Temperature Sensor

Abstract

To improve the heat resistance of a temperature sensor and secure the high accuracy of measurement.SOLUTION: Provided is a temperature sensor used in a molding machine, comprising: a cylindrical fiber probe which an optical fiber is inserted through; an outer casing part having a shaft part which the fiber probe is inserted into while being displaceable in the axial direction; a protective window part located at the tip side of the fiber probe, for protecting the tip of the fiber probe; and an elastic member for urging the fiber probe to the protective window part side. Thus, the tip of the fiber probe is pressed against the protective window part by an urging force of the elastic member, irrespective of the expansion or shrinkage degree of the fiber probe and the outer casing part when heated or cooled.SELECTED DRAWING: Figure 1

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 known, for example, as a temperature sensor in which a fiber probe having an optical fiber inserted therein for measuring the temperature of the resin filled in the cavity is connected to the cavity, and infrared rays emitted from the resin are transmitted to a detector through the optical fiber (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-232753 Summary of the Invention [Problem to be solved by the invention]

[0004] Some of the above-mentioned temperature sensors have a glass protective window at the tip of the fiber probe to improve heat resistance in order to perform measurements in higher temperature environments. Such temperature sensors with a protective window are provided with an outer casing to support the protective window and protect the fiber probe from heat.

[0005] However, in a temperature sensor equipped with a protective window, the heat emitted from the molding machine causes the outer casing to become hotter than the fiber probe, causing the outer casing to expand more than the fiber probe, creating a gap between the fiber probe and the protective window, which can cause optical interference in the gap and reduce measurement accuracy.

[0006] Therefore, an object of the present invention is to improve heat resistance while ensuring high measurement accuracy. [Means for solving the problem]

[0007] First, the temperature sensor of the present invention is a temperature sensor used in a molding machine, and comprises a cylindrical fiber probe through which an optical fiber is inserted, an outer casing having a shaft portion into which the fiber probe is inserted in a state in which the fiber probe can be displaced in the axial direction, a protective window portion located on the tip side of the fiber probe and protecting the tip of the fiber probe, and an elastic member that biases the fiber probe toward the protective window portion.

[0008] As a result, the tip of the fiber probe is pressed against the protective window by the biasing force of the elastic member, regardless of the degree of expansion or contraction of the fiber probe and the outer casing when heated or cooled.

[0009] Secondly, in the above-described temperature sensor, it is desirable to provide an adjustment screw for adjusting the biasing force of the elastic member against the fiber probe.

[0010] This makes it possible to adjust the biasing force of the elastic member against the fiber probe by means of the adjustment screw.

[0011] Thirdly, in the above-described temperature sensor, it is desirable that the outer casing has a lid for protecting the fiber probe, and that the adjusting screw be threadedly engaged with the lid.

[0012] This allows the lid to have the function of supporting the adjustment screw and the function of covering the fiber probe and the like.

[0013] Fourth, in the above-described temperature sensor, it is desirable that a spring be used as the elastic member.

[0014] As a result, the elastic member has high heat resistance, so there is no need to use a dedicated elastic member depending on the measurement environment.

[0015] Fifth, in the above-described temperature sensor, it is desirable that the base end surface of the fiber probe is formed as the pressed surface, that a flat rubber is used as the elastic member, and that the elastic member be in surface contact with the pressed surface.

[0016] This makes it easier for the biasing force of the elastic member to be applied uniformly to the pressed surface. [Effects of the Invention]

[0017] According to the present invention, regardless of the degree of expansion or contraction of the fiber probe and the outer casing during heating or cooling, the tip of the fiber probe is pressed against the protective window portion by the force of the elastic member, so that no gap is formed between the fiber probe and the protective window portion, ensuring high measurement accuracy. [Brief explanation of the drawings]

[0018] [Figure 1] 2 to 5 show an embodiment of the present invention, and this figure is a cross-sectional view of a temperature sensor. [Figure 2] 10A and 10B are explanatory diagrams showing the state of displacement of the fiber probe when the temperature sensor is heated; [Figure 3] 10A and 10B are explanatory diagrams showing the state of displacement of the fiber probe when the temperature sensor is cooled. [Figure 4] FIG. 10 is a cross-sectional view showing an example in which rubber is used as the elastic member. [Figure 5] 10 is a cross-sectional view showing an example in which an elastic member is supported by a lid portion and a fiber probe. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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 5).

[0020] The temperature sensor 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 indicated below are for the convenience of explanation, and the implementation of the present invention is not limited to these directions.

[0021] <Temperature sensor configuration> First, the configuration of the temperature sensor will be described (see FIG. 1).

[0022] The temperature sensor 1 is attached to an injection molding machine (not shown) and is used to measure the temperature of resin in an injection unit, 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.

[0023] The temperature sensor 1 has a fiber probe 2 , a protective window 3 , an outer casing 4 and an elastic member 5 .

[0024] The fiber probe 2 has a cylindrical portion 6 whose axial direction is in the up-down direction and a flange portion 7 that is continuous with the upper end of the cylindrical portion 6. The outer diameter of the flange portion 7 is larger than the outer diameter of the cylindrical portion 6. The upper surface of the flange portion 7 is formed as a pressed surface 7a. The fiber probe 2 is made of, for example, a metal material.

[0025] An optical fiber 8 is inserted and held in the fiber probe 2. One end 8a of the optical fiber 8 is inserted into the cylindrical portion 6, and a bent portion 8b connected to the one end 8a is bent, for example, at a substantially right angle inside the flange portion 7. In the optical fiber 8, a portion between the bent portion 8b and the other end is provided as an intermediate portion 8c, and the intermediate portion 8c is positioned outward from the outer peripheral surface of the flange portion 7 toward the outside of the fiber probe 2. A detector or the like (not shown) is connected to the other end of the optical fiber 8.

[0026] The protective window 3 is composed of a small diameter section 9 and a large diameter section 10, each of which is formed in a cylindrical shape, with the large diameter section 10 continuing to the upper end side of the small diameter section 9. The upper surface of the large diameter section 10 is formed as a contact surface 10a. The protective window 3 is supported by a window support section (described later) of the outer casing 4 with the contact surface 10a in contact with the tip surface 2a of the fiber probe 2. The protective window 3 is formed of, for example, sapphire glass.

[0027] The outer casing 4 has a shaft portion 11, a window support portion 12, an arrangement portion 13, and a lid portion 14. The outer casing 4 is formed of, for example, a metal material. The fiber probe 2 is arranged inside the outer casing 4.

[0028] The shaft portion 11 is formed in a cylindrical shape with its axial direction oriented in the up-down direction, and the cylindrical portion 6 of the fiber probe 2 is inserted through it. An installation nut 40 is attached to the outside of the shaft portion 11 to attach the temperature sensor 1 to the injection molding machine.

[0029] The window support part 12 is cylindrical with its axial direction in the up-down direction, and its upper end is fitted onto the lower end of the shaft part 11. The lower end of the window support part 12 is provided with a flange-shaped receiving part 12a that protrudes inward.

[0030] Inside the window support part 12, there are arranged the protective window part 3 excluding its tip part, a spacer 15, and an O-ring 16. The spacer 15 is formed in a cylindrical shape, and its upper and lower end faces respectively contact the lower surface of the shaft part 11 and the outer periphery of the contact surface 10a of the protective window part 3. The O-ring 16 is formed in an annular shape and is in close contact with the lower surface of the large diameter part 10 and the upper surface of the receiving part 12a.

[0031] The arrangement portion 13 has a flange portion 17 that projects outward from the upper end of the shaft portion 11, and an annular portion 18 that projects upward from the outer periphery of the flange portion 17. A notch 18a that opens upward and penetrates radially is formed in the annular portion 18. Mounting holes 18b, 18b, ... that open upward are formed at the upper end of the annular portion 18 and are spaced apart in the circumferential direction. The flange portion 7 of the fiber probe 2 is arranged inside the arrangement portion 13, and the middle portion 8c of the optical fiber 8 is inserted into the notch 18a.

[0032] The lid portion 14 is formed in an annular shape, with a threaded hole 19 formed in the center. An adjustment screw 20 is threaded into the threaded hole 19. Screw insertion holes 14a, 14a, ... that penetrate vertically are formed on the outer periphery of the lid portion 14 at positions that correspond to the mounting holes 18b, 18b, ... of the annular portion 18. The lid portion 14 is attached to the upper surface of the placement portion 13 by inserting a mounting screw 50 through the screw insertion hole 14a and threading it into the mounting hole 18b. When the lid portion 14 is attached to the placement portion 13, an elastic member 5 is disposed between the lower surface of the adjustment screw 20 and the pressed surface 7a of the fiber probe 2.

[0033] For example, a compression coil spring is used as the elastic member 5. The fiber probe 2 is urged downward (toward the tip) by the elastic force of the elastic member 5, and the tip surface 2a is pressed against the contact surface 10a of the protective window portion 3. Note that the elastic member 5 may also be a disc spring, a leaf spring, or the like.

[0034] In the temperature sensor 1, the biasing force of the elastic member 5 against the fiber probe 2 can be adjusted by rotating the adjustment screw 20 to change the screw engagement position with the screw hole 19.

[0035] <Function of elastic material> Next, the function of the elastic member 5 in the temperature sensor 1 will be described (see FIGS. 2 and 3).

[0036] 2 and 3, in order to make it easier to understand how the fiber probe 2 and the protective window portion 3 are displaced, some parts are omitted and the amount of displacement of the fiber probe 2 and the protective window portion 3 is exaggerated.

[0037] 2 shows the temperature sensor 1 in an unheated state. Line A indicates the vertical height between the tip surface 2a of the fiber probe 2 and the contact surface 10a of the protective window portion 3 at this time.

[0038] The temperature sensor 1 is heated, for example, by heat generated in an injection molding machine during measurement. In the initial stage of measurement, the temperature sensor 1 receives more heat from the outer casing 4 located on the outside than from the fiber probe 2 located on the inside, so the degree of expansion of the outer casing 4 is greater than the degree of expansion of the fiber probe 2. When the outer casing 4 expands, the expansion of the window support 12 displaces the protective window 3 supported by the window support 12 in a direction (downward) away from the fiber probe 2, and the contact surface 10a is displaced downward from line A (see line B in the right diagram of Figure 2).

[0039] In this way, the protective window portion 3 is displaced downward, but in the temperature sensor 1, the fiber probe 2 is urged toward the protective window portion 3 by the force of the elastic member 5, so the fiber probe 2 is displaced downward following the protective window portion 3, and the tip surface 2a remains pressed against the contact surface 10a of the protective window portion 3.

[0040] If the temperature sensor 1 is further heated from the above state, the fiber probe 2 located inside the outer casing 4 will gradually become hotter, increasing the degree of expansion of the fiber probe 2. At this time, the protective window 3 may move up and down depending on the relative degree of expansion between the fiber probe 2 and the outer casing 4, but the pressing force of the fiber probe 2 against the protective window 3 due to the expansion is absorbed by the elastic member 5, and the state in which the tip surface 2a is pressed against the contact surface 10a is maintained in a state in which excessive pressing of the fiber probe 2 against the protective window 3 is prevented.

[0041] On the other hand, when the heating of the temperature sensor 1 is stopped from a state in which each part of the temperature sensor 1 has expanded due to heating (see the left diagram in Figure 3), the fiber probe 2 and the outer casing 4 begin to contract. At this time, the degree of contraction of the outer casing 4 first becomes greater than the degree of contraction of the fiber probe 2, and the protective window 3 is displaced in a direction (upward) approaching the fiber probe 2 (see the right diagram in Figure 3).

[0042] At this time, the fiber probe 2 is pressed from below by the protective window 3, and the fiber probe 2 is displaced upward relative to the shaft portion 11 against the biasing force of the elastic member 5, and the tip surface 2a of the fiber probe 2 and the contact surface 10a of the protective window 3 are displaced upward from line C to line D. Therefore, excessive force is not applied to the protective window 3 when the outer casing 4 contracts, and damage to the protective window 3 can be prevented.

[0043] If the temperature sensor 1 is further cooled from the above state, the degree of contraction of the fiber probe 2 increases. At this time, the protective window 3 may move up and down depending on the degree of relative contraction between the fiber probe 2 and the outer casing 4, but the pressing force of the protective window 3 against the fiber probe 2 due to contraction is absorbed by the elastic member 5, and the state in which the tip surface 2a is pressed against the contact surface 10a is maintained in a state in which the protective window 3 is prevented from pressing excessively against the fiber probe 2.

[0044] In this way, regardless of the degree of expansion or contraction of the fiber probe 2 and the outer casing 4 when heated or cooled, the temperature sensor 1 maintains a state in which the tip of the fiber probe 2 is pressed against the protective window portion 3 by the force of the elastic member 5, and the pressing force generated between the fiber probe 2 and the protective window portion 3 is absorbed by the elastic member 5.

[0045] Therefore, no gap is formed between the fiber probe 2 and the protective window 3, ensuring high measurement accuracy by the temperature sensor 1. In addition, excessive force is not applied to the protective window 3, preventing damage to the protective window 3.

[0046] The temperature sensor 1 is also provided with an adjustment screw 20 for adjusting the biasing force of the elastic member 5 against the fiber probe 2.

[0047] This makes it possible to adjust the biasing force of the elastic member 5 on the fiber probe 2 using the adjustment screw 20, so that the biasing force of the elastic member 5 on the fiber probe 2 can be selected arbitrarily depending on the type of fiber probe 2, injection molding machine, and configuration of the temperature sensor 1, thereby putting the temperature sensor 1 into an optimal measurement state.

[0048] Furthermore, in the temperature sensor 1, an adjustment screw 20 is screwed into the lid 14 of the outer casing 4.

[0049] As a result, the cover portion 14 has the function of supporting the adjustment screw 20 and the function of covering the fiber probe 2, etc., so there is no need for a dedicated member to support the adjustment screw 20, and the number of parts can be reduced while also allowing the biasing force of the elastic member 5 to be selected as desired.

[0050] Furthermore, in the temperature sensor 1, a spring is used as the elastic member 5.

[0051] As a result, the elastic member 5 has high heat resistance, so there is no need to use a dedicated elastic member 5 depending on the measurement environment, and the temperature sensor 1 can be made highly versatile.

[0052] <Other> Although the above example shows the use of a spring as the elastic member 5, rubber may also be used as the elastic member 5 (see FIG. 4). The elastic member 5 is formed, for example, in a flat plate shape, and both the upper and lower surfaces are in surface contact with the adjustment screw 20 and the pressed surface 7a of the fiber probe 2, respectively.

[0053] This makes it easier for the biasing force of the elastic member 5 to be applied uniformly to the pressed surface 7a, thereby suppressing displacement of the fiber probe 2 in directions other than the axial direction, and ensuring that the fiber probe 2 is biased toward the protective window portion 3.

[0054] The rubber used for the elastic member 5 is not limited to natural rubber or synthetic rubber, and silicone rubber may also be used. By using silicone rubber, which has higher heat resistance than natural rubber or the like, as the elastic member 5, it is possible to ensure high versatility of the temperature sensor 1. Furthermore, instead of the above-mentioned spring or rubber, foam or the like may be used as the elastic member 5.

[0055] Furthermore, in the above example, the adjusting screw 20 is screwed into the annular lid portion 14, but instead of the lid portion 14, a disk-shaped lid portion 14A may be provided, and the elastic member 5 may be disposed between the lower surface of the lid portion 14A and the pressed surface 7a (see FIG. 5). This allows the number of parts to be reduced. [Explanation of symbols]

[0056] 1...Temperature sensor 2...Fiber probe 2a…Tip surface 3...Protective window 4...Outer casing 5...Elastic member 7a...Pressed surface 8...Optical fiber 11...Shaft section 14...Lid part 20...Adjusting screw

Claims

1. A temperature sensor for use in a molding machine, a cylindrical fiber probe through which an optical fiber is inserted; an outer casing having a shaft portion into which the fiber probe is inserted in a state in which the fiber probe is displaceable in the axial direction; a protective window portion positioned on the tip side of the fiber probe and protecting the tip portion of the fiber probe; an elastic member that biases the fiber probe toward the protective window portion; Temperature sensor.

2. An adjustment screw is provided to adjust the biasing force of the elastic member against the fiber probe. The temperature sensor of claim 1 .

3. the outer casing has a lid for protecting the fiber probe, The adjusting screw is screwed into the lid. The temperature sensor according to claim 2 .

4. A spring is used as the elastic member. The temperature sensor according to any one of claims 1 to 3.

5. a base end surface of the fiber probe is formed as a pressure-receiving surface; A flat rubber plate is used as the elastic member, The elastic member is in surface contact with the pressed surface. The temperature sensor according to any one of claims 1 to 3.

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