JPS6165104A - Connecting structure of gauge lead of strain gauge to lead wire and its producing device - Google Patents

Abstract

PURPOSE:To save power in a field by coating the periphery of a connection part between gauge leads and lead wires with a synthetic resin mold, forming a plane fitting part on its external surface and then forming a connection part protecting body on the end part from which the leads and the lead wires are led out. CONSTITUTION:Two gauge leads 6 of a foil type strain gauge 1 are connected to one ends of cores 7a of the lead wires 7 by soldering and the connection part and its periphery are coated with the connection part protecting body 9 molded by polystyrene or the like. The protection body 9 is formed like a rectangular plate as a whole, protecting projection parts 10, 11 are formed on the end parts for leading out the leads 6 and the lead wires 7 and the fitting part 9a is fitted and fixed to a member to be measured by adhesion or the like.

Description

Detailed Description of the Invention (a) Technical Field The present invention relates to a strain gauge having one end connected to a terminal of a strain gauge having a resistive element exhibiting a rate of change in resistance corresponding to strain attached to a gauge base made of an insulating material. The present invention relates to a connection structure between a gauge lead and a lead wire, and an apparatus for manufacturing the same.

(b) Prior Art Generally, strain gauges are extremely compact, so a thick lead wire with diameter a is connected directly to the strain gauge terminal (
(Gauge tab) and is connected via the gauge lead. and.

Conventionally, a relay terminal called a gauge terminal was interposed between the gauge lead and the lead wire to prevent the weight of the lead wire or external impact from directly being applied to the gauge lead, especially in measurements involving vibration or shock. In some cases, the lead wire is fixed. Gauge terminals include foil-type terminals, so-called caramel-type terminals made of polystyrene, and gauge terminals provided with partition plates to prevent lead wires arranged in parallel from coming into contact with each other.

Figure 2 is a plan view showing the configuration of a terminal/lead wire strain gauge using a conventional foil-type gauge terminal, and Figure 3 is a plan view showing the configuration of a conventional lead wire strain gauge that does not use a gauge terminal. It is.

The strain gauge 1 shown in FIG. 2 is called a foil gauge, and has a grid portion 3 and gauge tabs (hereinafter referred to as terminals) 4 formed on a gauge base 2 by photo-etching or die-cutting a thin resistance foil. ing. Conventionally, when attaching this strain gauge 1 etc. to a member to be measured,
First, after gluing the strain gauge 1, the gage terminal 5 was bonded, and then the gage lead 6 and the lead wire 7 were connected to both ends of the gage terminal 5 by soldering, respectively.

However, the conventional mounting method described above requires a lot of time to install, and especially with foil-type gauge terminals, if the soldering iron is in contact with the terminal for a long time, the insulation will be poor, so it is necessary to solder quickly. Requires hot wire.

On the other hand, the conventional lead wire strain gauge shown in Fig. 3 is
After the strain gauge 1 is adhered to the member to be measured and the gauge leads 6 and lead wires 7 are soldered, the lead wire covering material is softened by a heat source and stretched to cover the soldered portion.

However, in this latter conventional example, although soldering reduces the work area, since the soldering part is only covered with the lead wire sheathing material, it has poor moisture resistance, and the weight of the lead wire 7 and the external There was a problem in that the impact from the strain gauge was easily transmitted to the strain gauge l via the gauge lead 6. In the case shown in FIGS. 2 and 3 above, and in the case using the so-called conventional caramel-type gauge terminal, the soldering work is troublesome, and the gauge lead 6 and the lead wire 7
The mechanical strength of the connection with the gauge is low, and even if a moisture-proof coating is applied, in a high humidity environment, moisture will enter from the gauge lead 6 and the lead wire 7 and the core wire will oxidize, causing the gauge to oxidize. The resistance value was changed, which caused measurement errors.

(c) Purpose The present invention has been made in view of the above circumstances, and its purpose is to save labor at the measurement site, improve the mechanical strength and moisture resistance of the connection part between the gauge lead and the lead wire. It is an object of the present invention to provide a connection structure between a gauge lead and a lead wire of a strain gauge and a manufacturing device thereof, which can realize improvements in performance and are easy to manufacture and process.

(d) Configuration In order to achieve the above object, the connection structure between the gauge leads and the lead wires of the strain gauge of the present invention (hereinafter referred to as the first invention) is such that the gauge leads and the lead wires are soldered together, The gauge is connected by a joining means such as welding, and is formed by molding a synthetic resin so as to integrally enclose the outer periphery of the connecting part and has a planar attachment part formed on a part of the outer surface of the gauge. The present invention is characterized in that a connecting portion protector is provided in which a protruding portion of a predetermined length is formed at the end from which the lead and the lead wire are led out.

Further, the manufacturing device for the connection structure between the gauge leads and the lead wires of the strain gauge of the present invention (hereinafter referred to as invention of tube 2) includes:
an injection molding machine, and a strain gauge relief part that forms a gap with a margin for the strain gauge at a position corresponding to the abutting part of the separated upper mold and lower mold attached to the injection molding machine; A gauge lead relief part that forms a gap with an allowance for the gauge lead, a lead wire relief part that forms a gap with an allowance for the lead wire, and a connection part between the gauge lead and the lead wire. and a molded part that forms a space corresponding to a connection part protector around the molded part, and a gauge lead protection that forms a somewhat large gap with respect to the gauge lead between this molded part and the gauge lead escape part. a protrusion molded part for protecting a lead wire, a protrusion molded part for protecting a lead wire having a somewhat large gap with respect to the lead wire between the molded part and the lead wire relief part; A sealing elastic body insertion part that forms a concave space between the protrusion molded part and the gauge lead relief part, and a concave space between the lead wire protection protrusion molded part and the lead wire relief part. a mold in which a sealing elastic body insertion part to be formed, a resin press-fit gate part communicating with the molded part from the outside, and a mold formed in one or both of the upper mold or the lower mold; A heat-resistant sealing elastic body is fitted into the sealing elastic body insertion part so that a part thereof protrudes, and the first invention is achieved by using such a manufacturing apparatus. The connection structure between the gauge leads and the lead wires of the strain gauge can be easily and inexpensively manufactured.

Hereinafter, the configuration of the present invention will be described in detail with reference to embodiments shown in the accompanying drawings.

Figures 4(a), 4(b) and 4(c) respectively show the configuration of an embodiment of the first invention.
) is a partially cutaway plan view, FIG. 2(b) is a front view, and FIG. 2(c) is a sectional view taken along line A--A in FIG. In this figure, parts that can be considered common to those in FIGS. 2 and 3 are given the same reference numerals.

In FIGS. 4(a) to (c), ■ is a foil gauge type strain gauge similar to that shown in FIG. 2, and one end of two gauge leads 6 are soldered to its two terminals 4. The other end of the gauge lead 6, which is connected by a joining means such as spot welding, is connected to one end of the core wire 7a of the lead wire 7 by soldering, and furthermore, the other end of the gauge lead 6 is connected to one end of the core wire 7a of the lead wire 7 by soldering, and further, is a molded connection protection body 9
are integrated.

That is, this connection portion protector 9 has a rectangular plate shape as a whole, and the connection portion 8 between the gauge lead 6 and the lead wire 7 and the gauge connected thereto are arranged along the longitudinal center (in the horizontal direction in the figure) of the connection portion protector 9. The ends of the leads 6 and the ends of the lead wires 7 are buried so as to be integrally enclosed. Both ends of the connection portion protector 9 in the lateral direction, that is, the gauge leads 6
A protrusion 10 for protecting the gauge lead and a protruding part 10 for protecting the lead wire of a predetermined length are provided at the end where the lead wire 7 is led out and the end where the lead wire 7 is led out, so as to surround the periphery of the gauge lead 6 and the lead wire. protrusions 11 are provided respectively. The gauge lead 6 has its core wire 6a covered with an insulating coating 6b made of polyester, polyvinyl formal, polyimide, polyurethane resin, etc., and the lead wire 7 has its core wire 7a covered with an insulating coating 6b made of polyester, polyvinyl formal, polyimide, polyurethane resin, etc. The 6-connection protector 9 covered with an insulating coating 7b made of resin such as vinyl chloride, polyethylene, tetrafluoroethylene, polyimide, etc. is made of polystyrene, polypropylene, ABS, polyamide resin, neoprene rubber, etc. by the method described below. Molded. Note that one surface of the connection portion protector 9 (lower surface in FIG. 4(b)) is an attachment portion 9a attached to the member to be measured by means such as adhesive. FIG. 3 is a sectional view showing the configuration of main parts.

In the figure, 12 and 13 are an upper mold and a lower mold separated into two parts, which are not shown but are fixed to the mold attachment part of the injection molding machine. 1
3 shows a state in which they are in contact (pressure contact). 14 is a lower mold mounting base for fixing the lower mold 13 with a mounting screw. The following parts are formed at positions corresponding to the abutting parts of the upper mold 12 and lower mold 13.

That is, a strain gauge relief part 15 that forms a gap with a margin with respect to the outer shape of the strain gauge 1 so that the strain gauge l can be accommodated with a margin, and a strain gauge relief part 15 with a margin with respect to the gauge lead and the above-mentioned strain gauge relief part. 15, a lead wire relief portion 17 forming a gap with an allowance for the outer diameter of the lead wire 7, and a connecting portion 8 between the gauge lead 6 and the lead wire 7 and the vicinity thereof. There is a molded part 18 that forms a space corresponding to the connection part protector 9 (see FIGS. 4(a) to (C)), and a gauge lead 6 between this molded part 18 and the gauge lead relief part 16. A protrusion molded part 19 for protecting the gauge lead which forms a gap somewhat larger than that of the lead wire 7, and a gap slightly larger than the lead wire 7 between the molded part 18 and the lead wire escape part 17. a protrusion molded part 20, a sealing elastic body insertion part 21, 22 forming a concave space between the protrusion molded part 19 for protecting the gauge lead and the gauge lead escape part 16, and a protrusion for protecting the lead wire. Part molding part 2
A sealing elastic body insertion part 23 that forms a concave space between the lead wire relief part 17 and the lead wire escape part 17 is formed at the abutting part between the upper mold 12 and the lower mold 13. Further, a resin press-fitting gate portion 24 is formed in the upper mold 12 and communicates with the molded portion 18 from the outside (from above in the figure). Numerals 25, 26 and 27 are sealing elastic bodies each having heat resistance and elasticity, such as silicone rubber, fluororubber, neoprene rubber, etc. Of these, the sealing elastic bodies 25 and 26 are O-ring shaped. It is fitted into the lower mold 13 from the side and fitted into the fitting parts 21 and 23, respectively, but a part of it is fitted into the fitting part 2.
1.22 protrudes toward the upper mold 12. Further, another sealing elastic body 27 has a bar shape with a rectangular cross section, and is also fitted into the fitting part 22, with a part of it being fitted into the fitting part 22.
2 protrudes toward the lower mold 13.

The operation of the manufacturing apparatus configured as described above will be explained.

First, strain gauge 1. The gauge lead 6 and the lead wire 7 are connected as described above and set as shown in FIG.
3 is attached to a predetermined part of the injection molding machine and is pressed at a predetermined pressure.0 In the hopper of the injection molding machine (not shown), for example, polystyrene, polypropylene,
When a molding resin such as ABS or polyamide resin is introduced, the molding resin is heated by a heater and transformed into a liquid while being transported by a transport means such as a screw. This liquefied molding resin is injected into the molding part 18 from the resin press-fitting gate part 24 under high pressure, filling the space between the molding part 18 and the protruding part molding part 19. The connecting portion 8 of the gauge lead 6 and the lead wire 7 located in the section and the vicinity thereof are integrally included, and the protruding portion molding portion 19 and the gauge lead relief portion 16 are integrally included.
The sealing elastic bodies 25 and 27 are strongly pressed against each other, and the sealing elastic body 26 is between the protrusion molded part 20 and the lead wire relief part 17. Since the contact portion of the upper mold 12 is strongly pressed to achieve a sealing effect, the liquefied resin is directed outward (in the right or left direction in FIG. 1) from the sealing elastic bodies 25, 27 and 26. ) After a predetermined period of time has elapsed, the upper mold 12 is raised by hydraulic pressure or the like to open the abutting part of the mold, and the strain gauge 1. The gauge lead 6 and lead wire 7 are taken out from the lower mold 13 to complete one molding process.

The connection structure between the gauge leads and the lead wires of the strain gauge manufactured as described above has the following first-order advantages.

First, since the connection part 8 between the gauge lead 6 and the lead wire 7 and its vicinity are integrally contained inside the molded connection part protector 9, the mechanical strength is increased throughout the flight path. increase Second, since the connection portion protector 9 completely isolates the connection portion 8 from the outside air, it is possible to prevent changes in the gauge resistance value due to moisture intrusion in a high humidity environment. Thirdly, since the protrusions 10 and 11 are formed at the gauge lead lead-out end and the lead wire lead-out end of the connection portion protector 9, there is a high possibility that the gauge lead 6 and the lead wire 7 will break even if they are repeatedly bent. There are few. Fourth, when conventional gauge terminals were used, one end had to be connected to the gauge lead 6 and the other end to the lead wire 7, which required soldering in at least two places. Soldering becomes easier as only one location is required. Fifth, in the manufacturing apparatus, sealing elastic bodies 25, 27 and 2 are provided at both ends of the protrusion molding parts 19 and 20 of the mold.
6 eliminates the risk of molten resin flowing out from around the lead wire 7 and causing so-called plashes, which was the case in the past, eliminating the need for post-processing such as removing plashes, resulting in a low-cost appearance. You can get a good product.

It should be noted that the present invention should not be construed as being limited only to the above-described embodiments, and various modifications can be made without departing from the spirit thereof.

For example, in the embodiment shown in FIG.
However, the present invention is also applicable when a plurality of strain gauges 1 are arranged in parallel. Figures 5 (,) and (b) show the configuration of another embodiment of the first invention. They are a partially broken plan view and a sectional view taken along the line B--B in FIG.

In this embodiment, a triaxial strain gauge 31 is shown in which three grid parts 29 and terminals (gauge tabs) 30 are formed on one gauge base 28. A total of six gauge leads 6 are connected to the terminals of each strain gauge, and one end of each two lead wires 7 is connected to the other end of each gauge lead 6 by single-point welding or other joining means. has been done. This connection part is shown in FIGS. 4(a), (b),
Similar to the embodiment shown in FIG. 3(c), it is protected by a connection portion protector 32 molded with molded resin. 3
3 and 34 are protrusions for protecting the gauge leads and protecting the lead wires. What is shown in this example.

This method is called a 3-wire connection method in which three lead wires are used for one strain gauge, but in such a case, the two lead wires 7 can be soldered directly to the terminals 30 of the strain gauge by However, it is extremely difficult to connect, and it is also inconvenient in terms of moisture proofing.

As in the above embodiment, it is easy to connect the two lead wires 7 to the gauge lead 6, and the connecting portion protector 3
Since these connecting portions are completely enclosed by 2, the moisture-proofing effect is also perfect. Further, this three-axis strain gauge can also be manufactured easily and inexpensively in the same manner as described in the embodiment of FIG.

Further, in the above embodiments, a foil gauge was used as an example of the strain gauge, but in addition to a wire gauge and a vapor deposition gauge, semiconductors (bulk and vapor deposition gauges) can also be used.

Diffusion type, PN junction and other pressure sensitive element type) gauges are also applicable.

Further, in the embodiment shown in FIG. 1, the sealing elastic body 26 was provided only on the lower mold 13.

It may also be provided at a corresponding position on the upper mold 12 side.

Further, the external shape of the connection portion protector 9 is not limited to a plate shape with a rectangular cross section as shown in the figure, but may be at least a flat surface as an attachment portion that can be attached to the surface of the object to be measured by adhesive or other means. It may be formed in any other shape as long as the shaped part is formed on a part of the outer surface and the protrusions 10 and 11 are formed on the lead-out ends of the gauge lead 6 and the lead wire 7.

Further, the connection portion between the strain gauge 1 and the gauge lead 6 may be subjected to moisture-proofing treatment, which is easy and has a high moisture-proofing effect.

(e) Effects As detailed above, according to the present invention, the mechanical strength and moisture resistance of the connection part between the gauge lead and the lead wire are dramatically improved, the manufacturing process is easy, and the cost can be reduced. Furthermore, it is possible to provide a connection structure between the gauge leads and lead wires of a strain gauge, which can also save labor at the measurement site, and an apparatus for manufacturing the same.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main part configuration of an embodiment of the second invention, and FIG. 2 is a terminal using a conventional can-shaped gauge terminal.
FIG. 3 is a plan view showing the structure of a strain gauge with a lead rope, and FIG. 4 is a plan view showing the structure of a conventional strain gauge with a lead rope that does not use gauge terminals.
5(a) and () are a partially cutaway plan view, a front view, and a sectional view taken along the line A-A in FIG. b) is a partially cutaway plan view showing the configuration of another embodiment of the first invention, and FIG.
) is a sectional view taken along the line B-B in the arrow direction. 1.31...Strain gauge, 2.28...Gage base, 3.29...Grid section, 4,3o Old...Terminal, 6...・・Gauge lead, 7・・Group lead wire, 8・・・Connection part, 9, 32・・・・
・Connection protector, 10.11, 33.34・Old...Protrusion, 12.13...Mold. 15...Strain gauge relief part, 16...
・Gauge lead relief part. 17...Lead wire relief part, 18...Mold forming part. 19.20...Protrusion molding part, 21-23...
...Sealing elastic body insertion part, 24...
Resin press-fit gate part, 25-27... Elastic body for sealing. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a connection structure between a gauge lead and a lead wire connected to a strain gauge in which a resistance element exhibiting a resistance change rate corresponding to strain is attached to a gauge base made of an insulating material, the gauge lead and the lead wire are connected to the strain gauge. It is connected to the lead wire by a joining means such as soldering or welding, and is formed by molding synthetic resin so as to integrally enclose the outer periphery of the connection part, and has a planar shape on a part of the outer surface. Gauge leads and lead wires of a strain gauge, characterized in that a connecting part protector is provided in which a protruding part of a predetermined length is formed at an end part from which an attached part is formed and the gauge lead and the lead wire are led out. Connection structure with. (2) In a device that manufactures a connection structure between the gauge leads and lead wires of a strain gauge, the injection molding machine and the separated upper and lower molds attached to the injection molding machine are placed at positions corresponding to the abutting parts of the separated upper and lower molds. , a strain gauge relief part forming a gap with an allowance for the strain gauge, a gauge lead relief part forming a gap with an allowance for the gauge lead, and a gap with an allowance for the lead wire. a lead wire relief portion to be formed; a molded portion forming a space corresponding to a connection portion protector around and around the connection portion between the gauge lead and the lead wire; the molded portion and the gauge lead relief portion; a protruding molded part for protecting the gauge lead forming a somewhat large gap with respect to the gauge lead between the molded part and the lead wire escape part; and a somewhat large gap with respect to the lead wire between the molded part and the lead wire escape part. a sealing elastic body fitting part that forms a concave space between the gauge lead protection protrusion molded part and the gauge lead escape part, and the lead wire protection A mold comprising: a sealing elastic body fitting part that forms a concave space between the lead wire relief part and the lead wire relief part; and a resin press-fitting gate part communicating with the mold part from the outside. and a heat-resistant sealing elastic body that is fitted into the sealing elastic body insertion portion formed in one or both of the upper mold or the lower mold so that a portion thereof projects. A manufacturing device for a connection structure between strain gauge gauge leads and lead wires.