JPH065183B2 - Method for manufacturing moisture-proof load cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a load cell, and more particularly, in order to protect the strain gauge from moisture and humidity, a strain gauge attached surface of the load cell is covered with a moisture-proof member. The present invention relates to a method for manufacturing the moisture-proof load cell.

[Prior Art] Conventionally, as a moisture-proof type load cell, the actual load is 59-183639
The load cell described in the issue is known. This load cell attaches a strain gauge to the strain-generating part of the strain-generating body,
A space is provided around the strain gauge, a sealing material is attached to a predetermined thickness, and the upper surface of the sealing material is covered with a waterproof sheet such as a metal foil. Then, on the upper surface of this waterproof sheet, at a position substantially corresponding to the strain gauge, so as not to interfere with the bending characteristics of the strain-flexing portion,
Wrinkles were formed in the direction perpendicular to the main axis of the strain-flexing portion. Then, the wrinkle was formed in a bellows shape by attaching the waterproof sheet to the flexure element and then pressing the predetermined portion with a pressing die.

Further, as a conventional technique for forming a bellows-shaped unevenness on a sheet-shaped metal, Japanese Patent Publication No. 55-49932 discloses a rotary drum having a wavy uneven portion, which is adapted to the rotation speed of the rotary drum. A metal tape is continuously supplied, and compressed air is blown to the metal tape to form a bellows-like unevenness on the metal tape. JP-A-60-174218 discloses a pressing die or a manual work. The method of bending is described.

[Problems to be Solved by the Invention] However, in the load cell described in Japanese Utility Model Laid-Open No. 59-183639, after covering the waterproof putty provided on the load cell strain element with a waterproof sheet of metal foil, Wrinkles are formed near the strain gauge. The formation of the wrinkles is performed by pressing from the upper surface at a predetermined position of the waterproof sheet with a pressing die in which the pressing surface is formed in an uneven shape, but as described above, between the strain gauge and the waterproof sheet. Is a void, and depending on the amount of force that presses the push die, a pinhole is created in the waterproof sheet, or the push die contacts the strain gauge or lead wire through the waterproof sheet and cuts the strain gauge or lead wire. There is a risk.

In addition, since the wrinkles having a fine pitch cannot be formed by the pressing method, the stress generated in the waterproof sheet on the upper surface of the strain gauge due to the bending of the load cell cannot be sufficiently dispersed, so that the creep characteristics are deteriorated and a highly accurate moisture-proof load cell cannot be expected.

Incidentally, after forming the unevenness on the metal tape by the method described in JP-B-55-49932, when the metal tape is attached with the sealing material, the metal tape and the sealing material do not completely adhere to each other, Moisture enters the gap between the metal tape and the sealing material, and the moisture-proof effect is impaired.

In addition, when the metal foil is bent by a bending method using a pressing die or a manual bending method described in JP-A-60-174218 and then the metal foil is attached to a sealing material, the same drawbacks as described above are generated. In addition, the bending pitch becomes large, and when the load cell is used as a moisture-proof member, the stress is not dispersed when the strain generating portion of the load cell bends, which affects the accuracy of the load cell.

The present invention has been made in view of the above circumstances, a sufficient moisture-proof effect is obtained, and the moisture-proof member has little influence on the accuracy of the load cell, and a work for forming wrinkles on the metal sheet on the upper surface of the sealing material. However, it is an object of the present invention to provide a method for manufacturing a moisture-proof load cell that does not cause cutting of a strain gauge or a lead wire.

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a moisture-proof load cell of the present invention is such that the peeling member 4 is attached to the back surface and the thin metal sheet 2 is attached to the surface. The flat moisture-proof member 1 made of the plate-like sealing material 3 having adhesiveness and plasticity is rolled and plastically deformed with the metal sheet 2 inside, and then the peeling member 4 side is substantially flat. The first step of forming fine wrinkles 2a with innumerable pitches in the direction substantially perpendicular to the rolled direction a on the upper surface of the metal sheet 2, and from the back surface of the sealing material 3 of the moisture-proof member 1. Second step of removing the peeling member 4 and the moisture-proof member 1 from which the peeling member 4 has been removed
The seal cell 3 side of the load cell 8 is formed by attaching the strain gauge 7 to the strain generating portion 5a of the strain generating body 5, and the direction b of the wrinkles 2a formed on the upper surface of the metal sheet 2 is the main axis of the load cell 8. And a third step of adhering it to the attachment surface 6 of the strain gauge 7 of the load cell 8 so as to intersect the direction c at substantially right angles.

[Operation] In the first step, by rolling the moisture-proof member 1 with the metal sheet 2 inside, the adhesive and plastic sealing material 3 undergoes plastic deformation, and its inner surface (metal sheet 2 The attached surface) wrinkles, and the outer surface (the surface to which the peeling member 4 is attached) extends. Due to the wrinkling of the inner surface, the inner surface of the sheet material 3 is rolled in the direction a.
And innumerable fine wrinkles 2a are formed in a substantially perpendicular direction.
The wrinkles 2a formed on the inner surface of the sealing material 3 are thin metal sheets 2 adhered to the surface by an adhesive force.
Is deformed to similarly generate innumerable fine wrinkles 2a having a pitch on the metal sheet 2.

At this time, the peeling member 4 attached to the outer surface of the seal material 3 is in a state of being peeled from the seal material 3 and does not affect the plastic deformation of the seal material 3.

Then, the moisture-proof member 1 is returned until the peeling member 4 becomes substantially flat. As a result, the outer surface of the sealing material 3 shrinks,
Although the inner surface is slightly stretched, the wrinkles 2a formed on the inner side of the seal material 3 and the metal sheet 2 remain almost as they are due to the plastic deformation. Therefore, the lengths of the metal sheet 2 and the sealing material 3 are shorter than those before the rounding because the wrinkles 2a are formed. Since the peeling member 4 is peeled from the sealing material 3 as described above, it does not affect the plastic deformation of the metal sheet 2 and the sealing material 3.

Therefore, by the first step, the substantially flat sealing material 3
An infinite number of fine wrinkles 2a with a fine pitch are formed on the entire surface of the metal sheet 2 on the surface of the sheet.

In the second step, the peeling member 4 is removed from the back surface of the sealing material 3 of the moisture-proof member 1 to expose the adhesive surface.

In the third step, the sealing material 3 side (bonding surface) of the moisture-proof member 1 from which the peeling member 4 is removed is attached to the metal sheet 2
Is adhered to the attachment surface 6 of the strain gauge 7 of the load cell 8 so that the direction b of the wrinkles 2a formed on the upper surface of the load cell 8 intersects the direction c of the main axis of the load cell 8 at a substantially right angle.

A waterproof load cell in which the adhesion surface 6 of the strain gauge 7 is covered with the moisture-proof member 1 including the metal sheet 2 on which countless fine wrinkles 2a are formed through the first, second and third steps is described. To manufacture.

[Embodiment] An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 2 shows the structure of the moisture-proof member 1 used in the present invention. In the figure, 3 is a sticky and plastic plate-like sealing material having a predetermined thickness and having a sealing material 3 on its surface. The metal sheet 2 having a thin film thickness is attached by the adhesive force of the above, and the peeling member 4 having a relatively strong force is attached by the adhesive force of the sealing material 3 on the back surface thereof.

In the present embodiment, butyl rubber is used as the sealing material 3, but natural rubber, synthetic rubber, or other material having adhesiveness and plasticity, or any other polymer compound having moisture resistance and adhesiveness and plasticity can be used. Good.

The metal sheet 2 generally has a film thickness of 25 μ due to the moisture-proof effect.
The above-mentioned thin aluminum foil is used. With an aluminum foil having a film thickness of 25 μm or less, several pinholes are stochastically present in an area of 1 m ² , which reduces the moisture-proof effect. Therefore, when using an aluminum foil having a film thickness of 25 μm or less, it is necessary to check the presence or absence of pinholes before use.

The peeling member 4 is made of paper or resin. The peeling member 4 is coated with silicon or the like on the surface to which the seal material 3 is attached in order to facilitate peeling when peeled from the seal material 3 and to peel easily when peeled from the seal material 3. There is.

The sealing material 3 needs to have a certain thickness from the viewpoint of the formation of wrinkles and the moisture-proof effect described later, but if the thickness is too thick, absorption of water from the side surface becomes a problem. .
5 mm to 3.5 mm is suitable, and a thickness of 2.0 mm is used in the embodiment.

According to the present invention, in the first step, the operator first cuts the moisture-proof member 1 configured as described above into substantially the same size as the strain gauge adhering surface 6 of the load cell 8, and then the main axis of the load cell 8 described later. The metal sheet 2 is turned up and rolled from the short side so that the direction c of the metal sheet 2 is perpendicular to the direction b of the wrinkles 2a.

In this way, by rolling the moisture-proof member 1 with the metal sheet 2 inside, the adhesive and plastic sealing material 3 undergoes plastic deformation and its inner surface (metal sheet 2
(The surface to which the peeling member 4 is attached) is wrinkled, and the outer surface (the surface to which the peeling member 4 is attached) extends. Due to the creases on the inner surface, numerous creases 2a having a myriad of pitches are formed on the inner surface of the sealing material 3 in a direction substantially perpendicular to the rolling direction a. The wrinkles 2a formed on the inner surface of the sealing material 3 deform the thin metal sheet 2 adhered to the surface by an adhesive force to form the wrinkles 2a having innumerable fine pitches on the metal sheet 2 as well. Give rise to.

At this time, the peeling member 4 attached to the outer surface of the seal material 3 is in a state of being peeled from the seal material 3 and does not affect the plastic deformation of the seal material 3.

After that, the worker returns the moisture-proof member 1 to the original state until the peeling member 4 becomes substantially flat. As a result, the outer surface of the sealing material 3 contracts and the inner surface thereof is slightly stretched, but the wrinkles 2a formed on the inner surface of the sealing material 3 and the metal sheet 2 remain substantially as they are due to plastic deformation. Therefore, the metal sheet 2
And the length of the sealing material 3 is larger than that before it is rounded.
The length is shortened by the amount of the formation of the slab (a length of 80 mm shortens by about 5 mm). As described above, the peeling member 4
Since is separated from the sealing material 3, it does not affect the plastic deformation of the metal sheet 2 and the sealing material 3.

Therefore, by the first step, as shown in FIGS. 3 and 4, innumerable fine wrinkles 2a having a large number of pitches adhered to the sealing material 3 on the entire surface of the metal sheet 2 on the surface of the substantially planar sealing material 3.
Is formed.

In addition, FIG. 3 is a view in which the wrinkles 2a are formed substantially in parallel to one direction,
FIG. 4 is a view in which the direction and the interval of the wrinkles 2a are not formed so uniform.

In this way, after rolling the moisture-proof member 1 by the first step,
The wrinkles 2a having a fine pitch, which cannot be formed by the pressing die, can be formed on the metal sheet 2 only by returning to the original state.

Next, in the second step, the operator removes the peeling member 4 from the moisture-proof member 1 in which the innumerable fine wrinkles 2a are formed on the metal sheet 2 in the first step, and exposes the adhesive surface of the sealing material 3. Let

In the above first step, as shown in FIG.
The moisture-proof member 1 may be wound long with the width of the short side of the strain gauge attachment surface 6 of the load cell 8 and used while being cut into a predetermined length immediately before the second step. In addition, in the first step, the large moisture-proof member 1 may be wound in advance, and immediately before the second step, the large moisture-proof member 1 may be unwound and cut into a predetermined size before use. In this way, since the wrinkles 2a are once rolled to form the wrinkles, the material can be managed in the wound state, and the work can be performed while the end portion is rewound from that state, so that the work is easy to perform.

Then, in the third step, the operator removes the peeling member 4 as shown in FIG.
The side (bonding surface) is bonded to the attachment surface 6 of the strain gauge 7 of the load cell 8 so that the direction b of the wrinkles 2a formed on the upper surface of the metal sheet 2 intersects the direction c of the main axis of the load cell 8 at substantially right angles. Let

The load cell strain element 5 is a double beam type strain element having upper and lower beams, and four thin strain elements 5a are formed at predetermined positions of the upper and lower beams. It should be noted that the flexure element 5 is mainly made of high-strength aluminum. Strain gauges 7 are attached to each of four locations at substantially central positions of the upper and lower beam surfaces corresponding to the strain-flexing portion 5a to form load cells 8. The moisture-proof member 1 from which the peeling member 4 has been removed in the second step is adhered to the attachment surface 6 of the strain gauge 7 of the load cell 8.

At this time, as described above, the sealing material 3 is bonded so that the direction b of the wrinkles 2a of the moisture-proof member 1 is substantially perpendicular to the direction c of the main axis of the load cell 8.

In the present invention, the adhesion surface 6 of the strain gauge 7 is covered with the moisture-proof member 1 provided with the metal sheet on which the countless fine wrinkles 2a are formed through the first, second and third steps. A moisture-proof load cell is manufactured.

It is needless to say that the moisture-proof member 1 may be wound by a machine in the first step.

In addition, a laminate layer may be formed on the surface of the metal sheet 2 in order to obtain a more complete moisture-proof structure.

[Effects of the Invention] According to the method of manufacturing the moisture-proof load cell of the present invention, the following beneficial effects can be obtained.

Since the moisture-proof member 1 provided with the thin metal sheet 2 formed with innumerable fine wrinkles 2a is used as the moisture-proof member of the load cell 8, it is possible to manufacture a highly accurate moisture-proof load cell that does not prevent the deflection of the load cell. .

Unlike the method of forming wrinkles by the pressing die, the wrinkles 2a do not completely remove the layer of the sealing material 3 and press the strain gauge 7 or the lead wire, so that the strain gauge 7 or the lead wire can be made defective in insulation. Also, it does not break the metal sheet or create pinholes.

Even if wrinkles 2a are formed on the metal sheet 2, the sealing material 3
There is no gap between the metal sheet 2 and the metal sheet 2, and since the peeling member 4 side of the sealing material 3 is a flat surface, the sealing material 3 comes into close contact with the attachment surface 6 of the strain gauge 7 of the load cell 8 and a high moisture-proof effect is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a method for forming wrinkles on a moisture-proof member in the first step of the present invention, FIG. 2 is a perspective view showing the moisture-proof member before forming wrinkles, and FIGS. 3 and 4 show wrinkles. The figure which shows a state, FIG. 5 is the figure which shows the state which wound the moisture-proof member, 6th
The figure is a perspective view of a moisture-proof load cell to which a moisture-proof member having wrinkles is adhered. In the drawing, 1 ... Moisture-proof member, 2 ... Metal sheet 2a ... Wrinkle, 3 ... Sealing material, 4 ... Peeling member, 5 ... Strain element 5a ... Strain portion, 6 ... Gauge attachment surface 7 ... Strain gauge, 8 ... Load cell 9 ... Moisture-proof type-Decel, a ... Rolling direction b ... Wrinkle direction, c ... Spindle direction

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-174218 (JP, A) Sekikai Shou 59-183639 (JP, U) JP-B-55-49932 (JP, B2)

Claims (1)

[Claims] 1. A planar moisture-proof member 1 comprising a sticky and plastic plate-like sealing material 3 having a peeling member 4 attached to the back surface and a thin metal sheet 2 attached to the front surface,
After the metal sheet 2 is rolled inward and plastically deformed, the metal sheet 2 is returned until the peeling member 4 side becomes substantially flat, and the metal sheet 2 has an infinite number of directions substantially perpendicular to the rolling direction a on the upper surface thereof. For forming wrinkles 2a having a fine pitch
And the second step of removing the peeling member 4 from the back surface of the sealing material 3 of the moisture-proof member 1, and the sealing material 3 side of the moisture-proof member 1 from which the peeling member 4 has been removed. The load cell 8 is formed by attaching a strain gauge 7 to the portion 5a so that the direction b of the wrinkles 2a formed on the upper surface of the metal sheet 2 intersects the direction c of the main axis of the load cell 8 at a substantially right angle. And a third step of adhering the strain gauge 7 to the attachment surface 6 of the strain gauge 7, and a method for manufacturing a moisture-proof load cell, comprising: