JPH11105106A - Structure of thermocouple mount for heating cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly and accurately measure temperature in addition to satisfactory responsiveness. SOLUTION: A coiled spring 11 is fixed to an upper end, as shown, of a thermocouple receiving member 7 fixed to a heating cylinder 1 via a mounting fixture 8. In a sheathed thermocouple 5, a thermocouple end 5a is inserted into a thermocouple inserting hole 3 in a close contact state, and the other end side is passed through the spring 11 via the member 7 and the fixture 8. A suitable site of the spring 11 is fixed to the thermocouple 5 in the state that a tensile force is given between the spring 11 and the fixture 8 by clamping a set screw 13 of a spring fixture 12. A heat insulator 9 is interposed between the member 7 and the thermocouple 5. The upper end of the member 7 and a bottom 3a of the hole 3 are sealed therebetween by a sealing member 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple mounting portion in a heating cylinder for mounting a thermocouple used for measuring the temperature of a heating cylinder in an injection molding machine, an extrusion molding machine, or the like to a temperature measuring portion of the heating cylinder. It is about structure.

[0002]

2. Description of the Related Art Generally, the temperature of a heating cylinder in an injection molding machine or an extrusion molding machine is measured by attaching a thermocouple to a temperature measuring portion of the heating cylinder. Hereinafter, an example of a structure of a thermocouple mounting portion in a conventional heating cylinder will be described.

As shown in FIG. 4, a screw hole 10 for mounting a thermocouple receiving member 104 extending from an outer wall surface 101a to an inner wall surface 101b is provided at a temperature measuring portion of a heating cylinder 101.
2 and a thermocouple insertion hole 103 having a smaller diameter than the screw hole 102 for inserting a thermocouple 105 from the bottom of the screw hole 102 toward the inner wall surface 101b.

A cylindrical thermocouple receiving member 104, one end of which is screwed into a screw hole 102 of a heating cylinder 101, has an inner diameter larger than the outer diameter of the thermocouple 105 and the compensating conductor 106, and is located near the upper end in the figure. Has an engagement projection 104b projecting outward in the radial direction.

[0005] On the other hand, the thermocouple 105 has a tip portion (temperature sensing portion) for preventing a short circuit of the thermocouple wire due to bending.
When inserted into the thermocouple insertion hole 103 so as to abut against the bottom surface of the thermocouple insertion hole 103 of the heating cylinder 101, the rear end side is set to have a length slightly protruding toward the screw hole 102 side or less, The flexible compensating lead wire 106 connected to the rear end is formed with a bent portion for coping with the spatial limitation by the heater cover 111, and a coil spring 107 to be described later is mounted.

A coil spring 107 mounted on the compensating lead wire 106 has a spring receiver 108 fixed to one end side, and a ring-shaped spring fixing tool 109 inserted into an appropriate portion on the other end side. By tightening the screw 110, the portion between the spring receiver 108 and the spring fixture 109 is fixed to the compensating lead wire 106 in a state where a tensile force is applied.

After the thermocouple 105 is inserted into the thermocouple insertion hole 103 through the thermocouple receiving member 104 attached to the heating cylinder 101, the spring receiver 108 is fitted to the thermocouple receiving member 104 and the spring receiver 108 is fitted. The engagement protrusion 10 of the thermocouple receiving member 104 is
4b are attached to the heating cylinder in a state where the pressing force in the direction of the arrow generated by the resilient force of the coil spring 107 is applied to the thermocouple 105 via the compensating wire 106 by integrating the springs 4b. .

[0008]

In the above prior art,
Since the coil spring is fixed to the flexible compensating conductor, there are the following problems.

(1) Pressing force of thermocouple The pressing force generated by the coil spring is not sufficiently transmitted to the tip (thermosensitive part) of the thermocouple, and the tip of the thermocouple contacts the bottom of the thermocouple insertion hole. The condition gets worse. Further, depending on how the compensating conductor bends, the pressing force of the thermocouple changes, and the contact state becomes unstable. Therefore, quick and highly accurate temperature measurement cannot be performed.

Further, when the thermocouple and the thermocouple insertion hole have a close contact structure (tolerance designation: designation of diameter and tip angle),
The flexibility of the compensating wire absorbs the frictional resistance generated between the thermocouple tip and the thermocouple insertion hole, making it difficult to insert it reliably. Therefore, the diameter of the thermocouple insertion hole must be relatively large so that the gap Δt between the thermocouple insertion hole and the thermocouple is widened. As a result, the tip portion (thermosensitive portion) of the thermocouple causes a state of poor contact.

(2) Regarding the closed structure of the thermocouple insertion hole A relatively wide gap (air layer: about 1.5 mm) is provided between the thermocouple insertion hole and the thermocouple and between the thermocouple receiving member and the compensating conductor.
２2 mm) and only an open spring receiver is mounted on the upper end side of the thermocouple receiving member. That is, since the thermocouple insertion hole is almost open to the atmosphere, heated air existing around the thermocouple is easily released (heat radiated) into the atmosphere, and the response characteristic of the temperature measurement is improved. It is a cause of deterioration.

(3) Influence of heat flow of heating heater A band heater is disposed around a portion of the heating cylinder where the thermocouple is mounted, and the heat flow generated when heating by the band heater is generated by the heating cylinder. It travels to the inner wall surface and is transmitted to the tip (thermosensitive part) of the thermocouple. One of the important roles of a thermocouple is to quickly and accurately capture the temperature change due to this heat flow.

However, the heat flow generated by the band heater is transmitted to the tip of the thermocouple via the thermocouple receiving member and the compensating lead wire. That is, the heat flow generated by the band heater directly flows to the thermocouple tip. When this heat flow is generated, the thermocouple itself is heated by the heat of the band heater even if the peripheral portion of the thermocouple tip (heating cylinder side) does not reach the predetermined temperature. Will be measured incorrectly,
Accurate temperature measurement becomes impossible.

(4) Reduction of Thermocouple Diameter (Improvement of Responsiveness) As described above, the flexible compensating wire has a function of transmitting the pressing force generated by the elastic force of the coil spring to the thermocouple. I have. Therefore, it is necessary to reduce the bending of the compensating lead wire due to the elastic force of the coil spring, and it is difficult to reduce the diameter of the compensating lead wire, and it is also difficult to reduce the diameter of the thermocouple connected to the compensating lead wire. Become. Therefore, it is not possible to improve the responsiveness by reducing the diameter of the thermocouple.

The present invention has been made in view of the above-mentioned problems of the prior art, and has improved responsiveness.
In addition, it is another object of the present invention to realize a structure of a thermocouple mounting portion in a heating cylinder that can quickly and accurately measure a temperature.

[0016]

In order to achieve the above object, the structure of the thermocouple mounting portion of the heating cylinder according to the present invention is such that a hole is formed in the temperature measuring portion of the heating cylinder in order from the outer wall surface to the inner wall surface. A mounting hole, a thermocouple insertion hole having a diameter smaller than the mounting hole, a cylindrical thermocouple receiving member having one end fixed to the mounting hole, and a mounting tool at the other end of the thermocouple receiving member. A fixed coil spring and a sheath-type thermocouple having a thermocouple tip inserted into the thermocouple insertion hole in a tightly contacted state and the other end penetrating the coil spring through the thermocouple receiving member and the fixture. An appropriate part of the coil spring is fixed to the sheath-type thermocouple by a spring fixing tool in a state where a tensile force is applied between the coil spring and the mounting tool, and A heat insulating member is interposed between the thermocouple receiving member and the sheath-type thermocouple, and the thermocouple receiving member is formed by a seal member interposed between the other end of the thermocouple receiving member and the fixture. Is sealed between the other end and the bottom surface of the thermocouple insertion hole.

A mounting hole which is successively drilled from an outer wall surface to an inner wall surface at a temperature measuring portion of the heating cylinder, an intermediate hole smaller in diameter than the mounting hole, and a thermocouple insertion hole smaller in diameter than the intermediate hole; A tubular thermocouple receiving member having one end fixed to the mounting hole; a coil spring fixed to the other end of the thermocouple receiving member via a mounting tool; and a thermocouple tip portion in the thermocouple insertion hole. And a sheath-type thermocouple whose other end penetrates the coil spring through the thermocouple receiving member and the fixture, and an appropriate portion of the coil spring is pulled between the fixture and the fixture. The sheath-type thermocouple is fixed to the sheath-type thermocouple by a spring fixing tool in a state where a force is applied, and an insulating member is interposed between the thermocouple receiving member and the sheath-type thermocouple. And sealing between the other end of the thermocouple receiving member and the bottom surface of the thermocouple insertion hole by a seal member interposed between the other end of the thermocouple receiving member and the mounting member. A sealed heat-insulated space is formed between the hole and the sheath-type thermocouple.

[0018]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to the first embodiment.

In the present embodiment, a thermocouple receiving member 7 extending from the outer wall surface 1a to the inner wall surface 1b is provided at the temperature measuring portion of the heating cylinder 1 which is configured to be heated by the heating means such as the band heater 4. A mounting hole 2 for mounting and a thermocouple insertion hole 3 into which the thermocouple tip 5a of the sheath-type thermocouple 5 is inserted in close contact with each other are sequentially drilled.

In the mounting hole 2 of the heating cylinder 1, a cylindrical thermocouple receiving member 7 is formed at one end thereof with a male screw portion 7a.
Is formed on the inner surface of the mounting hole 2 and is fixed by screwing into the screw portion 2a.
A coil spring 11 is detachably fixed to the other end side (upper end in the figure) of the other end via a fixture 8 made of a cap nut or the like.

The sheath-type thermocouple 5 has a thermocouple tip (temperature sensing portion) 5a inserted in the thermocouple insertion hole 3 in a tightly contacted state, and the other end through the thermocouple receiving member 7 and the mounting member 8. Is penetrated through the coil spring 11, and the other end protruding from the coil spring 11 is connected to the compensating lead wire 6 via the joint 6a.

The sheath-type thermocouple 5 is one in which an insulating material such as magnesia (MgO) is sealed in a protective tube, and has a predetermined rigidity. Absent. Therefore, the sheath-type thermocouple 5
Is bent together with the coil spring 11 so as to be accommodated in the space between the heater cover 14 and the heating cylinder 1. By tightening the set screw 13 of the ring-shaped spring fixing tool 12 inserted into an appropriate portion thereof, the coil spring Eleven appropriate portions are fixed to the sheath-type thermocouple 5 in a state where a tensile force is applied to the fitting 8.

In the sheath-type thermocouple 5, the thermocouple tip 5a is inserted into the thermocouple insertion hole 3 in close contact with the pressing force in the direction of the arrow generated by the coil spring 11 being constantly applied. In addition, a heat insulating member 9 is interposed between the thermocouple receiving member 7 and the sheath-type thermocouple 5, and a thermoelectric member is interposed between the other end of the thermocouple receiving member 7 and the mounting member 8. The space between the other end of the receiving member 7 and the bottom surface 3a of the thermocouple insertion hole 3 is sealed.

Here, the length L of the thermocouple tip 5a of the sheath-type thermocouple 5 inserted into the thermocouple insertion hole 3 is set to an appropriate length at which high-precision temperature measurement can be performed. Only by performing tolerance processing by designating the tolerance of the diameter d (part of L) and the angle θ of the distal end surface, the thermocouple distal end portion 5a of the sheath type thermocouple 5 can be inserted into the thermocouple insertion hole 3 in a close contact state. I do.

FIG. 2 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to a second embodiment.

In the present embodiment, as in the case of a heating cylinder of a large injection molding machine or an extrusion molding machine, the wall thickness of the heating cylinder is large, so that the thermocouple insertion hole becomes deep, and the insertion length of the sheath type thermocouple is increased. This is suitable when the length is long. Hereinafter, the same portions as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted, and different portions will be described.

At the temperature measurement site of the heating cylinder 21, the mounting hole 22 extending from the outer wall surface 21a to the inner wall surface 21b, the bottom of the mounting hole 22, the intermediate hole 24 toward the inner wall surface 21b, and the bottom of the intermediate hole 24 are connected. The thermocouple insertion hole 23 into which the thermocouple tip 5a of the sheath-type thermocouple 5 heading toward the inner wall surface 21b is tightly inserted is formed by gradually reducing the inner diameter, and is formed at the bottom of the mounting hole 22. Has a spacer 25 inserted therein.

In the sheath type thermocouple 5, the thermocouple tip 5a is inserted into the thermocouple insertion hole 23 in a state of close contact with the pressing force in the arrow direction generated by the coil spring 11 being constantly applied. And a thermocouple receiving member 7
A heat insulating member 9 is interposed between the thermocouple receiving member 7 and the sheath-type thermocouple 5, and the sealing member 10 is interposed between the other end of the thermocouple receiving member 7 and the fixture 8. A sealed adiabatic space is formed between the other end and the bottom surface 23 a of the thermocouple insertion hole 23, and between the intermediate hole 24 and the sheath-type thermocouple 5.

FIG. 3 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to a modification.

The present modification is suitable for the case where the thickness of the heating means attached to the heating cylinder 21 is large, such as when the heat insulating cover 40 surrounding the outer peripheral surface of the band heater 4 is provided. Hereinafter, the same portions as those of the second embodiment shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted, and different portions will be described.

In the present embodiment, by using a thermocouple receiving member 7 having a length protruding outward from the outer peripheral surface of the heat retaining cover 40, the mounting member 8 formed of a cap nut or the like is connected to the heat retaining cover 40. It is devised so as not to interfere.

[0033]

Since the present invention is configured as described above, the following effects can be obtained.

(1) Since the sheath-type thermocouple can secure rigidity as compared with the compensating lead wire, the pressing force of the spring can be transmitted to the distal end portion without fail. Therefore, even if the fitting between the thermocouple tip and the thermocouple insertion hole is manufactured at a tolerance level, the pressing force is sufficiently transmitted to the thermocouple tip, and the contact state in the thermocouple insertion hole of the heating cylinder is kept good. And accurate temperature measurement with good responsiveness becomes possible. Also, good reproducibility can be ensured when the thermocouple is reattached.

(2) Since the space from the upper end of the thermocouple receiving member to the bottom of the thermocouple insertion hole is sealed, the release (heat radiation) of the heated air in the thermocouple insertion hole (temperature sensing portion). Is eliminated, and the response of the sheath-type thermocouple is improved.

(3) Since the heat insulating member is interposed between the thermocouple receiving member and the sheath-type thermocouple, the heat flow from the heating means such as a band heater may directly flow into the sheath-type thermocouple. Is eliminated, and it becomes possible to accurately detect a temperature change around the thermocouple tip (temperature sensing).

(4) Since the sheath-type thermocouple has excellent rigidity, the pressing force is transmitted to the tip of the thermocouple even if it has a relatively small diameter. Therefore, it is possible to improve the responsiveness of temperature measurement by reducing the outer diameter of the sheath-type thermocouple.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to a first embodiment.

FIG. 2 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to a second embodiment.

FIG. 3 is a schematic partial sectional view showing a thermocouple mounting structure in a heating cylinder according to a modification.

FIG. 4 is a schematic partial cross-sectional view showing a thermocouple mounting structure in a heating cylinder according to a conventional example.

[Explanation of symbols]

 1,21,31 Heating cylinder 1a, 21a Outer wall surface 1b, 21b Inner wall surface 2,22 Mounting hole 2a, 22a Female thread 3,23 Thermocouple insertion hole 4 Band heater 5 Sheath type thermocouple 5a Thermocouple tip 6 Compensation Conductor wire 6a Joint 7 Thermocouple receiving member 7a Male thread portion 8 Mounting tool 9 Heat insulating member 10 Sealing member 11 Coil spring 12 Spring fixing tool 13 Set screw 24 Intermediate hole 25 Spacer 40 Heat insulating cover

Claims (2)

[Claims] 1. A mounting hole (2) which is successively drilled from an outer wall surface (1a) to an inner wall surface (1b) at a temperature measuring portion of a heating cylinder (1), and a thermocouple insertion hole having a diameter smaller than the mounting hole. (3) a cylindrical thermocouple receiving member (7) having one end fixed to the mounting hole, and a coil spring (7) fixed to the other end of the thermocouple receiving member via a fixture (8). 11) and a thermocouple tip (5) in the thermocouple insertion hole.
a) includes a sheath-type thermocouple (5), which is inserted in close contact with the thermocouple receiving member and the mounting tool, and the other end of which penetrates the coil spring, and an appropriate part of the coil spring is the mounting tool. Spring fixture (12) with a tensile force applied between
, And a heat insulating member (9) is interposed between the thermocouple receiving member and the sheath thermocouple, and the other end of the thermocouple receiving member is provided. Heating characterized in that a seal member (10) interposed between the side and the mounting member seals between the other end of the thermocouple receiving member and the bottom surface (3a) of the thermocouple insertion hole. Structure of thermocouple mounting part in cylinder. 2. A mounting hole (22) which is sequentially drilled from an outer wall surface (21a) to an inner wall surface (21b) at a temperature measuring portion of a heating cylinder (21), and an intermediate hole (24) having a smaller diameter than the mounting hole. ) And a thermocouple insertion hole (23) smaller in diameter than the intermediate hole (24), a cylindrical thermocouple receiving member (7) having one end fixed to the mounting hole, and the other end of the thermocouple receiving member. A coil spring (11) fixed to the side via a fixture (8), a thermocouple tip (5a) is inserted into the thermocouple insertion hole in a tight contact state, and the thermocouple receiving member and the mounting are installed. A spring-type thermocouple (5) having the other end side penetrating the coil spring through the tool, and a spring fixing tool (12) in a state where an appropriate portion of the coil spring applies a tensile force to the mounting tool.
, And a heat insulating member (9) is interposed between the thermocouple receiving member and the sheath thermocouple, and the other end of the thermocouple receiving member is provided. The other end of the thermocouple receiving member and the bottom surface (23a) of the thermocouple insertion hole are sealed by a seal member (10) interposed between the side and the mounting fixture, so that the intermediate hole and the sheath-type thermocouple are sealed. A structure of a thermocouple mounting portion in a heating cylinder, wherein a sealed heat insulating space is formed between the pair.