Wear testing equipment and pressure die casting machines

Abstract

The invention relates to a wear state measuring device and a pressure die casting machine. According to the invention, the wear state measuring device is a device for measuring the wear state of injection bushings and ejector piston tips in a pressure die casting machine with a mold holder, cylindrical injection bushings, ejector piston tips, and injection drive unit, which has an elastic wave measuring device configured to measure elastic waves propagating through the injection bushing as the ejector piston tip moves, and a determination device configured to determine the wear state of at least one of the injection bushings or ejector piston tips based on the output signal of the elastic wave measuring device.

Description

Wear condition measuring device and die casting machine

[0001] The present invention relates to a wear condition measuring device and a die casting machine, and more particularly to a wear condition measuring device in a die casting machine that injects molten metal in an injection sleeve into a mold using a plunger tip, and a die casting machine equipped with a wear condition measuring device.

[0002] Conventionally, die casting machines have been known in which molten metal in an injection sleeve is injected into a mold by a plunger tip. Such a die casting machine is disclosed, for example, in Japanese Patent Application Laid-Open No. 2017-104871.

[0003] The above-mentioned Japanese Patent Application Laid-Open No. 2017-104871 discloses a die casting machine in which molten metal is supplied into an injection sleeve and a plunger tip slidably provided in the injection sleeve is advanced at low and high speeds by a cylinder, thereby injecting the molten metal into a cavity of a mold.

[0004] JP 2017-104871 A discloses that repeated injection of molten metal causes wear on the plunger tip, and solidified metal particles may be present in the injection sleeve, resulting in so-called galling, such as undulating changes in injection speed. Therefore, JP 2017-104871 A discloses a method for evaluating the degree of galling by setting multiple evaluation zones within the range of movement of the plunger tip, calculating the average and maximum casting pressures for each evaluation zone, and comparing the difference between these values ​​and a preset value to assign a score to each evaluation zone.

[0005] JP 2017-104871 A

[0006] The occurrence of the "galling" described in JP 2017-104871 A is primarily caused by wear on one or both of the sliding surfaces, the outer peripheral surface of the plunger tip and the inner peripheral surface of the injection sleeve. In addition to the occurrence of galling, when the gap between the plunger tip and the injection sleeve increases due to wear on the sliding surfaces, a phenomenon called backflush occurs, in which pressure escapes through the gap. Because abnormalities in sliding parts such as galling and backflush can cause a decrease in product quality, worn plunger tips and injection sleeves are replaced. It is desirable to accurately detect the wear of the plunger tip and injection sleeve so that the need for sliding part replacement can be determined at the appropriate time before wear progresses to the point where it affects product quality.

[0007] However, the evaluation method disclosed in JP 2017-104871 A indirectly detects the change in sliding resistance due to the occurrence of galling by measuring it as a change in injection pressure, and it is difficult to detect slight changes that do not cause fluctuations in injection pressure. In other words, when a change in injection pressure due to the occurrence of galling is actually detected, there is a high possibility that a product of reduced quality or a defective product that does not meet quality standards has been produced.

[0008] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a wear condition measuring device and a die casting machine that can grasp the wear of the plunger tip and injection sleeve with high accuracy.

[0009] To achieve the above object, the inventors of the present invention conducted extensive research and discovered that a sliding noise is generated when the plunger tip slides within the injection sleeve, and that even if this sliding noise is undetectable in air, it can be detected as a high-frequency (ultrasonic) elastic wave propagating within the injection sleeve. The inventors also discovered that even if the wear level is low enough to not cause a significant change in sliding resistance that can be detected as a change in injection pressure, the elastic wave propagating through the injection sleeve during sliding exhibits a change that reflects the wear level. Based on this finding, the inventors have come up with the following invention.

[0010] In other words, a wear condition measuring device according to a first aspect of the present invention is a wear condition measuring device for measuring the wear conditions of an injection sleeve and a plunger tip in a die casting machine including a mold holding unit for holding a mold having a cavity, a cylindrical injection sleeve to which molten metal is supplied, a plunger tip slidably disposed within the injection sleeve and for injecting the molten metal supplied to the injection sleeve into the cavity, and an injection drive unit for moving the plunger tip back and forth within the injection sleeve, the wear condition measuring device including: an elastic wave measuring unit for measuring elastic waves propagating through the injection sleeve as the plunger tip moves; and a determining unit for determining the wear conditions of at least one of the injection sleeve and the plunger tip based on an output signal from the elastic wave measuring unit. Note that in the present invention, "wear" is a broad concept that includes not only wear on the sliding surfaces of the injection sleeve and the plunger tip but also the formation of areas of increased sliding resistance due to scratches (damage) formed on the sliding surfaces.

[0011] As described above, the wear condition measuring device according to the first aspect of the present invention includes an elastic wave measuring unit that measures elastic waves propagating through the injection sleeve during movement of the plunger tip. This allows for the measurement of high-frequency elastic waves (acoustic emissions, AE waves) generated by sliding between the plunger tip and the injection sleeve and propagating through the injection sleeve, thereby enabling the determination of changes in elastic waves corresponding to the degree of wear on the sliding surfaces. Because elastic waves generated by sliding propagate through the injection sleeve, even slight changes that cannot be measured as sliding noise transmitted through the air or changes in injection pressure can be captured. Furthermore, by including a determination unit that determines the wear condition of at least one of the injection sleeve and the plunger tip based on the output signal of the elastic wave measuring unit, the wear condition (the progression of wear) can be determined from the output signal of the elastic wave measuring unit. This allows for the wear of the plunger tip and the injection sleeve to be determined with high accuracy.

[0012] In the wear condition measuring device according to the first aspect, the elastic wave measuring unit preferably includes an elastic wave detection sensor attached to the other end of the propagation member and configured to measure elastic waves propagating from the injection sleeve via the propagation member. With this configuration, for example, instead of measuring elastic waves propagating toward the mold holding unit that holds the injection sleeve, the elastic waves generated by the sliding movement between the plunger tip and the injection sleeve can be measured directly from the injection sleeve using the propagation member. Furthermore, because the injection sleeve becomes extremely hot (several hundred degrees Celsius) when molten metal is supplied, it is difficult to attach even a heat-resistant sensor directly to the injection sleeve. Therefore, by propagating the elastic waves through a propagation member in contact with the injection sleeve, the elastic waves can be measured while suppressing the thermal effects on the elastic wave detection sensor.

[0013] In this case, preferably, the die casting machine further includes a sleeve holding portion that fixes the injection sleeve to the mold holding portion while holding it, and a holding member that holds the transmission member. The holding member can be attached to the sleeve holding portion or the mold holding portion without contacting the injection sleeve, and is configured to bias one end of the transmission member toward the injection sleeve. With this configuration, the biasing force of the holding member can reliably maintain contact between the transmission member and the injection sleeve. Furthermore, because the holding member can be attached to the sleeve holding portion or the mold holding portion that are part of the die casting machine, there is no need to provide a separate base or the like to fix the holding member in a predetermined position. Furthermore, because the holding member does not contact the injection sleeve, the holding member does not get in the way of the replacement work when replacing a worn injection sleeve.

[0014] The wear condition measuring device according to the first aspect preferably further includes a signal processing unit that calculates an elastic wave intensity index per unit time based on the output signal of the elastic wave measuring unit acquired during movement of the plunger tip, and the determining unit is configured to determine the degree of wear of at least one of the injection sleeve and the plunger tip based on the calculated intensity index. With this configuration, the degree of wear can be accurately determined based on changes in the intensity index per unit time during movement (sliding) of the plunger tip, for example, from the appearance of a sudden spike-like intensity peak or a significant deviation of the baseline.

[0015] In the wear condition measuring device according to the first aspect, the determination unit is preferably configured to acquire position information of the plunger tip during movement by the injection drive unit, and estimate the wear location of the injection sleeve based on the output signal of the elastic wave measurement unit and the position information during movement of the plunger tip. This configuration makes it possible to determine which location of the injection sleeve is experiencing wear. Therefore, useful information can be obtained for considering adjustment of the assembly angle of the injection sleeve and the injection drive unit and optimization of injection operation control in order to suppress the progression of wear.

[0016] The wear condition measuring device according to the first aspect preferably further includes an extraction processing unit that extracts signal components corresponding to elastic waves with frequencies in the ultrasonic range from the output signal of the elastic wave measuring unit. Here, the ultrasonic range refers to frequencies of 20 kHz or higher. With this configuration, for example, vibrations (displacement, chatter, etc.) generated during the injection operation and vibrations transmitted from other parts of the die-casting machine have frequencies sufficiently lower than the ultrasonic range. Therefore, such vibration components can be removed and signal components resulting from sliding between the plunger tip and the injection sleeve can be extracted. As a result, the signal-to-noise ratio of the signal components related to the determination of the wear condition can be improved.

[0017] In the above-described configuration including a holding member, the holding member preferably includes a first bracket attached to the sleeve holding portion or the mold holding portion and holding the transmission member, and a biasing member provided between the first bracket and the transmission member and biasing one end of the transmission member against the injection sleeve. With this configuration, the transmission member can be stably held by the first bracket, and the biasing member can bias the transmission member against the first bracket to easily ensure contact between the one end of the transmission member and the injection sleeve.

[0018] In this case, the biasing member is preferably a leaf spring disposed between the first bracket and the transmission member in a deformed state that biases one end of the transmission member against the injection sleeve, or a compression coil spring disposed between the first bracket and the transmission member in a compressed state that biases one end of the transmission member against the injection sleeve. With this configuration, when the biasing member is a leaf spring, the first bracket can more stably hold the transmission member via the leaf spring with relatively high rigidity. When the biasing member is a compression coil spring, vibrations are less likely to be transmitted between the first bracket and the transmission member than when a biasing member with relatively high rigidity is interposed between the first bracket and the transmission member. Therefore, vibrations (noise) transmitted from the sleeve holding portion or mold holding portion of the die-casting machine to which the first bracket is attached are less likely to be transmitted to the elastic wave detection sensor attached to the transmission member.

[0019] The wear condition measuring device according to the first aspect preferably further includes a sleeve holding part that fixes the injection sleeve to the mold holding part while holding the injection sleeve, and the elastic wave measuring part includes a second bracket that is attached to the sleeve holding part or the mold holding part and that directly holds the propagation member so that one end of the propagation member abuts against the injection sleeve, and an elastic wave detection sensor that is attached to the second bracket and measures elastic waves propagating from the injection sleeve via the propagation member. With this configuration, the propagation member can be directly held by the second bracket, and the second bracket can have multiple functions, including a function of attaching to the sleeve holding part or the mold holding part, a function of attaching the elastic wave detection sensor, and a function of holding the propagation member. Therefore, the configuration of the wear condition measuring device can be simplified compared to when the propagation member is indirectly held by the second bracket or when the above functions are performed by multiple members separately.

[0020] In this case, the second bracket is preferably formed so that the thickness of the portion that holds the propagation member is thinner than the thickness of the portion where the elastic wave detection sensor is attached. With this configuration, the thickness of the portion of the second bracket that holds the propagation member from the propagation member can be made relatively thin, so that elastic waves transmitted from the propagation member to the second bracket vibrate the thin portion of the second bracket relatively strongly, thereby improving the accuracy of elastic wave detection by the elastic wave detection sensor.

[0021] A die-casting machine in a second aspect of the present invention comprises a mold holding unit that holds a mold having a cavity, a cylindrical injection sleeve into which molten metal is supplied, a plunger tip that is slidably arranged within the injection sleeve and injects the molten metal supplied to the injection sleeve into the cavity, an injection drive unit that moves the plunger tip back and forth within the injection sleeve, an elastic wave measuring unit that measures elastic waves that propagate through the injection sleeve as the plunger tip moves, and a determination unit that determines the wear condition of at least one of the injection sleeve and the plunger tip based on an output signal from the elastic wave measuring unit, and the elastic wave measuring unit includes a propagation member having one end that contacts the injection sleeve and the other end that is remote from the injection sleeve.

[0022] A die casting machine according to a second aspect of the present invention, like the first aspect, includes an elastic wave measuring unit that measures elastic waves propagating through the injection sleeve when the plunger tip moves. This allows for the measurement of high-frequency elastic waves (acoustic emissions, AE waves) generated by sliding between the plunger tip and the injection sleeve and propagating through the injection sleeve, thereby enabling the determination of changes in elastic waves corresponding to the degree of wear on the sliding surfaces. Furthermore, by including a determination unit that determines the wear status of at least one of the injection sleeve and the plunger tip based on the output signal of the elastic wave measuring unit, the wear status (progression of wear) can be determined from the output signal of the elastic wave measuring unit. This allows for the wear of the plunger tip and the injection sleeve to be determined with high accuracy.

[0023] According to the present invention, as described above, the wear of the plunger tip and the injection sleeve can be determined with high accuracy.

[0024] 1 is a schematic diagram showing the overall configuration of a die casting machine equipped with a wear condition measuring unit. FIG. 2 is a block diagram illustrating the wear condition measuring unit and the control device of the die casting machine. FIG. 3 is a schematic graph illustrating the movement control of the plunger tip in the injection process of the die casting machine. FIG. 4 is a schematic diagram illustrating wear occurring in a sliding part and elastic waves generated due to sliding of the sliding part. FIG. 5 is a schematic enlarged plan view of the vicinity of the injection sleeve, illustrating the structure of the elastic wave measuring unit of the first embodiment. FIG. 6 is a schematic diagram illustrating the shape of one end of a propagation member that contacts the injection sleeve. FIG. 7 is a graph illustrating the output signal of the AE sensor after frequency filtering. FIG. 8 is a graph illustrating the intensity index data generated from the output signal of the AE sensor. FIG. 9 is a schematic diagram of intensity index-position change data generated from the intensity index data and position information of the plunger tip, where (A) is a graph when wear of the sliding part has progressed and (B) is a graph in normal condition. FIG. 10 is a flow chart illustrating the wear condition measurement process of the sliding part. FIG. 11 is a schematic enlarged plan view of the vicinity of the injection sleeve, illustrating the structure of the elastic wave measuring unit of the second embodiment. 10A and 10B are schematic enlarged plan views of the vicinity of an injection sleeve showing the structure of an elastic wave measuring unit according to a third embodiment. 11A and 11B are schematic views showing an example of the configuration of a wear condition measuring device independent of a die casting machine. 12A and 12B are schematic views showing modified examples of the shape of one end of a propagation member.

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0026] First Embodiment The configuration of a die-casting machine 1 equipped with a wear condition measuring unit 8 according to a first embodiment will be described with reference to Figures 1 to 9. The wear condition measuring unit 8 is an example of a "wear condition measuring device" as defined in the claims. In the drawings, the Z direction is defined as the up-down direction, with the Z1 direction of the Z direction defined as the upward direction and the Z2 direction of the Z direction defined as the downward direction. The X direction and the Y direction are defined as two directions perpendicular to each other in a horizontal plane, with the X1 direction of the X direction defined as the forward direction of a plunger tip 6a (described later) and the X2 direction of the X direction defined as the backward direction of the plunger tip 6a.

[0027] (Configuration of the die-casting machine) As shown in Figure 1, the die-casting machine 1 is a horizontal machine in which a movable die 2a moves horizontally. The die-casting machine 1 is a cold chamber type machine that is configured to produce a die-cast product (molded product) by injecting molten metal, which is a liquid metal material, into a die 2 (cavity C formed by the movable die 2a and fixed die 2b) attached to the die-casting machine 1.

[0028] The die-casting machine 1 includes a mold holding unit 3, an injection unit 4, a sleeve holding unit 40, and a wear condition measuring unit 8. The die-casting machine 1 of Fig. 1 also includes a molten metal supply device 9, a lid mechanism 10, a mold clamping unit 11, a control device 12, a display unit 13, and an alarm 14.

[0029] The mold holding unit 3 holds a mold 2 having a cavity C. The mold holding unit 3 includes a fixed die plate 3a and a movable die plate 3b.

[0030] The mold 2 includes a movable mold 2a and a fixed mold 2b. The fixed mold 2b is fixed to a fixed mold plate 3a. The movable mold 2a is attached to a movable die plate 3b that is movable in the direction (X direction) of contact with or separation from the fixed mold 2b. The cavity C is formed by contacting the movable mold 2a with the fixed mold 2b. The cavity C is a hollow portion for molding a die-cast product (molded article).

[0031] The movable die plate 3b is moved in the X direction by a mold clamping unit 11. The mold clamping unit 11 is equipped with a drive unit 11a that drives the movable die plate 3b. The drive unit 11a is, for example, an electric motor, and drives the movable die plate 3b in the X direction via a transmission mechanism 11b such as a ball screw shaft. The drive unit 11a is not limited to an electric type, and may be a hydraulic drive unit that drives a transmission mechanism consisting of a toggle mechanism, or may be a hybrid drive unit that combines electric and hydraulic types.

[0032] The injection unit 4 includes an injection sleeve 5 , a plunger 6 , and an injection drive unit 7 .

[0033] The injection sleeve 5 has a cylindrical shape with both ends open. The injection sleeve 5 extends linearly in the X direction. The injection sleeve 5 is fixed to the mold holding part 3 via a sleeve holding part 40. The sleeve holding part 40 has a cylindrical shape, and holds the injection sleeve 5 by inserting the injection sleeve 5 through it. The sleeve holding part 40 is fixed to the mold holding part 3 while holding the injection sleeve 5. The injection sleeve 5 is configured to be able to pour molten metal material. The injection sleeve 5 is configured to slidably accommodate the plunger tip 6a within the injection sleeve 5. Sliding means relative movement in a contact state.

[0034] Specifically, the injection sleeve 5 includes a pouring port 5a and a molten metal passage 5b. The pouring port 5a is provided so that the molten metal can be poured into the molten metal passage 5b by the melt supply device 9. The pouring port 5a penetrates the upper part (Z1 direction side) of the injection sleeve 5 in the Z direction. The molten metal passage 5b is a through hole that penetrates the injection sleeve 5 in the X direction. The molten metal passage 5b communicates with the cavity C at the X1 direction end.

[0035] The plunger 6 includes a plunger tip 6a and a plunger rod 6b. The plunger tip 6a is slidably disposed within the injection sleeve 5. The plunger tip 6a is attached to one end (the end on the X1 direction side) of the plunger rod 6b. The plunger rod 6b has a columnar shape extending along the X direction. The other end (the end on the X2 direction side) of the plunger rod 6b is attached to the piston rod of the injection drive unit 7 (hydraulic cylinder 7a). The plunger tip 6a is configured to inject molten metal supplied to the injection sleeve 5 into the cavity C by being moved back and forth within the injection sleeve 5 by the injection drive unit 7 via the plunger rod 6b.

[0036] The injection drive unit 7 is configured to move the plunger tip 6a back and forth within the injection sleeve 5. The injection drive unit 7 includes a hydraulic cylinder (hydraulic cylinder) 7a that operates by hydraulic pressure (hydraulic pressure) and a hydraulic circuit 7b. The hydraulic cylinder 7a is connected to the hydraulic circuit 7b and is configured to be operated by the hydraulic circuit 7b. The position (X direction position) of the plunger tip 6a moved by the hydraulic cylinder 7a is detected by a position sensor 7c.

[0037] The position sensor 7c is configured to detect the position of the plunger tip 6a (stroke amount of the hydraulic cylinder 7a) and is, for example, a stroke sensor, a magnetic or optical linear encoder, or a laser length measuring device.

[0038] The melt supply device 9 is configured to draw molten metal, which is a liquid metallic material, from a holding furnace (not shown) and supply (pour) it into the injection sleeve 5. Specifically, the melt supply device 9 includes a ladle 9a and an arm 9b. The ladle 9a is a container that draws molten metal, which is a liquid metallic material, from the holding furnace. The arm 9b is configured to move the ladle 9a to the pouring port 5a of the injection sleeve 5 and tilt the ladle 9a to pour the molten metal into the injection sleeve 5.

[0039] The lid mechanism 10 is configured to close the pouring port 5a after the molten metal is poured into the injection sleeve 5 by the melt supply device 9. Specifically, the lid mechanism 10 includes a lid portion 10a and an arm 10b. When viewed from the Z1 direction, the lid portion 10a has a shape that follows the shape of the pouring port 5a. The lid portion 10a is disposed at the tip of the arm 10b. The arm 10b is configured to move the lid portion 10a to the pouring port 5a.

[0040] The wear condition measuring unit 8 includes an elastic wave measuring unit 8a and a determining unit 8b.

[0041] The elastic wave measuring unit 8a is configured to measure elastic waves EW (see FIG. 4) propagating through the injection sleeve 5 when the plunger tip 6a moves.

[0042] The determination unit 8b is configured to determine the wear state of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal of the elastic wave measurement unit 8a. Hereinafter, the injection sleeve 5 and the plunger tip 6a will be collectively referred to as a sliding part SP (see FIG. 3).

[0043] The control device 12 is configured to control the driving of each part of the die casting machine 1. The control device 12 is electrically connected to each part of the die casting machine 1. As shown in FIG. 2 , the control device 12 includes a control unit 12a and a memory unit 12b. The control unit 12a is configured by a computer including, for example, a processor such as a CPU (Central Processing Unit) and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The memory unit 12b includes a non-volatile recording medium such as a flash memory. The control device 12 also includes a display unit 13.

[0044] The storage unit 12b stores a program to be executed by the control unit 12a (processor). The storage unit 12b is configured to store measurement data (intensity index-position change data 22d, which will be described later) measured by the elastic wave measuring unit 8a. The storage unit 12b also stores in advance setting information such as a judgment threshold for determining the wear state of the sliding part SP from the measurement data measured by the elastic wave measuring unit 8a.

[0045] The display unit 13 includes a display medium such as a liquid crystal monitor and is configured to display various information related to the die casting machine 1. The alarm 14 is, for example, an indicator light. The indicator light includes a light-emitting element such as a lamp and is configured to alert the user by lighting up or flashing. The alarm 14 also includes a speaker that outputs a buzzer sound.

[0046] (Outline of Injection Process) Next, an outline of the operation of the injection process by the die casting machine 1 will be described with reference to Fig. 3 and Fig. 1. The injection process is performed by the control unit 12a controlling each part of the die casting machine 1.

[0047] First, the control unit 12a controls the molten metal supply device 9 to pour molten metal into the injection sleeve 5 from the pouring port 5a of the injection sleeve 5 shown in Figure 1, and after pouring, controls the lid mechanism 10 to close the pouring port 5a.

[0048] After the pouring port 5a is closed, the control unit 12a controls the injection drive unit 7 to perform the injection process. As shown in FIG. 3, the injection process is broadly divided into an injection forward process shown in FIG. 3(A) and an injection return process shown in FIG. 3(B). The horizontal axis of the graphs in FIGS. 3(A) and 3(B) indicates the X-direction position of the plunger tip 6a, which corresponds to the schematic diagram inside the injection sleeve 5 shown at the top of the figure. The vertical axis of the graph indicates the movement speed of the plunger tip 6a. The positive direction (upward in the figure) of the vertical axis indicates the speed in the X1 direction (forward direction), and the negative direction (downward in the figure) indicates the speed in the X2 direction (reverse direction).

[0049] The injection forward step in Fig. 3(A) is a step in which the plunger tip 6a is advanced in the X1 direction within the injection sleeve 5 to inject molten metal into the mold 2. The injection return step in Fig. 3(B) is a step in which the plunger tip 6a advanced in the injection forward step is advanced backward in the X2 direction within the injection sleeve 5 to move the plunger tip 6a to a standby position for the next injection of molten metal.

[0050] The injection forward movement process in FIG. 3A includes a low-speed forward movement process and a high-speed forward movement process. The control unit 12a controls the injection drive unit 7 to switch between a low-speed injection process in which the plunger tip 6a is moved at a low speed and a high-speed injection process in which the plunger tip 6a is moved at a high speed. The low-speed injection process is a process in which the plunger tip 6a is moved at a first speed V1 as a target speed. The high-speed injection process is a process in which the plunger tip 6a is moved at a second speed V2, which is faster than the first speed V1, as a target speed. The position at which the low-speed forward movement process switches to the high-speed forward movement process (high-speed switch position Cp) is a position at which the plunger tip 6a blocks the injection sleeve 5 to prevent the pressure in the injection sleeve 5 from escaping through the inlet 5a. Specifically, the high-speed switch position Cp is set at a position where the X1-direction surface of the plunger tip 6a reaches the X1-direction side beyond the X1-direction end of the inlet 5a. The low-speed forward movement step is performed to increase the filling rate of the molten metal in the injection sleeve 5. The high-speed forward movement step is performed to distribute the molten metal throughout the mold 2 (cavity C). After the high-speed forward movement step, a holding step is performed in which the pressure in the cavity C is maintained at an elevated level to solidify the molten metal, and then the mold is opened (the movable mold 2 a and the fixed mold 2 b are separated) and the molded product is ejected from the mold 2.

[0051] Thereafter, the control unit 12a controls the injection drive unit 7 to perform an injection return process. The injection return process is a process in which the plunger tip 6a is moved in the X2 direction to the standby position at a target speed of the third speed V3. One injection process includes one injection forward movement process and one injection return process. Note that one injection process is also referred to as "one shot." The control unit 12a controls the position and speed of the plunger tip 6a (operation of the injection drive unit 7) during the injection process based on position information PI (see FIG. 2) of the plunger tip 6a acquired by the position sensor 7c (see FIG. 2).

[0052] (Configuration of Wear State Measuring Unit) Next, the wear state measuring unit 8 will be described in detail.

[0053] <Explanation of Elastic Waves Generated Due to Sliding> As shown in FIG. 4 , the plunger tip 6 a is slidable on the inner surface of the injection sleeve 5 without contacting it closely, and is positioned within the injection sleeve 5 with a fitting dimension that allows the molten metal M to be extruded without leaking injection pressure. With each injection operation, the plunger tip 6 a and the injection sleeve 5 come into contact (slide), causing wear on their respective sliding surfaces (the outer surface of the plunger tip 6 a and the inner surface of the injection sleeve 5). When the gap CL between the sliding surfaces increases due to wear, a phenomenon called backflash occurs, in which pressure leaks through the gap CL, as shown in FIG. 4 . Furthermore, because the molten metal M of aluminum die casting, for example, reaches a high temperature of around 700°C, deformation occurs in the injection sleeve and plunger tip 6 a when they are in contact with the molten metal M. If the deformation causes impact contact between the plunger tip 6 a and the injection sleeve 5 during the injection operation, scratches DG are formed on the sliding surfaces, resulting in "galling." The wear (increase in the clearance CL and occurrence of scratches DG) that occurs in the sliding part SP gradually progresses (expands) as the injection process is repeated.

[0054] When the plunger tip 6a slides within the injection sleeve 5, sound waves are generated in response to the sliding resistance. The generated sound waves propagate through the injection sleeve 5 as elastic waves EW. Such elastic waves EW are called acoustic emissions (AE waves) and belong to the ultrasonic frequency band of several tens of kHz to several MHz. Because the elastic waves EW are generated by the sliding between the plunger tip 6a and the injection sleeve 5, they reflect the wear status of the sliding parts SP (plunger tip 6a and injection sleeve 5). The wear status measuring unit 8 of the first embodiment measures the elastic waves EW propagating within the injection sleeve 5 to grasp the wear status of these sliding parts SP (plunger tip 6a and injection sleeve 5).

[0055] 5, the elastic wave measuring unit 8a includes a propagation member 21 and an acoustic emission sensor (hereinafter referred to as an AE sensor 22). The acoustic emission sensor (AE sensor) 22 is an example of an "elastic wave detection sensor" in the claims.

[0056] The propagation member 21 is a rod-shaped (thin plate-shaped) member that is movable relative to the injection sleeve 5 and contacts the injection sleeve 5 to propagate the elastic wave EW (see FIG. 4 ) from the injection sleeve 5 to the propagation member 21. The propagation member 21 has one end 21a that contacts the injection sleeve 5 and the other end 21b that is separated from the injection sleeve 5. The elastic wave EW propagating within the injection sleeve 5 is transmitted from the one end 21a to the propagation member 21 and then propagates to the other end 21b. The propagation member 21 is made of the same iron-based material as the injection sleeve 5. The injection sleeve 5 is made of a steel material (iron material) such as tool steel, and the propagation member 21 is made of the same steel material (iron material) as the injection sleeve 5. This allows the propagation characteristics of the elastic wave EW in the propagation member 21 to be closer to the propagation characteristics of the injection sleeve 5.

[0057] The shape of the end face of one end 21a of the propagation member 21 (the shape of the contact surface with the injection sleeve 5) is not particularly limited, but for example, as shown in Fig. 6, one end 21a of the propagation member 21 has a concave shape that is curved along the outer peripheral surface of the injection sleeve 5. This allows the boundary surface between the injection sleeve 5 and one end 21a of the propagation member 21 to be in close contact with each other, thereby reducing loss of the elastic wave EW at the boundary surface. In the example shown in Fig. 5, the propagation member 21 is curved between one end 21a and the other end 21b so as not to interfere with the structure of the die casting machine 1 near the injection sleeve 5, but the propagation member 21 may also extend linearly.

[0058] The AE sensor 22 is attached to the other end 21b of the propagation member 21. In FIG. 5, the AE sensor 22 is attached to the other end 21b of the propagation member 21 and is spaced a distance D1 from the injection sleeve 5. The AE sensor 22 detects the elastic wave EW (see FIG. 4) propagating from the injection sleeve 5 via the propagation member 21. The AE sensor 22 has a piezoelectric element such as PZT (lead zirconate titanate) and outputs a signal corresponding to pressure fluctuations (strain) acting on the piezoelectric element caused by the elastic wave EW propagating to the AE sensor 22. Note that an acceleration sensor is also an example of a sensor having a piezoelectric element, but the acceleration sensor has a weight attached to the piezoelectric element and outputs a signal corresponding to the displacement of the weight, whereas the AE sensor does not have a weight and detects pressure fluctuations acting directly on the piezoelectric element. Due to the difference in resonance frequency caused by the presence or absence of a weight, the acceleration sensor has sensitivity in a frequency band of, for example, several Hz to several tens of kHz, whereas the AE sensor 22 has sensitivity in a frequency band of several tens of kHz to 1 MHz.

[0059] 5 , the wear condition measuring unit 8 (elastic wave measuring unit 8a) includes a holding member 23 that holds the propagation member 21. The holding member 23 can be attached to the sleeve holding portion 40 without contacting the injection sleeve 5, and is configured to bias one end 21a of the propagation member 21 toward the injection sleeve 5. One end 21a of the propagation member 21 is attached to the holding member 23 in a state where it can move relative to the injection sleeve 5.

[0060] Specifically, the holding member 23 includes a bracket 24 attached to the sleeve holding portion 40, a biasing member 25, and an adjustment member 26. The bracket 24 is an example of a "first bracket" in the claims. The bracket 24 has an L-shape, and one end of the bracket 24 is fixed to the sleeve holding portion 40 with a bolt 27. The bracket 24 is attached to the sleeve holding portion 40 and holds the transmission member 21. Specifically, the bracket 24 is fixed to the edge of the sleeve insertion opening 40c in the sleeve holding portion 40, to which the injection sleeve 5 is attached, without contacting the injection sleeve 5. In FIG. 5, the bracket 24 is attached to the sleeve holding portion 40. If the injection sleeve 5 is attached to the fixed die plate 3a via an intermediate plate (not shown), the bracket 24 may be attached to the intermediate plate. The other end of the bracket 24 extends generally parallel to the injection sleeve 5.

[0061] The biasing member 25 is provided at the other end of the L-shaped bracket 24, and between the bracket 24 and the transmission member 21. The biasing member 25 is attached to the bracket 24 by an adjustment member 26 without contacting the injection sleeve 5. The biasing member 25 is disposed between the bracket 24 and the transmission member 21 in a deformed state so as to bias one end 21 a of the transmission member 21 toward the injection sleeve 5. The biasing member 25 is a leaf spring bent into a U-shape, and one end of the biasing member 25 is fixed to the bracket 24, and the transmission member 21 is fixed to the other end side of the biasing member 25.

[0062] The adjustment member 26 is a bolt (screw member) that engages with a threaded hole formed in the other end of the bracket 24. The adjustment member 26 passes through both one end and the other end of the U-shaped biasing member 25, extends toward the injection sleeve 5, and is attached to the other end of the bracket 24. Therefore, the biasing member 25 is sandwiched between the bracket 24 and the screw head of the adjustment member 26. The more the adjustment member 26 is rotated to bring the screw head closer to the bracket 24, the closer the other end of the biasing member 25 is to the injection sleeve 5. The pressing force that presses one end 21 a of the transmission member 21 attached to the other end of the biasing member 25 against the injection sleeve 5 is adjusted by the amount of rotation of the adjustment member 26.

[0063] With this configuration, the transmission member 21 is biased toward the injection sleeve 5 by the holding member 23 (biasing member 25 ) so that the one end 21 a is kept in constant contact with the injection sleeve 5 .

[0064] In the example of Fig. 5, the propagation member 21 is arranged in a position in the X direction that overlaps with the pouring port 5a of the injection sleeve 5 (the X direction position of the propagation member 21 is within the X direction formation range of the pouring port 5a). The propagation member 21 is arranged facing in the Y direction from a position horizontally lateral (Y direction) away from the injection sleeve 5 so as to contact the horizontal (Y direction) side surface of the injection sleeve 5. Note that the elastic wave measuring unit 8a including the propagation member 21 cannot be shown in the side view shown in Fig. 1 as it is, so for convenience, the elastic wave measuring unit 8a is shown in Fig. 1 as being below the injection sleeve 5.

[0065] 2, the wear condition measuring unit 8 includes an amplifier unit 8c, an arithmetic unit 8d, and the above-mentioned determination unit 8b. The AE sensor 22 is connected to the determination unit 8b (control unit 12a of the die-casting machine 1) via the amplifier unit 8c and the arithmetic unit 8d. The output signal 22a output from the AE sensor 22 is a time-varying signal of the output voltage.

[0066] The amplifier unit 8c includes an amplifier 31, an extraction processing unit 32, and an AD conversion unit 33. The amplifier 31 acquires the output signal 22a from the AE sensor 22, and amplifies the acquired output signal 22a by a preset amplification factor.

[0067] The extraction processing unit 32 extracts signal components corresponding to elastic waves EW of frequencies in the ultrasonic range from the output signal 22a of the elastic wave measuring unit 8a. That is, the extraction processing unit 32 acquires the output signal (output voltage) amplified by the amplifier 31 and performs frequency filtering on the acquired output signal to extract signal components of frequencies in a predetermined ultrasonic range. The frequency filtering includes at least high-pass filtering, which removes frequency components lower than a low frequency threshold. The frequency filtering in the first embodiment is band-pass filtering (a combination of a high-pass filter and a low-pass filter).

[0068] The extraction processing unit 32 extracts at least signal components of 20 kHz or higher (ultrasonic range) from the output signal 22a and removes signal components below 20 kHz. In the first embodiment, the extraction processing unit 32 extracts signal components of frequencies in the ultrasonic range of 50 kHz or higher and lower than 500 kHz (removing signal components below 50 kHz and signal components above 500 kHz). This removes signal components in frequency bands unnecessary for determining the wear state of the sliding part SP, leaving signal components in the frequency band corresponding to the elastic waves EW caused by sliding of the sliding part SP.

[0069] The AD conversion unit 33 performs A / D conversion processing on the output signal (amplified and signal component extracted) that has passed through the amplification unit 31 and the extraction processing unit 32. As a result, the amplifier unit 8c outputs the digitally converted output signal 22b to the calculation unit 8d. The output signal 22b is a time-varying signal of the output voltage value (digital value) after frequency filtering by the extraction processing unit 32. Figure 7 is a graph showing the output signal 22b, with the horizontal axis representing time and the vertical axis representing the output voltage value.

[0070] 2, the arithmetic unit 8d is configured by a computer equipped with a processor and a memory, and is connected to the amplifier unit 8c and the control unit 12a so as to be able to communicate with each other. The arithmetic unit 8d acquires the digitally converted output signal 22b of the AE sensor 22 from the amplifier unit 8c as measurement data of the elastic wave measuring unit 8a.

[0071] The arithmetic unit 8d includes a signal processing unit 34 as a functional block of software processing by executing a program stored in the memory. The signal processing unit 34 is configured to calculate an intensity index of the elastic wave EW per unit time based on the output signal 22b of the elastic wave measuring unit 8a (AE sensor 22) acquired during movement of the plunger tip 6a.

[0072] The intensity index of the elastic wave EW may be the maximum amplitude of the output signal per unit time, the energy of the output signal per unit time, or the effective value of the output signal per unit time. In the first embodiment, the signal processing unit 34 calculates the energy of the output signal per unit time from the time-varying waveform of the output signal 22b (see FIG. 7).

[0073] Specifically, the signal processing unit 34 calculates the area of ​​the time-varying waveform of the output signal (output voltage value) as the energy of the output signal 22b. The signal processing unit 34 then generates intensity index data 22c based on the time-varying waveform of the output signal 22b of the elastic wave measuring unit 8a (AE sensor 22), and outputs the generated intensity index data 22c to the determining unit 8b. The intensity index data 22c is data obtained by converting the output signal of the AE sensor 22 into a time-varying waveform of energy (intensity index). Figure 8 is a graph showing the intensity index data 22c, with the horizontal axis representing time and the vertical axis representing the intensity index (energy).

[0074] 2, in the first embodiment, the determination unit 8b is configured by the same processor as the control unit 12a as a software processing functional block that executes a program stored in the storage unit 12b by the control unit 12a. In other words, the control unit 12a of the die casting machine 1 executes the program to function as the determination unit 8b of the wear condition measuring unit 8. The control device 12 may be provided with separate processors for the control unit 12a and the determination unit 8b.

[0075] The determination unit 8b determines the wear state of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal (intensity index data 22c) of the elastic wave measurement unit 8a. Specifically, the determination unit 8b is configured to determine the degree of wear of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal (intensity index data 22c) of the elastic wave measurement unit 8a.

[0076] In the first embodiment, the determination unit 8b acquires position information PI of the plunger tip 6a during movement by the injection drive unit 7. That is, the determination unit 8b acquires the X-axis position of the plunger tip 6a over time during the injection process based on the output signal of the position sensor 7c of the injection drive unit 7. The acquired position information PI is time-varying data of the X-axis position of the plunger tip 6a.

[0077] The determination unit 8b is configured to estimate the wear location of the injection sleeve 5 based on the output signal (intensity index data 22c) of the elastic wave measurement unit 8a during movement of the plunger tip 6a and the position information PI. Specifically, the determination unit 8b generates intensity index-position change data 22d indicating the change in intensity index for each X-axis position of the plunger tip 6a based on the intensity index data 22c (i.e., the time change in energy value) and the position information PI (the X-axis position of the plunger tip 6a at each time). As shown in FIG. 9, the intensity index-position change data 22d can be represented as graphs (graphs 41a and 41b) with the X-axis position coordinate of the plunger tip 6a on the horizontal axis and the intensity index (energy) on the vertical axis. The determination unit 8b then estimates the degree of wear for each position of the plunger tip 6a from the intensity index-position change data 22d.

[0078] The determination unit 8b acquires strength index-position change data 22d for each shot (each injection process) of the die-casting machine 1, and determines the wear state of the sliding part SP each time the strength index-position change data 22d is acquired. The determination unit 8b determines whether or not to issue an alert based on the wear state of the sliding part SP. If the wear state of the sliding part SP satisfies the alert condition, the determination unit 8b displays information on the display unit 13 of the control device 12 and issues an alert via the alarm 14. Upon receiving the alert, the worker considers whether or not to replace the sliding part SP, and if it is determined to be necessary, can replace at least one of the injection sleeve 5 and the plunger tip 6a.

[0079] <Example of Method for Determining Wear State> Hereinafter, an example of a method for determining the wear state of the sliding part SP by the determining unit 8b will be described.

[0080] Graph 41a shown in Fig. 9(A) is a plot of the strength index-position change data 22d acquired during the forward injection process in a state where the sliding part SP has worn out and needs to be replaced. Graph 41b shown in Fig. 9(B) is a plot of the strength index-position change data 22d acquired during the forward injection process in a normal state where the sliding part SP has not worn out, such as immediately after replacing the sliding part SP.

[0081] First, we will use graph 41b under normal conditions to explain the overall trend of the strength index-position change data 22d. During the injection forward movement process, when the plunger tip 6a begins to move forward from a stationary state at the standby position (the right end of graphs 41a and 41b), the strength index temporarily spikes upward due to a change from static friction to dynamic friction. Subsequently, during the low-speed forward movement process, the plunger tip 6a moves at a constant low speed, so the strength index remains roughly constant at a low level. When the plunger tip 6a reaches the high-speed switch position Cp and switches to the high-speed forward movement process, the strength index begins to rise as the movement speed of the plunger tip 6a changes. During the high-speed forward movement process, the pressure inside the injection sleeve 5 increases as the plunger tip 6a moves forward, which tends to increase the strength index. At the end of the high-speed forward movement process, the strength index also rises sharply due to a sudden increase in the reaction force transmitted from the cavity C via the molten metal M.

[0082] In graph 41a, where wear of the sliding part SP is progressing, spike-like (thorn-like) peaks 42 with clearly higher intensity than those in graph 41b are generated at multiple positions in the X direction. This indicates that "galling" or similar local wear has formed at the locations of the peaks 42 in the injection sleeve 5. Therefore, by setting threshold value Th1 to an intensity index value that is higher than the maximum intensity in graph 41b under normal conditions and that can distinguish peaks 42 in graph 41a, local wear of the injection sleeve 5 can be detected.

[0083] The judgment unit 8b judges the wear condition of the injection sleeve 5 (whether local wear has occurred and the location where the local wear has occurred) based on whether or not a peak 42 greater than a predetermined threshold value Th1 exists in the strength index-position change data 22d.

[0084] Furthermore, in graph 41a, where wear of the sliding part SP is progressing, the baseline 43 of the intensity waveform is elevated compared to graph 41b. In other words, in graph 41a, elastic waves EW of higher intensity than those of graph 41b are generated over the entire stroke range of the plunger tip 6a. This increase in the intensity index that is independent of the X-direction position of the plunger tip 6a is thought to be due to wear occurring on the sliding surface side of the plunger tip 6a, not on the injection sleeve 5. Therefore, wear of the plunger tip 6a can be detected by setting a threshold value Th2 to an intensity index value that can distinguish between the intensity of the baseline 43 in graph 41b and the intensity of the baseline 43 in graph 41a.

[0085] The determination unit 8b determines the wear state (whether or not wear has occurred) of the plunger tip 6a based on whether or not the baseline 43 of the strength index-position change data 22d is equal to or greater than a preset threshold value Th2.

[0086] In the example described above, the determination unit 8b determines the wear state from the strength index-position change data 22d during the forward injection stroke. Alternatively, the wear state may be determined from the strength index-position change data 22d during the return injection stroke shown in FIG. 3. During the return injection stroke, the molten metal M (see FIG. 4) is not contained within the injection sleeve 5, so deformation of the sliding part SP due to the molten metal temperature is suppressed, and the reaction force of the molten metal M does not act on the plunger tip 6a. Therefore, the waveform of the strength index-position change data 22d acquired during the return injection stroke differs from that shown in FIG. 9. Therefore, in another example, the determination unit 8b determines the wear state of the sliding part SP based on the strength index-position change data 22d during the return injection stroke in addition to the strength index-position change data 22d during the forward injection stroke. This makes it possible to detect wear states that cannot be grasped solely from the strength index-position change data 22d during the forward injection stroke, and improve the accuracy of wear state detection.

[0087] Furthermore, the method for determining the wear status of the sliding part SP is not limited to the above. For example, data (graph 41b) showing a normal state in which the sliding part SP is not worn may be stored in the memory unit 12b, and the wear status may be determined by comparing the stored normal data (graph 41b) with the strength index-position change data 22d acquired for each shot. Wear of the sliding part SP gradually progresses with each shot. Therefore, as the number of injections increases, the acquired strength index-position change data 22d approaches the waveform of graph 41a, which shows gradually advanced wear, from a waveform similar to that of graph 41b showing a normal state. Therefore, the determination unit 8b may determine the degree of wear by calculating, for example, the difference, deviation (similarity), or correlation function between the waveform of graph 41b showing a normal state and the waveform obtained from the acquired strength index-position change data 22d.

[0088] (Processing for Measuring Wear Condition of Sliding Part) The processing for measuring the wear condition of the sliding part SP by the determination unit 8b will be described with reference to Figure 10. The processing for measuring the wear condition is performed for each shot of the molding operation by the die-casting machine 1. The following flow is premised on the start of the timing when the molten metal M is poured into the injection sleeve 5 and, after pouring, the pouring port 5a is closed by the lid mechanism 10.

[0089] In step S1, the determination unit 8b starts elastic wave measurement simultaneously with the start of the injection process of the die casting machine 1. That is, when the control unit 12a starts controlling the injection sleeve 5 to execute the forward injection process, the determination unit 8b instructs the arithmetic unit 8d to start collecting an output signal from the AE sensor 22 of the elastic wave measuring unit 8a. The output signal from the AE sensor 22 is processed in each of the amplifier unit 8c and the arithmetic unit 8d, and is output to the determination unit 8b in the form of strength index data 22c (time change of the strength index, see FIG. 8 ).

[0090] After the injection forward step is completed in the die casting machine 1 and the molded product is removed from the mold 2 by mold opening, the injection return step is performed in the die casting machine 1. The determination unit 8b also acquires strength index data 22c for the injection return step from the calculation unit 8d.

[0091] In step S2, the determination unit 8b ends the elastic wave measurement upon completion of the injection return process of the die casting machine 1. Strictly speaking, the determination unit 8b performs two measurements, one during the forward injection process and one during the return injection process, or performs one measurement from the start of the forward injection process to the end of the return injection process.

[0092] In step S3, the judgment unit 8b generates intensity index-position change data 22d (see Figure 9) based on the measurement data of the elastic wave EW (intensity index data 22c) and the position information PI of the plunger tip 6a acquired by the position sensor 7c.

[0093] In step S4, the determination unit 8b determines the wear state of the sliding part SP based on the strength index-position change data 22d. As described above, the determination of the wear state includes determining the worn part of the injection sleeve 5 and the degree of wear at that worn part (whether or not the peak 42 is equal to or greater than the threshold value). The determination of the wear state also includes determining whether or not wear has occurred on the plunger tip 6a.

[0094] In step S5, the determination unit 8b determines whether or not to issue a notification based on the determination result of the wear state of the sliding part SP. The notification conditions are stored in advance in the storage unit 12b as setting information. Examples of the notification conditions include the detection of a set number (a predetermined number equal to or greater than one) of peaks 42 equal to or greater than the threshold value, or the intensity of the baseline 43 exceeding the threshold value Th2. The notification conditions may be set by combining other information other than the measurement data, such as the elapsed time since the last replacement of the sliding part SP or the cumulative number of shots.

[0095] If the determination unit 8b determines in step S5 that the notification conditions are satisfied, the process proceeds to step S6, where the determination unit 8b performs notification processing using one or both of the display unit 13 and the alarm 14, and then ends the determination processing. If the determination unit 8b determines in step S5 that the notification conditions are not satisfied, the determination processing ends without performing notification processing.

[0096] By performing each of the above steps for each injection process of the die-casting machine 1, the wear condition of the sliding part SP is notified to the worker when the wear condition meets the preset notification conditions.

[0097] (Effects of First Embodiment) The effects of the first embodiment will be described.

[0098] As described above, the first embodiment includes an elastic wave measuring unit 8a that measures the elastic waves EW propagating through the injection sleeve 5 when the plunger tip 6a moves. This allows for the measurement of high-frequency elastic waves EW generated by sliding between the plunger tip 6a and the injection sleeve 5 and propagating through the injection sleeve 5, thereby enabling the determination of changes in the elastic waves EW corresponding to the degree of wear on the sliding surfaces. Because the elastic waves EW generated by sliding propagate through the injection sleeve 5, even slight changes that cannot be measured as sliding noise transmitted through the air or changes in injection pressure can be detected. Furthermore, by including a determination unit 8b that determines the wear status of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal of the elastic wave measuring unit 8a, the wear status (progression of wear) can be determined from the output signal of the elastic wave measuring unit 8a. This allows the wear of the plunger tip 6a and the injection sleeve 5 to be determined with high accuracy.

[0099] Furthermore, in the first embodiment, as described above, the elastic wave measuring unit 8a includes the AE sensor 22 attached to the other end 21b of the propagation member 21 and measuring the elastic wave EW propagating from the injection sleeve 5 via the propagation member 21. As a result, instead of measuring the elastic wave EW propagated toward the mold holding unit 3 that holds the injection sleeve 5, for example, the elastic wave EW generated by the sliding between the plunger tip 6a and the injection sleeve 5 can be measured directly from the injection sleeve 5 using the propagation member 21. Furthermore, because the injection sleeve 5 becomes extremely hot (around 700°C in the first embodiment) when the molten metal M is supplied, it is difficult to attach even a heat-resistant sensor directly to the injection sleeve 5. Therefore, by propagating the elastic wave EW through the propagation member 21 that is in contact with the injection sleeve 5, the elastic wave EW can be measured while suppressing the influence of heat on the AE sensor 22.

[0100] Furthermore, in the first embodiment, as described above, the holding member 23 can be attached to the sleeve holding portion without contacting the injection sleeve 5, and is configured to urge one end 21a of the transmission member 21 toward the injection sleeve 5. This allows the holding member 23 to reliably maintain contact between the transmission member 21 and the injection sleeve 5. Furthermore, because the holding member 23 can be attached to the sleeve holding portion, which is part of the die-casting machine 1, there is no need to provide a separate base or the like for fixing the holding member 23 in a predetermined position. Furthermore, because the holding member 23 does not come into contact with the injection sleeve 5, the holding member 23 does not get in the way of the replacement work when replacing a worn injection sleeve 5.

[0101] Furthermore, in the first embodiment, as described above, the signal processing unit 34 is further provided, which calculates the intensity index (intensity index data 22c) of the elastic wave EW per unit time based on the output signal of the elastic wave measuring unit 8a acquired during the movement of the plunger tip 6a, and the determining unit 8b is configured to determine the degree of wear in at least one of the injection sleeve 5 and the plunger tip 6a based on the calculated intensity index. As a result, the degree of progress of wear can be accurately determined based on the change in the intensity index during the movement (sliding) of the plunger tip 6a, for example, from the appearance of a sudden spike-like peak 42 or the appearance of a significant displacement of the baseline 43.

[0102] Furthermore, in the first embodiment, as described above, the determination unit 8b is configured to acquire position information PI of the plunger tip 6a during movement by the injection drive unit 7, and estimate the worn portion of the injection sleeve 5 based on the output signal of the elastic wave measurement unit 8a during movement of the plunger tip 6a and the position information PI. This makes it possible to determine which portion of the injection sleeve 5 is experiencing wear. Therefore, it is possible to obtain useful information for considering adjustment of the assembly angles of the injection sleeve 5 and the injection drive unit 7 and optimization of injection operation control in order to suppress the progression of wear.

[0103] Furthermore, as described above, the first embodiment further includes an extraction processing unit 32 that extracts signal components corresponding to elastic waves EW of frequencies in the ultrasonic range from the output signal of the elastic wave measuring unit 8 a. As a result, since vibrations (displacement, chatter, etc.) generated during the injection operation and vibrations transmitted from other parts of the die-casting machine 1 have frequencies sufficiently lower than the ultrasonic range, such vibration components can be removed and signal components resulting from the sliding between the plunger tip 6 a and the injection sleeve 5 can be extracted, thereby improving the S / N ratio of the signal components related to the determination of the wear state.

[0104] Furthermore, in the first embodiment, as described above, the holding member 23 is attached to the sleeve holding portion 40 and includes the bracket 24 that holds the transmission member 21, and the urging member 25 that is provided between the bracket 24 and the transmission member 21 and urges one end 21 a of the transmission member 21 against the injection sleeve 5. This allows the transmission member 21 to be stably held by the bracket 24, and the urging member 25 urges the transmission member 21 against the bracket 24, making it possible to easily ensure contact between the one end 21 a of the transmission member 21 and the injection sleeve 5.

[0105] Furthermore, in the first embodiment, as described above, the biasing member 25 is a leaf spring that is disposed between the bracket 24 and the transmitting member 21 in a deformed state that biases the one end 21 a of the transmitting member 21 against the injection sleeve 5. This allows the bracket 24 to more stably hold the transmitting member 21 via the leaf spring, which has a relatively high rigidity.

[0106] Second Embodiment Next, a wear condition measuring unit 208 according to a second embodiment will be described with reference to FIG. 11 . In the second embodiment, unlike the first embodiment in which the AE sensor 22 is attached to the transmission member 21, an example will be described in which the AE sensor 22 is attached to a bracket 224 rather than to the transmission member 221. Note that parts similar to those in the first embodiment are given the same reference numerals, and description thereof will be omitted. The bracket 224 is an example of a "second bracket" in the claims. The wear condition measuring unit 208 is an example of a "wear condition measuring device" in the claims.

[0107] The wear condition measuring unit 208 includes an elastic wave measuring unit 208a and a determining unit 8b (see FIG. 2). The elastic wave measuring unit 208a is disposed on one side of the injection sleeve 5 in the Y direction. The elastic wave measuring unit may be disposed directly below the injection sleeve, for example. The determining unit 8b determines the wear condition of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal (strength index data 22c (see FIG. 2)) of the elastic wave measuring unit 208a.

[0108] The elastic wave measuring unit 208 a includes a propagation member 221 , an AE sensor 22 , a bracket 224 , and an adjustment member 226 .

[0109] The transmission member 221 is made up of a rod-shaped member. For example, the transmission member 221 is made up of a bolt, and the adjustment member 226 is made up of a nut that screws onto the bolt that is the transmission member 221. One end 21 a of the bolt that is the transmission member 221 abuts against the injection sleeve 5, and is arranged so as to extend in a direction perpendicular to the outer surface of the cylindrical injection sleeve 5.

[0110] The bracket 224 is attached directly to the sleeve holding portion 40, and is configured to directly hold the transmission member 221 and bring one end 21 a of the transmission member 221 into contact with the injection sleeve 5. The transmission member 221 is configured so that the transmission member 221, which is in contact with the injection sleeve 5, can be biased against the injection sleeve 5 by adjusting the screw engagement positions of the bolt and nut that constitute the transmission member 221.

[0111] In detail, the adjustment member 226 abuts against the bracket 224 from the injection sleeve 5 side and presses the bracket 224 in a direction away from the injection sleeve 5, causing elastic deformation. As a result, the bracket 224 generates a restoring force that biases the transmission member 221 toward the injection sleeve 5. The magnitude of the biasing force of the transmission member 221 can be adjusted by adjusting the screw engagement position of the adjustment member 226 (nut) relative to the transmission member 221 (bolt).

[0112] The bracket 224 is a plate member bent into an L-shape. The bracket 224 has a linear portion 224a extending linearly along the longitudinal direction (X direction) of the injection sleeve 5, and a linear portion 224b extending linearly in the lateral direction (Y direction) of the injection sleeve 5. The AE sensor 22 is attached to the linear portion 224a of the bracket 224. In the X direction, the AE sensor 22 is disposed closer to the linear portion 224b of the linear portion 224a. A bolt 27 for fixing the bracket 224 to the sleeve holding portion 40 is attached to the linear portion 224b.

[0113] The bracket 224 is formed so that the thickness T2 of a portion 224d that holds the transmitting member 221 is smaller than the thickness T1 of a portion 224c where the AE sensor 22 is attached (T1>T2).

[0114] That is, the straight portion 224a of the bracket 224 has a thick portion 224c to which the AE sensor 22 is attached and a thin portion 224d on the side that holds the transmitting member 221. The straight portion 224b of the bracket 224 is formed to have the same thickness as the thick portion 224c to which the AE sensor 22 is attached.

[0115] For example, the thickness T2 of the thin portion 224d on the side holding the propagation member 221 is smaller than half the thickness T1 of the thick portion 224c on which the AE sensor 22 is attached. As a specific example, the thickness T1 is 6 mm, and the thickness T2 is 1.2 mm. Therefore, the thin portion 224d on the side holding the propagation member 221 has a shape that is more easily elastically deformed than the thick portion 224c on which the AE sensor 22 is attached.

[0116] The other configurations of the second embodiment are similar to those of the first embodiment.

[0117] (Effects of the Second Embodiment) The effects of the second embodiment will be described.

[0118] As described above, the second embodiment includes an elastic wave measuring unit 208a that measures elastic waves propagating through the injection sleeve 5 when the plunger tip 6a moves. This makes it possible to grasp the wear of the plunger tip 6a and the injection sleeve 5 with high accuracy, similar to the first embodiment.

[0119] Moreover, as described above, the second embodiment further includes the sleeve holding unit 40 that fixes the injection sleeve 5 to the mold holding unit 3 while holding the injection sleeve 5, and the elastic wave measuring unit 208a includes a propagation member 221 having one end 21a that contacts the injection sleeve 5, a bracket 224 that is attached to the sleeve holding unit 40 and directly holds the propagation member 221 so that the one end 21a of the propagation member 221 abuts against the injection sleeve 5, and an AE sensor 22 that is attached to the bracket 224 and measures elastic waves propagating from the injection sleeve 5 via the propagation member 221. This allows the propagation member 221 to be directly held by the bracket 224, and allows the bracket 224 to have multiple functions, including a function of attaching it to the sleeve holding unit 40, a function of attaching the AE sensor 22, and a function of holding the propagation member 221. Therefore, the device configuration of the wear condition measuring unit 208 can be simplified compared to when the propagation member is indirectly held by a bracket or when the above functions are provided by multiple members separately.

[0120] Furthermore, in the second embodiment, as described above, the bracket 224 is formed so that the thickness T2 of the portion 224d on the side that holds the propagation member 221 is smaller than the thickness T1 of the portion 224c to which the AE sensor 22 is attached. This allows the thickness T2 of the portion 224d on the side of the bracket 224 that holds the propagation member 221 from the propagation member 221 to be made relatively thin, so that the elastic waves transmitted from the propagation member 221 to the bracket 224 vibrate the thin portion 224d of the bracket 224 relatively strongly, thereby improving the accuracy of elastic wave detection by the AE sensor 22.

[0121] Other effects of the second embodiment are similar to those of the first embodiment.

[0122] Third Embodiment Next, a wear condition measuring unit 308 according to a third embodiment will be described with reference to FIG. 12 . In the third embodiment, unlike the first embodiment in which the biasing member 25 is configured as a leaf spring, an example in which the biasing member 325 is configured as a compression coil spring will be described. Note that parts similar to those in the first embodiment are given the same reference numerals, and description thereof will be omitted. The wear condition measuring unit 308 is an example of a "wear condition measuring device" as defined in the claims.

[0123] The wear condition measuring unit 308 includes an elastic wave measuring unit 308a and a determining unit 8b (see FIG. 2). The elastic wave measuring unit 308a is disposed on one side of the injection sleeve 5 in the Y direction. The elastic wave measuring unit may be disposed directly below the injection sleeve, for example. The determining unit 8b determines the wear condition of at least one of the injection sleeve 5 and the plunger tip 6a based on the output signal (strength index data 22c (see FIG. 2)) of the elastic wave measuring unit 308a.

[0124] The elastic wave measuring unit 308 a includes a propagation member 21 , an AE sensor 22 , and a holding member 323 .

[0125] The holding member 323 includes a bracket 24 , a biasing member 325 , and an adjustment member 26 .

[0126] The transmission member 21 and the bracket 24 are both members bent into an L shape. The urging member 325 is formed of a compression coil spring. The urging member 325 is disposed between the bracket 24 and the transmission member 21 in a compressed state so as to urge one end 21 a of the transmission member 21 against the injection sleeve 5. The urging member 325 is attached to the bracket 24 by an adjustment member 26 (bolt and nut) without coming into contact with the injection sleeve 5.

[0127] A predetermined maximum value of the separation distance between the bracket 24 and the propagation member 21 is defined by an adjustment member 26 (bolt and nut). As the biasing member 325 expands and contracts when an elastic wave EW (see FIG. 4) is generated, the distance between the bracket 24 and the propagation member 21 varies within a range equal to or less than the predetermined maximum value of the separation distance.

[0128] The propagation member 21 has a linear portion 21c extending linearly along the longitudinal direction (X direction) of the injection sleeve 5, and a linear portion 21d including one end 21a and extending linearly in the lateral direction (Y direction) of the injection sleeve 5. The bracket 24 has a linear portion 24a extending linearly along the longitudinal direction (X direction) of the injection sleeve 5, and a linear portion 24b including one end 21a and extending linearly in the lateral direction (Y direction) of the injection sleeve 5. The AE sensor 22 is attached to the linear portion 21c of the propagation member 21. The linear portion 21c of the propagation member 21 and the linear portion 24a of the bracket 24 are arranged parallel to each other. A bolt 27 for fixing the bracket 24 to the sleeve holding portion 40 is attached to the linear portion 24b.

[0129] In the Y direction, the entire propagation member 21 is disposed closer to the injection sleeve 5 than the linear portion 24a of the bracket 24. The biasing member 325 is disposed between the linear portion 21c of the propagation member 21 and the linear portion 24a of the bracket 24, and is configured to expand and contract in the Y direction. In the X direction, the biasing member 325 is disposed closer to one end 21a of the linear portion 21c. In the X direction, the AE sensor 22 is disposed closer to the other end 21b of the linear portion 21c.

[0130] The other configurations of the third embodiment are similar to those of the first embodiment.

[0131] (Effects of the Third Embodiment) The effects of the third embodiment will be described.

[0132] As described above, the third embodiment includes an elastic wave measuring unit 308a that measures elastic waves propagating through the injection sleeve 5 when the plunger tip 6a moves. This makes it possible to grasp the wear of the plunger tip 6a and the injection sleeve 5 with high accuracy, similar to the first embodiment.

[0133] Furthermore, in the third embodiment, as described above, the holding member 323 is attached to the sleeve holding portion 40 and includes the bracket 24 that holds the transmission member 21, and the urging member 325 that is provided between the bracket 24 and the transmission member 21 and urges the one end 21 a of the transmission member 21 against the injection sleeve 5. This allows the transmission member 21 to be stably held by the bracket 24, and the urging member 325 can urge the transmission member 21 against the bracket 24, making it possible to easily ensure contact between the one end 21 a of the transmission member 21 and the injection sleeve 5.

[0134] Furthermore, in the third embodiment, as described above, the biasing member 325 is a compression coil spring that is arranged between the bracket 24 and the transmission member 21 in a compressed state so as to bias the one end 21a of the transmission member 21 against the injection sleeve 5. This makes it possible to make it less likely for vibrations to be transmitted between the bracket 24 and the transmission member 21 than when a biasing member with a relatively high rigidity is interposed between the bracket 24 and the transmission member 21, and therefore makes it possible to make it less likely for vibrations (noise) transmitted from the sleeve holding portion 40 side of the die casting machine 1 to which the bracket 24 is attached to be transmitted to the AE sensor 22 attached to the transmission member 21.

[0135] Other effects of the third embodiment are similar to those of the first embodiment.

[0136] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0137] For example, in the first to third embodiments, the die casting machine 1 is configured as a horizontal type, but the present invention is not limited to this. In the present invention, the die casting machine may be configured as a vertical type.

[0138] In the first to third embodiments, the determination unit 8b is configured as a software control block executed by the control unit 12a of the die-casting machine 1 (i.e., the control unit 12a and the determination unit 8b are configured by the same hardware), but the present invention is not limited to this. In the present invention, the determination unit 8b may be configured as a standalone determination processing device (computer) equipped with a processor that executes the determination process. The determination unit 8b may be provided in the arithmetic unit 8d.

[0139] In particular, in the first to third embodiments, the determination unit 8b is incorporated into the control device 12 of the die-casting machine 1, thereby configuring the wear condition measuring unit 8 as part of the die-casting machine 1. However, the determination unit 8b may be provided separately from the control device 12 of the die-casting machine 1, thereby configuring a wear condition measuring device independent of the die-casting machine 1. For example, the wear condition measuring device 107 shown in FIG. 13 includes an elastic wave measuring unit 8a and a determination unit 8b, and can be installed as a retrofit measuring device on an existing die-casting machine 101 that does not have a wear condition determination function. The determination unit 8b may output the wear condition to the control device 110 of the die-casting machine 101, or an alarm (not shown) provided in the wear condition measuring device 107 may issue a notification according to the wear condition.

[0140] In the first to third embodiments, the wear condition measuring unit 8 (see FIG. 2) is provided with the amplifier unit 8c, the calculation unit 8d, and the determination unit 8b separately, but the present invention is not limited to this. In the present invention, the wear condition measuring unit 8 may be configured as a single device including, for example, the amplifier unit 8c, the calculation unit 8d, and the determination unit 8b. Furthermore, the amplifier unit 8c and the calculation unit 8d may be configured as a single unit.

[0141] Furthermore, in the first to third embodiments, an example was shown in which the signal processing unit 34 (arithmetic unit 8d) that calculates the intensity index of the elastic wave EW is provided, but the present invention is not limited to this. In the present invention, the signal processing unit 34 (arithmetic unit 8d) does not have to be provided. The determination unit 8b may determine the wear state of the sliding part SP from the output signal 22a (output voltage value) of the AE sensor 22, which is the measurement data of the elastic wave EW itself, rather than the intensity index of the elastic wave EW.

[0142] In the first to third embodiments, an example was shown in which the extraction processing unit 32 was provided to extract signal components corresponding to elastic waves EW of frequencies in the ultrasonic range from the output signal 22a of the elastic wave measuring unit 8a (208a, 308a), but the present invention is not limited to this.

[0143] Furthermore, in the above-described first to third embodiments, an example was described in which the elastic wave measuring unit 8a (208a, 308a) included the propagation member 21 and the AE sensor 22, but the present invention is not limited to this. In the present invention, the propagation member 21 does not have to be provided in the elastic wave measuring unit 8a. Furthermore, in the present invention, the propagation member 21 does not have to be biased against the injection sleeve 5 by the holding member 23. For example, the injection sleeve 5 may be provided with a propagation piece having a shape similar to the propagation member 21 shown in FIG. 4 so as to protrude from the outer circumferential surface of the injection sleeve 5, and the AE sensor 22 may be attached to the propagation piece. Furthermore, the AE sensor 22 may be attached to the sleeve holding portion 40 that holds the injection sleeve 5. For example, the AE sensor 22 may be attached to the edge of the sleeve insertion opening 40c of the sleeve holding portion 40 to which the injection sleeve 5 is attached, and the elastic wave EW propagated to the portion that holds the injection sleeve 5 may be detected by the AE sensor 22.

[0144] In addition, in the first to third embodiments, an example has been shown in which one end 21a of the propagation member 21 has a concave shape that is curved along the outer circumferential surface of the injection sleeve 5, but the present invention is not limited to this. One end 21a of the propagation member 21 may be flat as shown in Fig. 14(A) or may have a convex curved surface as shown in Fig. 14(B).

[0145] Furthermore, in the above first to third embodiments, an example was shown in which the propagation member 21 contacts the side surface of the injection sleeve 5 in the Y direction, but the present invention is not limited to this. The contact position of the propagation member 21 on the injection sleeve 5 is arbitrary, and the propagation member 21 may contact the upper surface or lower surface of the injection sleeve 5. The contact position in the X direction is also arbitrary, and the propagation member 21 may contact a position other than near the pouring sprue 5a.

[0146] In addition, in the first to third embodiments, an example in which only one elastic wave measuring unit 8a (208a, 308a) is provided is shown, but the present invention is not limited to this. In the present invention, a plurality of elastic wave measuring units 8a may be provided.

[0147] Furthermore, in the first to third embodiments, the determination unit 8b determines the wear status of the sliding part SP from the strength index-position change data 22d for the entire injection forward movement process, including the low-speed forward movement process and the high-speed forward movement process. However, the present invention is not limited to this. In the present invention, the wear status may be determined from data for only a portion of the injection forward movement process. Experience has shown that wear of the injection sleeve 5 is more likely to progress in the region where the plunger tip 6a moves during the high-speed forward movement process than in the region where the plunger tip 6a moves during the low-speed forward movement process. In other words, since there is a high possibility that a wear area exceeding the threshold value will occur first in the region where the plunger tip 6a moves during the high-speed forward movement process, the determination unit 8b may determine the wear status only from the strength index-position change data 22d for the high-speed forward movement process.

[0148] Furthermore, in the above-described first to third embodiments, examples of the wear status determination method by the determination unit 8b include a method of determining the wear status based on whether the strength index exceeds a threshold value and a method of determining the wear status by comparing the strength index with normal strength index-position change data 22d (graph 41b) in which no wear has occurred. However, the present invention is not limited to these. In the present invention, for example, the determination unit 8b may determine the wear status using a trained model created by machine learning. Specifically, measurement data from the elastic wave measurement unit 8a (208a, 308a) is experimentally collected for each wear status of the sliding part SP, and a trained model is created in advance using the collected data groups for each wear status as training data to perform machine learning to output the wear status for the input data. The determination unit 8b may use this trained model to determine the wear status ascertained from the latest measurement data acquired from the elastic wave measurement unit 8a for each shot. The measurement data of the elastic wave EW acquired by the elastic wave measuring unit 8a is basically acquired by repeating the same injection process operation thousands or tens of thousands of times as the die-casting machine 1 operates, and is suitable for collection and processing as learning data for machine learning.

[0149] In addition, in the above first to third embodiments, examples have been shown in which the brackets 24, 224 are attached to the sleeve holding portion 40, but the present invention is not limited to this. In the present invention, the brackets may be attached to other components, such as a fixed die plate of a die holding portion, instead of the sleeve holding portion.

[0150] In the above embodiment, for convenience of explanation, the processing operation of the determination unit 8b is described using a flow-driven flowchart in which processing is performed in order according to a processing flow, but the present invention is not limited to this. In the present invention, the processing operation of the control unit may be performed by event-driven processing in which processing is performed on an event-by-event basis. In this case, the processing may be performed completely event-driven, or may be performed in a combination of event-driven and flow-driven.

[0151] REFERENCE SIGNS LIST 1 Die casting machine 2 Mold 3 Mold holding part 5 Injection sleeve 6a Plunger tip 7 Injection drive part 8, 208, 308 Wear condition measuring part (wear condition measuring device) 8a, 208a, 308a Elastic wave measuring part 8b Determination part 21, 221 Propagation member 21a One end 21b Other end 22 AE sensor (elastic wave detection sensor) 22a, 22b Output signal 22c Strength index data 22d Strength index-position change data 23, 323 Holding member 24 Bracket (first bracket) 25, 325 Pressing member 32 Extraction processing part 34 Signal processing part 40 Sleeve holding part 107 Wear condition measuring device 224 Bracket (second bracket) 224c (AE sensor attached) part 224d Part (on the side holding the transmitting member) C Cavity EW Elastic wave M Molten metal PI Position information T1 Thickness (of the part where the AE sensor is attached) T2 Thickness (of the part holding the transmitting member)

Claims

1. A wear condition measuring device for measuring the wear condition of an injection sleeve and a plunger tip in a die casting machine comprising: a mold holding section for holding a mold having a cavity, a cylindrical injection sleeve into which molten metal is supplied, a plunger tip arranged slidably within the injection sleeve and for injecting the molten metal supplied to the injection sleeve into the cavity, and an injection drive section for moving the plunger tip back and forth within the injection sleeve, the wear condition measuring device comprising: an elastic wave measuring section for measuring elastic waves propagating through the injection sleeve as the plunger tip moves; and a judgment section for judging the wear condition of at least one of the injection sleeve and the plunger tip based on an output signal from the elastic wave measuring section, the elastic wave measuring section including a propagation member having one end in contact with the injection sleeve and the other end remote from the injection sleeve.

2. A wear condition measuring device as described in claim 1, wherein the elastic wave measuring unit includes an elastic wave detection sensor attached to the other end side of the propagation member and measuring elastic waves propagating from the injection sleeve via the propagation member.

3. A wear condition measuring device as described in claim 2, further comprising: a sleeve holding portion that fixes the injection sleeve to the mold holding portion while holding the injection sleeve; and a holding member that holds the transmission member, wherein the holding member can be attached to the sleeve holding portion or the mold holding portion without contacting the injection sleeve, and is configured to bias the one end of the transmission member against the injection sleeve.

4. A wear condition measuring device as described in claim 1, further comprising a signal processing unit that calculates an intensity index of elastic waves per unit time based on the output signal of the elastic wave measuring unit acquired during movement of the plunger tip, and the judgment unit is configured to judge the degree of wear in at least one of the injection sleeve and the plunger tip based on the calculated intensity index.

5. A wear condition measuring device as described in any one of claims 1 to 3, wherein the judgment unit is configured to acquire position information of the plunger tip during movement by the injection drive unit, and to estimate the wear location of the injection sleeve based on the output signal of the elastic wave measuring unit and the position information during movement of the plunger tip.

6. A wear condition measuring device as described in any one of claims 1 to 3, further comprising an extraction processing unit that extracts signal components corresponding to elastic waves of frequencies in the ultrasonic range from the output signal of the elastic wave measuring unit.

7. The wear condition measuring device as described in claim 3, wherein the holding member includes: a first bracket attached to the sleeve holding portion or the mold holding portion and holding the transmission member; and a biasing member provided between the first bracket and the transmission member and biasing the one end of the transmission member against the injection sleeve.

8. A wear condition measuring device as described in claim 7, wherein the biasing member is a leaf spring arranged between the first bracket and the transmission member in a deformed state in which the biasing member biases the one end of the transmission member against the injection sleeve, or a compression coil spring arranged between the first bracket and the transmission member in a compressed state in which the biasing member biases the one end of the transmission member against the injection sleeve.

9. A wear condition measuring device as described in claim 1, further comprising a sleeve holding part that fixes the injection sleeve to the mold holding part while holding it, and the elastic wave measuring part includes: a second bracket that is attached to the sleeve holding part or the mold holding part and directly holds the propagation member to abut the one end of the propagation member against the injection sleeve; and an elastic wave detection sensor that is attached to the second bracket and measures elastic waves propagating from the injection sleeve via the propagation member.

10. A wear condition measuring device as described in claim 9, wherein the second bracket is formed so that the thickness of the portion holding the transmission member is smaller than the thickness of the portion on which the elastic wave detection sensor is attached.

11. A die casting machine comprising: a mold holding section for holding a mold having a cavity; a cylindrical injection sleeve into which molten metal is supplied; a plunger tip arranged to be slidable within the injection sleeve and for injecting the molten metal supplied to the injection sleeve into the cavity; an injection drive section for moving the plunger tip back and forth within the injection sleeve; an elastic wave measuring section for measuring elastic waves propagating through the injection sleeve as the plunger tip moves; and a judgment section for judging a wear condition of at least one of the injection sleeve and the plunger tip based on an output signal from the elastic wave measuring section, wherein the elastic wave measuring section includes a propagation member having one end in contact with the injection sleeve and the other end remote from the injection sleeve.

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