Injection molding machine

Abstract

An injection molding machine (1), comprising: a cylinder (2); a screw (3) installed in the cylinder (2); and a condition detection device, wherein the state detection device includes a first sensor and a second sensor (23) for detecting a state of the screw (3), wherein the condition detection device is attached to the screw (3) outside the cylinder (2), wherein a housing (26) of the condition detection device is made of a non-conductor, wherein the housing (26) of the condition detection device is composed of a pair of housing parts (26a, 26b), wherein the condition detection device is attached to the screw (3) by enclosing the screw (3) through the pair of housing parts (26a, 26b), wherein the first sensor (23) is arranged in a housing part (26a), wherein the second sensor (23) is arranged in another housing part (26b), and wherein the first sensor and the second sensor (23) are arranged in positions that are symmetrical to the rotational center axis of the screw (3).

Description

TECHNICAL FIELD

[0001] The present invention relates to an injection molding machine and relates, for example, to an injection molding machine having a cylinder and a screw built into the cylinder. STATE OF THE ART

[0002] The injection molding machine includes a cylinder and a screw built into the cylinder. The raw material introduced into the cylinder is kneaded, transported, melted, etc. by the screw rotating in the cylinder. An injection molding machine can be, for example, an extruder.

[0003] For example, JP 2001-129 870 A describes a technology for an extruder. Furthermore, DE 10 2011 107 198 B4 describes a plasticizing screw for an injection molding machine. US 2009 / 0 135 016 A1 shows a load monitoring device for an extruder. US 2010 / 0 062 095 A discloses a coupling for an injection molding machine, and US 2017 / 0 246 789 A1 shows a technology for a twin-screw extruder. SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] If the screw in an injection molding machine is damaged, replacing it is time-consuming and laborious. Production of plastic products using the injection molding machine must be suspended until the screw replacement is completed. Therefore, it is desirable to be able to accurately detect the condition of the screw during operation of the injection molding machine to facilitate the control of the injection molding machine and the management of the production process using the injection molding machine.

[0005] The other problems and new features will be apparent from the description of this specification and the accompanying drawings. MEANS TO SOLVE THE PROBLEMS

[0006] According to one embodiment, an injection molding machine comprises a cylinder, a screw installed in the cylinder, and a condition detection device. The condition detection device includes a sensor for detecting a condition of the screw. The condition detection device is mounted on the screw outside the cylinder.

[0007] According to one embodiment, an injection molding machine comprises a cylinder, a screw installed in the cylinder, a shaft connected to the screw outside the cylinder, and a condition detection device. The condition detection device includes a sensor for detecting a condition of the screw. The condition detection device is mounted either on the screw, on the shaft, or on both outside the cylinder. EFFECTS OF THE INVENTION

[0008] According to one embodiment, it is possible to accurately detect the condition of the screw of the injection molding machine. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of an injection molding machine according to an embodiment; Fig. 2 is a cross-sectional view of a screw of the injection molding machine according to the invention; Fig. 3 is a plan view showing the main part of the injection molding machine according to the invention; Fig. 4 is a cross-sectional view of the injection molding machine according to the embodiment; Fig. 5 is a block diagram showing the configuration of a range finder and a base unit; Fig. 6 is a cross-sectional view showing the main part of the injection molding machine according to the embodiment; Fig. 7 is a partially enlarged cross-sectional view showing a part of Fig. 6 in enlarged form; Fig. 8 is a plan view showing the main part of the distance measuring device used in the injection molding machine according to the present invention; Fig. 9 is a cross-sectional view showing the main part of the injection molding machine according to the embodiment; Fig. 10 is a plan view showing the main part of an injection molding machine according to another embodiment; and Fig. 11 is a plan view showing the main part of an injection molding machine according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments will be described in detail below with reference to the drawings. Note that elements with the same function are denoted by the same reference numerals in the drawings to describe the embodiments, so a repeated description is omitted. In the following explanations, the description of the same or similar parts will, in principle, not be repeated unless specifically necessary. (First embodiment)

[0010] Fig. 1 is a side view of an injection molding machine (molding apparatus) 1 according to the present embodiment, Fig. 2 is a cross-sectional view of a screw 3 of the injection molding machine 1, Fig. 3 is a plan view of the main part of the injection molding machine 1 (partially enlarged plan view), and Fig. 4 is a cross-sectional view of the injection molding machine 1. In Fig. 2, the mounting position of a rangefinder 11 is shown by a dotted line. Fig. Figure 3 shows a top view of a region RG1, which in Fig. 1 seen from above. The cross-sectional view at the position of line AA in Fig. 3 corresponds to Fig. 4.

[0011] The injection molding machine 1 is an injection molding machine configured for molding synthetic resin. In the present embodiment, the case where the injection molding machine 1 is an extruder is described as an example, but as another aspect, an injection molding machine, a magnesium injection molding machine, a granulator, a film molding machine, a blow molding machine, or the like can also be used as the injection molding machine 1.

[0012] First, the structure of the injection molding machine 1 is described with reference to the Fig. 1 to Fig. 4. The Fig. 1 to Fig. The injection molding machine 1 shown in Fig. 4 includes a cylinder 2, a screw 3 installed in the cylinder 2 for kneading, transporting, and melting a resin raw material, a rotary drive mechanism 4 for rotating the screw 3 within the cylinder 2, and a nozzle (mold) 5 mounted at the downstream tip of the cylinder 2. The injection molding machine 1 is mounted on a base 6. The temperature of the cylinder 2 is controlled by a temperature adjusting device (temperature adjusting mechanism) (not shown) such as a heater. An opening (not shown) for introducing a raw material (resin or the like) into the cylinder 2 is formed in the top of the cylinder 2.

[0013] The rotary drive mechanism 4 includes a motor 4a and a reduction gear 4b connected to the motor 4a. The reduction gear 4b is arranged between the motor 4a and the worm gear 3, and the rotational motion of the motor 4a is transmitted to the worm gear 3 via the reduction gear 4b, thereby rotating the worm gear 3. Specifically, the front end of an output shaft 7 of the reduction gear 4b and the rear end of the worm gear 3 are coupled (fixed) by a joint (coupling portion, coupling means) 8, and the worm gear 3 is also rotated together when the output shaft 7 is rotated. The joint 8 is a member (coupling member) that connects the output shaft 7 and the worm gear 3. The reduction gear 4b functions to convert (decelerate) the rotational speed of the motor 4a into a rotational speed suitable for the worm gear 3.When the rotational movement of the motor 4a is transmitted to the reduction gear 4b, the output shaft 7 of the reduction gear 4b rotates at a speed lower than that of the motor, and the worm 3 coupled to the output shaft 7 rotates at the same speed as that of the output shaft 7.

[0014] In addition, if a filling device (not shown) is used, the desired filler is filled from the filling device into the cylinder 2.

[0015] The screw 3 is inserted into the cylinder 2 and is movably mounted therein. In the cases of Fig. 1 to Fig. 4, two screws 3 are arranged in the barrel 2, and the injection molding machine 1 can be considered a twin-screw extruder in this case. The two screws 3 arranged in the barrel 2 are rotated so that they mesh with each other.

[0016] In the present embodiment, the case where the twin-screw extruder (in this case, two screws) is used as the injection molding machine 1 is described, but it is also possible to use a single-screw extruder (in this case, one screw) or an extruder with three or more screws as the injection molding machine 1, which is another aspect.

[0017] Each screw 3 is installed in the cylinder 2, but a part of each screw 3 is located outside the cylinder 2. Specifically, a part of each screw 3 protrudes from the rear end (upstream end) of the cylinder 2. The output shaft 7 of the reduction gear 4b is connected via the joint 8 to a part of the screw 3 outside the cylinder 2, specifically to a part of the screw 3 protruding from the rear end (upstream) of the cylinder 2. The screw 3 and the output shaft 7 are coupled via the joint 8 so that the center axis of the screw 3 (rotation center axis) and the center axis of the output shaft 7 (rotation center axis) match each other.

[0018] When referring to cylinder 2, "downstream" and "upstream" refer to the downstream side of the resin flow in cylinder 2, and "upstream" refers to the upstream side of the resin flow in cylinder 2. Therefore, in cylinder 2, the side closer to the tip of cylinder 2 is the downstream side, and the side farther from the tip of cylinder 2 is the upstream side. Therefore, the rear end of cylinder 2 is the upstream end of cylinder 2. The tip of cylinder 2 corresponds to the end of cylinder 2 on the side where the molten resin (molded resin) is extruded, and the nozzle 5 is attached to the tip of cylinder 2.

[0019] The nozzle 5 can be used to shape the molten resin extruded from the cylinder 2 into a predetermined cross-sectional shape and discharge it. In this case, the nozzle 5 is an extrusion die (molding die).

[0020] The injection molding machine 1 according to the present embodiment further includes a distance sensor 11 as a state detection device. The distance sensor 11 is provided as a state detection device for detecting the state of the screw 3. Therefore, the distance sensor 11 includes a sensor 23, described later, for detecting the state of the screw 3. The distance sensor 11 can also be considered a measuring device. In the injection molding machine 1 according to the present embodiment, wireless power supply to the distance sensor 11 and wireless data transmission (signal transmission) from the distance sensor 11 are possible.

[0021] The distance sensor 11 is attached to the screw 3 and can detect the state of the screw 3. However, the distance sensor 11 is attached to the screw 3 outside the cylinder 2, not inside the cylinder 2. Namely, the distance sensor 11 is attached to a part of the screw 3 located outside the cylinder 2. Specifically, a part of each screw 3 protrudes from the rear end (upstream) of the cylinder 2, and the distance sensor 11 is attached to a part of the screw 3 protruding from the rear end (upstream) of the cylinder 2. Therefore, the distance sensor 11 is attached to the screw 3 between the rear (upstream) end of the cylinder 2 and the joint 8. When the injection molding machine 1 includes a plurality of screws 3, it is advantageous to attach the distance sensor 11 to each of the plurality of screws 3.

[0022] The worm 3 has a worm shaft 3a and a plurality of worm pieces 3b which are attached to the worm shaft 3a (see Fig. 2). The screw pieces 3b are attached to a part of the screw shaft 3a located inside the cylinder 2. The screw thread of the screw 3 is formed on the screw pieces 3b. As a result, a screw is formed on the surface of the screw 3 (on the surface formed by the screw pieces 3b) in the cylinder 2. When the screw shaft 3a rotates, the screw pieces 3b attached to the screw shaft 3a also rotate with the screw shaft 3a. The screw shaft 3a has a cylindrical shape. The diameter of the part of the screw shaft 3a to which the screw piece 3b is attached is smaller than the diameter of the part of the screw shaft 3a to which the screw piece 3b is not attached. The screw piece 3b is therefore not attached to the part of the screw shaft 3a which is located outside the cylinder 2, ie to the part of the screw shaft 3a which protrudes from the rear end (upstream) of the cylinder 2.Therefore, the part of the screw 3 protruding from the rear end (upstream end) of the cylinder 2 is formed from the screw shaft 3a, and the screw is not integrally formed therewith. The rangefinder 11 is attached to the screw 3 outside the cylinder 2, more specifically, to the screw shaft 3a of the screw 3 outside the cylinder 2.

[0023] It is difficult to find a place for attaching the rangefinder 11 to the worm gear 3 in the cylinder 2. However, since the rangefinder 11 is attached to the worm gear 3 outside the cylinder 2 in the present embodiment, the rangefinder 11 can be attached to the worm gear 3 without the cylinder 2 getting in the way.

[0024] In connection with the attachment of the distance meter 11 to the screw 3, the injection molding machine 1 is equipped with a base unit 12 for supplying power to the distance meter 11 and for receiving the data (signals) sent by the distance meter 11.

[0025] The base unit 12 is arranged to face the rangefinder 11 attached to the worm gear 3. The base unit 12 is arranged below the rangefinder 11 attached to the worm gear 3. The rangefinder 11 rotates together with the worm gear 3 when the worm gear 3 rotates. Therefore, the base unit 12 and the rangefinder 11 are not in contact with each other, so the rotation of the rangefinder 11 is not hindered, and there is a gap between the base unit 12 and the rangefinder 11. The base unit 12 and the rangefinder 11 are not connected by wiring (i.e., not wired), so wireless communication is possible. Therefore, the distance between the base unit 12 and the rangefinder 11 is adjusted to enable wireless power supply from the base unit 12 to the rangefinder 11 and wireless data transmission from the rangefinder 11 to the base unit 12.

[0026] If the injection molding machine 1 is a twin-screw extruder with two screws 3 or an extruder with three or more screws 3, it is advantageous if the distance sensor 11 is mounted on each screw 3. Since there are multiple distance sensors 11 in this case, the base unit 12 should be mounted so that it faces the multiple distance sensors 11. However, the shape of the base unit 12 varies depending on the communication method. For example, the base unit 12 can be divided, or the base unit 12 can be arranged at a distance using an antenna.

[0027] The configurations of the rangefinder 11 and the base unit 12 are described below with reference to Fig. 5 to Fig. 7 described. Fig. Figure 5 is a block diagram showing the configurations of the rangefinder 11 and the base unit 12. In Fig. 5, a part surrounded by a dotted line is included in the rangefinder 11, and a part surrounded by an alternating long and two short lines is included in the base unit 12. Fig. 6 is a cross-sectional view showing the main part of the injection molding machine 1, and a part of Fig. 4 is shown in enlarged form. Namely, Fig. 6 shows a cross-sectional view of the rangefinder 11 and the auger 3 in a position in which the rangefinder 11 is attached to the auger 3. Fig. 7 is a partially enlarged cross-sectional view showing a part of Fig. 6 is shown enlarged, and an area RG2, which is surrounded by an alternating long and two short dashed lines in Fig. 6 is shown in an enlarged form. The enlarged view of an area RG3 in Fig. 6 corresponds to the view you get when you look at the top and bottom of Fig. 7 and replaces a reference numeral 26a, which denotes a housing 26a, with a reference numeral 26b, which denotes a housing 26b. Although Fig. 6 is a cross-section, hatching has been omitted in order to make the drawing clearer. Fig. Fig. 8 is a plan view showing the main part of the distance meter 11, and a planar positional relationship is shown between the sensor 23, an elastic film 41, a metal plate 42, a screw nut 43, and a bolt 44. Although the metal plate 42 in Fig. 8 is not shown, the outer circumferential position of the metal plate 42 almost coincides with the outer circumferential position of the elastic film 41.

[0028] As in Fig. As shown in Figure 5, the rangefinder 11 includes a power receiving coil 21, an AC / DC converter 22, a sensor 23, a processor (control unit, control semiconductor chip) 24, and a data transmission coil 25. Furthermore, the base unit 12 includes an oscillator 31, a power transmission coil 32, a data receiving coil 33, an AD converter (analog / digital converter) 34, and a processor (control unit, control semiconductor chip) 35.

[0029] The rangefinder 11 is powered via the base unit 12 from a power source (external power source) 36 located outside the base unit 12. Specifically, the power supplied from the power source 36 to the base unit 12 is transmitted to the power transmission coil 32 via the oscillator 31, and an alternating current flows through the power transmission coil 32. Since the power transmission coil 32 of the base unit 12 functions as the primary coil and the power reception coil 21 of the rangefinder 11 functions as the secondary coil, an alternating current flows through the power transmission coil 32, so that an alternating current flows through the power reception coil 21. This is because the power supply is wirelessly transmitted from the power transmission coil 32 of the base unit 12 to the power reception coil 21 of the rangefinder 11.Therefore, the base unit 12 contains a power supply unit for the rangefinder 11 (here the oscillator 31, the power transmission coil 32 and the like).

[0030] The alternating current sent to the power receiving coil 21 is converted into direct current by the AC / DC converter 22 and then supplied to the sensor 23 and the processor 24. This enables the operation of the sensor 23 and the processor 24. The sensor 23 detects the condition of the screw 3. Examples of the condition of the screw 3 include torsional strain, bending strain, thermal strain, torque, bending, deformation degree, deformation type, vibration, vibration degree, vibration type, fatigue due to the accumulation of fatigue, fatigue degree, and the like. Furthermore, the condition detection device (here, the distance meter 11) can be equipped with various sensors and estimate the condition using the sensor data.Since the sensor 23 in the present embodiment is a sensor that detects the deformation (shape change, elongation) of the screw 3 and is, for example, a strain gauge, the deformation (shape change, elongation) of the screw 3 can be detected as a resistance change of the resistor constituting the sensor (strain gauge). Other examples of sensors included in the state detection device (here, the distance sensor 11) include a displacement sensor, a speed sensor, an acceleration sensor, a temperature sensor, a gyro sensor, a humidity sensor, a color / optical sensor, a microphone, and the like.

[0031] The processor 24 controls the sensor 23 and sends a signal (data signal) corresponding to the state (deformation, shape change) of the screw 3 detected by the sensor 23 to the data transmission coil 25. The data transmission coil 25 of the rangefinder 11 functions as the primary coil, and the data reception coil 33 of the base unit 12 functions as the secondary coil, so that a signal (data signal) is wirelessly sent from the data transmission coil 25 of the rangefinder 11 to the data reception coil 33 of the base unit 12. Namely, the data is wirelessly transmitted from the data transmission coil 25 of the rangefinder 11 to the data reception coil 33 of the base unit 12.The signal (data signal) sent to the data receiving coil 33 is converted by the AD converter 34, subjected to the necessary processing by the processor 35, and sent to a personal computer (external PC) 37 external to the base unit 12. The necessary processing and recording of data are performed in the personal computer 37. Therefore, the base unit 12 includes a communication unit for the distance meter 11 (here, the data receiving coil 33, the AD converter 34, the processor 35, and the like). Based on the data sent from the base unit 12 to the personal computer 37, management of the injection molding machine 1 and management of the manufacturing process using the injection molding machine 1 can be performed. For example, the condition of the screw 3 can be checked, the replacement timing of the screw 3 can be determined, or the continuous operation time of the injection molding machine 1 can be set or changed.

[0032] As a method for supplying energy to the rangefinder 11, the wireless energy supply described above can be imagined, but environmental energy generation (energy generation by vibration, light, heat, electromagnetic waves, etc.) is also possible.

[0033] A specific structure of the rangefinder 11 will be described below with reference to Fig. 6 to Fig. 8 described.

[0034] As in Fig. 6, the rangefinder 11 includes a casing (resin casing) 26 defining the overall shape of the rangefinder 11, the power receiving coil 21, the AC / DC converter 22, the sensor 23, the processor 24, and the data transmitting coil 25.

[0035] The casing 26 is preferably made of a non-conductor (insulator), and a resin (resin material) can preferably be used. If the casing 26 is made of a metallic material, there is a risk that the casing 26 will interfere with the transmission and reception of electrical power and signals (data) between the rangefinder 11 and the base unit 12. Therefore, it is desirable that the casing 26 be made of a material that does not interfere with the transmission and reception of electrical power and signals (data) between the rangefinder 11 and the base unit 12. By making the casing 26 of a material other than metal, preferably a non-conductor (e.g., resin), the casing 26 can be prevented from interfering with the transmission and reception of electrical power and signals (data) between the rangefinder 11 and the base unit 12.A resin (resin material), for example, is suitable as the non-conductor from which the housing 26 is made. When the housing 26 is made of the resin, the housing 26 can be easily manufactured and handled. In addition to the resin, ceramic or the like can also be used as the non-conductor from which the housing 26 is made.

[0036] The power receiving coil 21, the AC / DC converter 22, the processor 24 and the data transmission coil 25 are housed in the housing 26. In the case of Fig. 6, the power receiving coil 21, the AC / DC converter 22, the processor 24, and the data transmission coil 25 are embedded in the housing 26, but they may also be arranged in the concave parts formed in the housing 26. The power receiving coil 21, the AC / DC converter 22, the sensor 23, the processor 24, and the data transmission coil 25 are electrically connected to each other via the wiring provided in the housing 26 or the like, as needed.

[0037] The sensor 23 is arranged in a concave part 27 on the inside of the housing 26. The inner surface of the housing 26 corresponds to the surface on the side facing the screw 3, and the outer surface of the housing 26 corresponds to the surface of the housing 26 on a side opposite the inner surface of the housing 26.

[0038] The sensor 23 is in contact with the surface (outer surface, outer circumference) of the screw 3. The sensor 23 is a sensor that detects the deformation (shape change, elongation) of the screw 3, such as a strain gauge. Therefore, the sensor 23 includes a resistor, and the resistance of the resistor included in the sensor 23 changes when the screw 3 is deformed. In this way, the deformation of the screw 3 can be detected as a resistance change of the resistor included in the sensor 23. Therefore, it is advantageous that the sensor 23 is in close contact with the surface of the screw 3, whereby the deformation of the screw 3 can be accurately detected by the sensor 23. Accordingly, the sensor 23 is preferably pressed onto the surface of the screw 3, and a structure that allows this is adopted in the present embodiment.

[0039] A structure for pressing the sensor 23 to the screw 3 is described with reference to Fig. 6 to Fig. 8 described.

[0040] The sensor (strain gauge) 23 is attached to the elastic film (elastic body plate) 41. Note that the sensor 23 is attached to the underside of the elastic film 41, and the wiring 46 connected to the sensor 23 is also arranged on the underside of the elastic film 41. Therefore, the sensor 23 is in contact with the elastic film 41, specifically, with the lower surface of the elastic film 41. Of the two surfaces of the elastic film 41, the lower surface of the elastic film 41 corresponds to the surface facing the screw 3. The upper surface of the elastic film 41 is a surface on the opposite side of the lower surface of the elastic film 41 and therefore corresponds to a surface of the elastic film 41 on the opposite side of the surface in contact with the sensor 23. Therefore, the sensor 23 is located between the elastic film 41 and the screw 3.The sensor 23 is pressed against the screw 3 by the elastic film 41.

[0041] The elastic film 41 is designed as an elastic body, e.g., made of silicone rubber. The planar dimension (flat surface) of the elastic film 41 is larger than the planar dimension (flat surface) of the sensor 23, and the sensor 23 is enclosed by the elastic film 41 in plan view. The planar shape of the elastic film 41 can be selected from various shapes, e.g., it can be rectangular.

[0042] The metal plate 42 is arranged on the elastic sheet 41, that is, on the upper surface of the elastic sheet 41. The planar shape and planar dimension (planar surface) of the metal plate 42 are substantially the same as the planar shape and planar dimension (planar surface) of the elastic sheet 41. The metal plate 42 is in contact with the upper surface of the elastic sheet 41. Therefore, the elastic sheet 41 is located between the metal plate 42 and the sensor 23, and the metal plate 42 is not in contact with the sensor 23. The metal plate 42 is a plate-like (plate-shaped) member, but is not flat but curved. Namely, the lower surface of the metal plate 42 (the surface that comes into contact with the elastic sheet 41) is a curved surface. The lower surface of the metal plate 42 is preferably a curved surface corresponding to the surface of the part of the screw 3 to which the rangefinder 11 is attached.Specifically, the metal plate 42 is preferably curved so that the bottom surface of the metal plate 42 and the surface of the screw 3 are substantially parallel in the state where the metal plate 42 is pressed onto the surface of the screw 3 via the elastic film 41 and the sensor 23 by the bolt (worm, screw member) 44. Therefore, the radius of curvature of the bottom surface of the metal plate 42 is preferably approximately the same as the radius of curvature of the part of the surface of the screw 3 to which the rangefinder 11 is attached. Of the two surfaces of the metal plate 42, the lower surface of the metal plate 42 corresponds to the surface in contact with the elastic film 41. The upper surface of the metal plate 42 is the surface on the opposite side to the lower surface of the metal plate 42 and therefore corresponds to the surface on the opposite side of the surface of the metal plate 42 in contact with the elastic film 41.The metal plate 42 is pressed against the elastic film 41 by the bolt 44.

[0043] The screw nut 43 is arranged on the metal plate 42, that is, on the upper surface of the metal plate 42. The screw nut 43 is formed from a metal material and is a plate-shaped member. A screw hole 43a is formed in the screw nut 43, penetrating the screw nut 43, and a worm thread is formed on the side surface (inner wall surface) of the screw hole 43a. The bolt 44 is inserted into the screw hole 43a of the screw nut 43. The screw nut 43 can serve as a nut for the bolt 44. The bolt 44 can also be considered a screw (worm element).

[0044] In the case of Fig. 7, the bolt 44 has a threaded portion 44a having a thread formed on a side surface thereof, and a head portion 44b connected to the threaded portion 44a and having a larger planar dimension than the threaded portion 44a. The shape (structure) of the bolt (worm) 44 can be changed in various ways, and for example, a worm element without the portion corresponding to the head portion 44b can be used instead of the bolt 44. The screw nut 43 has a larger planar dimension (flat surface) than a normal nut, and preferably, the flat surface of the screw nut 43 is six times or more the flat surface of the worm hole 43a of the screw nut 43. Furthermore, in the case of Fig. 7, the planar dimension (flat surface) of the screw nut 43 is slightly smaller than the planar dimension (flat surface) of the metal plate 42, but the present invention is not limited thereto. Of the two surfaces of the screw nut 43, the lower surface of the screw nut 43 corresponds to the surface facing the metal plate 42. The upper surface of the screw nut 43 is a surface on a side opposite the lower surface of the screw nut 43.

[0045] When the bolt 44 is tightened to improve the contact of the sensor 23 with the surface of the screw 3, the upper surface of the screw nut 43 (the surface on the opposite side of the surface facing the metal plate 42) comes into contact with the housing 26 and exerts a force that pushes the housing 26 upward (in the direction away from the screw 3) toward the contact portion of the housing 26. Specifically, the upper surface of the screw nut 43 is pressed against the bottom surface of the concave part 27b of the housing 26, and the force to push the bottom surface of the concave part 27b of the housing 26 upward (in the direction away from the screw 3) acts through the screw nut 43.In the present embodiment, since the screw nut 43 has a larger planar dimension (flat area) than the ordinary nut, the force pushing upward the bottom surface of the concave part 27b of the housing 26 does not act locally in a small area, but is distributed over the entire screw nut 43. Therefore, the housing 26 is less likely to be damaged at the bottom surface of the concave part 27b of the housing 26, and it is possible to prevent damage to the housing 26. This makes it possible to reduce the thickness of the housing 26.

[0046] The threaded portion 44a of the bolt 44 is inserted into the screw hole 43a of the nut 43, and the planar dimension (flat surface) of the head portion 44b of the bolt 44 is larger than the planar dimension (flat surface) of the screw hole 43a. Since the bolt 44 is inserted into the screw hole 43a of the nut 43 from the top surface of the nut 43, the head portion 44b of the bolt 44 protrudes from the top surface of the nut 43. In addition, the length of the threaded portion 44a of the bolt 44 is larger than the thickness of the nut 43, and a portion of the threaded portion 44a of the bolt 44 protrudes from the bottom surface of the nut 43. Therefore, the tip of the threaded part 44a of the bolt 44 is in contact with the upper surface of the metal plate 42. The amount of protrusion (protrusion length) of the threaded part 44a from the bottom of the screw nut 43 can be controlled by adjusting the tightening of the bolt 44.Namely, when the bolt 44 is loosened, the amount of protrusion of the threaded portion 44a from the bottom of the screw nut 43 decreases, and when the bolt 44 is tightened, the amount of protrusion of the threaded portion 44a from the bottom of the screw nut 43 increases.

[0047] Since the tip of the threaded portion 44a of the bolt 44 is in contact with the top surface of the metal plate 42, the bolt 44 can press the metal plate 42 toward the screw 3. Namely, the metal plate 42 is pressed against the elastic film 41 by the bolt 44. Furthermore, the force with which the tip of the threaded portion 44a of the bolt 44 presses the metal plate 42 can be controlled by adjusting the strength of the bolt 44. By increasing the strength of the bolt 44, the extent to which the threaded portion 44a protrudes from the bottom surface of the nut 43 can be increased, and the force with which the tip of the threaded portion 44a of the bolt 44 presses the metal plate 42 can be increased. When the bolt 44 is tightened, the top of the screw nut 43 comes into contact with the housing 26 (the bottom of the concave part 27b) and presses the contact part of the housing 26.

[0048] When the tip of the threaded portion 44a of the bolt 44 presses the metal plate 42, the metal plate 42 can press the elastic sheet 41 toward the screw 3. When the elastic sheet 41 is pressed by the metal plate 42, the elastic sheet 41 is pressed against the surface of the screw 3, so that the sensor 23 located between the lower surface of the elastic sheet 41 and the surface of the screw 3 is also pressed against the surface of the screw 3, and the contact between the sensor 23 and the surface of the screw 3 is improved. Namely, the metal plate 42 is pressed against the elastic sheet 41 by the bolt 44, and the sensor 23 is pressed against the screw 3 by the elastic sheet 41, so that the contact between the sensor 23 and the surface of the screw 3 can be improved.

[0049] It is assumed that the metal plate 42 is omitted, unlike the present embodiment. In this case, the tip of the threaded part 44a of the bolt 44 presses directly on the elastic sheet 41. Therefore, the force with which the elastic sheet 41 is pressed against the surface of the screw 3 acts at the location where the tip of the threaded part 44a of the bolt 44 presses on the elastic sheet 41, but the force with which the elastic sheet 41 is pressed against the surface of the screw 3 does not act at other locations. Namely, the force with which the elastic plate 41 is pressed against the surface of the screw 3 is generated locally on a part of the elastic sheet 41, not on the entire elastic sheet 41.Therefore, the force with which the sensor 23 located between the underside of the elastic film 41 and the surface of the screw 3 is pressed onto the surface of the screw 3 is also generated locally on a part of the sensor 23 instead of on the entire sensor 23, and there is therefore a risk that the contact between the sensor 23 and the surface of the screw 3 is reduced.

[0050] On the other hand, in the present embodiment, the structure is adopted in which the tip of the threaded part 44a of the bolt 44 presses the metal plate 42, and the metal plate 42 presses the elastic sheet 41. Since the metal plate 42, instead of the tip of the threaded part 44a of the bolt 44, contacts the elastic sheet 41 and presses the elastic sheet 41, the force with which the elastic sheet 41 is pressed against the surface of the screw 3 can be generated almost over the entire elastic sheet 41. Since the force with which the sensor 23 located between the bottom of the elastic sheet 41 and the surface of the screw 3 is pressed against the surface of the screw 3 is also generated almost over the entire sensor 23, the contact between the sensor 23 and the surface of the screw 3 can be improved.By improving the contact between the sensor 23 and the surface of the screw 3, the state of the screw 3 can be accurately detected by the sensor 23.

[0051] Further, assume the case where the metal plate 42 is not curved and is completely flat, unlike the present embodiment. In this case, the force with which the elastic sheet 41 is pressed becomes large at the central part of the metal plate 42, but the force with which the metal plate 42 presses the elastic sheet 41 decreases with increasing distance from the central part of the metal plate 42. Therefore, the force with which the elastic sheet 41 is pressed onto the surface of the screw 3 becomes uneven, and the force with which the sensor 23 located between the bottom of the head part 41 and the surface of the screw 3 is pressed onto the surface of the screw 3 also becomes uneven, so there is a risk that the contact between the sensor 23 and the surface of the screw 3 decreases.

[0052] On the other hand, in the present embodiment, the metal plate 42 is not completely flat but curved. Therefore, the force with which the metal plate 42 presses the elastic film 41 can be made substantially uniform regardless of the position of the elastic film 41. As a result, the force with which the elastic film 41 is pressed against the surface of the screw 3 becomes substantially uniform, and the force with which the sensor 23 located between the underside of the head part 41 and the surface of the screw 3 is pressed against the surface of the screw 3 also becomes substantially uniform, and thus the contact between the sensor 23 and the surface of the screw 3 can be improved. By improving the contact between the sensor 23 and the surface of the screw 3, the state of the screw 3 can be accurately detected by the sensor 23.

[0053] Further, assume the case where the elastic sheet 41 is omitted and the sensor 23 is pressed against the screw 3 by the metal plate 42, unlike the present embodiment. In this case, since the surface of the screw 3 at the position where the rangefinder is mounted is not a flat but a curved surface, and the metal plate 42 is not an elastic body and therefore not easily deformed, the force with which the sensor 23 located between the underside of the metal plate 42 and the surface of the screw 3 is pressed against the surface of the screw 3 may become uneven, and there is a risk that the contact between the sensor 23 and the surface of the screw 3 may decrease.

[0054] On the other hand, in the present embodiment, the structure is adopted in which the elastic sheet 41 made of an elastic body presses the sensor 23. Although the surface of the screw 3 at the position where the rangefinder 11 is mounted is not a flat but a curved surface, since the elastic sheet 41 is made of an elastic body and is easily deformed, it can be deformed to conform to the shape of the gap between the surface of the screw 3 and the underside of the metal plate 42 when the metal plate 42 presses the elastic sheet 41 toward the screw 3. Therefore, the force with which the sensor 23 located between the underside of the elastic sheet 41 and the surface of the screw 3 is pressed onto the surface of the screw 3 can be made substantially uniform, and thus the contact between the sensor 23 and the surface of the screw 3 can be improved.By improving the contact between the sensor 23 and the surface of the screw 3, the state of the screw 3 can be accurately detected by the sensor 23.

[0055] Furthermore, consider the case where, unlike the present embodiment, the sensor 23 is attached to the surface of the screw 3 with an adhesive. In this case, once the sensor 23 is attached to the screw 3, it cannot be removed from the screw 3 later. Even if the adhesive can be removed with a solvent or the like, the sensor 23 must be replaced, which significantly impairs usability.

[0056] On the other hand, in the present embodiment, the structure is adopted in which the sensor 23 is not fixed to the surface of the screw 3 using an adhesive, but the sensor 23 is pressed onto the surface of the screw 3. Therefore, when the distance meter 11 is removed from the screw 3, the sensor 23 does not remain adhered to the surface of the screw 3, and the sensor 23 can be removed together with the distance meter 11.

[0057] In the present embodiment, as described above, since the metal plate 42 presses the elastic film 41 and the elastic sheet 41 presses the sensor 23 to the surface of the screw 3, the contact between the sensor 23 and the surface of the screw 3 can be improved. By improving the contact between the sensor 23 and the surface of the screw 3, the state of the screw can be accurately detected by the sensor 23. Since the contact between the sensor 23 and the surface of the screw 3 can be effectively improved with a small force, the stress exerted on the casing 26 (26a, 26b) can be suppressed. As a result, damage to the casing 26, which is made of plastic, can be suppressed or prevented.

[0058] The sensor 23, the elastic film 41, the metal plate 42, and the screw nut 43 are arranged in this order from the side closer to the surface of the screw 3. Therefore, the sensor 23, the elastic film 41, the metal plate 42, and the screw nut 43 are arranged in the concave part 27 on the inside of the housing 26. The concave portion 27 consists of a concave part 27a and a concave part 27b provided on the bottom of the concave part 27a and has the same planar dimension (planar area) as the concave portion 27a or a smaller planar dimension (planar area) than the concave portion 27a. The sensor 23, the elastic film 41 and the metal plate 42 are arranged (housed) in the concave part 27a, and the screw nut 43 is arranged (housed) in the concave part 27b.Furthermore, a hole (through hole) 45 penetrating the housing 26 is formed on the underside of the concave portion 27b, and the head portion 44b of the bolt 44 is disposed (housed) in the hole 45. Consequently, the strength of the bolt 44 can be adjusted from the outside of the housing 26. Furthermore, a bolt 44 coated with an adhesive can also be used as the bolt 44, which can prevent the bolt 44 from loosening after tightening due to machine vibration or the like.

[0059] Next, an example of the mechanism for attaching (fixing) the rangefinder 11 to the worm 3 will be explained with reference to Fig. 9 described. Fig. Fig. 9 is a cross-sectional view showing the main part of the injection molding machine 1, and is a cross-sectional view of the distance meter 11 and the screw 3 at the position where the distance meter 11 is attached to the screw 3. Although Fig. 9 is a cross-section, hatching has been omitted in order to make the drawing clearer.

[0060] When the rangefinder 11 is attached to the worm gear 3, the rangefinder 11 has an annular (cylindrical) shape that encloses the worm gear 3. However, to facilitate the attachment and detachment of the rangefinder 11 to and from the worm gear 3, the rangefinder 11 is composed of several (in this case, two) separate annular elements. Namely, the housing 26 constituting the rangefinder 11 is composed of several housings, in this case, a pair (two) of housings 26a and 26b. The rangefinder 11 is attached to the worm gear 3 by enclosing the worm gear 3 between the two housings 26a and 26b. This will be explained in more detail below.

[0061] In the case of Fig. 9, a common hinge pin 51 penetrates a hinge part provided at one end of the housing 26a and a hinge part provided at one end of the housing 26b. Consequently, one end of the housing 26a and one end of the housing 26b are coupled via the hinge pin 51. Therefore, before the housings 26a and 26b are attached to the worm gear 3, the housings 26a and 26b can rotate around the hinge pin 51 as an axis. The other end of the housing 26a and the other end of the housing 26b are connected by a bolt (worm, worm element) 52 and a nut 53.

[0062] When removing the rangefinder 11 from the worm 3, the rangefinder 11 can be removed from the worm 3 by removing the bolt 52 from the worm holes of the housings 26a and 26b and rotating the housing 26a and the housing 26b around the hinge pin 51 as an axis.

[0063] When attaching the distance sensor 11 to the worm gear 3, the housing 26a and the housing 26b are rotated around the hinge pin 51 to clamp the worm gear 3 between the housing 26a and the housing 26b, and then the bolt 52 is inserted into the worm gear holes of the housings 26a and 26b, thereby fastening the housing 26a and the housing 26b through the bolt 52 and the nut 53. Consequently, the housings 26a and 26b are attached to the worm gear 3 in a state where the worm gear 3 is sandwiched between the housing 26a and the housing 26b. After the housings 26a and 26b are attached to the worm gear 3, the sensor 23 can be pressed onto the worm gear 3 by tightening the pressure bolts 44 with a constant (predetermined) torque.

[0064] In the present embodiment, the case where one end of the casing 26a and one end of the housing 26b are coupled using the hinge portions and the hinge pin 51 has also been described. It is also possible to fasten the casing 26a and the casing 26b enclosing the worm 3 with the same bolt and nut as the bolt 52 and the nut 53 instead of the hinge portions and the hinge pin 51.

[0065] The power receiving coil 21, the AC / DC converter 22, the processor 24, and the data transmission coil 25 are each arranged (built-in) in either the housing 26a or the housing 26b. Fig. 6 illustrates the case where the AC / DC converter 22 and the data transmission coil 25 are arranged (built-in) in the casing 26a, and the power reception coil 21 and the processor 24 are arranged (built-in) in the casing 26b, but the present invention is not limited to this. The wiring in the casing 26a is for electrically connecting the components in the casing 26a, and the wiring in the casing 26b is for electrically connecting the components in the casing 26b. It is also possible to electrically connect the components in the casing 26a and the components in the casing 26b by bringing the terminal at the end of the casing 26a and the terminal at the end of the casing 26b into electrical contact with each other when the casings 26a and 26b are attached to the worm gear 3.

[0066] Furthermore, the distance meter 11 comprises one or more sensors 23, and at least one sensor 23 is arranged in at least one of the two housings 26a and 26b. In Fig. Figure 6 illustrates, by way of example, the case where the sensor 23 is arranged in each of the housings 26a and 26b. By arranging the sensor 23 in each of the housings 26a and 26b, the deformation (stretching) of the screw can be easily detected. In this case, it is advantageous to arrange the sensors 23 at positions symmetrical to the center (rotational center axis) of the screw 3.

[0067] When a bridge circuit (Wheatstone bridge circuit) is formed as the circuit for detecting the deformation (strain) of the screw 3, four resistance elements are required. In this case, a total of four sensors 23 are required. If a sensor 23 has only one resistance element, two sensors 23 are required. If a sensor 23 has two resistance elements, a total of two sensors 23 are required. If a sensor 23 has four resistance elements, only one sensor 23 is required. If the distance meter 11 has one sensor 23, the sensor 23 can be arranged either in the housing 26a or in the housing 26b. If the distance meter 11 has two sensors 23, for example, one sensor 23 can be arranged in each of the housings 26a and 26b. For example, if the distance meter 11 has four sensors 23, two sensors 23 can be arranged in each of the housings 26a and 26b.Other sensor arrangements and changing the number of resistance elements for each sensor are also possible.

[0068] Assume the case where, instead of the power receiving coil 21 arranged in the rangefinder 11, a battery is installed in the rangefinder 11, and the rangefinder 11 is operated using the battery, unlike the present embodiment. In this case, the size of the battery that can be installed in the rangefinder is limited, so the battery capacity is limited. Therefore, the rangefinder cannot be operated for a long time. Accordingly, if the injection molding machine is continuously operated for a long time, the state of the screw of the injection molding machine cannot be constantly monitored (detected) by the rangefinder. Since the rotation speed of the screw of the injection molding machine is relatively high, the measurement frequency of the rangefinder must be increased.However, this also increases power consumption and shortens battery life, thus shortening the operating time of the rangefinder. In this respect, the condition of the injection molding machine's screw cannot be continuously monitored (detected) by the rangefinder if the injection molding machine is operated continuously for an extended period of time.

[0069] On the other hand, in the present embodiment, the distance meter 11 has the power receiving coil 21, and the power is wirelessly supplied from the base unit 12 to the distance meter 11 by using the power transmission coil 32 of the base unit 12 and the power receiving coil 21 of the distance measuring device 11. Therefore, the power source for operating the distance meter 11 can be arranged outside the range meter 11 rather than inside the range meter 11. Since the range meter 11 can be continuously supplied with power wirelessly, the range meter 11 can be operated for a long period of time. Therefore, when the injection molding machine 1 is continuously operated for an extended period of time, the state of the screw 3 of the injection molding machine 1 can be constantly monitored (detected) by the range meter 11. Another aspect is the periodic, wireless charging of an energy storage device, such asa battery or capacitor, as a form of wireless power supply.

[0070] Furthermore, assume the case where the power supply to the rangefinder 11 is not wireless but via a cable, unlike the present embodiment. In this case, the external power source and the rangefinder are connected via a cable (external wiring), but since the cable gets tangled when the auger rotates, it is difficult to rotate the auger without the cable getting in the way. Although it is possible to realize power supply via a wire when using a sliding component such as a brush, this is undesirable due to wear, stability, and component complexity. Therefore, it becomes difficult to detect the state of the rotating auger.

[0071] On the other hand, in the present embodiment, the rangefinder 11 includes the power receiving coil 21, and power is wirelessly supplied from the base unit 12 to the rangefinder 11 by using the power transmitting coil 32 of the base unit 12 and the power receiving coil 21 of the rangefinder 11. Therefore, since it is not necessary to connect the external power source and the rangefinder 11 by wiring (external wiring), the wiring does not become tangled when the worm 3 rotates. Therefore, the state of the rotating worm 3 can be accurately monitored (detected) by the rangefinder 11.

[0072] In the present embodiment, it is also advantageous that the rangefinder 11 is attached to the worm gear 3 between the rear end of the cylinder 2 and the joint 8. Namely, it is preferable that the rangefinder 11 be attached to the worm gear 3 outside the cylinder 2 and as close as possible to the rear end of the cylinder 2. Since the position of the worm gear 3 where the rangefinder 11 is attached can be brought closer to the part of the worm gear 3 located inside the cylinder 2, the state of the worm gear 3 detected by the rangefinder 11 accurately reflects the state of the part of the worm gear 3 located inside the cylinder 2. Therefore, the state of the worm gear 3 in the cylinder 2 can be determined from the data detected by the rangefinder 11.

[0073] Furthermore, in the present embodiment, the distance sensor 11 can be attached to and detached from the screw 3. Namely, the distance sensor 11 is detachably attached to the screw 3. Therefore, it is also possible to attach the distance sensor 11 to the screw 3 after using the injection molding machine for a while without attaching the distance sensor 11 to the screw 3. Namely, the distance sensor 11 can be attached later.

[0074] The following describes the functionality of the Fig. 1 to Fig. 4 shown injection molding machine 1 is described in broad terms.

[0075] In the injection molding machine 1, the resin (thermoplastic resin) supplied from the raw material inlet port (not shown) into the cylinder 2 is melted in the cylinder 2 while being advanced by the rotation of the screw 3 (that is, converted into the molten resin). When the filler is supplied into the cylinder 2 from the filler supply device (not shown), the resin (molten resin) and the filler in the cylinder 2 of the injection molding machine 1 are kneaded by the rotation of the screw 3, so that the molten resin in the cylinder 2 is brought into a state containing the filler.

[0076] In the injection molding machine 1, the molten resin, which is conveyed into the cylinder 2 by the rotation of the screw 3, is extruded from the nozzle 5 attached to the tip of the cylinder 2. The molten resin extruded from the nozzle 5 is cooled and processed into a resin molded part.

[0077] When the injection molding machine 1 is not an extruder but an injection molding machine, the molten resin is injected into the mold from the tip of the cylinder 2, and the molten resin solidifies in the mold to form a resin molded product.

[0078] In the injection molding machine 1, the screw 3 rotates in the cylinder 2, and the resin is kneaded by the screw 3. Therefore, mechanical and thermal stress are exerted on the screw 3. Accordingly, there is a risk of the screw 3 being deformed during use of the injection molding machine 1. Therefore, by attaching the distance sensor 11 to the screw 3 and monitoring (detecting) the condition of the screw 3, when an abnormality occurs in the screw 3 (deformation of the screw 3 beyond the reference value, etc.), it can be immediately detected. This facilitates the management of the injection molding machine 1 and the management of the manufacturing process using the injection molding machine 1. (Second embodiment)

[0079] Fig. Fig. 10 is a plan view showing the main part of the injection molding machine 1 according to the second embodiment, and corresponds to the above-mentioned Fig. 3 of the first embodiment. The injection molding machine 1 according to the second embodiment is referred to as injection molding machine 1a by designating it with the reference symbol 1a.

[0080] The injection molding machine 1a according to the second embodiment differs from the injection molding machine 1 according to the first embodiment in the mounting position of the distance meter 11. In the second embodiment, the distance meter 11 is attached to a shaft (here, the output shaft 7) coupled to the screw 3 outside the cylinder 2, rather than to the screw 3 itself. Since the second embodiment is almost identical to the first embodiment, a repeated description is omitted here.

[0081] When the worm gear 3 is deformed, the shaft coupled to the worm gear 3 (here, the output shaft 7) outside the cylinder 2 tends to deform in accordance with the deformation. Therefore, in the second embodiment, by attaching the rangefinder 11 to the shaft (the output shaft 7), the state (deformation, shape change) of the shaft coupled to the worm gear 3 (here, the output shaft 7) is detected by the sensor 23 of the distance sensor 11, and the state (deformation, shape change) of the worm gear 3 can be indirectly detected based on the data. Accordingly, not only the case where the rangefinder 11 is attached to the worm gear 3 itself, as in the first embodiment, but also the case where the rangefinder is attached to the shaft (here, the output shaft 7) coupled to the worm gear 3, as in the second embodiment, is effective.

[0082] However, if the distance sensor 11 is attached to the worm gear 3 itself, as in the first embodiment, the state (deformation, shape change) of the worm gear 3 can be directly detected, and the state of the worm gear 3 can be determined more accurately. Therefore, the above-described case of the first embodiment is more advantageous than the case of the second embodiment because the state of the worm gear 3 can be detected more accurately. On the other hand, if it is difficult to secure a location for attaching the distance sensor 11 to the worm gear 3, the distance sensor 11 may be attached to the shaft (here, the output shaft 7) coupled to the worm gear 3, as in the second embodiment. (Third embodiment)

[0083] Fig. Fig. 11 is a plan view showing the main part of the injection molding machine 1 according to the third embodiment, and corresponds to the above-mentioned Fig. 3 of the first embodiment. The injection molding machine 1 according to the third embodiment is referred to as injection molding machine 1b by designating it with the reference symbol 1b.

[0084] The injection molding machine 1b according to the third embodiment differs from the injection molding machine 1 according to the first embodiment in that the distance meter 11 and the joint 8 are provided separately in the first embodiment, while the distance meter 11 and the joint 8 are integrated in the third embodiment.

[0085] For example, it is possible to equip the joint 8 with the function of the distance meter 11 by incorporating various components that form the distance meter 11 into the joint 8. Alternatively, it is also possible to couple the worm 3 and the output shaft 7 through the distance meter 11, by having the distance meter 11 take over the function of the joint 8. In these cases, as in Fig. 11, the distance measuring device 11, which also serves as the joint 8 (in other words, the joint 8 also serves as the distance measuring device 11), is fixed to both the worm 3 and the output shaft 7 to couple the end of the worm 3 and the end of the output shaft 7.

[0086] Since the third embodiment integrates the rangefinder 11 and the joint 8, it is not necessary to separately secure a space for mounting the joint and a space for mounting the distance measuring device. Therefore, the third embodiment is useful when it is difficult to separately secure a space for mounting the rangefinder and a space for mounting the joint.

[0087] On the other hand, in the case of the first embodiment described above, since the rangefinder 11 and the joint 8 are provided separately, a structure suitable for the desired function can be selected for each of the rangefinder 11 and the joint 8. Therefore, it is easy to manufacture the rangefinder 11 and the joint 8 with good performance (function).

[0088] In the foregoing, the invention of the present inventors has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments, and various modifications can be made within the scope without departing from the gist of the invention. List of reference symbols 1 injection molding machine 2 cylinders 3 snail 4 Rotation drive mechanism 4a Engine 4b Reduction gear 5 nozzle 7 Output shaft 8 joint 11 Rangefinder 12 base unit 21 Power receiving coil 22 AC / DC converters 23 Sensor 24 processor 25 Data transmission coil 26, 26a, 26b housing 27, 27a, 27b concave part 31 Oscillator 32 Power transmission coil 33 Data receiving coil 34 AD converters 35 processor 36 Power source 37 personal computers 41 elastic film 42 metal plate 43 Screw nut 43a Snail hole 44 bolts 44a threaded part 44b Headboard 45 holes 46 Wiring 51 Hinge pin 52 bolts 53 Mother

Claims

[1] An injection molding machine (1), comprising: a cylinder (2); a screw (3) built into the cylinder (2); and a condition detection device, wherein the condition detection device includes a first sensor and a second sensor (23) for detecting a condition of the screw (3), wherein the condition detection device is mounted on the screw (3) outside the cylinder (2), wherein a housing (26) of the condition detection device is made of a non-conductor, wherein the housing (26) of the condition detection device is composed of a pair of housing parts (26a, 26b), wherein the Condition detection device is attached to the screw (3) by enclosing the screw (3) by the pair of housing parts (26a, 26b), wherein the first sensor (23) is arranged in a housing part (26a), wherein the second sensor (23) is arranged in another housing part (26b), and wherein the first sensor and the second sensor (23) are arranged at positions which are symmetrical to the rotational center axis of the screw (3). [2] The injection molding machine (1) according to claim 1, further comprising: a power source unit for the state detection device; and a communication unit for the state detection device. [3] The injection molding machine (1) according to claim 2, wherein a wireless power supply of the state detection device and a wireless data transmission from the state detection device are possible. [4] The injection molding machine (1) according to claim 1, wherein the housing (26) of the condition detecting device is made of a resin. [5] The injection molding machine (1) according to claim 1, wherein the sensor (23) detects a deformation of the screw (3). [6] The injection molding machine (1) according to claim 5, wherein the sensor (23) is a strain gauge. [7] The injection molding machine (1) according to claim 1, wherein the sensor (23) is pressed against the screw (3). [8] The injection molding machine (1) according to claim 7, wherein the state detection device further comprises an elastic film (41), and wherein the sensor (23) is arranged between the elastic film (41) and the screw (3) and is pressed against the screw (3) by the elastic film (41). [9] The injection molding machine (1) according to claim 8, wherein the state detecting device further comprises a metal plate (42), and wherein the metal plate (42) is arranged on a surface of the head part (44b) on an opposite side of a surface in contact with the sensor (23) and is pressed against the elastic film (41). [10] The injection molding machine (1) according to claim 9, wherein a surface of the metal plate (42) in contact with the elastic film (41) is a curved surface. [11] The injection molding machine (1) according to claim 10, wherein the state detecting device further includes a screw element (44), and wherein the metal plate (42) is pressed against the elastic film (41) by the screw element (44). [12] The injection molding machine (1) according to claim 11, wherein the condition detecting device further comprises a nut (43) into which the screw member (44) is inserted, and wherein the nut (43) has a plate-like shape and is in contact with the housing (26) of the condition detecting device. [13] The injection molding machine (1) according to claim 1, wherein a first part of the screw (3) protrudes from an upstream end of the cylinder (2), and wherein the condition detecting device is attached to the first part of the screw (3). [14] The injection molding machine (1) according to claim 2, wherein a method of supplying power to the state detection device is wireless power supply or environmentally friendly power generation. [15] The injection molding machine (1) according to claim 2, further comprising: a base unit (12) arranged at a position opposite the state detection device, wherein the base unit (12) supplies power to the condition detection device, and wherein data is transmitted from the condition detection device to the base unit (12). [16] The injection molding machine (1) according to claim 1, further comprising: another screw (3) which is identical to the screw (3), wherein the condition detection device is attached to each of the two screws (3). [17] An injection molding machine (1), comprising: a cylinder; a screw (3) built into the cylinder (2); a shaft connected to the screw (3) outside the cylinder (2); and a condition detection device, wherein the condition detection device includes a first sensor and a second sensor (23) for detecting a condition of the screw (3), wherein the condition detection device is mounted either on the screw (3) or on the shaft outside the cylinder (2), wherein a housing (26) of the condition detection device is made of a non-conductor, wherein the housing (26) of the condition detection device is composed of a pair of housing parts (26a, 26b), wherein the condition detection device is attached to the worm (3) or the shaft by enclosing the worm (3) or the shaft by the pair of housing parts (26a, 26b), wherein the first sensor (23) is arranged in a housing part (26a), wherein the second sensor (23) is arranged in another housing part (26b), and wherein the first sensor and the second sensor (23) are arranged at positions symmetrical to the rotational center axis of the screw (3) or the shaft. [18] The injection molding machine (1) according to claim 17, wherein a wireless power supply of the state detection device and a wireless data transmission from the state detection device are possible. [19] The injection molding machine (1) according to claim 18, further comprising: an engine (4a); and a reduction gear (4b) connected to the motor (4a), wherein the shaft is an output shaft (7) of the reduction gear (4b). [20] An injection molding machine (1), comprising: a cylinder (2); two screws (3) built into the cylinder (2); and two condition detection devices, each mounted on the two screws (3) outside the cylinder (2), wherein each of the two condition detection devices comprises a first sensor and a second sensor (23) for detecting a state of the attached screw (3), wherein a housing (26) of each of the two state detection devices is made of a non-conductor, wherein the respective housing (26) of the two condition detection devices is composed of a pair of housing parts (26a, 26b), wherein the two state detection devices are each attached to the two screws (3) by enclosing the screws (3) by a pair of housing parts (26a, 26b), wherein the first sensor (23) is arranged in a housing part (26a) in a first condition detection device, wherein the second sensor (23) is arranged in another housing part (26b) in a second state detection device, and wherein the first sensor and the second sensor (23) are arranged at positions which are symmetrical to the central axis of rotation of the screw (3), and whereby a wireless power supply of the two Condition detection devices and wireless data transmission from the two condition detection devices is possible.

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