Injection device

Abstract

This invention relates to an injection device (1) for injection molding of materials, comprising: a screw (13) that is rotated around a rotation axis (12) and retracted in the axial direction; an injection motor (21) that is the driving source for the retraction of the screw (13); a motion conversion mechanism (41) including a lead screw (42) that rotates together with the rotational motion of the injection motor (21) and a nut (43) disposed inside the lead screw (42), and converting the rotational motion of the injection motor (21) into linear motion in the axial direction; a metering motor (31) that is the driving source for the rotation of the screw (13); and a driving force transmission component (51) connected to the screw (13) for transmitting the force based on... The rotational driving force of the metering motor (31) and the forward and backward driving force of the lead screw shaft (42) based on the motion conversion mechanism (41) are respectively transmitted to the screw (13); and the axial force detection unit (61) detects the axial force acting on the screw (13) in the axial direction. The axial force detection unit (61) has: an annular axial force sensor (62) configured to rotate relative to the screw (13) and the driving force transmission member (51) around the rotation axis (12) of the screw (13); and a rotation limiting member (63) that limits the rotation of the axial force sensor (62) relative to the rotation of the screw (13) and the driving force transmission member (51).

Description

Technical Field

[0001] This invention relates to an injection device that uses a screw to inject and mold materials, and in particular to a technique that helps to improve the detection accuracy of the axial force acting on the screw. Background Technology

[0002] The injection unit used in injection molding machines uses a screw to meter and inject molding materials such as resin. The screw is driven by a metering motor to rotate and by an injection motor to move forward and backward.

[0003] Typically, during metering, a screw driven by a metering motor rotates, melting a predetermined amount of molding material and feeding it to the front end of the cylinder. During injection, a screw driven by an injection motor advances, injecting the predetermined amount of molding material fed to the front end of the cylinder during metering into the mold assembly. Then, as a pressure holding process, the screw is sometimes advanced further by the injection motor to apply the required pressure to the molding material within the mold assembly.

[0004] When the injection motor of an injection device outputs rotational motion as a rotary motor, a motion conversion mechanism is used to convert this rotational motion into axial linear motion of the screw. For example, Patent Document 1 describes an injection device that, as such a motion conversion mechanism, includes a lead screw that rotates using the rotational motion of the injection motor and a nut disposed inside the lead screw. Furthermore, a drive force transmission member is disposed between the metering motor and the injection motor and the screw, which is used to transmit the rotational drive force from the metering motor and the axial forward / reverse drive force transmitted from the injection motor via the motion conversion mechanism to the screw, respectively.

[0005] However, an axial force sensor is provided in the injection device, which detects, for example, the axial force acting on the screw in the axial direction during the pressure holding process, as the reaction force borne by the screw from the molding material.

[0006] The axial force sensor does not rotate with the screw, and the closer its installation position is to the screw, the higher the accuracy of axial force detection, making it a preferred option. However, in injection devices like the one described above, where the transmission path of driving force from the injection motor and metering motor to the screw is complex, it is not easy to install the axial force sensor near the screw without rotating it.

[0007] In this regard, Patent Document 1 proposes an injection device having a "pressure detector disposed between the rotating moving shaft and the drive shaft" and a "rotation limiting mechanism for limiting the rotation of the pressure detector".

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-47576 Summary of the Invention

[0011] The technical problem to be solved by the invention

[0012] In Patent Document 1, the "pressure detector" is "distributed between the rotating moving shaft and the drive shaft." From the viewpoint of further improving the detection accuracy of axial force, this "pressure detector" still has room for improvement.

[0013] The present invention addresses this problem and aims to provide an injection device capable of detecting the axial force acting on the screw with relatively high accuracy.

[0014] means for solving technical problems

[0015] An injection molding apparatus capable of solving the above-mentioned problems comprises: a screw, which is rotated around a rotation axis and is driven to move forward and backward in the axial direction; an injection motor, which is the source of the forward and backward movement of the screw; a motion conversion mechanism, which includes a lead screw that rotates together with the rotational movement of the injection motor and a nut disposed inside the lead screw, and converts the rotational movement of the injection motor into linear motion in the axial direction; a metering motor, which is the source of the rotational movement of the screw; a drive force transmission member, which is connected to the screw and transmits the rotational drive force based on the rotational movement of the metering motor and the forward and backward drive force based on the linear motion of the lead screw of the motion conversion mechanism to the screw respectively; and an axial force detection unit, which detects the axial force acting on the screw in the axial direction, the axial force detection unit having: an annular axial force sensor configured to rotate relative to the screw and the drive force transmission member around the rotation axis of the screw; and a rotation limiting member that limits the rotation of the axial force sensor relative to the rotation of the screw and the drive force transmission member.

[0016] The effects of the invention

[0017] The aforementioned injection device can detect the axial force acting on the screw with relatively high accuracy. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view along the axial direction of an injection device according to one embodiment of the present invention.

[0019] Figure 2 It is an enlarged representation Figure 1 A cross-sectional view of the main parts of the injection device.

[0020] Figure 3 It means in Figure 2 A cross-sectional view of the state after the screw is advanced in the injection device.

[0021] Figure 4 This is a cross-sectional view showing an injection device according to another embodiment.

[0022] Figure 5 It means Figure 1 An enlarged cross-sectional view of the connection between the screw and the drive force transmission component of the injection device.

[0023] Figure 6 This is a cross-sectional view showing the connection between the screw and the drive force transmission component of an injection device according to another embodiment.

[0024] Figure 7 It means in Figure 1 A cross-sectional view of the step of removing the axial force detection unit from the injection device.

[0025] Figure 8 This indicates that the subsequent Figure 7 A cross-sectional view of the steps.

[0026] Figure 9 This indicates that the subsequent Figure 8 A cross-sectional view of the steps.

[0027] Figure 10 This indicates that the subsequent Figure 9 A cross-sectional view of the steps. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0029] Figure 1 The injection device 1 illustrated herein is, for example, mounted on a sliding base 101 of a moving device that moves the injection device 1 forward and backward in an injection molding machine, and injects molding material into a mold assembly. In this embodiment, the injection device 1 includes: a screw 13, which is rotatably driven about a rotation axis 12 inside a cylinder 11, and axially ( Figure 1 The screw 13 is driven to move forward and backward in the left and right directions; the injection motor 21 is the driving source for the forward and backward movement of the screw 13; and the metering motor 31 is the driving source for the rotation of the screw 13. The rotational driving force from the metering motor 31 and the forward and backward driving force from the injection motor 21 are respectively transmitted to the screw 13 through the driving force transmission path.

[0030] (Screw)

[0031] The screw 13 has a rotating shaft 12 extending from the inside of the metering motor 31 into the cylinder 11. A spiral scraper is provided around its main body 13a, which is mainly located inside the cylinder 11. Furthermore, the front end 13b of the screw inside the cylinder 11 is tapered towards the axially upward front side, and the base end 13c of the screw is located inside the metering motor 31 and connected to the driving force transmission path.

[0032] Furthermore, here, the direction along the rotation axis 12 of the screw 13 will be referred to as the axial direction, which is in Figure 1 The center corresponds to the left and right direction. Along the axial direction of screw 13, the front end 13b side of the screw ( Figure 1 The left side in the middle is regarded as the front side, and the screw base end 13c side ( Figure 1 The right side of the middle is considered the rear side.

[0033] (Injection motor and metering motor)

[0034] The injection motor 21 and the metering motor 31 can be configured, for example, to be supported on the rear side of the screw 13 in the axial direction by the injection motor support member 22 and the metering motor support member 32 erected on the sliding base 101. The injection motor support member 22 and the metering motor support member 32 are connected to each other at multiple locations around the metering motor 31 by rods 24, 25, etc.

[0035] Both the injection motor 21 and the metering motor 31 are rotary motors that output rotational motion, and each can include: rotors 21a and 31a as rotors; stators 21b and 31b as stators, including coils disposed on the outer periphery of the rotors 21a and 31a; and stator frames 21c and 31c, with the stators 21b and 31b mounted on their inner surfaces. Furthermore, bearing portions 21d and 31d can be provided between the rotors 21a and 31a and the stator frames 21c and 31c. An encoder 25b is provided on the rear end face of the stator frame 21c of the injection motor 21, and this encoder 25b is connected to the rotor 21a via a shaft portion 25a to detect the rotation of the rotor 21a.

[0036] The metering motor 31 is located further forward than the injection motor 21 in the axial direction of the screw 13, and is configured such that the drive force transmission path passes through its inner side.

[0037] (Drive force transmission path)

[0038] In the injection device 1 of this embodiment, the driving force transmission path is mainly configured to include: a motion conversion mechanism 41, which converts the rotational motion of the injection motor 21 into linear motion in the axial direction of the screw 13; and a driving force transmission component 51, which is connected to the screw base end 13c of the screw 13, and transmits the rotational driving force based on the rotational motion of the metering motor 31 and the forward and backward driving force based on the linear motion converted by the motion conversion mechanism 41 to the screw 13 respectively.

[0039] The motion conversion mechanism 41 includes: a lead screw 42 that rotates together with the rotational motion of the injection motor 21; and a nut 43, on the inner side of the lead screw 42. In this example, the nut 43 is fixedly installed on the cylinder 22a, which connects the stator frame 21c of the injection motor 21 to the injection motor support component 22.

[0040] The lead screw shaft 42 is splined to the inner circumferential surface of a cylindrical rotating component 23 located on the inner circumferential side of the rotor 21a of the injection motor 21 via a lead screw shaft base end 42a. It rotates within the nut 43 using the rotational motion generated by the injection motor 21, allowing it to move forward or backward axially. A key 42b is provided on the outer circumferential surface of the lead screw shaft base end 42a, and a corresponding keyway is provided on the inner circumferential surface of the cylindrical rotating component 23. Thus, the rotational motion of the injection motor 21 is converted into linear motion axially.

[0041] However, the motion conversion mechanism is not limited to the motion conversion mechanism shown in the figure, which is splinedly connected to the cylindrical rotating part 23 on the side of the injection motor 21, as long as it includes a lead screw and a nut and can convert the rotational motion of the injection motor 21 into linear motion.

[0042] The driving force transmission component 51 can, for example, be structured as described below. In this embodiment, as... Figure 2 As shown, the drive force transmission component 51 disposed inside the metering motor 31 has: a cylindrical body portion 52 surrounding the front end portion 42c of the lead screw shaft 42 that protrudes axially from the nut 43 to the front side; and a front end wall portion 53, which is provided to cover the opening on the front side of the cylindrical body portion 52 in the axial direction.

[0043] The lead screw shaft front end 42c can be connected to the rear axial side of the front end wall 53 of the drive force transmission component 51 via a bearing 54, such as an self-aligning thrust roller bearing or other thrust bearing. Thus, the lead screw shaft front end 42c can rotate relative to the drive force transmission component 51. Furthermore, the inner ring of the bearing 54 is mounted on the lead screw shaft front end 42c, and the outer ring of the bearing 54 is mounted on the front end wall 53. A key 52a is provided on the outer circumferential surface of the cylindrical main body 52 of the drive force transmission component 51, which fits into the keyway on the inner circumferential surface of the rotor 31a of the metering motor 31, thereby spline-connecting the cylindrical main body 52 and the rotor 31a.

[0044] On the other hand, the screw 13 is connected to the front side of the front end wall 53 of the driving force transmission component 51 in the axial direction via the screw base end 13c.

[0045] If the drive force transmission component 51 is structured as described above, it can rotate together with the rotational motion of the metering motor 31, and independently of this rotation, it can move linearly along with the linear motion of the lead screw shaft 42 of the motion conversion mechanism 41. Thus, the rotational driving force based on the rotational motion of the metering motor 31 and the forward / backward driving force based on the linear motion of the lead screw shaft 42 of the motion conversion mechanism 41 are effectively transmitted to the screw 13 connected to the drive force transmission component 51.

[0046] (Axial Force Detection Department)

[0047] However, when injection molding is performed using an injection molding machine, in the injection unit 1, the metering motor 31 rotates the screw 13, thereby melting the molding material and feeding it to the front end of the cylinder 11 for metering. Then, the injection motor 21 advances the screw 13, injecting the molding material from the front end of the cylinder 11 into the mold unit. Next, the injection motor 21 advances the screw 13 further to maintain pressure on the molding material within the mold unit, applying a predetermined pressure.

[0048] During pressure holding and other processes, it is necessary to detect the axial force acting on the screw 13 in the axial direction. In order to detect the axial force acting on the screw 13, the injection device 1 is equipped with an axial force sensor.

[0049] The axial force sensor can also be located at the rear of the aforementioned drive force transmission path in the axial direction, for example, at the location of the cylinder 22a between the injection motor 21 and the injection motor support member 22. However, in this case, the axial force is transmitted from the screw 13 to the axial force sensor via the drive force transmission member 51, which is particularly capable of spline engagement with the metering motor 31 side, and the detection accuracy of the axial force will decrease due to the sliding resistance between the metering motor 31 side and the drive force transmission member 51. Alternatively, even if the axial force sensor is located inside the drive force transmission member 51 between it and the front end 42c of the lead screw shaft, the axial force detected by the axial force sensor may still include the same sliding resistance of the drive force transmission member 51, and therefore the desired high-precision detection result may not be obtained. Therefore, the axial force sensor is preferably located closer to the screw 13.

[0050] On the other hand, near the screw 13, when the driving force transmission component 51, which transmits the rotational driving force by the metering motor 31, and the screw 13 rotate, the axial force sensor also rotates along with this rotation, and the detection accuracy of the axial force sensor for the axial force will decrease.

[0051] In this case, in the illustrated embodiment, the axial force detection unit 61 that detects the axial force acting on the screw 13 in the axial direction includes: a washer-type force sensor or other annular axial force sensor 62, configured to rotate relative to the screw 13 and the drive force transmission member 51 around the rotation axis 12 of the screw 13; and a rotation limiting member 63 that limits the rotation of the axial force sensor 62 relative to the rotation of the screw 13 and the drive force transmission member 51.

[0052] In this way, the axial force sensor 62 is positioned axially ahead of the drive force transmission component 51, between it and the screw 13, and near the screw 13. Therefore, when detecting the axial force from the screw 13, it is almost unaffected by the sliding resistance of the drive force transmission component 51 in the drive force transmission path. Furthermore, the rotation of the axial force sensor 62 is restricted by the rotation limiting component 63 relative to the screw 13 and the drive force transmission component 51. As a result, the axial force sensor 62 can be used to detect axial force with high accuracy.

[0053] Here, the rotation limiting member 63 can, for example, limit the rotation of the axial force sensor 62 by connecting the axial force sensor 62 to a component that does not rotate together with the screw 13 and the drive force transmission member 51. Figure 2 , 3 The rotation limiting member 63 illustrated in the figure connects the axial force sensor 62 to the metering motor support member 32, thereby limiting the rotation of the axial force sensor 62 that may occur due to the rotation of the screw 13 and the drive force transmission member 51.

[0054] More specifically, a sliding hole 33 is provided on the metering motor support member 32, into which the rotation limiting member 63 is inserted. The shape of the sliding hole 33 for the rotation limiting member 63 can be appropriately determined to correspond to the shape of the rotation limiting member 63, so that the rotation limiting member 63 inserted therein can slide axially. As shown, the rotation limiting member 63 can be, for example, a cylindrical shape such as a cylinder surrounding the rotation shaft 12 of the screw 13. Alternatively, although not shown, the rotation limiting member 63 can also be one or more rods or plates extending axially on the outer periphery of the rotation shaft 12 of the screw 13, or a plurality of rods or plates spaced apart from each other in the circumferential direction.

[0055] Regardless of the shape of the rotation limiting member 63 described above, it is preferably axially slidable within the sliding hole 33 of the metering motor support member 32. Thus, for example, when the forward / reverse driving force in the forward direction is transmitted from the injection motor 21 to the screw 13 via the driving force transmission member 51, as... Figure 3 As shown, the rotation limiting member 63 can slide within the sliding hole 33 and advances together with the axial force sensor 62 between the driving force transmission member 51 and the screw 13. When the forward and backward driving force is transmitted to the screw 13, as... Figure 2 As shown, the rotation limiting member 63 and the axial force sensor 62 retract together with the driving force transmission member 51 and the screw 13. During this forward and backward movement, the sliding hole 33 restricts the circumferential displacement of the rotation limiting member 63 inserted therein towards the rotation axis 12, thus limiting the rotation of the rotation limiting member 63 and the axial force sensor.

[0056] In addition, at this time, such as Figure 3 As shown, the axially forward portion of the rotation limiting member 63 may sometimes penetrate the metering motor support member 32 and protrude further axially forward than the metering motor support member 32. However, the presence or absence of this protrusion and the amount of protrusion are preferably designed with consideration of the configuration relationship with surrounding components. Furthermore, the illustrated sliding hole 33 penetrates the metering motor support member 32 axially, but it can also be a sliding hole that does not penetrate the metering motor support member axially.

[0057] The rotation limiting component is not limited to the rotation limiting component that connects the axial force sensor 62 to the metering motor support component 32 as described above. For example, in Figure 4 In the axial force detection unit 161 of the other embodiments shown, a rotation limiting member 163 is provided to connect the axial force sensor 162 to the stator frame 31c of the metering motor 31.

[0058] As an example, Figure 4The rotation limiting member 163 has a shape including a cylindrical portion 163a extending axially from the axial force sensor 162 and a flange-like portion 163b extending axially from the front end of the cylindrical portion 163a to the outer periphery of the stator frame 31c. The stator frame 31c is fixedly mounted to the rear side of the metering motor support member 32 in the axial direction. By connecting the axial force sensor 62 to the stator frame 31c, the rotation limiting member 163 can perform the function of limiting the rotation of the axial force sensor 62.

[0059] Furthermore, by allowing the cylindrical portion 163a, which is configured as a rotation limiting member 163, to slide axially relative to the flange portion 163b, the axial force sensor 162 can move forward or backward together with the drive force transmission member 51 and the screw 13 when transmitting the forward or backward driving force. Regarding the structure of the axial force detection unit 161 other than the rotation limiting member 163, Figure 4 The implementation method can be compatible with Figure 2 , 3 The embodiments shown are essentially the same. Instead of the rotation limiting member 163, which includes the cylindrical portion 163a and the flange portion 163b, it can be a rod-shaped or plate-shaped rotation limiting member that is provided at one or more locations in the circumferential direction of the rotation shaft 12 and is bent along the axial direction.

[0060] When the axial force sensor 62 transmits and receives signals and / or is powered via a wired connection, such as Figure 2 , 3 As shown by the dashed line, the wiring 64 of the axial force sensor 62 included in the axial force detection unit 61 can extend from the axial force sensor 62, for example, inside the rotation limiting member 63, through the sliding hole 33 along the rotation limiting member 63. This prevents the wiring 64 from being cut or damaged during the rotation and forward / backward displacement of the surrounding drive force transmission member 51 and screw 13. Furthermore, in axial force sensors that communicate wirelessly and are powered without contact, this wiring can be omitted.

[0061] The drive force transmission component 51 is configured to rotate relative to the axial force sensor 62, therefore, as Figure 5 As shown in the enlarged view, the bearing 55 can be positioned between the front end wall 53 and the axial force sensor 62, thereby connecting the bearing 55 to the axial force sensor 62. The bearing 55 effectively supports the axial force sensor 62 axially from behind the axial force sensor 62, which transmits axial force through the screw 13. Therefore, a thrust bearing is preferred, and a self-aligning thrust roller bearing that is self-aligning and unaffected by installation errors is more preferred.

[0062] The illustrated axial force sensor 62 has an outer annular portion 62a protruding towards the rearward side on the outer periphery of its rearward side surface. Furthermore, a central bulge 53a protruding towards the frontward side is provided on the front end wall 53 of the drive force transmission member 51. The inner ring of the bearing 55 is mounted between the front end surface of the drive force transmission member 51 and the central bulge 53a, and the outer ring is mounted between the rearward side surface of the axial force sensor 62 and the outer annular portion 62a. Thus, when the inner ring of the bearing 55 is mounted on the front end wall 53 of the drive force transmission member 51 and the outer ring is mounted on the axial force sensor 62, the axial force sensor 62, configured as shown, is more reliably supported axially by the front end wall 53 of the drive force transmission member 51, thereby further improving the axial detection accuracy of the axial force sensor 62.

[0063] However, in the illustrated example, a connecting cylinder portion 53b extending axially is provided on the central raised portion 53a of the front end wall portion 53 of the drive force transmission member 51. On the other hand, the rotation shaft 12 of the screw 13 is such that the shaft end portion 12a of the screw base end portion 13c is inserted into the connecting cylinder portion 53b. These connecting cylinder portions 53b and shaft end portions 12a constitute a coupling portion that transmits rotational drive force from the drive force transmission member 51 to the screw 13, serving as the connection points between the screw 13 and the drive force transmission member 51.

[0064] Furthermore, in this embodiment, such as Figure 5 As shown, the screw 13 has a connecting flange 14 at its base end 13c. This connecting flange 14 is fixedly mounted on the rotating shaft 12 and extends outward from the rotating shaft 12 to hold the connecting cylinder portion 53b inside. For example, even when the screw 13 is retracted (so-called back suction) after pressure holding or metering, the connecting flange 14 reliably connects the screw 13 and the drive force transmission component 51 in the axial direction to prevent the screw 13 from moving too far away from the drive force transmission component 51.

[0065] The connecting flange 14 may include, for example, a flange portion 15, which is inserted into the rotating shaft 12 for connection and extends outward into an annular shape; and an annular portion 16, which engages with the rearward side of the flange portion 15 in the axial direction and surrounds the outer periphery of the connecting cylinder portion 53b. The flange portion 15 has an outer engaging portion 15a that extends from the outer periphery to the rearward side in the axial direction and is bent inward, and the annular portion 16 has an inner engaging portion 16a that extends from the inner periphery to the frontward side in the axial direction and is bent outward. The flange portion 15 and the annular portion 16 are engaged by these outer engaging portions 15a and inner engaging portions 16a. In addition, in order to facilitate disassembly during maintenance of the axial force detection unit 61 described later, the connecting flange 14 is preferably composed of flange portions 15, etc., which are made of two or more detachable parts, thereby allowing for detachable installation relative to the rotating shaft 12.

[0066] When the screw 13 has a connecting flange 14 as described above, the axial force sensor 62 can be positioned around the shaft end 12a and the connecting cylinder portion 53b between the connecting flange 14 of the screw 13 and the front end wall portion 53 of the drive force transmission member 51.

[0067] At this time, by positioning the bearing 17 between the annular portion 16 of the connecting flange 14 and the axial force sensor 62, the screw 13 and the axial force sensor 62 can be connected via the connecting flange 14 to be rotatable relative to each other. For the same reasons as described above for the bearing 55 between the drive force transmission component 51 and the axial force sensor 62, this bearing 17 between the connecting flange 14 and the axial force sensor 62 is preferably a thrust bearing, especially a self-aligning thrust roller bearing.

[0068] To more reliably transmit axial force from the connecting flange 14 to the axial force sensor 62, it is preferable to mount the inner ring of the bearing 17 between the connecting flange 14 and the axial force sensor 62 onto the axial force sensor 62, and to mount the outer ring of the bearing 17 onto the annular portion 16 of the connecting flange 14. Furthermore, in this example, the inner ring of the bearing 17 is mounted between the axially forward front surface of the axial force sensor 62 and the inner annular portion 62b provided on the inner periphery of the front surface and protruding forward. Additionally, a cylindrical protrusion 16b protruding rearward in the axial direction is formed on the outer edge of the annular portion 16 of the connecting flange 14, and the outer ring of the bearing 17 is supported by this cylindrical protrusion 16b.

[0069] In the illustrated embodiment, the axial force sensor 62 is supported by a bearing 17 between itself and the connecting flange 14 via an inner annular portion 62b, and by a bearing 55 between itself and the front end wall portion 53 of the drive force transmission member 51 via an outer annular portion 62a. Thus, the portion of the annular axial force sensor connected to the connecting flange 14 of the screw 13 via the bearing 17 is located further inward than the portion connected to the front end wall portion 53 of the drive force transmission member 51 via the bearing 55.

[0070] Furthermore, it is preferable to allow the shaft end 12a of the screw 13 and the connecting flange 14 and the connecting cylinder 53b to be axially displaced relative to each other, so that the axial force transmitted from the screw 13 to the connecting flange 14 via the rotating shaft 12 can be more reliably transmitted to the axial force sensor 62 between the connecting flange 14 and the front end wall 53.

[0071] Specifically, for example, a key and a keyway can be provided on the outer peripheral surface of the shaft end 12a and the inner peripheral surface of the connecting cylinder 53b, respectively. Furthermore, a key and a keyway can be provided on the outer peripheral surface of the connecting cylinder 53b and the inner peripheral surface of the annular portion 16 of the connecting flange 14, and these can be splined together. Additionally, small axial gaps C1 and C2 are provided between the end face of the shaft end 12a and the bottom surface of the connecting cylinder 53b, and between the peripheral surface of the opening of the connecting cylinder 53b and the connecting flange 14, respectively. As a result, the screw 13 can achieve a certain relative displacement in the axial direction relative to the driving force transmission member 51. The axial force acting on the screw 13 is effectively transmitted to the axial force sensor 62 between the connecting flange 14 and the driving force transmission member 51, thus enabling the axial force sensor 62 to detect the axial force with higher accuracy.

[0072] Furthermore, if the screw 13 does not have a connecting flange 14 as described above, it is possible to... Figure 6 As shown in the embodiment, an axial force transmission flange 214 is fixedly provided at the screw base end 13c of the rotating shaft 12 of the screw 13. The axial force transmission flange 214 is connected to the axial force sensor 62 via a bearing 17, allowing relative rotation. Figure 6 In this configuration, the shaft end 12a and the connecting cylinder 53b are connected by a spline joint, and gaps C1 and C2 are respectively provided between the shaft end 12a and the connecting cylinder 53b, and between the axial force transmission flange 214 and the connecting cylinder 53b. This allows axial force to be effectively transmitted from the screw 13 to the axial force sensor 62 via the axial force transmission flange 214. Except for replacing the connecting flange 14 with the axial force transmission flange 214, Figure 6 The embodiment has a structure that is substantially the same as the embodiment described above. Preferably, the axial force transmission flange 214 is composed of two or more disassembleable parts, thereby allowing it to be detachably mounted relative to the rotation shaft 12.

[0073] However, as Figures 1-3 As shown in embodiments 5 and 6, when the axial force sensor 62 is connected to the metering motor support member 32 by the rotation limiting member 63 of the axial force detection unit 61, the sensor connection portion of the metering motor support member 32 that connects to the axial force sensor 62 via the rotation limiting member 63 can also be integrated with the motor support portion supporting the metering motor 31. However, in order to facilitate maintenance of the axial force detection unit 61 as described later, it is preferable, as shown in the illustrated embodiment, to configure the sensor connection portion 32b of the metering motor support member 32 as separate from the frame-shaped motor support portion 32a, and to allow for detachment from the motor support portion 32a. In this case, as described above, the sensor connection portion 32b with the sliding hole 33 can be provided, and the shape of the rotation limiting member 63 can be taken into account, such as a rod-shaped, plate-shaped, or cylindrical shape, and thus be cylindrical or the like.

[0074] In addition, such as Figure 1 As shown, the metering motor support member 32 has a cylinder support 32c detachably mounted on the front side of the frame-shaped motor support 32a in the axial direction. The cylinder support 32c is provided with a hole 32d for the screw 13 to pass through. Although not shown in the figure, a cooler based on water cooling or the like can be provided near the supply port for supplying molding material into the cylinder 11 on the cylinder support 32c.

[0075] The aforementioned injection device 1, for example, is disassembled as follows when replacing the axial force sensor 62 or performing maintenance on other axial force detection units 61. First, the cylinder support 32c is removed from the cylinder body 11 along with the motor support 32a of the metering motor support component 32, thereby... Figure 7 As shown, the screw 13 is exposed.

[0076] Next, while the rotation limiting member 63 slides within the sliding hole 33, as... Figure 8 As shown, the sensor connection part 32b is detached from the motor support part 32a of the metering motor support component 32.

[0077] In this way, access to the screw base end 13c is possible, and the flange portion 15 of the connecting flange 14 on the screw base end 13c is disassembled and removed from the screw 13. The connection between the screw 13 and the drive force transmission member 51 is then released, and the shaft end 12a of the rotating shaft 12 of the screw 13 is pulled out from the connecting sleeve portion 53b of the drive force transmission member 51, thus becoming... Figure 9 The state shown.

[0078] Then, by disassembling the remaining annular portion 16 and bearing 17 of the connecting flange 14, the axial force sensor 62 and rotation limiting member 63 of the axial force detection unit 61 can be removed. Thus, it becomes... Figure 10 The state shown.

[0079] When this disassembly is performed, the metering motor 31, the drive force transmission component 51, and the injection motor 21 side portion can be removed without separation. Therefore, according to this embodiment, as described above, by placing the axial force detection unit 61 near the screw 13 inside the injection device 1, the accuracy of axial force detection can be improved while maintenance of the axial force detection unit 61 can be performed relatively quickly and easily. Furthermore, after disassembling the injection device 1 in this way, it can be reassembled by performing the reverse steps described above.

[0080] (Cylinder block)

[0081] A screw 13 is disposed inside the cylinder 11, and molding material supplied to the cylinder from a feed port (not shown) is melted by heating and rotation of the screw 13. A heater 18 is disposed around the cylinder 11 to heat the molding material inside.

[0082] The cylinder 67 has a nozzle 19 with a smaller inner and outer diameter on the front side in the axial direction, and a heater 18 is also arranged around the nozzle 19.

[0083] (The operation of the injection device)

[0084] The injection device 1 described above is mounted on an injection molding machine and can operate as described below to perform each process during injection molding.

[0085] In the metering process of the previous injection molding, the specified amount of molding material has been metered and placed inside the cylinder 11. Then, the mold closing process is performed to close the mold device (not shown) to achieve the mold closing state.

[0086] Next, the following steps are performed in sequence: a filling process, in which molding material is injected into the mold device by advancing the screw 13, and molding material is filled into the cavity of the mold device; and a pressure holding process, in which the screw 13 is advanced further to maintain the molding material inside the nozzle 19 of the cylinder 11 at a specified pressure.

[0087] Then, a cooling process is performed, in which the molding material filled in the mold device is cooled and solidified to obtain a molded product. At this time, a metering process is performed, in which the molding material supplied to the cylinder 11 is fed towards the nozzle 19 of the cylinder 11 by the rotation of the screw 13, and is melted by the heating of the heater 18, and a predetermined amount of molding material is placed in the nozzle 19.

[0088] After the cooling process, an extraction process is performed, in which the mold device is opened to the open state, and the molded product is removed from the mold device using an ejector or similar device.

[0089] Symbol Explanation

[0090] 1-Injection device, 11-Cylinder, 12-Rotating shaft, 12a-Shaft end, 13-Screw, 13a-Screw body, 13b-Screw front end, 13c-Screw base end, 14-Connecting flange, 214-Axial force transmission flange, 15-Flange, 15a-Outer fitting part, 16-Annular part, 16a-Inner fitting part, 16b-Cylindrical protrusion, 17-Bearing, 18-Heater, 19-Nozzle, 21-Injection motor, 31-Metering motor, 21a, 31a-Rotor, 21b, 31b-Stator, 21c, 31c-Stator frame, 21d, 31d-Bearing part, 22-Injection motor support component, 22a-Cylinder, 23-Cylindrical rotating component, 24, 25-Rod, 25a-Shaft, 25b-Encoder, 32-Metering motor support Components, 32a-motor support, 32b-sensor connection, 32c-cylinder support, 32d-hole, 33-sliding hole, 41-motion conversion mechanism, 42-lead screw shaft, 42a-lead screw shaft base end, 42b-key, 42c-lead screw shaft front end, 43-nut, 51-drive force transmission component, 52-cylindrical main body, 52a-key, 53-front end wall, 53a-central raised part, 53b-connecting cylinder, 54, 55-bearings, 61, 161-axial force detection part, 62, 162-axial force sensor, 62a-outer annular part, 62b-inner annular part, 63, 163-rotation limiting component, 163a-cylindrical part, 163b-flange part, 64-wiring, 67-cylinder, 101-sliding base, C1, C2-clearance.

Claims

1. An injection device for injection molding material, and comprising: The screw is driven to rotate around a rotation axis and is driven to move forward and backward in the axial direction; The injection motor is the driving source for the screw's forward and backward movement. The motion conversion mechanism includes a lead screw that rotates together with the rotational motion of the injection motor and a nut disposed on the inner side of the lead screw, and converts the rotational motion of the injection motor into linear motion in the axial direction. The metering motor is the drive source for the rotation of the screw; The drive force transmission component is connected to the screw and transmits the rotational drive force based on the rotational motion of the metering motor and the forward and backward drive force based on the linear motion of the lead screw shaft of the motion conversion mechanism to the screw respectively. and The axial force detection unit detects the axial force acting on the screw in the stated axial direction. The axial force detection unit includes: an annular axial force sensor configured to rotate relative to the screw and the drive force transmission component around the rotation axis of the screw; and a rotation limiting component that limits the rotation of the axial force sensor relative to the rotation of the screw and the drive force transmission component. The injection device includes a metering motor support component that supports the metering motor, the metering motor support component having a sliding hole through which the rotation limiting component passes. The rotation limiting member is located on the front side of the metering motor, and the rotation limiting member is configured to be inserted into the sliding hole in a manner that allows it to slide along the axial direction, protruding further forward axially than the metering motor support member. The axial force sensor is located at the shaft end of the coupling portion and around the connecting cylinder portion of the connection between the screw and the driving force transmission component, between the connecting flange of the screw and the front wall of the driving force transmission component.

2. The injection device according to claim 1, wherein, The axial force sensor is connected to the metering motor support component via the rotation limiting component, so that it can be displaced in the axial direction while being restricted from rotation.

3. The injection device according to claim 1, wherein, The rotation limiting component is in the form of one or more rods or plates extending along the axial direction on the outer periphery of the screw's rotation axis, or in the form of a cylinder surrounding the screw's rotation axis.

4. The injection device according to claim 1, wherein, The axial force detection unit has wiring that extends from the axial force sensor along the rotation limiting member through the sliding hole.

5. The injection device according to claim 2, wherein, The metering motor support component has: Motor support section, supporting the metering motor; and The sensor connection part is connected to the axial force sensor via a rotation limiting component and can be detached from the motor support part.

6. The injection device according to claim 1, wherein, The driving force transmission component has: The cylindrical main body surrounds the front end of the lead screw shaft; and The front wall portion is an opening located on the front side of the cylindrical main body portion along the axial direction.

7. The injection device according to claim 6, wherein, The drive force transmission component is connected to the axial force sensor via a bearing on the front wall, enabling relative rotation.

8. The injection device according to claim 7, wherein, The bearing between the front wall of the drive force transmission component and the axial force sensor is a thrust bearing.

9. The injection device according to claim 7, wherein, The inner ring of the bearing between the front end wall of the drive force transmission component and the axial force sensor is mounted on the front end wall of the drive force transmission component, and the outer ring of the bearing is mounted on the axial force sensor.

10. The injection device according to claim 7, wherein, The connecting cylinder extends along the axial direction from the front end wall of the driving force transmission component. The shaft end is located at the screw base end of the rotating shaft and is inserted into the connecting cylinder. The screw has a connecting flange at the screw base end, the connecting flange being mounted so as to be detached from the rotation axis and to hold the connecting cylinder inside.

11. The injection device according to claim 10, wherein, The shaft end and connecting flange are able to be displaced relative to the connecting cylinder in the axial direction, and the axial force acting on the screw is transmitted to the axial force sensor between the connecting flange of the screw and the front end wall of the driving force transmission component.

12. The injection device according to claim 10, wherein, The screw is connected to the axial force sensor via the connecting flange and bearing, enabling it to rotate relative to the bearing.

13. The injection device according to claim 12, wherein, The bearing between the connecting flange of the screw and the axial force sensor is a thrust bearing.

14. The injection device according to claim 12, wherein, The annular axial force sensor is located at the connection point of the bearing and the connecting flange of the screw, on the inner circumferential side, compared to the connection point of the bearing and the front end wall of the driving force transmission component.

15. The injection device according to claim 12, wherein, The inner ring of the bearing between the connecting flange of the screw and the axial force sensor is mounted on the axial force sensor, and the outer ring of the bearing is mounted on the connecting flange.

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