Temperature sensor

Abstract

Provided is a temperature sensor for a molding machine, comprising: a cylindrical fiber-optic probe into which an optical fiber is inserted; a window support part which is formed in a cylindrical shape and into which at least a part of the optical fiber probe is inserted; a protective window disposed on the tip side of the fiber optic probe while being at least partially inserted into the window support; and a sleeve member formed in an annular shape and having an inner peripheral surface in contact with an outer peripheral surface of the protection window and an outer peripheral surface in contact with an inner peripheral surface of the window support portion.

Description

Technical Field

[0001] The present disclosure relates to the technical field of temperature sensors using optical fibers for use in molding machines. Background Art

[0002] A molding machine that molds a resin molded product is provided with a sensor for measuring the temperature or pressure of the resin in a cavity, etc. Such a sensor may be, for example, a temperature sensor that measures the temperature by connecting a fiber probe (in which an optical fiber is inserted) to the cavity and transmitting infrared light emitted from the molten resin filled in the cavity to a detector through the optical fiber (see, for example, Japanese Laid-Open Patent Publication No. 2008-232753).

[0003] In the above temperature sensor, a glass protection window is arranged on the tip side of the fiber probe to measure the temperature of molten resin in a high temperature and high pressure environment such as a nozzle of an injection molding machine (see, for example, Japanese Laid-Open Patent Publication No. H1-124725).

[0004] The temperature sensor with such a protective window is provided with a window support portion for supporting the protective window, and the window support portion is usually made of a metal material. In the temperature sensor disclosed in Japanese Patent Publication No. H1-124725, a protective window made of a rod-shaped sapphire glass is inserted and fixed to a cylindrical window support portion (metal cover). Summary of the invention

[0005] In the above-mentioned temperature sensor, the temperature sensor may be heated by the heat emitted by the molding machine during measurement, and the window support portion or the protection window may expand. In this case, a gap may be generated between the protection window and the window support portion, and molten resin may enter the generated gap. If molten resin enters the gap between the protection window and the window support portion, when the temperature sensor is cooled, the resin that has entered the gap may be pressed against the protection window by the contraction of the window support portion. Therefore, excessive force may be applied to the protection window, and the protection window may be damaged.

[0006] Therefore, an object of the present disclosure is to prevent damage to the protection window.

[0007] According to one aspect of the present disclosure, there is provided a temperature sensor for a molding machine, comprising: a cylindrical fiber optic probe into which an optical fiber is inserted; a window support portion, which is formed in a cylindrical shape and into which at least a portion of the fiber optic probe is inserted; a protective window, which is arranged on the tip side of the fiber optic probe and at least partially inserted into the window support portion; and a sleeve member, which is formed in a ring shape and has an inner circumferential surface in contact with the outer circumferential surface of the protective window and an outer circumferential surface in contact with the inner circumferential surface of the window support portion.

[0008] Thus, the sleeve member is positioned between the protection window and the window support. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 and Figure 2 and Figure 4 Together, the embodiments of the present disclosure are shown. Figure 1 is a cross-sectional view of the temperature sensor.

[0010] Figure 2 is an enlarged cross-sectional view showing a part of the temperature sensor.

[0011] Figure 3 is an enlarged cross-sectional view showing an example of attaching a thermocouple to a protection window.

[0012] Figure 4 is an enlarged cross-sectional view showing an example in which a spacer is supported by a protection window. DETAILED DESCRIPTION

[0013] In the following, reference will be made to the accompanying drawings (see Figures 1 to 4 ) describes an embodiment of a temperature sensor for implementing the present disclosure.

[0014] The temperature sensor described below has a cylindrical optical fiber probe. In the following description, the upper side, the lower side, the right side, and the left side are defined by setting the axial direction of the optical fiber probe as the vertical direction and setting the tip side of the optical fiber probe as the lower side. However, for ease of description, the upper side, the lower side, the right side, and the left side are defined in the following description, and the embodiments of the present disclosure are not limited to these directions.

[0015] <Temperature Sensor According to First Embodiment>

[0016] First, a temperature sensor 1 according to a first embodiment (see Figures 1 to 3 ).

[0017] For example, the temperature sensor 1 is attached to an injection molding machine (not shown) and is used to measure the temperature of the molten resin in the nozzle. Further, the molding machine to which the temperature sensor 1 is attached is not limited to the injection molding machine, and the temperature sensor 1 can be attached to an extrusion molding machine, a blow molding machine, etc.

[0018] The various components required for the temperature sensor 1 are arranged or supported in the outer housing 2 (see Figure 1 ). The outer shell 2 has a shell 3 and a window support 4. For example, each component of the outer shell 2 is made of a metal material.

[0019] The housing 3 includes a shaft portion 5 , a placement portion 6 , and a cover portion 7 .

[0020] The shaft portion 5 is formed into a cylindrical shape whose axial direction coincides with the vertical direction. A mounting nut 50 for attaching the temperature sensor 1 to the injection molding machine is attached to the shaft portion 5 except for its upper and lower ends. The bottom surface of the shaft portion 5 serves as a pressing surface 5a (see Figure 1 and Figure 2 ).

[0021] The placement portion 6 has a flange portion 8 protruding outward from the upper end of the shaft portion 5 and a substantially cylindrical annular portion 9 protruding upward from the outer peripheral portion of the flange portion 8. For example, the placement portion 6 is formed integrally with the shaft portion 5. A cutout 9a opening upward is formed in the annular portion 9 to penetrate the annular portion 9 in the radial direction. A plurality of mounting holes 9b opening upward are formed at the upper end of the annular portion 9 while being spaced apart from each other in the circumferential direction.

[0022] The cover 7 is formed in an annular shape with a screw hole 7a at the center thereof. An adjustment screw 10 is screwed into the screw hole 7a. Screw insertion holes 7b are formed to vertically penetrate the outer peripheral edge of the cover 7 while being spaced apart in the circumferential direction. The cover 7 is attached to the placement portion 6 from the top by screwing the mounting screw 60 inserted through the screw insertion hole 7b into the mounting hole 9b.

[0023] The window support 4 is formed into a cylindrical shape with an axial direction that coincides with the vertical direction. The window support 4 is made of, for example, stainless steel and has a diameter of, for example, 11.5×10 -6 / ℃ to 12.5×10 -6 The thermal expansion coefficient (linear expansion coefficient) is in the range of / °C.

[0024] The window support portion 4 has a fixing portion 11, a holding portion 12 and a receiving portion 13. The fixing portion 11 and the holding portion 12 are both formed in a cylindrical shape, and the diameter of the fixing portion 11 is larger than the diameter of the holding portion 12. The holding portion 12 is continuously arranged from the lower end of the fixing portion 11 to a position below the fixing portion 11. The holding portion 12 has an upper surface serving as a pressure surface 12a and a bottom surface serving as a tip surface 12b. The fixing portion 11 of the window support portion 4 is attached to the lower end of the shaft portion 5 from the outside, and the pressing surface 5a of the shaft portion 5 is pressed against the pressure surface 12a of the holding portion 12.

[0025] The receiving portion 13 protrudes inwardly at the vertical middle portion of the holding portion 12 (see Figure 2). The upper surface of the receiving portion 13 serves as a first receiving surface 13a, and the bottom surface thereof serves as a second receiving surface 13b. The internal space of the receiving portion 13 serves as a through hole 14. The diameter of the through hole 14 is larger than the diameter of the optical fiber described later. In the internal space of the retaining portion 12, the space above the receiving portion 13 serves as a first insertion space 15, and the space below the receiving portion 13 serves as a second insertion space 16. In the inner circumferential surface of the retaining portion 12, the portion forming the first insertion space 15 serves as a first inner circumferential surface 12c, and the portion forming the second insertion space 16 serves as a second inner circumferential surface 12d. The first insertion space 15 and the second insertion space 16 are connected to each other through the through hole 14. For example, in the window support portion 4, the fixing portion 11, the retaining portion 12 and the receiving portion 13 are formed integrally.

[0026] The sleeve member 17 and the protection window 18 are arranged in the second insertion space 16 .

[0027] The sleeve member 17 is formed into an annular shape with the axial direction being consistent with the vertical direction. The sleeve member 17 is made of a material having a thermal expansion coefficient smaller than that of the window support 4, such as Kovar. For example, the thermal expansion coefficient of the sleeve member 17 is 4.9×10 -6 / ℃ to 6.2×10 -6 Further, it is desirable that the sleeve member 17 is made of a material having a thermal expansion coefficient close to that of the protection window 18 .

[0028] The sleeve member 17 is substantially completely inserted into the second insertion space 16 in a state where its upper surface is in contact with the second receiving surface 13b, and its bottom surface is positioned on the same plane as the tip surface 12b of the holding portion 12 or is positioned slightly lower than the tip surface 12b. When the sleeve member 17 is inserted into the second insertion space 16, the outer peripheral surface 17a of the sleeve member 17 is in contact with the second inner peripheral surface 12d of the holding portion 12. The sleeve member 17 is bonded to the holding portion 12 by, for example, welding. However, the sleeve member 17 and the holding portion 12 may be bonded by brazing, a heat-resistant adhesive, or the like.

[0029] The protective window 18 is formed into a cylindrical shape with the axial direction being consistent with the vertical direction. The protective window 18 is made of, for example, sapphire glass. The thermal expansion coefficient of the protective window 18 is smaller than the thermal expansion coefficient of the window support 4 and larger than the thermal expansion coefficient of the sleeve member 17. For example, it is 7.0×10 -6 / ℃ to 7.7×10 -6 / ℃ range.

[0030] The outer diameter of the protection window 18 is larger than the diameter of the through hole 14, and is substantially the same as or slightly smaller than the inner diameter of the sleeve member 17. The protection window 18 is inserted into the sleeve member 17 in a state where the outer peripheral edge portion of the upper surface is in contact with the second receiving surface 13b, and the lower end thereof protrudes downward from the holding portion 12. The outer peripheral surface 18a of the protection window 18 is bonded to the inner peripheral surface 17b of the sleeve member 17 by, for example, silver brazing. However, the sleeve member 17 and the protection window 18 may be bonded by low melting point glass, a heat-resistant adhesive, or the like.

[0031] The optical fiber probe 19 is arranged in the outer housing 2. The optical fiber probe 19 is made of, for example, a metal material, and has a cylindrical portion 20 whose axial direction coincides with the vertical direction and a collar portion 21 continuous with the upper end of the cylindrical portion 20. The outer diameter of the collar portion 21 is larger than the outer diameter of the cylindrical portion 20. The upper surface of the collar portion 21 serves as a pressure receiving surface 21a.

[0032] The optical fiber 23 is inserted and held in the optical fiber probe 19. One end 23a of the optical fiber 23 is inserted into the cylindrical portion 20, and a bent portion 23b continuous with the one end 23a is bent inside the collar portion 21, for example, at a substantially right angle. In the optical fiber 23, a portion between the bent portion 23b and the other end serves as an intermediate portion 23c, and the intermediate portion 23c passes through the cutout 9a from the outer peripheral surface of the collar portion 21 to be located outside the optical fiber probe 19. A detector (not shown) or the like is connected to the other end of the optical fiber 23. An end face (bottom surface) of the one end 23a of the optical fiber 23 serves as an incident face 23d on which infrared light is incident.

[0033] The cylindrical portion 20 of the optical fiber probe 19 is inserted into the shaft portion 5, and the tip thereof is inserted into and supported by the first insertion space 15 of the holding portion 12. The outer peripheral surface of the cylindrical portion 20 is in contact with the first inner peripheral surface 12c of the holding portion 12, and the tip surface (bottom surface) 19a of the optical fiber probe 19 is in contact with the first receiving surface 13a of the receiving portion 13. In this case, the center of the optical fiber 23 (incident surface 23d) is substantially consistent with the center of the through hole 14. Since the optical fiber probe 19 is arranged inside the window support portion 4 in a state in which the outer peripheral surface of the cylindrical portion 20 is in contact with the first inner peripheral surface 12c of the holding portion 12, a stable arrangement state of the optical fiber probe 19 is obtained without shaking against the window support portion 4.

[0034] The collar portion 21 is arranged in the placement portion 6. In a state where the cover portion 7 is attached to the placement portion 6, the elastic member 22 is arranged between the bottom surface of the adjustment screw 10 and the pressure receiving surface 21a of the collar portion 21.

[0035] For example, a compression coil spring is used as the elastic member 22. The optical fiber probe 19 is pressed downward by the pressing force of the elastic member 22. Therefore, the tip surface 19a of the optical fiber probe 19 is pressed against the first receiving surface 13a of the receiving portion 13 by the pressing force of the elastic member 22. Alternatively, a coil 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.

[0036] In the temperature sensor 1, by rotating the adjustment screw 10 and changing its screwing position relative to the screw hole 7a, the pressing force of the elastic member 22 relative to the optical fiber probe 19 can be adjusted. Further, the temperature sensor 1 may not include the elastic member 22.

[0037] When the temperature sensor 1 configured as described above is attached to a molding machine such as an injection molding machine and is used to measure the temperature of a molten resin, the temperature measurement is performed by transmitting infrared light that has passed through the protection window 18 and has been incident on the optical fiber 23 to a detector through the optical fiber 23. In this case, the temperature sensor 1 is heated by heat generated in the injection molding machine, for example, and the heated portion expands.

[0038] The temperature sensor 1 includes a sleeve member 17 formed in an annular shape and having an inner peripheral surface 17b in contact with an outer peripheral surface 18a of the protection window 18 and an outer peripheral surface 17a in contact with a second inner peripheral surface 12d of the holding portion 12 of the window support 4. Since the sleeve member 17 is arranged between the protection window 18 and the window support 4, the molten resin is suppressed from flowing into the gap between the protection window 18 and the window support 4, and an excessive force is less likely to be applied to the protection window during cooling of the temperature sensor 1. Thus, damage to the protection window can be prevented.

[0039] Further, in the temperature sensor 1, the thermal expansion coefficient of the protection window 18 is smaller than that of the window support portion 4, and the thermal expansion coefficient of the sleeve member 17 is smaller than that of the protection window 18. Therefore, the expansion degree of the sleeve member 17 becomes smaller than that of the protection window 18, and the protection window 18 is fastened by the sleeve member 17. Thus, the molten resin cannot enter the gap between the protection window 18 and the sleeve member 17, which makes it possible to reliably prevent the molten resin from entering the gap between the protection window 18 and the sleeve member 17.

[0040] Further, the protection window 18 is made of sapphire glass, and the sleeve member 17 is made of Kovar. Therefore, the thermal expansion coefficient of the sleeve member 17 becomes close to but smaller than the thermal expansion coefficient of the protection window 18, and the expansion degree of the protection window 18 and the expansion degree of the sleeve member 17 become similar. Therefore, in a state where the protection window 18 is fastened by the sleeve member 17 during expansion, close contact between the protection window 18 and the sleeve member 17 can be maintained without applying an excessive load from the sleeve member 17 to the protection window 18.

[0041] Further, the lower end of the protection window 18 protrudes downward from the holding portion 12. Therefore, during measurement, molten resin is less likely to remain at the tip of the temperature sensor 1, and excessive pressure is less likely to be applied to the protection window 18 from the molten resin.

[0042] Further, in the above-mentioned temperature sensor 1, the window support portion 4 has the receiving portion 13, and the first receiving surface 13a and the second receiving surface 13b are in contact with the optical fiber probe 19 and the protective window 18, respectively. Therefore, the pressing force of the elastic member 22 applied to the optical fiber probe 19 is less likely to be transmitted to the protective window 18. Further, when the 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 housing 2 through the receiving portion 13, so that the load caused by the pressure of the molten resin on the protective window 18 can be reduced.

[0043] In a temperature sensor in which infrared light is incident on an optical fiber through a protective window, 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 condition of the air layer, which may cause light interference. When the air layer has an extremely small thickness of the order of nanometers to micrometers, light interference occurs. For example, if the thickness of the air layer changes due to thermal expansion of the protective window, the degree of light interference also changes, which may affect the result of the temperature measurement of the sensor.

[0044] In the above-mentioned temperature sensor 1, the window support 4 has a receiving portion 13, so that a certain distance is maintained between the upper surface of the protective window 18 and the incident surface 23d of the optical fiber 23, and an air layer (through hole 14) is interposed therebetween. Since the receiving portion 13 is a structure, the thickness of the air layer is not on the order of nanometers or micrometers, but on the order of millimeters or more. Therefore, a certain distance can be maintained between the optical fiber 23 and the protective window 18 by the receiving portion 13, and a stable measurement state can be ensured while suppressing the occurrence of light interference.

[0045] Furthermore, in the temperature sensor 1, a window support 4A having a calibration insertion hole 24 may be used instead of the window support 4 (see Figure 3 ).

[0046] The window support portion 4A has a calibration insertion hole 24 that vertically passes through the holding portion 12. A calibration temperature sensor (e.g., 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 to the window support portion 4A by welding in a state where one end thereof is inserted into the calibration insertion hole 24. For example, the other end of the thermocouple 25 is taken out of the outer housing 2 through the cutout 9a, and is connected to a measuring device (not shown).

[0047] By forming the calibration insertion hole 24 in the window support portion 4A and attaching the thermocouple 25 to the calibration insertion hole 24, the temperature can be measured using both the optical fiber 23 and the thermocouple 25. Therefore, the measurement result can be calibrated, and the measurement accuracy of the temperature sensor 1 can be improved.

[0048] <Temperature Sensor According to Second Embodiment>

[0049] Next, a temperature sensor 1A according to a second embodiment (see Figure 4 ).

[0050] The temperature sensor 1A to be described below is different from the above-described temperature sensor 1 only in that a window support 4B and a spacer 26 are used instead of the window support 4. Therefore, only the difference between the temperature sensor 1A and the temperature sensor 1 will be described in detail. The same reference numerals will be used for the same parts as those of the temperature sensor 1, and redundant descriptions thereof will be omitted.

[0051] The window support portion 4B has a fixing portion 27, a connecting portion 28 and a holding portion 29 (see Figure 4 The fixing portion 27, the connecting portion 28 and the holding portion 29 are formed in a cylindrical shape. The connecting portion 28 is continuously arranged from the lower end of the fixing portion 27, and the holding portion 29 is continuously arranged from the lower end of the connecting portion 28. The sleeve member 17 and the protection window 18 are inserted into the holding portion 29 and supported by the holding portion 29.

[0052] The spacer 26 is also supported by the window support portion 4B. The spacer 26 is made of, for example, a metal material, and has a cylindrical portion 30 whose axial direction coincides with the vertical direction and a receiving portion 31 protruding inward from the lower end of the cylindrical portion 30. The upper surface of the receiving portion 31 serves as a first receiving surface 31a, and the bottom surface thereof serves as a second receiving surface 31b. The internal space of the receiving portion 31 serves as a through hole 32. For example, the cylindrical portion 30 and the receiving portion 31 are formed integrally.

[0053] The tip of the optical fiber probe 19 is inserted into the cylindrical portion 30. The outer peripheral surface of the cylindrical portion 20 contacts the inner peripheral surface of the cylindrical portion 30. The tip surface 19a of the optical fiber probe 19 contacts the first receiving surface 31a of the receiving portion 31. The upper surface of the sleeve member 17 and the upper surface of the protection window 18 contact the second receiving surface 31b of the receiving portion 31.

[0054] In the temperature sensor 1A, the pressure of the elastic member 22 applied to the optical fiber probe 19 through the receiving portion 31 is less likely to be transmitted to the protection window 18 , and the pressure of the molten resin is transmitted from the protection window 18 to the outer housing 2 through the spacer 26 .

[0055] By providing the receiving portion 31 separately from the window support 4B, the receiving portion 31 can be made of a material different from that of the window support 4B. For example, when the receiving portion 31 is made of a material having a higher strength, the high strength of the receiving portion 31 can be ensured.

Claims

1. A temperature sensor for a molding machine, comprising: A cylindrical optical fiber probe into which the optical fiber is inserted; a window support portion formed in a cylindrical shape and into which at least a portion of the optical fiber probe is inserted; a protective window arranged on the tip side of the optical fiber probe while being at least partially inserted into the window support; as well as The sleeve member is formed in an annular shape and has an inner peripheral surface in contact with the outer peripheral surface of the protection window and an outer peripheral surface in contact with the inner peripheral surface of the window support portion.

2. The temperature sensor according to claim 1, wherein: The thermal expansion coefficient of the protection window is smaller than the thermal expansion coefficient of the window support portion, and The thermal expansion coefficient of the sleeve member is smaller than the thermal expansion coefficient of the protection window.

3. The temperature sensor according to claim 2, wherein: The protective window is made of sapphire glass, and The sleeve member is made of Kovar.

4. The temperature sensor according to any one of claims 1 to 3, wherein: The window support portion has a receiving portion protruding inwardly, The receiving portion is arranged between the optical fiber probe and the protective window, and The receiving portion has one surface in contact with the optical fiber probe and another surface in contact with the protection window.

5. The temperature sensor according to any one of claims 1 to 3, wherein: A calibration insertion hole is formed in the window support portion, and A thermocouple is inserted into the calibrated insertion hole.

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