Injection pressure measuring device, injection pressure measuring method, and molding system

Abstract

To provide a device capable of correctly measuring injection pressure without adding a manual special operation.SOLUTION: An injection pressure measurement device comprises: an extrusion pin (21) facing molds (14, 15) and extruding a molded body from the molds (14, 15); a servo motor (35) as a driving source of the extrusion pin (21); and a controller (5) for controlling the driving of the servo motor (35). The controller (5) obtains the injection pressure (IP) of the molten raw material of the molded body charged to a cavity (16) of the molds based on the torque of the servo motor (35) produced by the pressing of the extrusion pin (21) by the molten raw material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for measuring the pressure in a molten material, such as a molten metal or molten resin, injected into a cavity of a mold. [Background technology]

[0002] For example, in die casting, the pressure generated inside the cavity when molten metal is injected into the mold cavity determines the quality of the casting. Therefore, it is necessary to determine this injection pressure at die casting sites. The injection pressure is calculated based on the pressure value measured by a pressure gauge attached to the cylinder head and rod that injects the molten metal, or based on the strain value measured by a strain gauge or load cell attached to the plunger rod or ejector cylinder rod. The latter method can determine the injection pressure more accurately than the former. However, the latter method requires various manual procedures, such as installing the strain gauge or load cell.

[0003] Patent Document 1 discloses a pressure detection device that can determine whether or not filling of a mold cavity with molten metal is complete. However, the pressure detection device in Patent Document 1 does not determine completion of filling by directly detecting a high filling pressure, but rather by detecting a low air pressure compared to the filling pressure, and does not determine injection pressure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-132679 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an apparatus that can accurately measure injection pressure without requiring special manual work. [Means for solving the problem]

[0006] The injection pressure measuring device according to the present invention comprises: an ejector pin that faces a mold and ejects a molded body from a cavity of the mold; The ejector pin is driven by a servo motor, and the servo motor is controlled by a controller. The controller according to the present invention determines the injection pressure of the molten material based on the torque of the servo motor generated when the molten material of the molding filled in the cavity presses against the ejector pin.

[0007] The injection pressure measuring device according to the present invention preferably includes a display that displays the injection pressure based on instructions from the controller.

[0008] The display according to the present invention preferably displays the current required injection pressure for the mould in progress or displays previously determined injection pressures.

[0009] The display according to the invention preferably displays the injection pressure as a diagram, or It is displayed as a representative value of the injection pressure.

[0010] The injection pressure measuring device according to the present invention preferably includes a servo motor that outputs a rotational driving force, and a motion conversion mechanism that is interposed between the servo motor and the ejector pin and converts the rotational driving force of the servo motor into linear motion.

[0011] In the injection pressure measuring device according to the present invention, the mold is preferably a mold for die-casting of a metal material or a mold for injection molding of a resin material, and the molten raw material is preferably a molten metal for die-casting or a molten resin for injection molding.

[0012] The present invention provides a method for measuring the injection pressure in a mold cavity of a molten raw material for a molding that is filled into the cavity. This injection pressure measurement method includes a first step of detecting the torque generated in a servo motor, which is the driving source of an ejector pin that pushes the molded body out of the cavity of the mold, and a second step of calculating the injection pressure based on the torque detected in the first step.

[0013] The present invention also provides a molding system comprising any one of the injection pressure measuring devices described above, a mold clamping device that performs opening and closing operations on a mold, and an injection device that injects molten raw material for a molded body into a cavity of the mold. [Effects of the Invention]

[0014] The present invention is premised on the premise that the ejector pin is driven by a servo motor, and the injection pressure can be calculated based on the torque of the servo motor generated when the molten material of the molded body presses against the ejector pin. In other words, according to the present invention, the injection pressure is calculated based on the torque generated in the servo motor by the molten material directly acting on the ejector pin, so the calculated injection pressure is highly accurate. Moreover, if a servo motor equipped with a torque detection function is used, special manual work such as attaching a strain gauge to calculate the injection pressure is not required. Furthermore, since the torque of the servo motor reflects even minute changes in the injection pressure, the calculated injection pressure is accurate. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a partial cross-sectional view showing a schematic configuration of a die-casting system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of the die-casting system of FIG. 1. [Figure 3] 2 is a diagram showing an example of the operation of the die-casting system of FIG. 1. [Figure 4] 2 is a diagram showing the torque and rotational speed generated in the servomotor and the actual measured position of the extrusion plate during forward and backward movements in the extrusion operation of the casting in the die casting system of FIG. 1. FIG. [Figure 5] 2 is a diagram showing the torque and rotation speed generated in the servo motor and the measured position of the ejector plate from the start of injection to before mold opening in the die-casting system of FIG. 1. FIG. [Figure 6] 2 is a table showing an example of data stored in a controller of the die-casting system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. This embodiment is an example in which the present invention is applied to a die-casting system 1, which calculates the injection pressure IP caused by the injection of molten metal into a cavity 16 based on the torque T generated in a servo motor 35 that is the drive source for an ejector pin 21. This torque T is the load caused by the injection pressure IP of the ejector pin 21 on the servo motor 35 whose rotation is stopped. The die-casting system 1 will be described below with reference to FIGS. 1 to 6.

[0017] [Die-casting system 1: Schematic diagram: Figure 1] As shown in FIG. 1, the die-casting system 1 mainly comprises a mold clamping unit 2 and an injection unit 3. In this embodiment, the description will focus mainly on the mold clamping unit 2, which is involved in the injection pressure IP. Therefore, only one part of the injection unit 3, the injection sleeve 4, is shown in FIG. 1. The injection sleeve 4 injects the molten metal to be injected into a cavity 16 formed between a fixed mold 14 and a movable mold 15. The die-casting system 1 also comprises a controller 5 that controls the operation of the mold clamping unit 2 and the injection unit 3. However, since this embodiment focuses on determining the injection pressure IP from the torque T generated in the servo motor 35, i.e., on the injection pressure measurement device and method, the function of the controller 5 will be described below, focusing mainly on determining the injection pressure IP.

[0018] [Clamping unit 2: Figure 1] As shown in FIG. 1 , the mold clamping unit 2 includes a fixed platen 12 and a movable platen 13, which respectively support a pair of fixed and movable dies 14 and 15 for obtaining a casting of a desired shape. The mold clamping unit 2 opens and closes the fixed and movable dies 14 and 15. A housing space 13A is provided inside the movable platen 13, which houses and supports an ejection mechanism 20 (described below). A cavity 16 having a shape corresponding to the desired casting is formed between the fixed and movable dies 14 and 15. Molten metal injected from the injection sleeve 4 passes through a runner 17 provided between the fixed and movable dies 14 and 15 and fills the cavity 16. By filling the cavity 16 with molten metal such as aluminum or an aluminum alloy, a casting corresponding to the molded product of the present invention is obtained. Note that the molten metal is not shown in FIG. 1 and other figures. The fixed platen 12 and the movable platen 13 are provided on a base 19. The fixed platen 12 is fixed in position, but the movable platen 13 can be moved back and forth relative to the fixed platen 12 by a drive source (not shown), such as a hydraulic cylinder or an electric motor.

[0019] [Extrusion mechanism 20: Figure 1, Figure 2] As shown in Figures 1 and 2, an ejection mechanism 20 is provided on the side of the movable platen 13 and the movable mold 15. The ejection mechanism 20 pushes the casting from the side of the movable mold 15 to remove the casting from the cavity 16. The ejection mechanism 20 uses a servo motor 35 as its drive source.

[0020] As shown in FIGS. 1 and 2, the pushing mechanism 20 includes a pushing pin 21 and a pushing plate 23 to which a rear end 21B of the pushing pin 21 is fixed and which is reciprocally movable in the front-rear direction. The ejector pins 21 are made of a metal material, such as stainless steel, and pass through the movable mold 15 so that their tips 21F face the cavity 16. Although four ejector pins 21 are shown here, this is merely an example, and fewer than four or five or more ejector pins 21 may be provided. The ejector plate 23 is reciprocatable based on the rotational driving force of the servo motor 35, and fixes the rear ends 21B of the ejector pins 21. Therefore, when the ejector plate 23 moves forward, the ejector pins 21 also move forward, and when the ejector plate 23 moves backward, the ejector pins 21 also move backward. Note that "forward" here refers to movement in the direction to push out the casting, that is, to the right in Figure 1, and "retraction" here refers to movement in the direction away from the cavity 16, that is, to the left in Figure 1.

[0021] 1 and 2, the push-out mechanism 20 includes a first fixed body 25 that slidably supports a push-out pin 21 that penetrates in the front-rear direction, and a second fixed body 27 that rotatably supports the rear end side of the ball screw shaft 31. A push-out plate 23 is provided between the first fixed body 25 and the second fixed body 27, and the push-out plate 23 is capable of reciprocating in the front-rear direction between the first fixed body 25 and the second fixed body 27.

[0022] The first fixed body 25 is disposed and fixed in the accommodation cavity 13A of the movable platen 13. The first fixed body 25 slidably supports the ejector pin 21, and also rotatably supports the front end side of the ball screw shaft 31, which will be described later. This support is achieved via a first bearing 26, which is fixed to the center of the first fixed body 25 and is made of, for example, a ball bearing. The second fixed body 27 is disposed and fixed to the rear end side of the movable platen 13. The second fixed body 27 rotatably supports the rear end side of the ball screw shaft 31 via a second bearing 28, which is, for example, a ball bearing, fixed to the center of the second fixed body 27.

[0023] 1 and 2, the push-out mechanism 20 includes a ball screw 29 that converts the rotational driving force of the servo motor 35 into linear motion to move the push-out plate 23 in the front-to-rear direction. In other words, the push-out mechanism 20 includes the ball screw 29 as a motion conversion mechanism of the present invention that is interposed between the servo motor 35 and the push-out pin 21. The ball screw 29 is composed of a ball screw shaft 31 and a ball screw nut 33. The balls are not shown. The ball screw shaft 31 penetrates the ejector plate 23, and its front end is rotatably supported by the first fixed body 25 via a first bearing 26, while its rear end is rotatably supported by the second fixed body 27 via a second bearing 28. Note that the portions of the ball screw shaft 31 that are supported by the first bearing 26 and the second bearing 28 do not necessarily have to be threaded. The ball screw nut 33 is fixed to the center of the ejector plate 23, and the ball screw shaft 31 penetrates through it. The ball screw shaft 31 and the ball screw nut 33 have a conventionally known configuration. For example, when the ball screw shaft 31 rotates clockwise, the ball screw nut 33 advances, and when the ball screw shaft 31 rotates counterclockwise, the ball screw nut 33 retracts. The advancement or retraction of the ball screw nut 33 advances or retracts the ejector plate 23 and the ejector pin 21.

[0024] 1 and 2, the ejection mechanism 20 includes a servo motor 35 that is a drive source for the ejector pins 21, an output shaft 36 of the servo motor 35, and a driven shaft 41 that is connected to the ball screw shaft 31 and transmits the rotational drive force of the servo motor 35 to the ball screw shaft 31. The servo motor 35 is fixed to the rear end side of the movable platen 13. A drive pulley 37 is journaled on the output shaft 36, and a driven pulley 39 is journaled on the driven shaft 41. A belt 43 that transmits the drive force is wound around the drive pulley 37 and the driven pulley 39. The servo motor 35 needs to have a function for detecting the torque T generated, and this torque T is sent to the controller 5 together with the rotation speed R. As long as the servo motor 35 has the function for detecting the torque T, other requirements for the servo motor 35 are optional.

[0025] [Extrusion operation of extrusion mechanism 20: Figure 3] Next, the extrusion operation of the extrusion mechanism 20 will be described with reference to FIG. Fig. 3(a) shows the mold clamping device 2 in a casting state, and Fig. 3(b) shows the state after casting in which the movable platen 13 and movable mold 15 are retracted relative to the fixed platen 12 and fixed mold 14 to open the molds. Note that the casting is not shown in Figs. 3(a) and (b). In the casting state, as shown in Figure 3(a), the tip of the ejector pin 21 remains in a position along the edge of the cavity 15A of the movable mold 15, but in the mold open state, as shown in Figure 3(b), the tip side of the ejector pin 21 protrudes into the inside of the cavity 15A of the movable mold 15, thereby pushing the casting out of the cavity 15A.

[0026] [Controller 5: Figure 1, Figure 4, Figure 5, Figure 6] Next, the controller 5 will be described. The controller 5 has elements necessary for executing a procedure for calculating the injection pressure IP (pressure calculation procedure), which will be described with reference to Fig. 4 etc. These elements include a program for executing the pressure calculation procedure. These elements also include detection and storage of the torque T (measurement data) of the servo motor 35, which is necessary for executing the pressure calculation procedure. 1, the controller 5 is provided with a display 6. The display 6 displays various data in accordance with instructions from the controller 5. Examples of the data to be displayed include those shown in FIGS. 4 to 6.

[0027] [Data obtained by the controller 5 from the ejector pin: Figures 4 and 5] Next, data that the controller 5 can obtain regarding the ejector pin 21 will be described with reference to FIGS. The ejector pins 21 are operated by a servo motor 35 to push out the casting. Therefore, the controller 5 can detect the rotation speed R and torque T of the servo motor 35 with respect to the ejector pins 21 during the ejection operation. Furthermore, because the position of the ejector pins 21 is moved during the ejection operation, the controller 5 can detect the actual position PP of the ejector plate 23 that operates the ejector pins 21. Based on the above, data acquired by the controller 5 during the operation to eject the casting will be described with reference to Figure 4, and then data acquired by the controller 5 before the ejection operation begins, from the start of injection to before the mold is opened, will be described with reference to Figure 5.

[0028] [Pushing operation in which the ejector pin 22 moves back and forth: Figure 4] As shown in Figure 4, the ejection operation includes a forward movement of the ejector pin 21 to push the casting out of the cavity, and a backward movement after the casting has been pushed out. In other words, the ejector pin 21 reciprocates during this movement. Figure 4 shows the rotation speed R and torque T of the servo motor 35, as well as the measured position PP of the ejector plate 23, as a diagram, and this diagram can be displayed, for example, instantly on the display 6 in response to a command from the controller 5. The same applies to the diagram in Figure 5, which will be explained next. During forward movement, the rotation speed R of the servo motor 35 is increased or decreased so that the ejector pin 21 (push plate 23) moves forward a predetermined distance. During backward movement, the rotation speed R of the servo motor 35 is increased or decreased so that the ejector pin 21 (push plate 23) moves backward a predetermined distance. The torque T varies during acceleration, deceleration, and constant speed movement of the servo motor 35, and the torque T becomes "0" while the servo motor 35 is stopped between forward movement and backward movement. When there are a plurality of ejector pins 21, the torque T can be the total value of the plurality of pins, or can be the average value.

[0029] [The ejector pin 21 remains in its fixed position from the start of injection to mold opening: Figure 5] Next, similar data from the start of injection to mold opening will be described with reference to Figure 5. However, during this time, the ejector pin 21 remains in a fixed position and the servo motor 35 is stopped. At this fixed position, the tip 21F of the ejector pin 21 is along the edge of the cavity 15A, as shown in Figure 3(a). Thus, even though no drive command is issued to the servo motor 35, the torque T rises and continues to rise. The rotation speed R of the servo motor 35 and the measured position PP of the ejector pin 21 remain near zero. Therefore, it is presumed that this rise in torque T is the torque T generated to maintain the ejector pin 21 in its fixed position. This is because there are no other factors that generate torque. Therefore, the injection pressure IP can be calculated based on the torque T obtained by the controller 5 from the start of injection to mold opening. Here, in the die-casting system 1, when the injection pressure IP is generated in the cavity 16 between the fixed mold 14 and the movable mold 15, the injection pressure IP is transmitted to the output shaft 36 of the servo motor 35 via a path consisting of the following mechanical elements, causing the servo motor 35 to generate torque T. Therefore, in this embodiment, the injection pressure IP can be calculated by calculating the thrust Fa of the ball screw 29. [Routes consisting of mechanical elements] Injection pressure IP → ejector pin 21 → ejector plate 23 → ball screw 29 → driven shaft 41 → driven side pulley 39 → driving side pulley 37 → output shaft 36 of servo motor 35

[0030] According to this embodiment, the injection pressure IP is calculated based on the torque T generated in the servo motor 35 by the molten metal directly acting on the ejector pin 21, so the calculated injection pressure is highly accurate. Moreover, because the servo motor 35 is equipped with a function for detecting the torque T, no special manual work such as attaching a strain gauge to calculate the injection pressure IP is required. Furthermore, because the torque T of the servo motor 35 reflects even minute changes in the injection pressure, the calculated injection pressure IP is accurate. Furthermore, according to this embodiment, the injection pressure IP can be constantly detected during the casting process.

[0031] When the ejector pin 21 receives the injection pressure IP, a thrust force Fa is generated in the ball screw 29. This thrust force Fa can be calculated by the following equation (1). The injection pressure IP can also be calculated by the following equation (2). The controller 5 has a program for executing equations (1) and (2). When the torque T is detected from the servo motor 35 (first step), the controller 5 executes equations (1) and (2) to calculate the injection pressure IP (second step). The injection pressure IP can be calculated immediately after the torque T is acquired, or the torque T can be stored in the memory area of ​​the controller 5 and then calculated after a predetermined period of time has passed. The injection pressure IP calculated immediately can be displayed on a graph together with the torque T, etc., as shown in FIG. 5, and may also be stored in the memory area of ​​the controller 5. The graph of the injection pressure IP calculated immediately can be displayed on the display 6 immediately, or it may be stored in the controller 5 and displayed on the display 6 as needed.

[0032] Fa=2·π·η·T / (L×10 -3 )…Formula (1) IP=Fa / A 21 …Formula (2)

[0033] Fa: Generated thrust (N), T: Torque of servo motor 35 (N m) η: Efficiency of ball screw 29, L: Lead of ball screw 29 (mm) IP: Injection pressure (MPa) A 21 : Total area of ​​the tip of the ejector pin 21 (mm 2 )

[0034] Examples of the torque T and injection pressure IP stored in the controller 5 are shown in FIGS. 6(a), (b), and (c). Of these, Figure 6(a) shows an example with the smallest amount of data, in which the date of molding (DATE), identification information (ch ID) that specifies the molding, the measured extrusion position, the rotation speed of the servo motor 35, and the torque T generated in the servo motor 35 are stored in correspondence with each other. The measured extrusion position, motor rotation speed, and torque T in Figure 6(a) are each representative values ​​from the start of injection to the mold opening. The representative value is typically an average value, but other values ​​such as the maximum value, minimum value, and standard deviation can also be used as representative values.

[0035] Next, in the case of the stored data group shown in Figure 6(a), the torque T from that data group is substituted into equations (1) and (2) to calculate the injection pressure IP. In this configuration, the data group is stored during casting, and the torque T is later calculated using that data group. In contrast, for the data group stored in Figure 6(b), the injection pressure IP is calculated using the torque T from that data group during casting. Figure 6(c) includes three values ​​measured for the torque T: the minimum value (min), maximum value (max), and average value (ave). Including the minimum and maximum values ​​in addition to the average value allows for a more advanced evaluation of the injection pressure IP. The representative values ​​of the injection pressure IP, torque T, etc. shown in Figures 6(a), (b), and (c) may be displayed on the display 6 immediately, or may be stored in the controller 5 and then displayed on the display 6 when necessary.

[0036] [effect] The effects achieved by the die-casting system 1 according to this embodiment will be described below. The die-casting system 1 uses a servo motor 35 as a drive source for the ejector pin 21. It has been discovered that the molten metal (molten raw material) filling the cavity 16 of the mold presses the ejector pin 21, generating a torque T in the servo motor 35, and the injection pressure IP of the molten raw material is calculated based on this torque T. In this way, the injection pressure IP is calculated based on the torque T generated in the servo motor 35 by the molten metal acting directly on the ejector pin 21, so the calculated injection pressure is highly accurate. Moreover, since the servo motor 35 is equipped with a function to detect the torque T, no special manual work such as attaching a strain gauge to calculate the injection pressure IP is required. Furthermore, the torque of the servo motor reflects even minute changes in the injection pressure, so the calculated injection pressure is accurate.

[0037] The die-casting system 1 includes a display 6 that displays the injection pressure IP based on instructions from the controller 5. Therefore, according to the die-casting system 1, by referring to the display 6, the injection pressure IP can be clearly recognized visually.

[0038] The display 6 may show the injection pressure IP required for the molding currently in progress, or may show an injection pressure IP determined in the past. Therefore, with this die-casting system 1, the injection pressure IP for the molding currently in progress can be recognized in real time and an appropriate response can be made. Furthermore, with this die-casting system 1, past injection pressures IP can be recognized retroactively, allowing evaluation of past injections.

[0039] The injection pressure IP displayed on the display 6 may be a line diagram or a representative value. A line diagram makes it easier to recognize the time-varying trend of the injection pressure IP, while a representative value makes it easier to make a numerical evaluation, such as whether the set value has been exceeded. In this case, if the set value is also displayed, it can be used to correct the set value thereafter.

[0040] In addition to the above, the configurations given in the above embodiments can be selected or changed as appropriate to other configurations without departing from the spirit of the present invention. For example, in the above embodiment, the rotationally driven servo motor 35 is exemplified, and the rotational driving force of the servo motor 35 is converted into linear motion using the ball screw 29, but the present invention can use a linear servo motor that moves linearly. In this case, it is possible to omit a motion conversion mechanism such as the ball screw 29 that converts the rotational driving force into linear motion.

[0041] Furthermore, while the above embodiments have exemplified die-casting for metal materials as a molding apparatus, the present invention can also be applied to injection molding for resin materials. Similar to die-casting, injection molding also includes a fixed platen, a movable platen, a fixed mold, and a movable mold, with a cavity formed between the fixed and movable molds. Molten resin is injected into the cavity, and the molded body obtained by solidification in the cavity is ejected with an ejector pin after the fixed and movable molds are opened, similar to die-casting. Furthermore, in injection molding, the ejector pin of the molded body receives injection pressure IP from the molten resin during injection molding in the cavity. [Explanation of symbols]

[0042] 1. Die-casting system 2 Mold clamping device 3 Injection device 4 Injection sleeve 5 Controller 6. Display 12 Fixed plate 13 Movable plate 13A Storage Cavity 14 Fixed mold 14A cavity 15 Movable mold 15A cavity 16 cavities 17 Yudo 19 Foundation 20 Extrusion mechanism 21 ejector pin 21B rear end 21F Tip 23 Extrusion Plate 25 First fixed body 26 First bearing 27 Second fixed body 28 Second bearing 29 Ball screw 31 Ball screw shaft 33 Ball screw nut 35 Servo motor 36 Output shaft 37 Drive pulley 39 Driven pulley 41 Driven axis 43 Belt IP injection pressure T Torque R rotation speed PP actual position

Claims

1. an ejector pin facing the mold and ejecting the molded body from the cavity of the mold; a servo motor that serves as a drive source for the ejector pin and outputs a rotational drive force; a ball screw mechanism interposed between the servo motor and the ejector pin, which converts the rotational driving force of the servo motor into linear motion; a controller that controls the driving of the servo motor, The controller an injection pressure measuring device for measuring an injection pressure of the molten raw material, characterized in that the injection pressure of the molten raw material is calculated based on the following formulas (1) and (2) relating to a thrust force Fa generated in the ball screw of the ball screw mechanism, which is generated when the molten raw material of the molded body filled in the cavity presses against the ejector pin, and a torque T of the servo motor: Fa=2・π・η・T / (L×10 −3 )…Formula (1) IP=Fa / A 21...Formula (2) Fa: Generated thrust (N), T: Servo motor torque (N m) η: Efficiency of the ball screw mechanism, L: Lead of the ball screw (mm) IP: Injection pressure (MPa) A21: Total area of ​​the tip of the ejector pin (mm2)

2. a display that displays the injection pressure based on an instruction from the controller; 2. The injection pressure measuring device according to claim 1.

3. The display includes: an instantaneous display of the required injection pressure for the ongoing moulding, or Displaying the previously determined injection pressure; 3. The injection pressure measuring device according to claim 2.

4. The display includes: Displaying the injection pressure as a diagram, or Display as a representative value of the injection pressure.

4. The injection pressure measuring device according to claim 2 or 3.

5. A plurality of the extrusion pins; a pusher plate supporting the plurality of pusher pins, The linear motion by the ball screw mechanism is applied to the pusher plate. The injection pressure measuring device according to any one of claims 1 to 4.

6. the mold is a mold for die-casting of a metal material or a mold for injection molding of a resin material, The molten raw material is the molten metal for die casting or the molten resin for injection molding. The injection pressure measuring device according to any one of claims 1 to 5.

7. A method for measuring an injection pressure in a cavity of a mold of a molten raw material for a molding product filled in the cavity, comprising: a first step of detecting torque generated in a servo motor that is a drive source of an ejector pin that ejects the compact from the cavity of the mold; a second step of determining the injection pressure based on the torque detected in the first step, In the first step, the rotational driving force of the servo motor is applied to the ejector pin as a linear motion via a ball screw mechanism, the second step of calculating the injection pressure of the molten raw material based on the following equations (1) and (2) relating to the thrust force Fa generated in the ball screw of the ball screw mechanism and the torque T of the servo motor: Fa=2・π・η・T / (L×10 −3 )…Formula (1) IP=Fa / A 21...Formula (2) Fa: Generated thrust (N), T: Servo motor torque (N m) η: ball screw efficiency, L: ball screw lead (mm) IP: Injection pressure (MPa) A21: Total area of ​​the tip of the ejector pin (mm2)

8. The injection pressure measuring device according to any one of claims 1 to 6, a mold clamping device that performs opening and closing operations on the mold; an injection device that injects the molten raw material of the molded body into the cavity of the mold, A molding system comprising:

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