lg can always be set from the accurate zero point Po. Therefore, even for the encoder E2, the mold gap Lg with high precision can be easily and low-costly set. Brief Description of the Drawings

[0025] Figure 1 is a flowchart for explaining the processing procedure of the injection molding method according to the preferred embodiment of the present invention.

[0026] Figure 2 is a structural diagram of the injection molding machine used to implement this injection molding method.

[0027] Figure 3 It is a specific circuit diagram shown by extracting the main part of the injection molding machine.

[0028] Figure 4 It is of the clamping mechanism part of the single-dot dash circle A part Figure 3 in the clamping die device of the injection molding machine, and it is an enlarged cross-sectional view.

[0029] Figure 5 It is a setting screen diagram showing a part of the display of the molding machine controller of the injection molding machine.

[0030] Figure 6 It is a schematic structural diagram showing the state of the injection molding machine.

[0031] Figure 7 It is a schematic structural diagram showing other states of the injection molding machine.

[0032] Figure 8 It is a schematic structural diagram showing other states of the injection molding machine.

[0033] Figure 9 It is a schematic structural diagram showing other states of the injection molding machine.

[0034] Figure 10 It is a schematic structural diagram showing other states of the injection molding machine.

[0035] Figure 11 It is a schematic structural diagram showing other states of the injection molding machine.

[0036] Reference numeral description

[0037] 2: Molding machine controller; 4: Tie rod mechanism part; 5: Movable platen; 6: Clamping die drive mechanism part; 7: Clamping die platen; 8: Clamping mechanism part; (S12~S14): Injection filling process; (S15~S17): Compression process; M: Injection molding machine; Mc: Clamping die device; Mi: Injection device; D: Mold; Dm: Movable mold; Dc: Fixed mold; Lg: Mold gap; Lgs: Stroke amount; Xo: Mold opening position; Xz: Mold closing position; R: Molding material; Po: Zero point; E2: Encoder; Fs: Zero point setting control function part; Fg: Mold gap setting control function part; Fi: Injection filling control function part; Fp: Compression control function part. Detailed implementation mode

[0038] Next, preferred implementation modes of the present invention will be given and described in detail based on the drawings.

[0039] First, with reference to Figures 2 to 4 the structure of the injection molding machine M capable of implementing the injection molding method of this implementation mode will be described.

[0040] In Figure 2 this, reference numeral M is an injection molding machine, which has an injection device Mi and a mold clamping device Mc disposed on the upper surface of the machine base Mb.

[0041] The injection device Mi is disposed on the machine base Mb so as to be movable forward and backward. The injection device Mi has a heating cylinder 11, which has an injection nozzle 11n at the front end and a hopper 11h at the rear end. A screw 12 is inserted inside the heating cylinder 11, and a screw driving portion 13 is disposed at the rear end of the heating cylinder 11. The screw driving portion 13 includes an injection cylinder 14 having a single-rod type injection plunger 15 built therein. A plunger rod 15r protruding forward of the injection plunger 15 is coupled to the rear end of the screw 12. Further, the rear end of the injection plunger 15 is spline-coupled to the shaft of a screw rotation motor (oil motor) 16 mounted on the injection cylinder 14. Reference numeral 17 denotes an injection device moving cylinder, which moves the injection device Mi forward and backward to contact or disengage from the nozzle of the mold D.

[0042] The mold clamping device Mc has, as a basic structure: a movable platen 5, which is supported by a tie bar mechanism portion 4 so as to be movable forward and backward, and the movable platen 5 supports a movable mold Dm; a mold clamping platen 7, which is supported by the tie bar mechanism portion 4 so as to be movable forward and backward, and the mold clamping platen 7 has a mold clamping drive mechanism portion 6 built therein, and the mold clamping drive mechanism portion 6 clamps the movable mold Dm; and a clamping mechanism portion 8, which is integrally provided on the mold clamping platen 7, and the clamping mechanism portion 8 can fix the mold clamping platen 7 at a prescribed position of the tie bar mechanism portion 4.

[0043] More specifically, as shown in Figure 2 and Figure 3 there are a first fixed platen 21 and a second fixed platen 22 separately fixed on the upper surface of the machine base Mb. Four parallel link rods 4m... are respectively erected at the four corners between the first fixed platen 21 and the second fixed platen 22. Moreover, the movable platen 5 and the mold clamping platen 7 are supported by the respective link rods 4m... so as to be slidably displaceable. Thus, the fixed mold Dc is supported by the front fixed platen 21, and 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.

[0044] And, as shown in Figure 3As shown, a mold clamping drive mechanism portion 6 is built into the mold clamping disk 7. The mold clamping drive mechanism portion 6 is composed of a single-rod type mold clamping cylinder 6c, and the front end of the mold clamping plunger 6cr protruding forward is fixed to the back surface of the movable disk 5. In this way, as long as the mold clamping cylinder 6c is used in the mold clamping drive mechanism portion 6, the hydraulic circuit 3 described later including the mold clamping cylinder 6c can be utilized, so that the impact buffering property of the molding material R during injection filling can be utilized to improve the molding quality. In addition, reference numerals 23 and 23 denote a pair of left and right single-rod type mold opening and closing cylinders installed between the rear fixed disk 22 and the movable disk 5.

[0045] Moreover, a clamping mechanism portion 8 is disposed on the back surface of the mold clamping disk 7 (the side of the second fixed disk 22). The clamping mechanism portion 8 is composed of four clamping portions 8m... corresponding to the respective link rods 4m.... In this case, as Figure 4 shown, an annular groove portion 25s is formed on the outer peripheral surface of one link rod 4m (the same applies to the other link rods 4m...), and the groove portions 25s... are provided at regular intervals along the axial direction.

[0046] One clamping portion 8m (the same applies to the other clamping portions 8m...) has clamping half bodies (split nuts) 8mu and 8md that are divided into upper and lower parts, and is configured to be fixed by clamping the link rod 4m with the clamping half bodies 8mu and 8md. In the illustrated case, as Figure 4 shown, an engaging portion 7r having a guide mechanism is provided on the back surface of the mold clamping disk 7, and the clamping half bodies 8mu and 8md are engaged with the engaging portion 7r so as to be liftable and lowerable, and the clamping half bodies 8mu and 8md are configured to be displaceable in opposite directions to each other by means of a link mechanism. Further, the clamping cylinder 24 is coupled to one of the clamping half bodies 8mu to configure the clamping half bodies 8mu and 8md to be liftable and displaceable, and annular protrusion portions 25p... that are engaged with the groove portions 25s... provided on the outer peripheral surface of the link rod 4m are formed on the inner peripheral surfaces of the clamping half bodies 8mu and 8md, and annular groove portions 25q... that are engaged with the protrusion portions 25t... provided on the outer peripheral surface of the link rod 4m are formed.

[0047] Thus, in Figure 4In [the figure], if the piston plunger of the clamping cylinder 24 protrudes, it displaces to the positions of the clamping semi-body parts 8mu and 8md shown in the solid line section, i.e., the clamping position Xs. Thus, the rib part 25t... and the groove part 25q... are engaged to fix the mold clamping disk 7. And if the piston plunger of the clamping cylinder 24 retracts, it displaces to the positions of the clamping semi-body parts 8mu and 8md shown by the phantom line, i.e., the clamping release position Xr. Thus, the rib part 25t... and the groove part 25q... are separated, thereby allowing the mold clamping disk 7 to move axially. Additionally, the structure of the illustrated clamping part 8m is an example. For example, there are four clamping parts 8m..., so the inner peripheral surface of the clamping semi-body part 8md... can be made flat, and the rib part 25p... is provided only on the inner peripheral surface of the clamping semi-body part 8mu.... Basically, it can be replaced with various known mechanisms having the same function.

[0048] Thus, as the mold clamping device Mc, as long as it is configured to have: a movable disk 5, which is supported by the tie rod mechanism part 4 to be movable forward and backward, and this movable disk 5 supports the movable mold Dm; a mold clamping disk 7, which is supported by the tie rod mechanism part 4 to be movable forward and backward, and this mold clamping disk 7 is internally provided with a mold clamping drive mechanism part 6 (mold clamping cylinder 6c), and this mold clamping drive mechanism part 6 (mold clamping cylinder 6c) performs the mold clamping of the movable mold Dm; and a clamping mechanism part 8, which is integrally provided on this mold clamping disk 7 and can fix this mold clamping disk 7 at a specified position of the tie rod mechanism part 4, the injection molding method of the present invention and the like can be easily and reliably implemented, and the ease of implementation and the reliability of implementation can be ensured.

[0049] On the other hand, reference numeral 3 is a hydraulic circuit, which, as the main part, has a variable ejection type hydraulic pump 3p as the hydraulic drive source and a valve circuit 32 for performing various switching and controls. And according to the present invention, it has an outlet throttling circuit 9 connected to the mold clamping cylinder 6c. Thus, as long as the injection device Mi and the mold clamping device Mc are driven by the hydraulic circuit 3 including the hydraulic pump 3p, the shock absorption property based on hydraulics can be utilized. Therefore, the injection molding method of the present invention can be implemented in an optimal manner. And in particular, it can buffer the impact on the molding material R during injection filling, which helps to improve the molding quality.

[0050] As Figure 3As shown, the hydraulic pump 3p has a pump section 35 and a servo motor 36 that rotationally drives the pump section 35. Additionally, reference numeral 37 denotes a rotary encoder that detects the rotational speed of the servo motor 36. The pump section 35 incorporates a pump body 38 composed of an inclined plate type piston pump. Thus, the pump section 35 has an inclined plate 42. If the inclination angle (swash plate angle) of the inclined plate 42 is increased, the stroke of the pump pistons of the pump body 38 becomes larger, and the discharge flow rate increases. And if the swash plate angle is decreased, the stroke of the pump pistons becomes smaller, and the discharge flow rate decreases. As a result, as long as the swash plate angle is set to a prescribed angle, a fixed discharge flow rate can be set in which the discharge flow rate (maximum capacity) is fixed to a prescribed magnitude. The inclined plate 42 is provided with a control cylinder 43 and a return spring 44, and the control cylinder 43 is connected to the discharge port of the pump section 35 (pump body 38) via a switching valve (solenoid valve) 45. Thereby, the angle (swash plate angle) of the inclined plate 42 can be changed by controlling the control cylinder 43.

[0051] Moreover, the suction port of the pump section 35 is connected to the 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 not only to the aforementioned injection cylinder 14, screw rotation motor 16, injection device moving cylinder 17, clamping cylinder 6c, mold opening / closing cylinder 23..., clamping cylinder 24... etc., but also to other various actuators such as an ejector cylinder (not shown). Therefore, the valve circuit 32 has switching valves (solenoid valves) respectively connected to these respective actuators. Additionally, each switching valve is composed of one or two or more valve components and necessary auxiliary hydraulic components etc., and has at least a switching function related to the supply, stop, and discharge of the working oil for the aforementioned injection cylinder 14, screw rotation motor 16, injection device moving cylinder 17, clamping cylinder 6c, mold opening / closing cylinder 23..., clamping cylinder 24... and other various actuators such as an ejector cylinder (not shown). Thereby, as long as the rotational speed of the servo motor 36 is variably controlled, the discharge flow rate and discharge pressure of the variable discharge type hydraulic pump 3p can be made variable.

[0052] And, as Figure 3 shown, the working oil pipeline 48 connected to the oil chamber (rear oil chamber) 6m of the clamping cylinder 6c is connected to the inflow side of the outlet throttle circuit 9, and the outflow side of the outlet throttle circuit 9 is connected to the oil tank 39. The outlet throttle circuit 9 has check valves 51, 52, a direction control valve (solenoid valve) 53, and an overflow valve (back pressure control valve) 54, and is configured by being connected as Figure 3 shown.

[0053] Thus, in the case of this embodiment, in the injection filling process, the mold clamping device Mc can be controlled only by the back pressure control using the outlet throttle circuit 9. That is, by the function of the outlet throttle circuit 9, when the pressure of the molding material R in the mold D is less than the set back pressure Pb [kN], it is maintained at this pressure, and when it exceeds the back pressure Pb [kN], it is maintained at the back pressure Pb [kN] by the function of the overflow valve 54.

[0054] In this way, if it is configured to be provided with the outlet throttle circuit 9 connected to the mold clamping cylinder 6c, the outlet throttle circuit 9 can be realized only by adding a relatively simple hydraulic circuit 3. Therefore, it has the advantages of being able to be easily and low-costly implemented and being able to easily and reliably perform back pressure control. And, the injection device Mi and the mold clamping device Mc can be driven by the shared hydraulic pump 3p. That is, the mold clamping device Mc during injection filling can be implemented only by back pressure control, and the driving force of the hydraulic pump is not required. Therefore, the hydraulic pump on the mold clamping device Mc side of the two hydraulic pumps required on the injection device Mi side and the mold clamping device Mc side during original injection filling is not required, which can contribute to a significant reduction in cost.

[0055] On the other hand, reference numeral 2 denotes a molding machine controller. The molding machine controller 2 includes a controller main body 61 and a display 62. The aforementioned servo motor 36 is connected to the servo amplifier output port of the controller main body 61, and the valve circuit 32 is connected to the control signal output port of the controller main body 61. On the other hand, the encoder pulse obtained from the rotary encoder 37 is connected to the servo amplifier of the controller main body 61. In addition, reference numeral 55 is a pressure sensor for detecting 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 61 of the molding machine controller 2.

[0056] The controller main body 61 has a computer function with hardware such as a built-in CPU and internal memory. Therefore, the internal memory stores a control program (software) for executing various control processes (sequential control), and includes a data memory for storing various data (database) types.

[0057] Therefore, the controller main body 61 has at least a basic control function unit for implementing the injection molding method of the present embodiment by controlling the execution of a control program. The basic control function unit has at least a zero point setting control function unit Fs, a mold gap setting control function unit Fg, and an injection filling control function unit Fi. Moreover, as a more preferable specific control function unit, the controller main body 61 has a compression control function unit Fp. In this case, the zero point setting control function unit Fs has the following functions: by using the mold clamping device Mc to move the movable mold Dm located at the open mold position Xo forward to the closed mold position Xz and setting the closed mold position Xz as the zero point Po, and the mold gap setting control function unit Fg has the following functions: by moving the movable mold Dm backward from the zero point Po detected by the zero point setting control function unit Fs by a stroke amount Lgs corresponding to the mold gap Lg to be set and setting the mold gap Lg. And the injection filling control function unit Fi has the function of injecting and filling the molding material R into the mold D with the mold gap Lg set, and the compression control function unit Fp has the function of pressurizing the movable mold Dm after the injection filling process of the injection filling control function unit Fi to perform a compression process.

[0058] On the other hand, as Figure 2 shown, a mold clamping disk position detection encoder (position sensor) E1 is provided on the upper surface of the machine base Mb. The encoder E1 is used to detect the position (moving position) of the mold clamping disk 7 in the front-rear direction, and the detected position data of the mold clamping disk 7 is provided to the controller main body 61. And a movable disk position detection encoder (position sensor) E2 is provided on the outer surface of the mold clamping disk 7. The encoder E2 is used to detect the position (moving position) of the movable disk 5 in the front-rear direction, and the detected position data of the movable disk 5 is provided to the controller main body 61. Therefore, the mold gap setting control function unit Fg for detecting the stroke amount Lgs of the backward movement of the movable mold Dm uses this encoder E2 (E1).

[0059] Moreover, the display 62 can perform various displays and is attached with a touch panel, and various setting operations and selection operations, etc. can be performed using this touch panel. In Figure 5Shown is a setting screen used in the injection molding method of this embodiment, particularly the state of the mold opening / closing screen Vm. On this mold opening / closing screen Vm, a "compression" switch 63 is provided. Therefore, by turning on this "compression" switch 63, the setting screen Vs used in the injection molding method of this embodiment can be displayed in a window. On this setting screen Vs, there are 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 clamping back pressure setting unit 65c for setting the clamping holding pressure (back pressure) [kN] during injection, a filling incomplete time setting unit 65d for setting the filling incomplete time Ts [seconds] when not transferred to the standby position, a compression start time setting unit 65e for setting the compression start time Ti [seconds], a first clamping pressure setting unit 65f for setting the compression pressure [kN] for the first clamping, a second clamping pressure setting unit 65g for setting the compression pressure [kN] for the second clamping, and a switching time setting unit 65h for setting the switching time [s] for switching to the second clamping. In addition, reference numeral 66 indicates the "close" key of the setting screen Vs.

[0060] Next, mainly with reference to Figures 6 to 11 in accordance with Figure 1 the flowchart shown, the injection molding method of this embodiment using the injection molding machine M will be described in sequence.

[0061] When implementing the injection molding method of this embodiment, first, setting processing is performed (step S1). In this setting processing, various normal molding conditions are set, and using Figure 5 the setting screen Vs shown, the above various items related to the injection molding method of this embodiment are set.

[0062] Currently, the movable mold Dm (clamping platen 7) of the clamping device Mc is located at Figure 6 the mold opening position Xo shown (step S2). This mold opening position Xo is the position obtained as follows: the clamping cylinder 24... is driven and controlled to switch the clamping portion 8m... to the clamping release position Xr, and the clamping cylinder 6c is driven and controlled to move the movable platen 5 to the retracted position (towards the second fixed platen 22), and the mold opening / closing cylinder 23... is driven and controlled to move the movable platen 5 and the clamping platen 7 backward. In addition, the positions of the clamping platen 7 and the movable platen 5 are detected by the clamping platen position detection encoder E1 and the movable platen position detection encoder E2.

[0063] During production, the mold opening / closing cylinder 23... is driven and controlled to move the movable platen 5 and the clamping platen 7 from the mold opening position Xo to move forward at high speed to Figure 7The clamping position Xc shown (step S3). Then, after reaching the clamping position Xc, drive control is performed on the clamping cylinder 24... to switch the clamping portion 8m... to the clamping position Xs and fix the mold clamping disk 7 to the connecting rod 4m... (step S4). Additionally, in Figure 7 the symbol La represents the moving stroke of the mold clamping disk 7 from the mold opening position Xo to the clamping position Xc.

[0064] Next, Figure 2 the zero-point setting control function unit Fs shown drives and controls the mold clamping cylinder 6c to move the movable platen 5 forward as shown in Figure 8 This forward movement is performed until the movable mold Dm reaches the mold closing position Xz (step S5). That is, the movable mold Dm is moved forward to a position where it abuts against the fixed mold Dc. Then, after the movable mold Dm reaches the mold closing position Xz, the movement of the movable mold Dm is stopped (steps S6, S7). Thus, this mold closing position Xz is set as the zero point Po (step S8). Additionally, in Figure 8 the symbol Lz represents the moving stroke of the movable mold Dm from the above-mentioned clamping position Xc to the mold closing position Xz.

[0065] After that, Figure 2 the mold clearance setting control function unit Fg shown drives and controls the mold clamping cylinder 6c to move the movable platen 5 backward as shown in Figure 9 Regarding this backward movement, the movable mold Dm is moved backward from the zero point Po (mold closing position Xz) by a stroke amount Lgs corresponding to the mold clearance Lg to be set. That is, it is moved backward from the mold closing position Xz to a preset standby position Xw (step S9). Then, after the movable mold Dm reaches the standby position Xw, the backward movement of the movable mold Dm is stopped (steps S10, S11). Thus, the accurate mold clearance Lg is set. Additionally, the backward movement amount of the stroke amount Lgs of this backward movement is detected by the movable platen position detection encoder (position sensor) E2. In this way, as long as the mold clearance setting control function unit Fg uses the encoder E2 that detects the stroke amount Lgs for moving the movable mold Dm backward, the mold clearance Lg can always be set from the accurate zero point Po, so even for the encoder E2, it is possible to easily and at low cost set a highly accurate mold clearance Lg.

[0066] As a result, the preparation for the start of injection on the mold clamping device Mc side is completed, so the direction control valve 53 of the outlet throttle circuit 9 is switched to the outlet throttle on side (step S12).

[0067] On the other hand, in the injection device Mi, the screw 12 is rotated by the drive control of the screw rotation motor 16, and the molding material R supplied to the hopper 11h is accumulated in front of the screw 12. Therefore, the molding machine controller 2 moves the injection device Mi forward by the drive control of the injection device moving cylinder 17 to Figure 9 the nozzle contact position shown. Thus, the preparation for the start of injection on the injection device Mi side is completed. Therefore, Figure 2 the injection filling control function unit Fi shown causes the screw 12 to move forward Figure 10 by the stroke Lr shown, thereby performing an injection filling process of injecting and filling the molding material R into the mold D with the mold gap Lg set (step S13).

[0068] In this case, since the injection starts, the screw 12 moves forward, and the molding material R is filled into the cavity of the mold D via the injection nozzle 11n, that is, the mold gap Lg between the movable mold Dm and the fixed mold Dc. In addition, immediately before the start of injection, there is a mold gap Lg between the movable mold Dm and the fixed mold Dc, the injection pressure is in a state of 0, and the clamping force is also in a state of 0. Therefore, the pressure difference before and after the movable disk 5 is 0 and in a balanced state, and the movable disk 5 is in a stopped state.

[0069] In addition, the molding material R of the embodiment uses a thermosetting resin material. In the molding of thermosetting resin materials, the heating temperature of the mold D is usually set to about 160°C to 180°C. However, even with such a mold temperature setting, by the above-mentioned setting method for the mold gap Lg, the mold gap Lg can be set with high precision without being affected by the metal expansion of the mold D. Therefore, the present invention can be provided as an optimal injection molding method (injection molding machine M) for molded products using thermosetting resin materials such as phenolic resin.

[0070] In the case of thermosetting resin materials, the molding material R is a molding material with relatively low fluidity. However, since the initial clamping force is in a state of 0, the molding material R can be injected and filled into the cavity of the mold D relatively smoothly. As the injection filling process proceeds, the pressure of the molding material R in the mold D rises, and the clamping disk 7 is fixed in position due to the clamping position Xs of the clamping portion 8m..., so the movable disk 5 gradually moves backward. At this time, by the function of the outlet throttle circuit 9, the set back pressure Pb [kN] is maintained.

[0071] Then, after the movable disk 5 reaches Figure 10 the set compression start position Xp shown, an end process for ending the injection filling process is performed. At this time, the screw 12 advances to a position near the most forward position. At Figure 10In this case, the label Pb represents the back pressure [kN] applied to the clamping plunger 6cr. Therefore, in this case, the movable disk 5 reaching the compression start position Xp becomes the injection end condition.

[0072] After that, after the compression start time Ti [seconds] set by the compression start time setting unit 65e arrives, the compression process of pressurizing the molding material R in the mold D using the movable mold Dm is started (step S14, step S15). In this case, the compression start time also includes "0". During the compression process, Figure 2 As shown, the compression control function unit Fp switches the outlet throttle circuit 9 to the off state and drives and controls the clamping cylinder 6c, whereby Figure 11 As shown, the movable disk 5 is pressurized forward (toward the first fixed disk 21 side) by a specified pressing force Pp. In Figure 11 this case, the label Lp represents the compression amount by which the clamping plunger 6cr is displaced due to the pressing force Pp.

[0073] As Figure 5 shown, the exemplified compression process is set by the first clamping pressure [kN] and the second clamping pressure [kN]. Therefore, during the compression process, the first compression process based on the first clamping pressure is first performed (step S16). Then, after reaching the switching time [seconds], it is switched to the second clamping pressure (step S17). As an embodiment, as long as such a compression process is performed, the accurate injection filling amount of the molding material R can be compressed, and thus it can be provided as an optimal injection molding method capable of performing high-quality and highly homogeneous compression molding.

[0074] After that, if the compression process is completed, the mold is opened and the ejection process of the molded product is performed (step S18). Then, in the case of continuing the next production, the same molding process is performed (step S19, step S2...).

[0075] In this way, in the injection molding method of the present embodiment, the above setting of the mold gap Lg is performed at each injection in the molding cycle. Thereby, the deviation of the mold gap Lg generated between injections can be avoided, and thus it can be implemented as the most preferred method from the viewpoint of ensuring molding quality and homogeneity.

[0076] Thus, according to such an injection molding method (injection molding machine M) of the present embodiment, as a basic method, the movable mold Dm located at the mold opening position Xo is advanced and moved to the mold closing position Xz by using the mold clamping device Mc, and the mold closing position Xz is set as the zero point Po. Then, the movable mold Dm is retracted from this zero point Po by a stroke amount Lgs corresponding to the mold gap Lg to be set, and the mold gap Lg is set. After that, an injection filling process of injecting and filling the molding material R into the mold D with the mold gap Lg set is performed. Therefore, even when injecting and filling the mold D in a state where a minute mold gap Lg is provided, the mold gap Lg can be set more accurately with high precision, and the quality and homogeneity of the molded product can be improved dramatically. Moreover, there is no need to attach a position detector or a position sensor, which is an accessory part (special part) of the mold D, to the mold D itself or its vicinity. Therefore, it is advantageous in terms of cost and maintenance. Furthermore, there is no need for a control system that requires high control precision, and there is no need for a processing function such as temperature correction processing of the detection data. Therefore, cost reduction for controlling the mold D including simplification of the control system can be achieved.

[0077] As described above, the preferred embodiments have been described in detail, but the present invention is not limited to such embodiments, and can be arbitrarily changed, added, or deleted in terms of the structure, shape, raw material, quantity, numerical value, etc. of the detailed part without departing from the gist of the present invention.

[0078] For example, regarding the setting of the die gap Lg, it is preferably carried out at each injection during the molding cycle. For example, in the illustrated embodiment, the detection of the zero point Po is shown and the detected zero point Po is directly used to set the die gap Lg, but the case of registering the detected zero point Po and using it for the next injection or multiple subsequent injections is not excluded. Also, regarding the molding material R, it is optimal to apply a thermosetting resin material. The type of the thermosetting resin material is not limited, and the application of other molding materials such as thermoplastic resin materials is not excluded. In addition, the case of using a hydraulic drive method as the drive method of the injection molding machine is illustrated, but other drive methods such as an electric drive method can also be implemented in the same manner. On the other hand, an example of performing a compression process of pressurizing the movable die D after the injection filling process of the molding material R into the die D is shown, but injection molding of other molding methods is not excluded. For example, the case of cooling by natural compression without performing a forced compression process is excluded. On the other hand, as the mold clamping device Mc, a mold clamping device having the following configuration is shown: a movable platen 5, which is supported by a tie bar mechanism portion 4 so as to be movable forward and backward, and the movable platen 5 supports the movable die Dm; a clamping platen 7, which is supported by the tie bar mechanism portion 4 so as to be movable forward and backward, and a mold clamping drive mechanism portion 6 is built in the clamping platen 7, and the mold clamping drive mechanism portion 6 performs the mold clamping of the movable die Dm; and a clamping mechanism portion 8, which is integrally provided on the clamping platen 7 and can fix the clamping platen 7 at a specified position of the tie bar mechanism portion 4, but the use of other mold clamping devices Mc that can be implemented in the same manner is not excluded. Also, the case where the die gap setting control function portion Fg uses an encoder E2 is shown, but various other position sensors capable of detecting positions can also be used.

[0079] Industrial applicability

[0080] The injection molding method and injection molding machine of the present invention can be used as various injection molding machines that fluidize various molding materials and inject and fill them into a mold for molding, and injection molding methods used in injection molding machines.

Claims

1. An injection molding method, which performs molding by injecting and filling a molding material into a mold in which a predetermined mold gap is provided between a movable mold and a fixed mold by means of a mold clamping device, characterized in that the mold clamping device is used to move the movable mold located at the mold opening position forward to the mold closing position, and this mold closing position is set as the zero point. The mold gap is set by moving the movable mold backward from this zero point by a stroke amount corresponding to the mold gap to be set. After that, an injection filling process of injecting and filling the molding material into the mold with the set mold gap is performed.

2. The injection molding method according to claim 1, characterized in that the setting of the mold gap is performed at each injection in the molding cycle.

3. The injection molding method according to claim 1, characterized in that the molding material is a thermosetting resin material.

4. The injection molding method according to claim 1, characterized in that after the injection filling process of the molding material into the mold, a compression process of pressurizing the movable mold is performed.

5. An injection molding machine, which has a molding machine controller that performs the following control: injecting and filling a molding material into a mold in which a predetermined mold gap is provided between a movable mold and a fixed mold by means of a mold clamping device, characterized in that the molding machine controller has: a zero point setting control function unit that sets the mold closing position as the zero point by using the mold clamping device to move the movable mold located at the mold opening position forward to the mold closing position; a mold gap setting control function unit that sets the mold gap by moving the movable mold backward from this zero point by a stroke amount corresponding to the mold gap to be set; and an injection filling control function unit that injects and fills the molding material into the mold with the set mold gap.

6. The injection molding machine according to claim 5, characterized in that the mold clamping device has: a movable platen that is supported by a tie rod mechanism part so as to be able to advance and retreat, and this movable platen supports the movable mold; a mold clamping platen that is supported by the tie rod mechanism part so as to be able to advance and retreat, and this mold clamping platen is internally provided with a mold clamping drive mechanism part that performs the mold clamping of the movable mold; and a clamping mechanism part that is integrally provided on this mold clamping platen and can fix the mold clamping platen at a predetermined position of the tie rod mechanism part.

7. The injection molding machine according to claim 5, characterized in that the mold gap setting function unit has an encoder that detects the backward movement amount of the stroke amount of the backward movement of the movable mold.

8. The injection molding machine according to claim 5, characterized in that the molding machine controller has a compression control function unit that pressurizes the movable mold after the injection filling process of the injection filling control function unit to perform a compression process.

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