Injection molding machine and method for estimating mold deposit accumulation

Abstract

To accurately determine the maintenance timing of a mold of an injection molding machine. [Solution] In the control unit 21 of the injection molding machine 1, the acquisition unit 211 acquires at least one of a first measurement value relating to the resistance when the ejector pin protrudes to release the molded product from the mold in an open state during the mold opening operation, and a second measurement value relating to the resistance when the ejector pin retracts, and the estimation unit 214 estimates the amount of mold deposit accumulated in the mold based on the first measurement value which excludes elements before the molded product is released or which lowers the priority of elements before the molded product is released.

Description

[Technical Field]

[0001] The present invention relates to an injection molding machine and a method for estimating the amount of mold deposit. [Background technology]

[0002] There is a known technology for determining whether an abnormality occurs when an ejector mechanism that releases a molded product from a mold in an injection molding machine is driven (for example, see Patent Document 1). This technology determines whether "galling" of the ejector pin has occurred from the current value detected when the ejector mechanism is driven. "Galling" refers to significant scratches that occur on the surface of a molded product and are caused by abnormal friction, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2004 / 080690 Summary of the Invention [Problem to be solved by the invention]

[0004] With conventional technology, it is not possible to completely eliminate the resistance generated when a molded product is released from the mold from the detected current value. As a result, it is not possible to accurately estimate the amount of mold deposits that accumulate on the mold as the number of ejector mechanism drives increases. This can lead to missed mold maintenance times.

[0005] An object of the present invention is to make it possible to accurately determine the timing for maintenance of the mold of an injection molding machine. [Means for solving the problem]

[0006] The injection molding machine of the present invention, which was completed with this objective in mind, is an injection molding machine characterized by having an acquisition means for acquiring at least one of a first measurement value relating to the resistance when an ejector pin that releases a molded product from the mold in an open state is protruded during the mold opening operation, and a second measurement value relating to the resistance when the ejector pin is retracted; and an estimation means for estimating the amount of mold deposit accumulated in the mold based on at least one of the first measurement value and the second measurement value, which excludes elements that occurred before the molded product was released or which lower the priority of those elements. Here, the device may be characterized in that it has a spring mechanism that generates a force in the direction in which the ejector pin performs the storage operation, and when the first measurement value and the second measurement value are acquired, the estimation means excludes the second measurement value or lowers the priority of the second measurement value to estimate the deposition amount. The apparatus may further comprise a detection means for detecting the timing of maintenance of the mold based on the estimated amount of deposition. The estimation means may also be characterized in that it estimates the amount of mold deposit accumulated on the mold based on the magnitude of frictional resistance generated between the ejector pin and the mold, which is obtained by excluding or lowering the priority of the collision resistance generated between the ejector pin and the molded product and noise of a motor that drives the ejector pin as elements from the acquired first measurement value. The device may further comprise a management unit that stores and manages the acquired first measurement value and second measurement value in an external storage medium. Furthermore, the method for estimating the amount of mold deposits of the present invention, which was completed with the above object in mind, is a method for estimating the amount of mold deposits, characterized by including the steps of: acquiring, during the mold opening operation of the mold, at least one of a first measurement value relating to the resistance when an ejector pin that releases a molded product from the mold in an open state is protruded, and a second measurement value relating to the resistance when the ejector pin is retracted; and estimating the amount of mold deposits accumulated on the mold based on at least one of the first measurement value and the second measurement value, excluding elements that occurred before the molded product was released or lowering the priority of those elements. [Effects of the Invention]

[0007] According to the present invention, it is possible to accurately determine the timing for maintenance of the mold of an injection molding machine. [Brief explanation of the drawings]

[0008] [Figure 1] 5A to 5D are diagrams illustrating an example of the operation of an ejector pin of an ejector mechanism included in the injection molding machine according to the present embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of a hardware configuration of an injection molding machine. [Figure 3] 3 is a diagram illustrating an example of a functional configuration of a control unit in FIG. 2. FIG. [Figure 4] FIG. 10 is a diagram showing a specific example of a graph showing a change in ejector torque over time. [Figure 5] FIG. 10 is a diagram showing a specific example of a graph showing a change in ejector torque over time. [Figure 6] 3 is a diagram showing a specific example of information displayed on the display of the display unit of FIG. 2. FIG. [Figure 7] FIG. 10 is a diagram showing a specific example of a graph showing the relationship between the number of shots and the ejector torque. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Ejector pin 111 operation> 1A to 1D are diagrams showing an example of the operation of an ejector pin 111 of an ejector mechanism 11 provided in an injection molding machine according to this embodiment. 1(A) to 1(D) is a mechanism that constitutes part of the mold clamping device 10 of an injection molding machine 1 that performs injection molding of a molded article 200 using a resin 100 as a molding material. The ejector mechanism 11 is a mechanism that releases the molded article 200 from the mold 50 in an open state during a mold opening operation of the mold clamping device 10 that performs mold opening and closing operations. In each of FIGS. 1(A) to 1(D), the right side of the mold 50 in the mold opening and closing direction is the fixed side, and the left side is the movable side.

[0010] The mold 50 is composed of a fixed-side mold 51 also called a cavity and a movable-side mold 52 also called a core. The fixed-side mold 51 is a mold whose position in the mold opening / closing direction is fixed. In contrast, the movable-side mold 52 is a mold whose position in the mold opening / closing direction is not fixed, and is movable in the mold opening / closing direction in accordance with the mold opening / closing operation of the mold clamping unit 10. Specifically, the movable-side mold 52 comes into contact with the fixed-side mold 51 by moving toward the fixed side in the mold opening / closing direction in accordance with the mold closing operation of the mold clamping unit 10. Furthermore, the movable-side mold 52 moves away from the fixed-side mold 51 by moving toward the movable side in the mold opening / closing direction in accordance with the mold opening operation of the mold clamping unit 10.

[0011] FIG. 1 shows the flow of mold opening and closing operations of the mold clamping unit 10 in the order of (A) to (D). FIG. 1(A) shows the state before the mold closing operation of the mold clamping unit 10 is performed. In the state shown in FIG. 1(A), the fixed mold 51 and the movable mold 52 are separated. FIG. 1(B) shows the state after the mold closing operation and mold clamping operation by the mold clamping unit 10 are performed, and molten resin 100 is injected from an injection unit (not shown), and then the resin 100 is cooled. In the state shown in FIG. 1(B), a molded product is about to be molded in the space formed by the contact between the fixed mold 51 and the movable mold 52.

[0012] FIG. 1(C) shows the state after the mold opening operation by the mold clamping device 10 has been performed. In the state shown in FIG. 1(C), the fixed mold 51 and the movable mold 52 are separated from each other. In addition, a molded article 200 (resin 100 before solidification) is attached to the movable mold 52. FIG. 1(D) shows the state in which the ejector mechanism 11 is operating. In the state shown in FIG. 1(D), the ejector pins 111 of the ejector mechanism 11 protrude toward the fixed side in the mold opening / closing direction, thereby pressurizing the molded article 200 and releasing it from the movable mold 52. This causes the molded article 200 to fall freely.

[0013] In this way, the ejector pin 111 repeats an action of protruding its tip end toward the fixed side in the mold opening / closing direction (hereinafter referred to as the "protruding action") and an action of retracting the protruding tip end (hereinafter referred to as the "retracting action"). The protruding action and retracting action of the ejector pin 111 are repeated by moving inside a through-hole 112 that extends in the mold opening / closing direction and is provided in the movable mold 52 as part of the ejector mechanism 11. For this reason, if the number of times the ejector mechanism 11 is driven increases, residues of additives and lubricants contained in the molding material will accumulate on the mold 50 as mold deposits.

[0014] Specifically, mold deposits accumulate in locations related to the operation of the ejector mechanism 11, such as the gap formed between the ejector pin 111 and the through hole 112, or near the entrance and exit of the through hole 112. Mold deposits accumulated in such locations can hinder the smooth operation of the ejector pin 111, and are therefore removed during periodic maintenance of the mold 50.

[0015] The timing for maintenance of the mold 50 is determined based on the extent to which mold deposits interfere with the smooth operation of the ejector mechanism 11. The extent to which mold deposits interfere with the smooth operation of the ejector mechanism 11 is determined based on the amount of mold deposits accumulated in locations related to the operation of the ejector mechanism 11. The amount of mold deposits accumulated in locations related to the operation of the ejector mechanism 11 is estimated based on the actual value of a measured value of the resistance of the ejector pins 111 (hereinafter referred to as "ejector torque"). When this estimated value exceeds a predetermined level, the injection molding machine 1 detects the time for maintenance of the mold 50. That is, since the ejector pins 111 are driven by a motor (not shown), the torque of the motor changes depending on the resistance of the ejector pins 111. Therefore, the resistance of the ejector pins 111 can be estimated by measuring the torque of the motor. In this embodiment, the motor current value is used as a means for estimating the motor torque.

[0016] FIG. 2 is a diagram showing an example of the hardware configuration of the injection molding machine 1. As shown in FIG. The injection molding machine 1 has a control unit 21, a memory 22, a storage unit 23, a communication unit 24, an operation unit 25, and a display unit 26. These units are connected to each other via a data bus, an address bus, a PCI (Peripheral Component Interconnect) bus, etc.

[0017] The control unit 21 is a processor that controls the functions of the injection molding machine 1 through the execution of various software such as an OS (operating system) and application software. The control unit 21 is composed of, for example, a CPU (Central Processing Unit). The memory 22 is a storage area that stores various software and data used for executing the software, and is used as a work area for calculations. The memory 22 is composed of, for example, a RAM (Random Access Memory).

[0018] The storage unit 23 is a storage area that stores input data for various software programs, output data from various software programs, etc. The storage unit 23 is configured with, for example, a hard disk drive (HDD), a solid state drive (SSD), a semiconductor memory, etc. that are used to store programs, various setting data, etc.

[0019] The communication unit 24 transmits and receives data to and from other devices and the outside via a network 90 such as the Internet. For example, the communication unit 24 transmits and receives the actual value of the ejector torque to and from a storage server (not shown) present on the network 90.

[0020] The operation unit 25 is composed of, for example, a keyboard, a mouse, mechanical buttons, and switches, and accepts input operations. The operation unit 25 also includes a touch sensor that forms a touch panel integrally with the display unit 26. The display unit 26 is composed of, for example, a liquid crystal display or an organic EL (Electro Luminescence) display used to display information, and displays image and text data, etc. The display unit 26 displays a user interface, etc.

[0021] FIG. 3 is a diagram illustrating an example of the functional configuration of the control unit 21 in FIG. The control unit 21 of the injection molding machine 1 functions as an acquisition unit, an acquisition unit 211 that acquires various information as acquisition means, a management unit 212 that manages various information as management means, and a generation unit 213 that generates various information as generation means. The control unit 21 also functions as an estimation unit, an estimation unit 214 that estimates the amount of mold deposit accumulated on the mold 50, a detection unit 215 that detects the time for maintenance of the mold 50, and an output control unit 216 that outputs various information as output means.

[0022] The acquisition unit 211 acquires various information related to the mold clamping unit 10 of the injection molding machine. For example, the acquisition unit 211 acquires the ejector torque measured by the ejector mechanism 11 of the mold clamping unit 10. The ejector torque acquired by the acquisition unit 211 includes at least that measured at the following times. That is, the ejector torque acquired by the acquisition unit 211 includes the ejector torque as a first measurement value measured during the protruding operation of the ejector pin 111 (see FIG. 1 ), and the ejector torque as a second measurement value measured during the retracting operation of the ejector pin 111. Hereinafter, when it is not necessary to distinguish between the first measurement value and the second measurement value of the ejector torque in the description, the ejector torque will be simply referred to as "ejector torque."

[0023] The management unit 212 manages various types of information required to estimate the amount of mold deposit accumulated in a location related to the driving of the ejector mechanism 11. For example, the management unit 212 stores and manages the ejector torque acquired by the acquisition unit 211 as a past performance value in a storage server present on the network 90 (see FIG. 2). The management unit 212 can also store and manage the ejector torque acquired by the acquisition unit 211 in an external storage medium such as an external hard disk.

[0024] The past actual values ​​of the ejector torque can be stored in the memory unit 23 of the injection molding machine, but because there is a physical limit to the amount of data that can be stored, the amount of data required to estimate the amount of mold deposit accumulation cannot be stored in the memory unit 23 of the injection molding machine. Therefore, the management unit 212 connects the injection molding machine 1 to a network 90 such as the Internet, and stores and manages the past actual values ​​of the ejector torque in a storage server (not shown) that exists on the network 90.

[0025] The generation unit 213 generates various information for estimating the amount of mold deposit accumulated in a location related to the driving of the ejector mechanism 11, based on the actual value of the ejector torque managed by the management unit 212. For example, the generation unit 213 generates a graph representing the time change of the ejector torque. From the graph representing the time change of the ejector torque, it is possible to read the ejector torque as a first measurement value measured during the protruding operation of the ejector pin 111, the ejector torque as a second measurement value measured during the retracting operation of the ejector pin 111, and the like. Note that specific examples of the graph representing the time change of the ejector torque generated by the generation unit 213 will be described later with reference to FIGS. 4 and 5.

[0026] The estimation unit 214 estimates the amount of mold deposits accumulated in locations related to the operation of the ejector mechanism 11 based on the information generated by the generation unit 213. For example, the estimation unit 214 estimates the amount of mold deposits accumulated in locations related to the operation of the ejector mechanism 11 based on the information generated by the generation unit 213 indicating the change in ejector torque over time.

[0027] The estimation unit 214 estimates the amount of mold deposit accumulated in a location related to the driving of the ejector mechanism 11, for example, by the following method. That is, among the ejector torques managed by the management unit 212, the ejector torque measured during the protruding operation of the ejector pin 111 includes the following four elements (first to fourth elements).

[0028] The first factor is the frictional resistance generated between the ejector pin 111 and the inner wall surface of the through hole 112. One of the factors that generates this frictional resistance is the presence of mold deposits accumulated in locations related to the drive of the ejector mechanism 11. Therefore, the frictional resistance generated between the ejector pin 111 and the inner wall surface of the through hole 112 is an important factor for estimating the amount of mold deposits.

[0029] The second factor is the collision resistance generated between the ejector pin 111 and the molded product 200. This collision resistance occurs independently of the accumulation of mold deposits, and is not a factor for estimating the amount of mold deposits. For this reason, the second factor is excluded or given a lower priority in the calculation process for estimating the amount of mold deposits.

[0030] The third factor is noise from a motor (not shown) that drives the ejector pin 111. This noise occurs independently of the buildup of mold deposits and is not a factor in estimating the amount of mold deposits. For this reason, the third factor is excluded or given a lower priority in the calculation process for estimating the amount of mold deposits.

[0031] The fourth element is the restoring force of a spring mechanism (not shown). The "spring mechanism" is a mechanism having a spring that generates a force in the direction in which the ejector pin 111 retracts (the movable side in the mold opening / closing direction in FIG. 1 ), and uses the spring's restoring force to support the retraction of the ejector pin 111. When the ejector pin 111 protrudes, it protrudes while contracting the spring of the spring mechanism, generating a restoring force of the spring of the spring mechanism (a force that tries to push back the ejector pin 111). This restoring force is generated independently of the accumulation of mold deposits and is not a factor in estimating the amount of mold deposits. For this reason, the fourth element is excluded or is subject to a calculation process with a lower priority in the process of estimating the amount of mold deposits.

[0032] That is, the estimation unit 214 performs a calculation process to remove or lower the priority of the second to fourth elements that occur unrelated to the accumulation of mold deposits from the graph representing the time change in ejector torque generated by the generation unit 213. Then, the estimation unit 214 estimates the amount of mold deposits accumulated in locations related to the operation of the ejector mechanism 11 based on the first element obtained by the calculation process to remove or lower the priority of the second to fourth elements from the graph representing the time change in ejector torque. Specific examples of methods to remove or lower the priority of the second to fourth elements from the graph representing the time change in ejector torque will be described later with reference to FIGS. 4 and 5.

[0033] Furthermore, the estimation unit 214 can estimate the amount of mold deposit buildup based on the first element of the graph showing the change in ejector torque over time and the ejector torque measured during the retraction operation of the ejector pin 111. The ejector torque measured during the retraction operation of the ejector pin 111 does not include the second element described above, and therefore the measured value is used as is.

[0034] The detection unit 215 detects the time for maintenance of the mold 50 based on the amount of mold deposit accumulated on the mold 50 estimated by the estimation unit 214. Specifically, the detection unit 215 detects the time for maintenance of the mold 50 when the estimated value of the amount of mold deposit accumulated on the mold 50 exceeds a predetermined level.

[0035] The output control unit 216 controls the output of information for notifying the maintenance time of the mold 50 detected by the detection unit 215. For example, the output control unit 216 displays an alert on the display of the display unit 26 of the injection molding machine as information for notifying the maintenance time of the mold 50.

[0036] <Example of a graph showing the change in ejector torque over time> 4 and 5 are diagrams showing specific examples of graphs showing changes in ejector torque over time. The graphs shown in Figures 4 and 5 are graphs with time (t) on the horizontal axis and ejector torque (%) on the vertical axis. Note that the graph shown in Figure 4 represents the change in ejector torque over time when no gas is accumulated in the mold 50, and the graph shown in Figure 5 represents the change in ejector torque over time when gas is accumulated in the mold 50. The graph shown in Figure 5 also shows the change in ejector torque over time before and after a mold deposit is accumulated in the mold 50. Line L1 in Figure 5 represents the ejector torque before a mold deposit is accumulated in the mold 50. Line L2 represents the ejector torque after a mold deposit is accumulated in the mold 50.

[0037] In the graph shown in Fig. 4, time period t1 is a time period before the first protrusion operation by the ejector pin 111 is performed. During time period t1, the ejector pin 111 is not driven, so the ejector torque is substantially constant (substantially zero). Time period t2 is a time period during which the first protrusion operation by the ejector pin 111 is performed. During time period t2, the ejector pin 111 is driven to perform the protrusion operation, so the ejector torque is larger than during time period t1.

[0038] Time period t3 is a time period during which the first retraction operation by the ejector pin 111 is performed. During time period t3, the ejector pin 111 performs the retraction operation with the assistance of the spring restoring force of the spring mechanism. Therefore, the absolute value of the ejector torque during time period t3, when the spring restoring force supports the retraction operation, is smaller than the absolute value of the ejector torque during time period t2, when the spring restoring force acts as resistance to the protrusion operation. Time period t4 is a time period during which the ejector pin 111 performs the second protrusion operation. During time period t4, the ejector pin 111 is driven to perform the protrusion operation, and therefore the ejector torque is larger than during time period t1.

[0039] Furthermore, time period t5 is a time period during which the ejector pin 111 performs a second retracting operation. During time period t5, the ejector pin 111 performs the retracting operation with the assistance of the spring restoring force of the spring mechanism. Therefore, the absolute value of the ejector torque during time period t5, when the spring restoring force supports the retracting operation, is smaller than the absolute value of the ejector torque during time period t4, when the spring restoring force acts as resistance to the protruding operation. Time period t6 is a time period after the ejector pin 111 performs a second retracting operation. During time period t6, the ejector pin 111 is not driven, so the ejector torque returns to the level of time period t1 and is approximately constant (approximately zero).

[0040] The graph shown in FIG. 4 includes the four elements (first to fourth elements) described above. However, of the four elements, the second to fourth elements are generated independently of the accumulation of mold deposits and are therefore excluded or have their priority lowered in the calculation process. For example, during time period t2, the ejector pin 111 performs its first ejection operation, causing the ejector pin 111 to collide with the molded product 200, resulting in collision resistance between the ejector pin 111 and the molded product 200. This collision resistance is a second element generated independently of the accumulation of mold deposits and is therefore excluded or has its priority lowered in the calculation process for estimating the amount of mold deposits. Therefore, for example, in the process for estimating the amount of mold deposits, the entire ejector torque during time period t2, when the first ejection operation was performed, is excluded or has its priority lowered. In other words, the ejector torque after a certain time has elapsed since the ejector mechanism 11 started operating is used.

[0041] During time period t3, the ejector pin 111 performs the retracting operation with the assistance of the spring restoring force of the spring mechanism. The spring restoring force is a fourth element that occurs unrelated to the accumulation of mold deposits, and is therefore excluded or subject to a lower priority in the calculation process for estimating the amount of mold deposits. For this reason, for example, in the process for estimating the amount of mold deposits, the entire ejector torque during time period t3, when the first retracting operation was performed, is excluded or subject to a lower priority in the calculation process.

[0042] Furthermore, in time period t4, the ejector pin 111 performs a second ejection operation, but because the molded product 200 has already been released and dropped from the movable mold 52 during the first ejection operation, no collision resistance occurs as occurs during the first ejection operation. For this reason, the ejector torque during time period t4, when the second ejection operation was performed, is used in the process of estimating the amount of mold deposit accumulation.

[0043] Furthermore, in time period t2, when the ejector pins 111 start their first protrusion operation, the motor drives the ejector pins 111, generating noise. Furthermore, when the ejector pins 111 start their second protrusion operation, the motor drives the ejector pins 111, generating noise. Because these noises are third factors that arise unrelated to the accumulation of mold deposits, they are subject to exclusion or lower priority in the calculation process for estimating the amount of mold deposits. Therefore, for example, in the process for estimating the amount of mold deposits, the entire ejector torque during time period t2, when the first protrusion operation was performed, is subject to exclusion or lower priority in the calculation process. Furthermore, the third factor of the ejector torque during time period t4, when the second protrusion operation was performed, is subject to exclusion or lower priority in the calculation process.

[0044] Furthermore, during time period t2, when the ejector pin 111 performs its first protrusion operation, the spring of the spring mechanism is contracted as it protrudes, generating a restoring force of the spring. During time period t4, when the ejector pin 111 performs its second protrusion operation, the spring of the spring mechanism is contracted as it protrudes, generating a restoring force of the spring. Because these spring restoring forces are a fourth element that occurs unrelated to the accumulation of mold deposits, they are excluded or subject to a lower priority in the calculation process for estimating the amount of mold deposits. Therefore, for example, in the process for estimating the amount of mold deposits, the entire ejector torque during time period t2, when the first protrusion operation occurred, is excluded or subject to a lower priority in the calculation process. Furthermore, the fourth element of the ejector torque during time period t4, when the second protrusion operation occurred, is excluded or subject to a lower priority in the calculation process.

[0045] During time period t5, the ejector pin 111 performs the retracting operation with the assistance of the spring restoring force of the spring mechanism. The spring restoring force is a fourth element that occurs unrelated to the accumulation of mold deposits, and is therefore excluded or subject to a lower priority in the calculation process for estimating the amount of mold deposits. For this reason, for example, in the process for estimating the amount of mold deposits, the entire ejector torque during time period t5, when the second retracting operation was performed, is excluded or subject to a lower priority in the calculation process.

[0046] 5, time period t11 is the time period before the first ejection operation is performed by the ejector pin 111. During time period t11, the ejector pin 111 is not driven, so the ejector torque is substantially constant before and after the mold deposit is accumulated in the mold 50, and both values ​​are approximately the same (substantially zero).

[0047] Time period t12 is the time period during which the ejector pin 111 performs the first ejection operation. During time period t12, the ejector pin 111 is driven to perform the ejection operation, and therefore the ejector torque is larger than that during time period t11 both before and after mold deposits are accumulated on the mold 50. However, when comparing the time period before mold deposits are accumulated on the mold 50 (line L1) with the time period after mold deposits are accumulated on the mold 50 (line L2), the following can be said. That is, the ejector torque after mold deposits are accumulated on the mold 50 is larger than the ejector torque before mold deposits are accumulated on the mold 50. In other words, it can be seen that there is a proportional relationship between the amount of mold deposits accumulated on the mold 50 and the magnitude of the ejector torque.

[0048] Time period t13 is a waiting period before the first retracting operation of the ejector pin 111 is performed. During time period t13, the ejector pin 111 waits while resisting the restoring force of the spring of the spring mechanism, so the ejector torque is larger than during time period t11 and is maintained in a substantially constant state. Note that it is not essential for the ejector pin 111 to wait before performing the retracting operation, and there are cases where the ejector pin 111 does not wait, as in the example of the graph in FIG. 4 described above.

[0049] Time period t14 is the time period during which the first retraction operation by the ejector pin 111 is performed. During time period t14, the ejector pin 111 performs the retraction operation using the restoring force of the spring of the spring mechanism. Therefore, the absolute value of the ejector torque during time period t14, when the restoring force of the spring supports the retraction operation, is smaller than the absolute value of the ejector torque during time period t12, when the restoring force of the spring acts as resistance to the protrusion operation. Also, during time period t14, the restoring force of the spring of the spring mechanism supports the retraction operation of the ejector pin 111. Therefore, the difference between the ejector torque (line L1) before mold deposits are accumulated on the mold 50 and the ejector torque (line L2) after mold deposits are accumulated on the mold 50 is smaller than that during time period t12.

[0050] Time period t15 is the time period during which the second ejection operation is performed by the ejector pin 111. During time period t15, the ejector pin 111 is driven to perform the ejection operation, and therefore the ejector torque is larger than that during time period t11 both before and after the mold deposit is accumulated on the mold 50. However, when comparing the time periods before and after the mold deposit is accumulated on the mold 50, the ejector torque (line L2) after the mold deposit is accumulated on the mold 50 is larger than the ejector torque (line L1) before the mold deposit is accumulated on the mold 50.

[0051] 5, the following can be said about the difference between the ejector torque before mold deposits accumulate on the mold 50 and the ejector torque after mold deposits accumulate on the mold 50. That is, the difference during time period t12 when the first ejection operation is performed is different from the difference during time period t15 when the second ejection operation is performed. This is because the ejector torque during the first ejection operation includes the collision resistance (second element) that occurs between the ejector pin 111 and the molded product 200, but the ejector torque during the second ejection operation does not include this.

[0052] Time period t16 is a standby time period before the second retraction operation of the ejector pin 111 is performed. During time period t16, the ejector pin 111 is on standby while resisting the restoring force of the spring of the spring mechanism, so the ejector torque is larger than during time period t11 and is maintained in a substantially constant state.

[0053] Time period t17 is a time period during which the second retraction operation by the ejector pin 111 is performed. During time period t17, the ejector pin 111 performs the retraction operation using the restoring force of the spring of the spring mechanism. Therefore, the absolute value of the ejector torque during time period t17, when the restoring force of the spring supports the retraction operation, is smaller than the absolute value of the ejector torque during time period t15, when the restoring force of the spring acts as resistance to the protrusion operation. Also, during time period t17, the restoring force of the spring of the spring mechanism supports the retraction operation of the ejector pin 111. Therefore, the difference between the ejector torque (line L1) before a mold deposit is accumulated on the mold 50 and the ejector torque (line L2) after a mold deposit is accumulated on the mold 50 is smaller than during time period t12 and time period t15.

[0054] Furthermore, when comparing time period t14 when the first retracting operation of the ejector pin 111 is performed with time period t17 when the second retracting operation is performed, there is almost no difference in the magnitude of the ejector torque.

[0055] Time period t18 is a time period after the second retraction operation by the ejector pin 111. During time period t18, the ejector pin 111 is not driven, so the ejector torque returns to the level of time period t1 and is approximately constant (approximately zero).

[0056] The graph shown in FIG. 5 includes the four elements (first to fourth elements) described above. However, of the four elements, the second to fourth elements are excluded or given a lower priority in the calculation process because they occur independently of the buildup of mold deposits. For example, in time period t12, the ejector pin 111 performs its first protrusion operation, causing the ejector pin 111 to collide with the molded product 200, resulting in collision resistance between the ejector pin 111 and the molded product 200. This collision resistance is the second element that occurs independently of the buildup of mold deposits. Therefore, in the process of estimating the buildup amount of mold deposits, the ejector torque in time period t12 is excluded or given a lower priority in the calculation process.

[0057] Furthermore, in time period t15, the ejector pin 111 performs a second ejection operation, but because the molded product 200 has already been released and dropped from the movable mold 52 during the first ejection operation, no collision resistance occurs as in the first ejection operation. For this reason, the ejector torque during time period t15 is used in the process of estimating the amount of mold deposit accumulation.

[0058] Additionally, in time period t12, when the ejector pins 111 start their first protruding operation, the motor drives the ejector pins 111, generating noise. Furthermore, when the ejector pins 111 start their second protruding operation, the motor drives the ejector pins 111, generating noise. These noises are third factors that occur unrelated to the buildup of mold deposits, and are therefore subject to calculations that exclude them or lower their priority in the process of estimating the amount of mold deposit buildup.

[0059] Furthermore, during time period t12, when the ejector pin 111 performs its first protrusion operation, the spring of the spring mechanism is contracted as it protrudes, generating a restoring force of the spring. Furthermore, during time period t15, when the ejector pin 111 performs its second protrusion operation, the spring of the spring mechanism is contracted as it protrudes, generating a restoring force of the spring. These spring restoring forces are a fourth element that occurs unrelated to the accumulation of mold deposits, and are therefore excluded or given lower priority in the calculation process for estimating the amount of mold deposits.

[0060] FIG. 6 is a diagram showing a specific example of information displayed on the display of the display unit 26 in FIG. As shown in Fig. 6, a screen labeled "Ejector Torque Monitoring" is displayed on the display of the display unit 26 of the injection molding machine 1. The screen shown in Fig. 6 displays "monitored values" and "measured values" for each of "Ejector Protrusion" and "Ejector Retraction" as information to assist the operator in determining when to perform maintenance on the mold 50. "Ejector Protrusion" refers to the time when the ejector pin 111 is protruding. "Ejector Retraction" refers to the time when the ejector pin 111 is retracting.

[0061] In the screen shown in FIG. 6, the "monitoring value" for "EJ protrusion" is set to "70.0" (%). This indicates that when the measured value of the current flowing through the motor that drives the ejector pins 111 to perform the protrusion operation exceeds 70% of the maximum value, it is detected that the mold 50 needs maintenance. Also, the "monitoring value" for "EJ retraction" is set to "70.0" (%). This indicates that when the measured value of the current flowing through the motor that drives the ejector pins 111 to perform the retraction operation exceeds 70% of the maximum value, it is detected that the mold 50 needs maintenance.

[0062] Also, on the screen shown in FIG. 6, the "measured value" for "EJ protrusion" is "24.2" (%). This indicates that the measured value of the ejector torque when the ejector pins 111 were protruding, i.e., the measured value of the current flowing through the motor that drives the ejector pins 111 to protrude, was the maximum value of "24.2" (%). Also, the "measured value" for "EJ retraction" is "18.3" (%). This indicates that the measured value of the ejector torque when the ejector pins 111 were retracting, i.e., the measured value of the current flowing through the motor that drives the ejector pins 111 to retract, was the maximum value of "18.3" (%).

[0063] 6, the "measured values" of both "Ejector ejection" and "Ejector retraction" have not reached the "monitoring values," and therefore the time for maintenance of the mold 50 is not detected. In contrast, if the "measured value" of either "Ejector ejection" or "Ejector retraction" reaches the "monitoring value," it is detected that the time for maintenance of the mold 50 is reached. In this case, an alert is output from the injection molding machine 1 to notify that the time for maintenance of the mold 50 has been detected.

[0064] The screen shown in FIG. 6 also shows that "Monitoring Selection" is "Fixed." This indicates that the "Monitoring Value" is fixed. In other words, it indicates that the "Monitoring Value" for both "Ejector Jig Protruding" and "Ejector Jig Retracting" is fixed to "70.0" (%). In addition to "Fixed" shown in FIG. 6, "Monitoring Selection" can also be set to "Automatic." When "Monitoring Selection" is set to "Automatic," the "Monitoring Value" fluctuates depending on the past measurement results of the ejector torque. Note that a case in which the "Monitoring Value" fluctuates depending on the past measurement results of the ejector torque will be described in a modified example below.

[0065] FIG. 7 is a diagram showing a specific example of a graph showing the relationship between the number of shots and the ejector torque. The "number of shots" refers to the number of times the mold clamping unit 10 of the injection molding machine 1 performs mold opening and closing operations. Therefore, the number of shots and the number of times the ejector mechanism 11 is driven are proportional to each other. In the example of FIG. 7, the ejector torque is generally stable at a constant magnitude up to the shot number "12,000," although it may suddenly increase. However, the ejector torque begins to increase once the shot number exceeds "12,000," and increases rapidly once the shot number exceeds "14,000." This is because mold deposits have accumulated on the mold 50, increasing the frictional resistance (first element) generated between the ejector pin 111 and the mold 50.

[0066] Although it depends on the specifications of the injection molding machine 1 and the molding conditions, generally, as shown in Figure 7, it is necessary to monitor the ejector torque value for about 12,000 shots before mold deposits accumulate in the mold 50 and this begins to become noticeable as a change in the ejector torque value. In other words, it is necessary to store and be able to reference the actual ejector torque values ​​corresponding to shot counts exceeding 12,000, but the functionality of a typical injection molding machine is not capable of storing such a large amount of data. For this reason, in the injection molding machine 1 according to this embodiment, the management unit 212 (see Figure 3) stores and manages the actual ejector torque values ​​in a storage server (not shown) located on the network 90.

[0067] <Modification> As described above, the ejector mechanism 11 according to this embodiment has a spring mechanism that assists the retracting operation of the ejector pins 111, but the spring mechanism is not essential for the ejector mechanism 11. In the case of an ejector mechanism 11 that does not have a spring mechanism, the ejector pins 111 perform the retracting operation without being assisted by the restoring force of the springs of the spring mechanism. Therefore, the ejector torque of the retracting operation of the ejector pins 111 is used as is.

[0068] Furthermore, in this embodiment, as shown in the specific example of the screen in FIG. 6 described above, the "monitoring value" serving as a threshold for determining the timing of maintenance of the mold 50 is fixed. However, the "monitoring value" may be automatically variable. For example, if past measurements of the ejector torque indicate a gradual increase in the ejector torque, the "monitoring value" may be varied so as to gradually increase accordingly. In other words, since the ejector torque naturally increases as the number of times the ejector pin 111 is driven increases, the "monitoring value" may be varied according to the purpose of monitoring. This makes it possible to perform monitoring primarily aimed at detecting a sudden increase in the ejector torque, for example.

[0069] In addition, in this embodiment, the first element is obtained by excluding the second to fourth elements from the acquired measurement value of the ejector torque or by performing a calculation process that lowers the priority of the elements, but this is not limited to this. For example, only the first element may be acquired at the stage of acquiring the ejector torque. Also, for example, there may be cases where it is clear that the protruding and retracting operations of the ejector pin 111 performed after the molded product 200 is released from the movable mold 52 are the nth (n is an integer value of 2 or greater) protruding and retracting operations during one mold opening and closing operation. In this case, the ejector torque for the nth and subsequent protruding and retracting operations may be acquired.

[0070] In summary, the injection molding machine 1 according to this embodiment only needs to have the following configuration, and can take on a variety of different embodiments. That is, the injection molding machine 1 is an injection molding machine characterized by having an acquisition unit 211 that acquires at least one of a first measurement value (ejector torque) relating to the resistance when the ejector pin 111 performs a protruding operation to release the molded product 200 from the mold 50 in an open state during the mold opening operation of the mold 50, and a second measurement value (ejector torque) relating to the resistance when the ejector pin 111 performs a retracting operation, and an estimation unit 214 that estimates the amount of mold deposit accumulated on the mold 50 based on at least one of the first measurement value and the second measurement value, which excludes elements before the molded product 200 is released or which lowers the priority of elements before the molded product 200 is released.

[0071] As a result, factors occurring before the molded article 200 is released that are unrelated to the accumulation of mold deposits are excluded from the first and second measurement values, or are subject to calculation processing with lower priority. As a result, it is possible to estimate the amount of mold deposit accumulation based only on the frictional resistance occurring between the ejector pin 111 and the mold 50.

[0072] Here, the device may be characterized in that it has a spring mechanism that generates force in the direction in which the ejector pin 111 is stored (the mold opening / closing direction), and when the first measurement value and the second measurement value are acquired, the estimation unit 214 excludes the second measurement value or lowers the priority of the second element to estimate the amount of mold deposit accumulated on the mold 50. This makes it possible to estimate the amount of mold deposit, taking into consideration the decrease in sensitivity caused by the restoring force of the spring of the spring mechanism assisting the retracting operation of the ejector pin 111.

[0073] The device may further include a detection unit 214 that detects the time for maintenance of the mold 50 based on the estimated amount of deposition. This allows the maintenance timing of the mold 50 to be determined with high accuracy.

[0074] The estimation unit 214 may also be characterized in that it estimates the amount of mold deposit accumulated on the mold 50 based on the magnitude of the frictional resistance generated between the ejector pin 111 and the mold 50, which is obtained by excluding or lowering the priority of the collision resistance generated between the ejector pin 111 and the molded product 200 and the noise of the motor that drives the ejector pin 111 as factors before the molded product 200 is released from the acquired first measurement value. This eliminates the collision resistance between the ejector pins 111 and the molded article 200 and noise from the motor that drives the ejector pins 111 as factors that occur before the molded article 200 is released and are unrelated to the accumulation of mold deposits. Alternatively, calculation processing is performed that lowers the priority. As a result, it becomes possible to estimate the amount of mold deposit accumulation based on the friction resistance that occurs between the ejector pins 111 and the mold 50.

[0075] The device may further include a management unit 212 that stores and manages the acquired first and second measurement values ​​in an external storage medium. This makes it possible to estimate the amount of mold deposit buildup based on the first and second measurement values ​​by accessing an external storage medium, even if the injection molding machine 1 does not have sufficient memory space to store the data of the first and second measurement values.

[0076] The method for estimating the amount of mold deposit according to this embodiment only needs to have the following configuration, and can be implemented in a variety of different ways. In other words, the method for estimating the amount of mold deposit accumulation is characterized by including the steps of: acquiring at least one of a first measurement value (ejector torque) relating to the resistance when the ejector pin 111 performs a protruding operation to release the molded article 200 from the mold 50 in an open state during the mold opening operation of the mold 50; and a second measurement value (ejector torque) relating to the resistance when the ejector pin 111 performs a retracting operation; and estimating the amount of mold deposit accumulated on the mold 50 based on the first measurement value that excludes elements before the molded article 200 is released or that lowers the priority of elements before the molded article 200 is released. [Explanation of symbols]

[0077] 1... injection molding machine, 10... mold clamping device, 11... ejector mechanism, 100... resin, 200... molded product, 50... mold, 51... fixed side mold, 52... movable side mold, 112... through hole, 21... control unit, 23... memory unit, 24... communication unit, 26... display unit, 211... acquisition unit, 212... management unit, 213... generation unit, 214... estimation unit, 215... detection unit, 216... output control unit, 90... network

Claims

1. An acquisition means for acquiring at least one of the following: a first measured value relating to the resistance when the ejector pins that release the molded product from the mold in the open state are ejected during the mold opening operation of the mold; and a second measured value relating to the resistance when the ejector pins are retracted. Estimation means for estimating the amount of mold deposit deposited in the mold based on at least one of the first measurement value obtained by excluding elements before the molded product is demolded or by lowering the priority of such elements, and the second measurement value, An injection molding machine characterized by having [a certain feature].

2. The ejector pin has a spring mechanism that generates force in the direction in which the retraction operation is performed. The estimation means is characterized in that, when the first measurement value and the second measurement value are obtained, the second measurement value is excluded or the priority of the second measurement value is lowered when estimating the amount of sediment. The injection molding machine according to claim 1.

3. The system further comprises a detection means for detecting the maintenance timing of the mold based on the estimated amount of deposits. The injection molding machine according to claim 1 or 2.

4. the estimation means estimates the amount of mold deposit accumulated on the mold based on the magnitude of frictional resistance occurring between the ejector pin and the mold, which is obtained by excluding or lowering the priority of the collision resistance occurring between the ejector pin and the molded product and noise of a motor that drives the ejector pin as the elements from the acquired first measurement value. The injection molding machine according to claim 1.

5. The system further comprises management means for storing and managing the acquired first measurement value and second measurement value on an external storage medium. The injection molding machine according to claim 1.

6. A step of obtaining at least one of the following: a first measured value relating to the resistance when the ejector pins that release the molded product from the mold in the open state are ejected during the mold opening operation of the mold; and a second measured value relating to the resistance when the ejector pins are retracted. A step of estimating the amount of mold deposit deposited in the mold based on at least one of the first measurement value obtained by excluding elements before the molded product was demolded or by lowering the priority of such elements, and the second measurement value, A method for estimating the amount of mold deposit, characterized by including [a specific element].

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