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-based 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 known is a temperature sensor that measures temperature by connecting a fiber probe through which an optical fiber is inserted 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 above-mentioned temperature sensors, there are some that are provided with 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, in 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 rod-shaped sapphire glass is fixed in a state of being inserted into a cylindrical window support (metal cover). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-232753 A [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-mentioned temperature sensor, the temperature sensor may be heated by heat generated by the molding machine during measurement, causing the window support and the protective window to expand. At this time, a gap may be formed between the protective window and the window support, and molten resin may enter the gap. If the molten resin enters the gap between the protective window and the window support, when the temperature sensor is cooled, the window support contracts, pressing the entered resin against the protective window, applying excessive force to the protective window, and causing the protective window to be damaged.

[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 of the present invention is a temperature sensor used in a molding machine, and comprises a fiber probe through which an optical fiber is inserted, a cylindrically formed window support portion into which at least a portion of the fiber probe is inserted, a protective window portion positioned at the tip side of the fiber probe with at least a portion of it inserted into the window support portion, and a sleeve material formed in an annular shape, whose inner surface is in contact with the outer surface of the protective window portion and whose outer surface is in contact with the inner surface of the window support portion.

[0008] This positions the sleeve material between the protective window portion and the window support portion. Effect 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 description of the drawings]

[0010] [Figure 1] 2 and 4, this figure shows an embodiment of the present invention, and is a cross-sectional view of a temperature sensor. [Diagram 2] FIG. 4 is an enlarged cross-sectional view showing a part of the temperature sensor. [Diagram 3]FIG. 11 is an enlarged cross-sectional view showing an example in which a thermocouple is attached to a protective window portion. [Figure 4] FIG. 11 is an enlarged cross-sectional view showing an example in which a spacer is supported by a protective window portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 downside, and the up-down, left-right directions are described. However, the up-down, left-right directions described below are for the convenience of description, 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 a 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 be attached to an extrusion molding machine, a blow molding machine, or the like.

[0015] The temperature sensor 1 is configured with each required part disposed or supported in an outer casing 2 (see FIG. 1). The outer casing 2 has a housing 3 and a window support part 4. Each part 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 extending vertically. An installation nut 50 for mounting the temperature sensor 1 to an injection molding machine is 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 Figs. 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 is formed with a notch 9a that opens upward and penetrates in the radial direction. The upper end of the annular portion 9 is formed with 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 screwed into the screw hole 7a. Screw insertion holes 7b penetrating vertically are formed at the outer periphery of the lid portion 7 at intervals in the circumferential direction. The lid portion 7 is attached to the placement portion 6 from above by inserting a mounting screw 60 through the screw insertion hole 7b and screwing it into the mounting hole 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. Both the fitting part 11 and the holding part 12 are formed in a cylindrical shape, and the diameter of the fitting part 11 is larger than the diameter of the holding part 12. The holding part 12 is provided below the fitting part 11 and continuous with 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 to the outside of 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 in the up-down direction of the holding portion 12 (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 through hole 14. The diameter of the through hole 14 is set to be larger than the diameter of the optical fiber described later. 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 part of the inner peripheral surface of the holding portion 12 that forms the first insertion space 15 is formed as a first inner peripheral surface 12c, and the part that forms the second insertion space 16 is formed as a second inner peripheral surface 12d. The first insertion space 15 and the second insertion space 16 are communicated via the through hole 14. The window support portion 4 includes a fitting portion 11, a holding portion 12, and a receiving portion 13, which are formed, for example, integrally with each other.

[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 having a thermal expansion coefficient smaller than that of the window support portion 4, for example, Kovar. The thermal expansion coefficient of the sleeve material 17 is, for example, 4.9×10 -6 / ℃ to 6.2×10 -6 / ° C. It is preferable that the sleeve material 17 is made of a material having a thermal expansion coefficient close to that of the protective window portion 18.

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

[0026] The protective window 18 is formed in a cylindrical shape with its axial direction in the up-down direction. The protective window 18 is formed 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 substantially 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 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 portion 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 outside the fiber probe 19 from the outer circumferential surface of the flange portion 21. 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 into which infrared light is incident.

[0030] The fiber probe 19 is supported by inserting the cylindrical portion 20 into the shaft portion 5 and inserting the tip portion into the first insertion space 15 in the holder 12. The cylindrical portion 20 is in a state where the outer circumferential surface is in contact with the first inner circumferential 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 disposed inside the window support portion 4 with the outer circumferential surface of the cylindrical portion 20 in contact with the first inner circumferential surface 12c of the holder 12, so that a stable arrangement state without rattling with respect to the window support portion 4 is ensured.

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

[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 part 13 by the urging force of the elastic member 22. Note that a disc spring, a leaf spring, or the like may be used as the elastic member 22, and the elastic member 22 may 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 screwing position relative to the screw hole 7a. Note that the temperature sensor 1 may also be configured without providing 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 guiding infrared light through the protective window portion 18, entering the optical fiber 23 from the incident surface 23d, and transmitting the infrared light 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 circumferential surface 17b in contact with an outer circumferential surface 18a of the protective window portion 18, and the outer circumferential surface 17a in contact with a first inner circumferential surface 12c of the holding portion 12 of the window support portion 4. Therefore, since the sleeve material 17 is positioned between the protective window portion 18 and the window support portion 4, intrusion of molten resin between the protective window portion 18 and the window support portion 4 is suppressed, and excessive force is unlikely 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. This makes the degree of expansion of the sleeve material 17 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 the molten resin to get between the protective window portion 18 and the sleeve material 17, so that the intrusion of the molten resin between the protective window portion 18 and the sleeve material 17 can be reliably prevented.

[0037] Furthermore, the protective window portion 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 and close to that of the protective window portion 18, and makes the degree of expansion of the protective window portion 18 and the sleeve material 17 similar. Therefore, when the protective window portion 18 is clamped by the sleeve material 17 during expansion, the sleeve material 17 can maintain a tight contact state between the two without applying excessive load to the protective window portion 18 from the protective window portion 18.

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

[0039] Furthermore, in the above-described temperature sensor 1, the receiving portion 13 is provided on the window support portion 4, 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 portion 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 portion 18, and when the pressure of the molten resin is applied to the protective window portion 18, the pressure of the molten resin is transmitted from the protective window portion 18 to the outer casing 2 via the receiving portion 13, thereby reducing the load on the protective window portion 18 due to the pressure of the molten resin.

[0040] In a temperature sensor in which infrared light is transmitted through a protective window and incident on 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, causing optical interference, depending on the conditions of the air layer, etc. Such optical interference occurs when the thickness of the air layer is extremely small, on the order of nanometers to micrometers, and if the thickness of the air layer changes due to, for example, 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 above-described temperature sensor 1, 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 on the order of millimeters or more, not on the order of nanometers or micrometers. Therefore, the receiving portion 13 maintains a certain distance or more between the optical fiber 23 and the protective window portion 18, suppressing the occurrence of optical interference and ensuring a stable measurement state.

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

[0043] The window support portion 4A is formed with a calibration insertion hole 24 that penetrates the holding portion 12 vertically. A temperature sensor for calibration, for example, a thermocouple 25, is inserted into the calibration insertion hole 24. As the thermocouple 25, for example, a sheath-type thermocouple is used, 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 taken out to the outside of the outer casing 2 from 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. This makes it possible to calibrate the measurement results, thereby 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 above-described temperature sensor 1 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 FIG. 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 part of the fitting part 27, and the holding part 29 being provided continuous with the lower end part 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] The 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 an axial direction extending in the up-down direction, 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 through 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 tubular portion 30, the outer peripheral surface of the cylindrical portion 20 is in contact with the inner peripheral surface of the tubular 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 surface of the sleeve material 17 and the upper surface of 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 hole 25 Thermocouple

Claims

1. A temperature sensor for use in a molding machine, comprising: a cylindrical fiber probe through which an optical fiber is inserted; a window support portion formed in a cylindrical shape and into which at least a part of the fiber probe is inserted; a protective window portion positioned on a tip side of the fiber probe in a state where at least a portion of the protective window portion is 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; 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 made smaller than the thermal expansion coefficient of the protective window portion. The temperature sensor according to 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, 2 or 3.

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

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