JP2013128953A - Injection molding method, and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method which can easily control injection molding capable of obtaining a satisfactory molded body, and an apparatus therefor.SOLUTION: The change in the inertia of an injection molding apparatus 10 during injection filling is measured. In this way, the power actually applied to molten metal during the injection filling can be grasped. Thus, injection molding conditions are corrected on the basis of the measured inertia to obtain a satisfactory molded body. For example, injection molding conditions are corrected in such a manner that the maximum measured value of the inertia in the injection molding apparatus 10 during the injection filling is controlled to the maximum pressing force command value or less to the molten metal in the cavity of a die 60. In this way, the opening of the die 60 during the injection filling of the molten metal can be prevented. Thus, the generation of burrs in the molded body is eliminated to obtain a satisfactory molded body.

Description

  The present invention relates to an injection molding method and apparatus for injecting and filling a molten metal into a cavity of a mold by hydraulic pressure and press-molding the molten metal in the cavity.

  For example, Patent Document 1 describes an injection molding method of an injection molding apparatus including a ball screw device and a hydraulic device. In this injection molding method, a ball screw device is driven to inject and fill a molten metal into a cavity of a mold, and a hydraulic device is driven to press the ball screw device to press-mold the molten metal in the cavity. The switching from the molten metal filling operation to the pressurizing operation is commanded when the load applied to the ball screw device detected by the load cell matches the preset maximum load applied to the ball screw device. As a result, the hydraulic device can perform only the pressurizing operation regardless of variations in the amount of hot water supply of the molten metal, and a stable boosting characteristic can be obtained.

  Patent Document 2 describes an apparatus for measuring the pressure in a cavity of a mold of an injection molding apparatus using a load cell provided on the mold. According to this apparatus, the pressure applied to the molten metal in the cavity can be measured with good reproducibility, and the durability of the injection molding apparatus can be improved.

JP-A-7-204823 JP 2010-42446 A

  In the method described in Patent Document 1 described above, injection filling of molten metal into the cavity is performed by a ball screw device, and pressure molding of the molten metal in the cavity is performed by a hydraulic device. For this reason, the injection filling force of the ball screw device remains applied during pressure molding by the hydraulic device. Therefore, there is a possibility that the mold is slightly opened due to the injection filling force of the ball screw device and so-called burr blowing occurs. On the other hand, in the apparatus described in Patent Document 1, since the pressure applied to the molten metal in the cavity can be measured, it is possible to suppress the occurrence of the above-described burr blowing. However, it is necessary to set the location of the load cell for each of a very wide variety of molds, which is troublesome and expensive, and it is difficult to control injection molding in order to obtain a good molded product. In addition, when the molded body has a complicated shape, there is a case where an accurate pressure in the cavity cannot be measured. In this case, there is a possibility that the above-described burr blowing or so-called sink is generated.

  This invention is made | formed in view of such a situation, and it aims at providing the injection molding method and its apparatus which can control easily the injection molding which can obtain a favorable molded object.

(Injection molding method)
(Claim 1) The injection molding method of the present invention uses a hydraulically operated injection device to inject and fill a molten metal into a cavity of a mold, and press-mold the molten metal injected and filled into the cavity. An injection molding method comprising: a measurement step of measuring a change in inertia of the injection device during injection filling; and a correction step of correcting injection molding conditions based on the measured inertia.

  (Claim 2) In the correction step, the injection molding condition is corrected so that the measured maximum value of the inertia of the injection device does not exceed the maximum pressure applied to the molten metal in the commanded cavity. Good.

  (Claim 3) In the correction step, the injection molding condition may be corrected so that the measured maximum value of the inertia of the injection device does not exceed the commanded maximum value of the inertia of the injection device.

  (Claim 4) Moreover, the said correction process is good to correct | amend the deceleration speed of the commanded deceleration area in the pattern of the injection filling speed of the said injection device as said injection molding conditions.

  (Claim 5) Further, in the correction step, the maximum measured value of the inertia of the injection device does not exceed the maximum pressure command value for the molten metal or the maximum command value of the inertia by correcting the deceleration speed. When this is not possible, the deceleration start position in the deceleration area commanded as the injection molding condition may be corrected.

  (Claim 6) Further, the correction step is based on the difference between the measured maximum and minimum values of the inertia of the injection device, and the control range of the injection filling speed of the commanded injection device and the inside of the cavity. It is preferable to correct the boundary position with the control range of the applied pressure to the molten metal.

(Injection molding equipment)
(7) An injection molding apparatus according to the present invention uses a hydraulically operated injection device to inject and fill a molten metal into a cavity of a mold, and press-mold the molten metal injected and filled into the cavity. An inertia measuring device that measures a change in inertia of the injection device during injection filling, and a correction device that corrects injection molding conditions based on the inertia measured by the inertia measuring device. Prepare.

  (8) The inertia measuring device may be provided on a connecting member that connects a first rod that receives the hydraulic pressure in the injection device and a second rod that injects and pressurizes the molten metal. .

  According to the present invention, the change in the inertia of the injection device during injection filling is measured. Thereby, the force actually applied to the molten metal during injection filling can be grasped. Therefore, a good molded article can be obtained by correcting the injection molding conditions based on the measured inertia.

  (Claim 2) The injection molding conditions are corrected so that the maximum measured value of the inertia of the injection apparatus during injection filling is equal to or less than the maximum pressure command value for the molten metal in the cavity. Thereby, the opening of the mold during the injection filling of the molten metal can be prevented. Therefore, generation | occurrence | production of the burr | flash in a molded object is eliminated and a favorable molded object can be obtained.

  (Claim 3) The injection molding conditions are corrected so that the maximum measured value of the inertia of the injection device during injection filling is equal to or less than the maximum command value of the inertia. Thus, it is effective when it is desired to obtain a compact having a uniform density while allowing a slight amount of burrs to be generated.

  (Claim 4) In general, the injection filling speed of the injection apparatus is constituted by a three-phase pattern of a low speed region, a high speed region, and a deceleration region. By correcting the deceleration command speed in the deceleration area in this pattern, it is possible to control the maximum measured value of the inertia of the injection device that occurs in the deceleration area after the high speed area.

  (Claim 5) When the maximum measured value of the inertia of the injection device cannot be exceeded by the correction of the deceleration command speed so as not to exceed the maximum pressure command value or the maximum command value of the inertia, the deceleration start command position in the deceleration region By correcting the above, it becomes possible to further control the maximum measured value of the inertia of the injection device generated in the deceleration region after the high speed region.

  (Claim 6) Based on the difference between the maximum measured value and the minimum measured value of the inertia of the injection device during injection filling, the control range of the injection filling speed of the injection device and the control range of the applied pressure to the molten metal in the cavity The boundary command position is corrected. Thereby, the density of the molten metal in a cavity can be made uniform, and the precision of a molded object can be improved.

  (Embodiment 7) According to the injection molding apparatus of the present invention, the same effects as in the above-described injection molding method can be obtained.

  (8) Since the inertia measuring device is provided in the connecting member that connects the first rod that receives the hydraulic pressure in the injection device and the second rod that injects and pressurizes the molten metal, it remains as it is even if the mold is replaced. Therefore, the cost can be reduced by a simple configuration. Further, it is possible to measure the pressure applied to the molten metal in the cavity, and it is possible to grasp the actual pressure instead of the apparent pressure applied by the conventional hydraulic pressure measurement, thereby improving the molding accuracy.

It is a figure which shows schematic structure of the injection molding apparatus which concerns on embodiment of this invention. It is an expanded sectional view of the coupling of the injection molding apparatus of FIG. It is a graph which shows injection molding conditions, and is a graph which shows the time-dependent change of the injection filling speed of an injection device, the applied pressure with respect to the molten metal in a cavity, and the inertia of an injection device. It is a flowchart for demonstrating correction | amendment of the time T3 of the high speed area | region of injection filling. It is a flowchart for demonstrating correction | amendment of the speed V2 of the high speed area of injection filling. It is a flowchart for demonstrating the 1st correction | amendment of the maximum value Ip of an inertia. It is a flowchart for demonstrating the 2nd correction | amendment of the maximum value Ip of an inertia. It is a flowchart for demonstrating correction | amendment of the minimum value Im of an inertia. It is a flowchart for demonstrating correction | amendment of time T1 until it becomes the minimum value Im from the maximum value Ip of an inertia. It is a flowchart for demonstrating correction | amendment of the applied pressure maximum value Mp with respect to the molten metal in a cavity. It is a flowchart for demonstrating correction | amendment of time T2 until it reaches near pressurization force maximum value Mp from minimum value Im of inertia. It is a graph which shows the relationship between the maximum value Ip of inertia, and the speed V3 of a deceleration area. It is a graph which shows the relationship between the speed V3 of a deceleration area | region, and the starting position P5 of a deceleration area | region.

(1. Machine configuration of injection molding equipment)
As an example of the injection molding apparatus 1, a die casting machine in which a molten metal is injected and filled in a cavity of a mold at high speed and high pressure by hydraulic pressure will be described as an example and described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the injection molding apparatus 1 is generally configured by a plunger 10, an accumulator 20, a manifold 30, a molten metal supply unit 40, a control device 50, and the like as an injection device.

  The plunger 10 is roughly constituted by a cylinder 11, a first rod 12, a second rod 13, and a coupling 14 as a connecting member. The cylinder 11 is formed in a hollow cylindrical shape and is connected to the manifold 30. The first rod 12 has columnar first pistons 12 a and 12 a fixed to both ends, and is inserted into the inner peripheral side of the cylinder 11 so as to be slidable in the axial direction. Columnar second pistons 13a, 13a having the same diameter as the first piston 12a are fixed to both ends of the second rod 13, and are slidable in the axial direction on the inner peripheral side of a cylinder 42 of a molten metal supply unit 40 described later. Inserted.

  As shown in FIG. 2, the coupling 14 includes a pair of hollow cylindrical connecting portions 14a and 14a. The connecting portion 14a is formed with a large-diameter columnar hollow portion 14b on one end side and a small-diameter columnar hollow portion 14c on the other end side. The hollow portion 14b is formed to have a slightly larger diameter than the diameters of the first and second pistons 12a and 13a. The hollow portion 14 c is formed to have a diameter slightly larger than the diameters of the first and second rods 12 and 13. The first rod 12 is inserted into the hollow portion 14c of the one connecting portion 14a, and the first piston 12a is inserted into the hollow portion 14b. The second rod 13 is inserted into the hollow portion 14c of the other connecting portion 14a, and the second piston 13a is inserted into the hollow portion 14b.

  The pair of connecting portions 14a, 14a are arranged so that the hollow portions 14b, 14b face each other so that the first rod 12 and the second rod 13 are coaxial, and are fastened and fixed by screws or the like not shown. Since the clearance is provided between the hollow portion 14b and the first and second pistons 12a and 13a and between the hollow portion 14c and the first and second rods 12 and 13, the first and second rods 12 are provided. , 13 can be automatically centered when sliding in the axial direction.

  Further, a columnar spacer 15 having the same diameter as that of the first and second pistons 12a and 13a is interposed between the first piston 12a and the second piston 13a. A load cell is provided on one end face side of the spacer 15 as an inertia measuring device for measuring a change in inertia of the first rod 12, the second rod 13, the coupling 14 and the like (hereinafter referred to as the plunger 10), which will be described in detail later. A hole 15a into which 16 is fitted is formed. The measurement convex portion 16a of the load cell 16 is in contact with the end surface of the second piston 13a, the bottom surface 16b of the load cell 16 is in contact with the bottom surface of the hole 15a of the spacer 15, and the other end surface of the spacer 15 is in contact with the first piston 12a. It is contact | abutted to the end surface.

  The accumulator 20 is connected to the manifold 30 and accumulates hydraulic pressure to be supplied to the plunger 10.

  The molten metal supply unit 40 includes a storage unit 41 in which the molten metal is stored, a cylinder 42 that communicates with the storage unit 41, and the like. The second rod 13 is inserted from one end side of the cylinder 42. The mold 60 is detachably mounted on the other end side of the cylinder 42 so as to communicate with the cavity of the mold 60.

  The control device 50 supplies the hydraulic pressure accumulated in the accumulator 20 to the plunger 10 via the manifold 30, and injects and fills the molten metal supplied from the molten metal supply unit 40 into the mold 60 and press-molds it. The control device 50 includes a correction device 51 having a memory (not shown) for correcting injection molding conditions based on the inertia of the plunger 10 measured by the load cell 16. The correction device 51 can be configured by hardware or can be realized by software.

(2. Injection control process by the controller)
Next, the injection control process by the control device 50 will be described with reference to the injection molding conditions in FIG. 3 shows the injection filling speed of the plunger 10 (indicated by the one-dot chain line in the figure) and the pressure applied to the molten metal in the cavity of the mold 60 when the stroke position (time) of the plunger 10 from the start of injection is taken on the horizontal axis. The change of the broken line in the figure is shown. The injection molding conditions include a speed control area AVC from the start of injection to the stroke position V / P of the plunger 10 where injection filling is completed, and a pressure control area APC after the stroke position V / P of the plunger 10. . The stroke position V / P of the plunger 10 is a boundary position between the speed control area AVC and the pressure control area APC.

  The injection filling speed of the plunger 10 (the one-dot chain line in the drawing) is a low speed range (low speed V1) where the stroke position of the plunger 10 is between P1 and P2, and a high speed range (high speed speed) where the stroke position of the plunger 10 is between P3 and P4. V2, time T3), and the stroke position of the plunger 10 is composed of a three-phase pattern in a deceleration region (deceleration speed V3) between P5 and V / P. The applied pressure (broken line in the figure) to the molten metal in the cavity of the mold 60 is configured in a pattern that reaches the applied pressure maximum value Mp after the stroke position V / P of the plunger 10.

  Here, the following is mentioned as a factor which generate | occur | produces a burr | flash on a molded object. That is, when the plunger 10 stops suddenly upon completion of the injection filling of the molten metal into the cavity of the mold 60, inertia (kinetic energy) is generated by the injection filling speed of the plunger 10 immediately before the stop and the own weight of the plunger 10, and the force It is considered that burrs are generated in the molded body. In order to suppress the occurrence of burr blowing, it is only necessary to reduce the inertia of the plunger 10 by reducing the injection filling speed immediately before stopping the plunger 10 by providing the above-described deceleration region. As apparent from FIG. 3, the change in the inertia of the plunger 10 cannot be monitored from the graph of the applied pressure (broken line in the figure) against the molten metal in the cavity of the mold 60. Therefore, in this injection molding apparatus 1, a load cell 16 for measuring a change in the inertia of the plunger 10 is provided in the coupling 14.

  As shown in FIG. 3, the inertia (illustrated solid line) of the plunger 10 rapidly increases when the injection of the molten metal into the cavity of the mold 60 by the plunger 10 is completed (the stroke position V / P of the plunger 10). Ip. Then, immediately after the time when the pressure suddenly drops and reaches the maximum value Ip, the minimum value Im is reached after the elapse of time T1, and thereafter the pressurization force is applied after the time T2 elapses from the time when the minimum value Im is followed following the applied pressure (broken line in the drawing). It reaches around the maximum value Mp.

  Here, when the maximum value Ip of the inertia of the plunger 10 exceeds the maximum pressure Mp, it has been found that burr blowing occurs in the molded body. On the other hand, when the minimum value Im of the inertia of the plunger 10 is too small, it has been found that a nest is generated in the molded body. Therefore, the correction device 51 corrects the injection molding condition so that the change in the inertia of the plunger 10 smoothly rises without taking the above-described sudden rise and fall and reaches the vicinity where the applied pressure maximum value Mp is not exceeded. Thereby, it is possible to obtain a good molded body in which the generation of burr blowing and nests is suppressed.

(3. Correction process by correction device)
Next, the injection molding condition correction process by the correction device 51 will be described with reference to the flowcharts of FIGS. Here, as correction items, a time T3 (see FIG. 4) of the high speed region of injection filling, a speed V2 (see FIG. 5) of the high speed region of injection filling, the maximum value Ip of inertia (see FIGS. 6 and 7), Minimum inertia value Im (see FIG. 8), time T1 (see FIG. 9) from the maximum inertia value Ip to the minimum value Im, maximum applied pressure Mp (see FIG. 10) for the molten metal in the cavity, The time T2 (refer FIG. 11) until it reaches the pressurizing force maximum value Mp vicinity from minimum value Im is mentioned. The time T1 from the maximum value Ip of inertia to the minimum value Im is only monitored without correction. Further, for example, by correcting the maximum value Ip of inertia, it may be necessary to correct other correction items, but only the correction of each correction item will be described below.

  As shown in FIG. 4, the correction device 51 inputs a high speed start command position P3 and a high speed end command position P4 in a high speed range commanded by an operator and stores them in the memory (step 1). When the injection filling is started, the high speed start position in the high speed range is measured and stored in the memory as the high speed start measurement position DP3 (step 2). The difference between the high speed start command position P3 in the high speed range and the high speed start measurement position DP3 is calculated, and it is determined whether or not the difference is less than a threshold related to the difference stored in the memory in advance (step 3). When the difference between the high speed start command position P3 in the high speed range and the high speed start measurement position DP3 is equal to or greater than the threshold value, the high speed start command position P3 in the high speed range is corrected so as to be less than the threshold value (step 4).

  On the other hand, if the difference between the high speed start command position P3 in the high speed range and the high speed start measurement position DP3 is less than the threshold value in step 3, or if the high speed start command position P3 in the high speed range is corrected in step 4, the high speed range Is measured and stored in the memory as a high-speed end measurement position DP4 (step 5). The difference between the high speed end command position P4 in the high speed range and the high speed end measurement position DP4 is calculated, and it is determined whether or not the difference is less than a threshold value relating to the difference stored in the memory in advance (step 6). When the difference between the high speed end command position P4 in the high speed range and the high speed end measurement position DP4 is greater than or equal to the threshold value, the high speed end command position P4 in the high speed range is corrected so as to be less than the threshold value (step 7). finish. As described above, the time T3 in the high speed region of injection filling can be corrected.

  As shown in FIG. 5, the correction device 51 inputs the high speed start command speed V2S and the high speed end command speed V2E instructed by the operator and stores them in the memory (step 11). When injection filling is started, the flow rate F3 of oil at the high speed start command position P3 in the high speed range is measured and stored in the memory (step 12). Based on the measured oil flow rate F3, the high speed start speed in the high speed range is calculated and stored in the memory as the high speed start calculation speed VHS (step 13). The difference between the high speed start command speed V2S in the high speed range and the high speed start calculation speed VHS is calculated, and it is determined whether or not the difference is less than a threshold value relating to the difference stored in the memory in advance (step 14). When the difference between the high speed start command speed V2S in the high speed range and the high speed start calculation speed VHS is equal to or greater than the threshold value, the high speed start command speed V2S in the high speed range is corrected so as to be less than the threshold value (step 15).

  On the other hand, if the difference between the high speed start command speed V2S in the high speed range and the high speed start calculation speed VHS is less than the threshold value in step 14, or if the high speed start command speed V2S in the high speed range is corrected in step 15, the high speed range The oil flow rate F4 at the high speed end command position P4 is measured and stored in the memory (step 16). Based on the measured oil flow rate F4, the high speed end speed in the high speed region is calculated and stored in the memory as the high speed end calculation speed VHE (step 17). The difference between the high speed end high speed end command speed V2E and the high speed end calculation speed VHE is calculated, and it is determined whether or not the difference is less than a threshold related to the difference stored in the memory in advance (step 18). When the difference between the high speed end command speed V2E in the high speed range and the high speed end calculation speed VHE is equal to or greater than the threshold value, the high speed end command speed V2E in the high speed range is corrected so as to be less than the threshold value (step 19). finish. As described above, the speed V2 in the high speed region of injection filling can be corrected.

  As shown in FIG. 6, the correction device 51 inputs the deceleration start command position P5 in the deceleration region, the deceleration start command speed V3S in the deceleration region, and the maximum pressure command value Mp, which are commanded by the operator, and stores them in the memory. (Step 21). When the injection filling is started, the maximum value of the inertia is measured and stored in the memory as the maximum measured value DIp (step 22). It is determined whether or not the maximum measured value DIp of the inertia is greater than the maximum pressure command value Mp (step 23). If the maximum measured value DIp of the inertia is equal to or less than the maximum pressure command value Mp, the process is terminated. .

  On the other hand, when the maximum measured value DIp of the inertia is larger than the maximum pressure command value Mp, the deceleration start command speed V3S in the deceleration region that is equal to or less than the maximum pressure command value Mp is set to the maximum inertia value stored in the memory in advance. Correction is made from the relationship between the value Ip and the deceleration speed V3 in the deceleration region (step 24). The relationship between the maximum value Ip of inertia and the deceleration speed V3 in the deceleration region is inversely proportional to the maximum value Ip of inertia decreasing as the deceleration speed V3 in the deceleration region increases, as shown in FIG.

  Then, it is determined whether or not the maximum measured value DIp of the inertia is greater than the maximum pressure command value Mp (step 25). If the maximum measured value DIp of the inertia is equal to or less than the maximum pressure command value Mp, the process is performed. finish. On the other hand, when the maximum measured value DIp of inertia is larger than the maximum pressure command value Mp, the operating speed of a valve (not shown) for controlling the injection filling speed provided in the manifold 30 is calculated (step 26). It is determined whether or not the valve operating speed is higher than the valve response speed (step 27). When the operation speed of the valve is smaller than the response speed of the valve, the process returns to step 24 to execute the above-described processing.

  On the other hand, when the operating speed of the valve is larger than the response speed of the valve, the deceleration start command position P5 is set between the deceleration speed V3 in the deceleration area stored in advance in the memory and the deceleration start position P5 in the deceleration area. Correction is made from the relationship (step 28), and the process is terminated. As shown in FIG. 13, the relationship between the deceleration speed V3 in the deceleration area and the deceleration start position P5 in the deceleration area is such that the deceleration speed V3 in the deceleration area increases as the deceleration start position P5 in the deceleration area approaches the injection filling start position. There is a proportional relationship. As described above, the maximum value Ip of the inertia can be corrected.

  In FIG. 6 described above, the maximum pressure command value Mp is commanded (step 21), and it is determined whether or not the maximum measured value DIp of inertia is larger than the maximum pressure command value Mp (steps 23 and 25). As shown in FIG. 7, the maximum value of inertia is commanded to obtain the maximum command value Ip of inertia (step 31), and it is determined whether or not the maximum measured value DIp of inertia is larger than the maximum command value Ip of inertia. You may make it (steps 33 and 35). In FIG. 7, step numbers 22, 24, 26, 27, and 28 that are the same as the step numbers shown in FIG.

  As shown in FIG. 8, the correction device 51 inputs the boundary position V / P between the speed control area AVC and the pressure control area APC commanded by the operator and stores them in the memory (step 51). When injection filling is started, the maximum value of the inertia is measured and stored in the memory as the maximum measured value DIp (step 52), and the minimum value of the inertia is measured and stored in the memory as the minimum measured value DIm (step 53). Then, the difference between the maximum measured value DIp of the inertia and the minimum measured value DIm of the inertia is calculated, and it is determined whether or not the difference is less than a threshold related to the difference stored in the memory in advance (step 54). When the difference between the maximum measured value DIp of inertia and the minimum measured value DIm of inertia is greater than or equal to the threshold value, the boundary position V / P between the speed control area AVC and the pressure control area APC is corrected so as to be less than the threshold value. (Step 55), and the process ends. As described above, the minimum value Im of the inertia can be corrected.

  As shown in FIG. 9, when the injection filling is started, the correction device 51 measures the time tip at which the inertia becomes maximum and stores it in the memory (step 61), and measures the time tim at which the inertia becomes minimum to measure the memory. (Step 62). Then, the difference between the time tim at which the inertia is minimum and the time tip at which the inertia is maximum is calculated, and it is determined whether or not the difference is less than a threshold value related to the difference stored in the memory in advance (step 63). ). If the difference between the time tim at which the inertia is minimum and the time tip at which the inertia is maximum is less than the threshold value, the process is terminated. If the difference is greater than or equal to the threshold value, a warning is issued by voice or image (step 64). ), The process is terminated. As described above, the time T1 from the maximum value Ip of inertia to the minimum value Im can be monitored.

  As shown in FIG. 10, the correction device 51 inputs the maximum pressure command value Mp commanded by the operator and stores it in the memory (step 71). When injection filling is started, the maximum value of the applied pressure to the molten metal in the cavity is measured and stored in the memory as the maximum applied pressure measurement value DMp (step 72). Then, a difference between the maximum applied pressure measurement value DMp and the maximum applied pressure command value Mp is calculated, and it is determined whether or not the difference is less than a threshold value relating to the difference stored in the memory in advance (step 73). When the difference between the maximum applied pressure measurement value DMp and the maximum applied pressure command value Mp is equal to or greater than the threshold value, the injection pressure is corrected so as to be less than the threshold value (step 74), and the process is terminated. As described above, the maximum value Mp of the pressure applied to the molten metal in the cavity can be corrected.

  As shown in FIG. 11, when the injection device is started, the correction device 51 measures the time tip when the inertia becomes maximum and stores it in the memory (step 81), and the time when the pressure applied to the molten metal in the cavity becomes maximum. tmp is measured and stored in the memory (step 82). Then, the difference between the time tmp at which the pressure applied to the molten metal in the cavity is maximized and the time tip at which the inertia is maximized is calculated, and whether or not the difference is less than the threshold value relating to the difference stored in the memory in advance. Is determined (step 83). When the difference between the time tmp at which the applied pressure to the molten metal in the cavity is maximum and the time tip at which the inertia is maximum is equal to or greater than the threshold, the injection filling speed provided in the manifold 30 is set to be less than the threshold. The opening of the valve to be controlled is corrected (step 84), and the process is terminated. As described above, the time T2 from the minimum value Im of the inertia to the vicinity of the maximum pressure Mp can be corrected.

(4. Effect of injection molding method)
Since the change in the inertia of the plunger 10 during injection filling is measured, the force actually applied to the molten metal during injection filling can be grasped. Then, the injection molding conditions are corrected based on the measured inertia, for example, injection molding so that the maximum measured value DIp of the inertia of the plunger 10 during injection filling is not more than the maximum pressure command value Mp for the molten metal in the cavity. The condition is corrected. Thereby, opening of the metal mold | die 60 during the injection filling of a molten metal can be prevented, generation | occurrence | production of the burr | flash blow in a molded object can be eliminated, and a favorable molded object can be obtained. For example, the injection molding conditions are corrected so that the maximum measured value DIp of the inertia of the plunger 10 during injection filling is equal to or less than the maximum command value Ip of the inertia. Thus, it is effective when it is desired to obtain a compact having a uniform density while allowing a slight amount of burrs to be generated.

  Further, by correcting the deceleration speed V3 in the deceleration area of the plunger 10, it is possible to control the maximum value Ip of the inertia of the plunger 10 generated in the deceleration area after the high speed area. If the maximum measured value DIp of the inertia of the plunger 10 cannot be exceeded by the correction of the deceleration speed V3 so as not to exceed the maximum pressure command value Mp for the molten metal or the maximum command value Ip of the inertia, the deceleration when entering the deceleration region By correcting the position P5, the maximum measured value DIp of the inertia of the plunger 10 can be further controlled. Further, based on the difference between the maximum measured value DIp and the minimum measured value DIm of the inertia of the plunger 10 during injection filling, a control area AVC for the injection filling speed of the plunger 10 and a control area APC for the pressure applied to the molten metal in the cavity; The boundary position V / P is corrected. Thereby, the density of the molten metal in a cavity can be equalize | homogenized and the precision of a molded object can be improved.

  In addition, since the load cell 16 is provided in the coupling 14 and the inertia of the plunger 10 is measured, it can be handled as it is even if the mold 60 is replaced, and the cost can be reduced by a simple configuration. It becomes. Further, it is possible to measure the pressure applied to the molten metal in the cavity, and it is possible to grasp the actual pressure instead of the apparent pressure applied by the conventional hydraulic pressure measurement, thereby improving the molding accuracy.

(5. Modifications)
In the above-described embodiment, the load cell 16 is used as the inertia measuring device, but any device that measures pressure can be used. Further, although the load cell 16 is disposed on the coupling 14, the load cell 16 may be disposed on the first rod 12 or the second rod 13.

1: Injection molding device 10: Plunger, 11: Cylinder, 12: First rod, 12a: First piston 13: Second rod, 13a: Second piston, 14: Coupling 14a: Connecting part, 14b, 14c: Hollow 15: Spacer 16: Load cell 20: Accumulator 30: Manifold 40: Molten metal supply part 41: Reservoir part 42: Cylinder 50: Control device 51: Correction device 60: Mold

Claims (8)

An injection molding method in which a molten metal is injected and filled into a cavity of a mold using a hydraulically operated injection device, and the molten metal injected and filled into the cavity is pressure-molded,
A measuring step for measuring a change in inertia of the injection device during the injection filling;
A correction step of correcting injection molding conditions based on the measured inertia. In claim 1,
In the injection molding method, the correction step corrects the injection molding condition so that the measured maximum value of the inertia of the injection device does not exceed the commanded maximum pressure force on the molten metal in the cavity. In claim 1,
In the injection molding method, the correction step corrects the injection molding condition so that the measured maximum value of the inertia of the injection device does not exceed the commanded maximum value of the inertia of the injection device. In claim 2 or 3,
The correction step is an injection molding method for correcting a deceleration speed in a commanded deceleration area in an injection filling speed pattern of the injection device as the injection molding condition. In claim 4,
When the correction step cannot correct the maximum measured value of the inertia of the injection device so as not to exceed the maximum pressure command value for the molten metal or the maximum command value of the inertia by correcting the deceleration speed, the injection molding condition An injection molding method for correcting the deceleration start position of the deceleration region commanded as In any one of Claims 1-5,
Based on the difference between the measured maximum value and minimum value of the inertia of the injection device, the correction step is a control range of the injection filling speed of the commanded injection device and a control range of the applied pressure to the molten metal in the cavity. Injection molding method for correcting the boundary position between An injection molding device that uses a hydraulically operated injection device to inject and fill a molten metal into a cavity of a mold, and press-molds the molten metal that has been injected and filled into the cavity,
An inertia measuring device for measuring a change in inertia of the injection device during the injection filling;
An injection molding apparatus comprising: a correction device that corrects injection molding conditions based on the inertia measured by the inertia measuring device. In claim 7,
The inertia measuring device is an injection molding device provided on a connecting member that connects a first rod that receives the hydraulic pressure in the injection device and a second rod that injects and pressurizes the molten metal.

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