Temperature Sensor

Abstract

To prevent a protection window part from being broken.SOLUTION: The present invention relates to a temperature sensor used for a molding machine, and the temperature sensor comprises a cylindrical fiber probe into which an optical fiber is inserted, a window support part into which at least a part of the cylindrically formed fiber probe is inserted, a protection window part which is located on a tip end side of the fiber probe with the at least part inserted into the window support part, and a sleeve material which has an annularly formed inner peripheral surface in contact with an outer peripheral surface of the protection window part and also an outer peripheral surface in contact with an inner peripheral part of the window support part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the technical field of optical fiber temperature sensors used in molding machines. [Background technology]

[0002] A molding machine that molds a resin molded product is provided with a sensor for measuring the temperature and pressure of the resin in a cavity, etc. One such sensor is a temperature sensor that measures the temperature by connecting a fiber probe having an optical fiber inserted therethrough to the cavity, etc., and transmitting infrared light emitted from the molten resin filled in the cavity, etc., through the optical fiber to a detector (see, for example, Patent Document 1).

[0003] Among the temperature sensors described above, some have a glass protective window at the tip of the fiber probe in order to measure the temperature of molten resin in a high-temperature and high-pressure environment, for example, at the nozzle of an injection molding machine (see, for example, Patent Document 2). Temperature sensors with such a protective window are provided with a window support for supporting the protective window, and the window support is generally made of a metal material. In the temperature sensor described in Patent Document 2, the protective window made of a rod-shaped sapphire glass is inserted into and fixed in a cylindrical window support (metal cover). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-232753 [Patent Document 2] Japanese Patent Application Publication No. 1-124725 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described temperature sensor, the temperature sensor may be heated by heat generated by the molding machine during measurement, causing the window support and protective window to expand. This can create a gap between the protective window and the window support, potentially allowing molten resin to penetrate into the gap. If molten resin penetrates the gap between the protective window and the window support, contraction of the window support can press the intruding resin against the protective window as the temperature sensor cools, applying excessive force to the protective window and potentially damaging it.

[0006] Therefore, an object of the present invention is to prevent damage to the protective window portion. [Means for solving the problem]

[0007] The temperature sensor according to the present invention is a temperature sensor used in a molding machine, and includes a fiber probe having an optical fiber inserted therein, a cylindrical window support into which at least a portion of the fiber probe is inserted, a protective window positioned at the tip side of the fiber probe with at least a portion of the fiber probe inserted into the window support, and a sleeve material formed in an annular shape, the inner peripheral surface of which contacts the outer peripheral surface of the protective window and the outer peripheral surface of which contacts the inner peripheral surface of the window support. The protective window portion protrudes from the window support portion. It is something.

[0008] This positions the sleeve material between the protective window portion and the window support portion. [Effects of the Invention]

[0009] According to the present invention, a sleeve material is positioned between the protective window portion and the window support portion, thereby suppressing the intrusion of molten resin between the protective window portion and the window support portion, thereby preventing damage to the protective window portion. [Brief explanation of the drawings]

[0010] [Figure 1] 2 and 4 show an embodiment of the present invention, and this figure is a cross-sectional view of a temperature sensor. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a part of the temperature sensor. [Figure 3]FIG. 10 is an enlarged cross-sectional view showing an example in which a thermocouple is attached to a protective window portion. [Figure 4] FIG. 10 is an enlarged cross-sectional view showing an example in which a spacer is supported by a protective window portion. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a temperature sensor according to the present invention will be described with reference to the accompanying drawings (see FIGS. 1 to 4).

[0012] The temperature sensor described below has a cylindrical fiber probe, and in the following description, the axial direction of the fiber probe is the up-down direction, and the tip side of the fiber probe is the downward direction, and the up-down, left-right directions are indicated. However, the up-down, left-right directions described below are for the convenience of explanation, and the implementation of the present invention is not limited to these directions.

[0013] <Temperature Sensor According to First Embodiment> First, a temperature sensor 1 according to a first embodiment will be described (see FIGS. 1 to 3).

[0014] The temperature sensor 1 is attached to an injection molding machine (not shown) and is used to measure the temperature of molten resin at the nozzle, for example. Note that the molding machine to which the temperature sensor 1 is attached is not limited to an injection molding machine, and the temperature sensor 1 may also be attached to an extrusion molding machine, a blow molding machine, or the like.

[0015] The temperature sensor 1 is configured by disposing or supporting required components in an outer casing 2 (see FIG. 1). The outer casing 2 has a housing 3 and a window support 4. Each component of the outer casing 2 is formed, for example, from a metal material.

[0016] The housing 3 has a shaft portion 5 , a mounting portion 6 and a cover portion 7 .

[0017] The shaft portion 5 is formed into a cylindrical shape with its axial direction aligned vertically. Installation nuts 50 for attaching the temperature sensor 1 to the injection molding machine are attached to the shaft portion 5 except for the upper and lower ends. The lower end surface of the shaft portion 5 is formed as a pressing surface 5a (see Figures 1 and 2).

[0018] The mounting portion 6 has a flange portion 8 that projects outward from the upper end of the shaft portion 5, and a substantially cylindrical annular portion 9 that projects upward from the outer periphery of the flange portion 8. The mounting portion 6 is formed, for example, integrally with the shaft portion 5. The annular portion 9 has a notch 9a that opens upward and penetrates in the radial direction. The upper end of the annular portion 9 has a plurality of mounting holes 9b that open upward and are spaced apart in the circumferential direction.

[0019] The lid portion 7 is formed in an annular shape and has a screw hole 7a in the center. An adjustment screw 10 is threaded into the screw hole 7a. Screw insertion holes 7b that penetrate vertically are formed at intervals in the circumferential direction on the outer periphery of the lid portion 7. The lid portion 7 is attached to the placement portion 6 from above by inserting mounting screws 60 through the screw insertion holes 7b and threading them into the mounting holes 9b.

[0020] The window support part 4 is formed in a cylindrical shape with its axial direction in the up-down direction. The window support part 4 is made of, for example, stainless steel, and has a thermal expansion coefficient (linear expansion coefficient) of, for example, 11.5×10 -6 / ℃ to 12.5 × 10 -6 / ℃ range.

[0021] The window support part 4 has a fitting part 11, a holding part 12, and a receiving part 13. The fitting part 11 and the holding part 12 are both formed in a cylindrical shape, with the diameter of the fitting part 11 being larger than the diameter of the holding part 12. The holding part 12 is provided below the fitting part 11, continuing from the lower end part of the fitting part 11. The upper surface of the holding part 12 is formed as a pressed surface 12a, and the lower surface is formed as a tip surface 12b. The fitting part 11 of the window support part 4 is attached in an externally fitted manner to the lower end part of the shaft part 5, and the pressing surface 5a of the shaft part 5 is pressed against the pressed surface 12a of the holding part 12.

[0022] The receiving portion 13 is provided in a state of protruding inward at the middle portion of the holding portion 12 in the up-down direction (see FIG. 2). The upper surface of the receiving portion 13 is formed as a first receiving surface 13a, and the lower surface is formed as a second receiving surface 13b. The space inside the receiving portion 13 is formed as a transmission hole 14. The diameter of the transmission hole 14 is equal to or greater than the diameter of the optical fiber described below. The space above the receiving portion 13 in the internal space of the holding portion 12 is formed as a first insertion space 15, and the space below the receiving portion 13 is formed as a second insertion space 16. The portion of the inner circumferential surface of the holding portion 12 that forms the first insertion space 15 is formed as a first inner circumferential surface 12c, and the portion that forms the second insertion space 16 is formed as a second inner circumferential surface 12d. The first insertion space 15 and the second insertion space 16 are in communication via the transmission hole 14. The window support portion 4 has a fitting portion 11, a holding portion 12 and a receiving portion 13, which are formed integrally, for example.

[0023] In the second insertion space 16, a sleeve material 17 and a protective window portion 18 are arranged.

[0024] The sleeve material 17 is formed in an annular shape with its axial direction in the up-down direction. The sleeve material 17 is made of a material, such as Kovar, whose thermal expansion coefficient is smaller than that of the window support part 4. The thermal expansion coefficient of the sleeve material 17 is, for example, 4.9×10 -6 / ℃ to 6.2 × 10 -6 / ° C. It is desirable that the sleeve material 17 be made of a material whose thermal expansion coefficient is close to that of the protective window portion 18.

[0025] The sleeve material 17 is inserted almost entirely into the second insertion space 16 with its upper surface in contact with the second receiving surface 13b, and its lower surface positioned flush with the tip surface 12b of the holder 12 or positioned slightly below the tip surface 12b. When inserted into the second insertion space 16, the sleeve material 17 has its outer peripheral surface 17a in contact with the second inner peripheral surface 12d of the holder 12. The sleeve material 17 is bonded to the holder 12 by, for example, welding. However, the sleeve material 17 and the holder 12 may also be bonded by brazing, a heat-resistant adhesive, or the like.

[0026] The protective window 18 is formed in a cylindrical shape with its axis oriented in the up-down direction. The protective window 18 is made of, for example, sapphire glass. The thermal expansion coefficient of the protective window 18 is smaller than that of the window support 4 and larger than that of the sleeve material 17, for example, 7.0×10 -6 / ℃ to 7.7 × 10 -6 / ℃ range.

[0027] The outer diameter of the protective window portion 18 is larger than the diameter of the transmission hole 14 and is approximately the same as or slightly smaller than the inner diameter of the sleeve material 17. The protective window portion 18 is inserted into the sleeve material 17 with the outer periphery on the upper surface in contact with the second receiving surface 13b, and the lower end portion protrudes downward from the holding portion 12. The outer periphery 18a of the protective window portion 18 is bonded to the inner periphery 17b of the sleeve material 17 by brazing with silver solder, for example. However, the sleeve material 17 and the protective window portion 18 may also be bonded by low-melting-point glass, a heat-resistant adhesive, or the like.

[0028] A fiber probe 19 is disposed inside the outer casing 2. The fiber probe 19 is formed, for example, from a metal material, and has a cylindrical portion 20 whose axial direction is in the up-down direction and a flange portion 21 that is continuous with the upper end of the cylindrical portion 20. The outer diameter of the flange portion 21 is larger than the outer diameter of the cylindrical portion 20. The upper surface of the flange portion 21 is formed as a pressed surface 21a.

[0029] An optical fiber 23 is inserted and held in the fiber probe 19. One end 23a of the optical fiber 23 is inserted into the cylindrical portion 20, and a bent portion 23b connected to the one end 23a is bent, for example, at a substantially right angle inside the flange portion 21. In the optical fiber 23, a portion between the bent portion 23b and the other end is provided as an intermediate portion 23c, and the intermediate portion 23c passes through the notch 9a and is positioned from the outer peripheral surface of the flange portion 21 to the outside of the fiber probe 19. A detector or the like (not shown) is connected to the other end of the optical fiber 23. An end face (lower end face) of the one end 23a of the optical fiber 23 is formed as an incident surface 23d onto which infrared light is incident.

[0030] The fiber probe 19 is supported by having its cylindrical portion 20 inserted into the shaft portion 5 and its tip inserted into the first insertion space 15 in the holder 12. The outer peripheral surface of the cylindrical portion 20 is in contact with the first inner peripheral surface 12c of the holder 12, and the tip surface (lower surface) 19a of the fiber probe is in contact with the first receiving surface 13a of the receiving portion 13. At this time, the center of the optical fiber 23 (incident surface 23d) is approximately aligned with the center of the transmission hole 14. In this way, the fiber probe 19 is arranged inside the window support 4 with the outer peripheral surface of the cylindrical portion 20 in contact with the first inner peripheral surface 12c of the holder 12, ensuring a stable arrangement without rattle relative to the window support 4.

[0031] The flange 21 is positioned in the placement portion 6, and when the cover 7 is attached to the placement portion 6, an elastic member 22 is disposed between the lower surface of the adjustment screw 10 and the pressed surface 21a of the flange 21.

[0032] For example, a compression coil spring is used as the elastic member 22. The fiber probe 19 is urged downward by the urging force of the elastic member 22. Therefore, the tip surface 19a of the fiber probe 19 is pressed against the first receiving surface 13a of the receiving portion 13 by the urging force of the elastic member 22. Note that a disc spring, a leaf spring, or the like may also be used as the elastic member 22, and the elastic member 22 may also be made of a rubber material or the like.

[0033] In the temperature sensor 1, the biasing force of the elastic member 22 against the fiber probe 19 can be adjusted by rotating the adjustment screw 10 to change the screw engagement position with respect to the screw hole 7a. Note that the temperature sensor 1 may also be configured without the elastic member 22.

[0034] When the temperature sensor 1 configured as described above is attached to a molding machine such as an injection molding machine and used to measure the temperature of molten resin, the temperature is measured by infrared light being guided through the protective window 18, entering the optical fiber 23 from the incident surface 23d, and being transmitted to a detector through the optical fiber 23. At this time, the temperature sensor 1 is heated by heat generated in the injection molding machine, for example, and the heated parts expand.

[0035] The temperature sensor 1 is provided with a sleeve material 17 that is formed in an annular shape and has an inner peripheral surface 17b that contacts an outer peripheral surface 18a of the protective window portion 18, and has the outer peripheral surface 17a that contacts a first inner peripheral surface 12c of the holding portion 12 of the window support portion 4. Therefore, because the sleeve material 17 is positioned between the protective window portion 18 and the window support portion 4, the intrusion of molten resin between the protective window portion 18 and the window support portion 4 is suppressed, and excessive force is less likely to be applied to the protective window portion 18 when the temperature sensor 1 is cooled, preventing damage to the protective window portion.

[0036] Furthermore, in the temperature sensor 1, the thermal expansion coefficient of the protective window portion 18 is made smaller than that of the window support portion 4, and the thermal expansion coefficient of the sleeve material 17 is made smaller than that of the protective window portion 18. As a result, the degree of expansion of the sleeve material 17 is smaller than that of the protective window portion 18, and the protective window portion 18 is clamped by the sleeve material 17. Therefore, there is no room for molten resin to get between the protective window portion 18 and the sleeve material 17, so that the intrusion of molten resin between the protective window portion 18 and the sleeve material 17 can be reliably prevented.

[0037] Furthermore, the protective window 18 is made of sapphire glass, and the sleeve material 17 is made of Kovar. This makes the thermal expansion coefficient of the sleeve material 17 smaller than but close to that of the protective window 18, and the degree of expansion of the protective window 18 and the sleeve material 17 is similar. Therefore, when the protective window 18 is clamped by the sleeve material 17 during expansion, the sleeve material 17 does not apply excessive load to the protective window 18, and the two can maintain a tight contact state.

[0038] In addition, the lower end of the protective window portion 18 protrudes downward from the holding portion 12. Therefore, molten resin is less likely to remain at the tip of the temperature sensor 1 during measurement, and excessive pressure is less likely to be applied to the protective window portion 18 from the molten resin.

[0039] Furthermore, in the temperature sensor 1 described above, the window support 4 is provided with a receiving portion 13, with the first receiving surface 13a in contact with the fiber probe 19 and the second receiving surface 13b in contact with the protective window 18. This makes it difficult for the biasing force of the elastic member 22 applied to the fiber probe 19 to be transmitted to the protective window 18, and when pressure of the molten resin is applied to the protective window 18, the pressure of the molten resin is transmitted from the protective window 18 to the outer casing 2 via the receiving portion 13, thereby reducing the load on the protective window 18 due to the pressure of the molten resin.

[0040] In a temperature sensor in which infrared light passes through a protective window and enters an optical fiber, if there is an air layer between the protective window and the incident surface, the light may be reflected at the interface between the protective window and the air layer or at the interface between the air layer and the incident surface, depending on the conditions of the air layer, resulting in optical interference. Such optical interference occurs when the thickness of the air layer is extremely small, on the order of nanometers to micrometers. For example, if the thickness of the air layer changes due to thermal expansion of the protective window, the degree of optical interference also changes, which may affect the measurement results of the temperature sensor.

[0041] In the temperature sensor 1 described above, by providing the receiving portion 13 on the window support portion 4, a certain distance is maintained between the upper surface of the protective window portion 18 and the incident surface 23d of the optical fiber 23 via an air layer (transmission hole 14). Because the receiving portion 13 is a structure, the thickness of this air layer is not on the order of nanometers or micrometers, but on the order of millimeters or more. Therefore, the receiving portion 13 maintains a certain distance or more between the optical fiber 23 and the protective window portion 18, which suppresses the occurrence of optical interference and ensures stable measurement conditions.

[0042] The temperature sensor 1 may be configured to use a window support part 4A in which a calibration insertion hole 24 is formed, instead of the window support part 4 (see FIG. 3).

[0043] The window support portion 4A has a calibration insertion hole 24 formed therein, which penetrates the holding portion 12 from top to bottom. A temperature sensor for calibration, such as a thermocouple 25, is inserted into the calibration insertion hole 24. For example, a sheath-type thermocouple is used as the thermocouple 25, and the thermocouple 25 is attached by welding to the window support portion 4A with one end inserted into the calibration insertion hole 24. The other end of the thermocouple 25 is extended out of the outer casing 2 through the notch 9a, for example, and is connected to a measuring instrument or the like (not shown).

[0044] In this way, a calibration insertion hole 24 is formed in the window support portion 4A, and a thermocouple 25 is attached to the calibration insertion hole 24, so that temperature is measured using both the optical fiber 23 and the thermocouple 25, making it possible to calibrate the measurement results and improving the measurement accuracy of the temperature sensor 1.

[0045] <Temperature Sensor According to Second Embodiment> Next, a temperature sensor 1A according to a second embodiment will be described (see FIG. 4).

[0046] The temperature sensor 1A described below differs from the temperature sensor 1 described above only in that a window support part 4B and a spacer 26 are used instead of the window support part 4. Therefore, only the parts that differ from the temperature sensor 1 will be described in detail, and the other parts will be given the same symbols as those used for similar parts in the temperature sensor 1 and will not be described again.

[0047] The window support part 4B has a fitting part 27, a connecting part 28, and a holding part 29 (see Figure 4). The fitting part 27, the connecting part 28, and the holding part 29 are all formed in a cylindrical shape, with the connecting part 28 being provided continuous with the lower end of the fitting part 27, and the holding part 29 being provided continuous with the lower end of the connecting part 28. The sleeve material 17 and the protective window part 18 are inserted into and supported by the holding part 29.

[0048] A spacer 26 is also supported by the window support portion 4B. The spacer 26 is formed, for example, from a metal material and has a cylindrical tubular portion 30 with its axial direction aligned vertically and a receiving portion 31 that protrudes inward from the lower end of the tubular portion 30. The upper surface of the receiving portion 31 is formed as a first receiving surface 31a, and the lower surface is formed as a second receiving surface 31b. The space inside the receiving portion 31 is formed as a transmission hole 32. The tubular portion 30 and the receiving portion 31 are formed, for example, as a single unit.

[0049] The tip of the fiber probe 19 is inserted into the cylindrical portion 30, the outer peripheral surface of the cylindrical portion 20 is in contact with the inner peripheral surface of the cylindrical portion 30, and the tip surface 19a of the fiber probe is in contact with the first receiving surface 31a of the receiving portion 31. The upper surfaces of the sleeve material 17 and the protective window portion 18 are in contact with the second receiving surface 31b of the receiving portion 31.

[0050] In the temperature sensor 1A, the receiving portion 31 makes it difficult for the biasing force of the elastic member 22 applied to the fiber probe 19 to be transmitted to the protective window portion 18, and the pressure of the molten resin is transmitted from the protective window portion 18 to the outer casing 2 via the spacer 26.

[0051] In this way, by providing the receiving portion 31 as a separate body from the window support portion 4B, it becomes possible to form the receiving portion 31 from a material different from that of the window support portion 4B. For example, by forming the spacer 26 from a material that is stronger than the window support portion 4B, it is possible to ensure high strength of the receiving portion 31. [Explanation of symbols]

[0052] 1, 1A temperature sensor 4, 4A, 4B Window support 11 Fitting part 12 Holding part 12d Second inner surface 13 Receiving part 13a First receiving surface 13b Second receiving surface 17 Sleeve material 17a Outer surface 17b Inner surface 18 Protective window 18a Outer surface 19 Fiber Probe 23 Optical Fiber 24 Calibration insertion hole 25 Thermocouple

Claims

1. A temperature sensor for use in a molding machine, a cylindrical fiber probe through which an optical fiber is inserted; a cylindrical window support portion into which at least a portion of the fiber probe is inserted; a protective window portion positioned on the distal end side of the fiber probe with at least a portion of the protective window portion inserted into the window support portion; a sleeve material formed in an annular shape, the inner peripheral surface of which contacts the outer peripheral surface of the protective window portion and the outer peripheral surface of which contacts the inner peripheral surface of the window support portion, The protective window portion protrudes from the window support portion. Temperature sensor.

2. The thermal expansion coefficient of the protective window portion is set to be smaller than the thermal expansion coefficient of the window support portion, The thermal expansion coefficient of the sleeve material is smaller than the thermal expansion coefficient of the protective window portion. The temperature sensor of claim 1 .

3. the protective window portion is formed of sapphire glass, The sleeve material is made of Kovar The temperature sensor according to claim 2 .

4. The window support portion is provided with a receiving portion that protrudes inward, the receiving portion is positioned between the fiber probe and the protective window portion; One surface of the receiving portion contacts the fiber probe, and the other surface contacts the protective window portion. The temperature sensor according to claim 1, claim 2 or claim 3.

5. a calibration insertion hole is formed in the window support portion; A thermocouple is inserted into the calibration insertion hole. The temperature sensor according to claim 1, claim 2 or claim 3.

6. The protective window portion and the sleeve material are bonded together. The temperature sensor according to claim 1, claim 2 or claim 3.

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