JPH0238826A - Temperature measuring device and temperature measuring structure using the same - Google Patents

Abstract

PURPOSE:To stably measure temp. with high accuracy by constituting a temp. measuring device by using a metal pipe having a large coefficient of thermal expansion as a protective pipe and receiving a temp. sensor therein so that the measuring part thereof is positioned at the internal leading end thereof to insert the same in a measuring hole. CONSTITUTION:A protective pipe 2 is composed of a material having a large coefficient of thermal expansion, for example, aluminum or brass and, for example, a thermocouple is received therein as a temp. sensor 4 and the gap in the protective pipe 6 is filled with an insulating material 6 and the temp. contact being the measuring part of the thermocouple 4 is welded to the copper plate 7 at the leading end part of said pipe 2. When this temp. measuring device is inserted in a measuring hole having sawtooth projections 8, for example, in such a case that an object to be measured is the heating cylinder of an injection molding machine, the protective pipe 2 expands in a heat insulating heated state to eliminate the gap width the measuring hole and is brought into close contact with the heating cylinder 1. Therefore, a heat transfer error becomes extremely small and stable measurement can be performed and this device can be sufficiently adapted to the precise measurement of temp.

Description

[Detailed Description of the Invention] [Industrial Field] The present invention relates to a temperature measuring device that is inserted into a measurement hole of an object to be temperature measured and measures the temperature inside the object with high accuracy, and the use of the temperature measuring device. The present invention relates to a temperature measurement structure.

[Conventional technology]

2. Description of the Related Art Conventionally, there is a temperature measuring device as shown in FIG. 4, which is inserted into a measurement hole of an object to be temperature measured and measures the temperature inside the object. This is the heating cylinder 1 of the injection molding machine.
Regarding the temperature measuring device that measures the temperature of
This installation involves fitting the sheathed thermocouple I3 into the measuring tube 12, and the cover unit 11 is equipped with a sheathed thermocouple I3 that is biased to expand by a spring 10, and the sheathed thermocouple 13 is fitted into the measurement hole. There is a known device in which the temperature measuring contact at the tip, which is the measuring part, is biased by a spring so that it comes into contact with the heating cylinder when the heating cylinder is turned on.

[Problem to be solved by the invention]

Conventionally, in a temperature measuring device such as the one shown in FIG. A gap 9 is created between the holes, and the existence of this gap increases the thermal conduction error. Especially when the measurement hole is shallow, the error becomes even larger as it is affected by the room temperature.
It will also change due to changes in room temperature.

In addition, since the spring is attached to the structure, the product has a complicated shape, and the sheathed thermocouple 13 must be attached after the tube body 12 is screwed in place, which is time-consuming and other disadvantages. there were.

The present invention provides a temperature measuring device that reduces heat conduction errors and provides stable and highly accurate temperature measurement results when the temperature measuring device is inserted into a measurement hole of an object to be measured. This provides a temperature measurement structure using a measuring device.

[Means to solve the problem]

The present invention relates to a temperature measuring device in which a temperature sensor 4 is housed inside a protective tube 2 made of a metal with a large coefficient of thermal expansion, with its measuring part located at the tip of the protective tube 2, and to an object to be temperature measured. A measurement hole having a plurality of protrusions 8 having a serrated cross section is provided in the upper entrance wall, and a temperature measuring device having the above structure is inserted into the measurement hole so that the measurement part of the temperature sensor 4 comes into contact with the measurement position of the object to be measured l. , which constitutes the inserted temperature measurement structure.

[For production]

FIGS. 3(a) and 3(a) show the deformation and action of the temperature measuring object 1 of the present invention due to heating.

FIG. 3(a) shows a temperature measurement structure in which the temperature measuring device of the present invention is inserted into the measurement hole and the temperature measurement object 1 is not heated, and FIG. ) Temperature measurement object 1
The temperature measuring device is shown in a deformed state due to heating.

In the temperature measuring device of the present invention, since the protective tube 2 is formed of a metal with a large coefficient of thermal expansion, for example, when the temperature to be measured If is a heating cylinder of an injection molding machine, the temperature measuring device is in a state of thermal insulation heating before starting melting heating. The protective tube 2 has already expanded and the gap 9 shown in FIG. 3(a) is lost, and the protective tube 2 comes into close contact with the heating cylinder 1 as shown in FIG. 3(t).

When the state shown in FIG. 3(b) is reached, there is no void inside the measurement hole, so there is no air convection and the measurement hole is not affected by the outside temperature. As a result, during the plastic melting heating operation of the heating cylinder 1 that requires temperature measurement, the measurement part of the temperature sensor and the heating cylinder are integrated without being affected by the void inside the measurement hole or the outside temperature. , the thermal conduction error is small and stable measurement is possible.

Further, as shown in FIG. 3(b), if the protective tube 2 expands and comes into close contact with the wall of the heating cylinder 1, the temperature measuring device will not be easily removed, and will remain fixed.

〔Example〕

As shown in FIG. 2, the embodiment of the temperature measuring device of the present invention houses, for example, a thermocouple as the temperature sensor 4 in the protective tube 2.
The gap inside the protective tube 2 is filled with inorganic powder such as magnesium oxide or alumina as an insulating material 6, and a heat-resistant resin 3 is filled.
It has a structure in which the upper end of the protective tube 2 is closed off, and the temperature measuring junction, which is the measuring part of the thermocouple 4, is welded to the copper plate 7 with good thermal conductivity selected as the bottom plate of the tip. or as in the embodiment shown in FIG.
A thermocouple having a measuring part that is brought into direct contact with the object 1 to be temperature measured is employed.

The protection tube 2 is made of a material with a high coefficient of thermal expansion, for example, a metal such as aluminum or brass.

The measurement result is outputted via a lead wire 5 by a meter (not shown).

Next, an example of a temperature measurement structure using the temperature measurement device of the present invention as an object to be measured will be described. FIGS. 1 and 3 show an example of use for measuring the temperature of a heating cylinder 1 in an injection molding machine. shows. In order to obtain a measurement temperature that approximates the plastic melting temperature inside the heating cylinder 1 in which the screw 15 is installed, a temperature measuring device is buried in a measurement hole drilled in the heating cylinder 1, and a thermocouple 4, which is the measurement part, is embedded in the measurement hole in the heating cylinder 1. The temperature measurement contact point is set at a position close to the height of the inside, and the temperature of that area is measured.

The entrance wall portion of the measurement hole of the heating cylinder 1 is threaded so that the temperature measuring device can be easily attached and detached. Alternatively, if it is inconvenient to rotate the measuring section and lead wire 5 during attachment and detachment, the temperature measuring device is fixed in the measuring hole with sawtooth protrusions 8 as shown in Figure 3 (a) of the measuring hole.

In addition, although the temperature sensor 4 used a thermocouple in the above embodiment, it is not limited to this, and may be a metal-based, semiconductor-based resistance temperature sensor, etc.
Things other than thermocouples can also be applied.

In addition, although we have described an example in which it was applied to the temperature measurement of the heating cylinder of an injection molding machine, similar products can not only be used to measure the temperature of the heating section of an extrusion molding machine, but also can be used to measure the temperature of the heating section of an extrusion molding machine. In short, the present invention is suitable for measuring and controlling the temperature inside a solid, such as when heating is performed in a solid with low thermal conductivity, and other applications include It is wide.

〔Effect of the invention〕

Since the temperature measuring instrument of the present invention has the above configuration,
Thermal expansion of the protection tube eliminates the gap between the wall of the measurement hole of the object to be measured and the temperature measuring device, and the measuring part of the temperature measuring device and the object to be measured are integrated, thereby improving heat conduction. The error is extremely small, stable measurement is possible, and it is fully applicable to precise temperature measurement.

In addition, when inserting the temperature measuring device of the present invention into the measuring hole of the object to be measured, since a plurality of protrusions with a sawtooth cross section are provided on the upper entrance wall of the measuring hole, the temperature measuring device can be lightly pushed into the measuring hole. Just by pushing in, the temperature measuring device is fixed by the frictional action of the protrusions, and in addition, the protective tube thermally expands as described above by heating the object to be measured, making it difficult to pull out the layer, and the fixing is complete.

[Brief explanation of the drawing]

Fig. 1 shows an example in which a temperature measuring device according to an embodiment of the present invention is applied to a heating cylinder of an injection molding machine, which is an embodiment of an object to be measured. A cross-sectional view showing one embodiment, FIG.
]) shows the state changed from FIG. 3(a) when the protective tube expands due to heating, and FIG. 4 shows a conventional temperature measuring device. 1... Temperature measured object (heating cylinder), 2... Protection tube, 4... Temperature sensor (thermocouple), 8... Serrated projection

Claims (2)

[Claims] (1) A temperature sensor 4 is installed inside the protection tube 2 made of a metal with a large coefficient of thermal expansion, with its measuring section located at the tip of the protection tube 2.
A temperature measuring device that stores . (2) A measurement hole having a plurality of protrusions 8 having a sawtooth cross section is provided in the upper entrance wall of the temperature measurement object 1, and a protection tube is inserted into the measurement hole into the protection tube 2 made of a metal with a large coefficient of thermal expansion. 2. A temperature measuring structure in which a temperature measuring instrument housing a temperature sensor 4 with its measuring part positioned at the tip thereof is inserted so that the measuring part of the temperature sensor 4 contacts the measuring position of the object to be temperature measured 1.