JPH0310892B2 - - Google Patents

Description

Detailed Description of the Invention The present invention utilizes the fact that when stress is applied to a magnetic material, the core loss of the magnetic material changes in relation to the stress. A magnetic sensor for an axial force meter used in an axial force meter that is placed in contact with the head surface of a bolt made of steel, measures iron loss, and determines the axial force acting on the bolt from the measured iron loss. The present invention relates to a manufacturing method thereof.

Generally, in structures connected with bolts,
Particularly when the structure is subjected to dynamic loads, it is necessary to appropriately manage the axial force of the bolts in order to prevent fatigue failure of the bolts. Therefore, the axial force of a bolt can be detected by using a torque wrench and calculating the axial force from the tightening torque, or by measuring the dimensional change of the bolt using a dial gauge, etc. A method is used in which the axial force is detected by measuring the stress acting on the bolt using a strain gauge and a strain gauge.

However, among these methods, the method using a torque wrench or dial gauge is simple and easy to use, but has poor measurement accuracy and reliability, and the method using a strain gauge has good measurement accuracy and reliability, but has poor measurement accuracy and reliability. The disadvantage is that the method is complicated and difficult to use in the field.

Therefore, by taking advantage of the close relationship between the iron loss of a magnetic material and the stress acting on the magnetic material as shown in Figures 1 and 2, we have developed An axial force meter is used that measures iron loss, inputs the measured iron loss into a calculator, calculates the stress acting on the bolt, and calculates the axial force of the bolt from that stress.

FIG. 1 shows the relationship between the stress acting on the magnetic material and iron loss, and FIG. 2 shows the relationship between the stress acting on the magnetic material and the rate of change in iron loss.

Here, the iron loss change rate is W i −W _p /W, where W _p is the iron loss when no stress is applied to the magnetic material, and _{W i} is the iron loss when a certain stress is applied. It is expressed as _p × 100 (%).

Therefore, for a certain magnetic material, it is possible to
If the relationship shown in the figure is determined experimentally, the iron loss of the magnetic material can be measured and the stress acting on the magnetic material can be determined.

Note that in order to measure the iron loss of a bolt made of magnetic material and determine the axial force of that bolt, the third method is usually used.
As shown in the figure, among the bolts 5 and nuts 6 that fasten the assembled structures 7 and 7', a primary coil (excitation coil) 3 and an iron core 2 having a substantially U-shaped cross section are attached to the head surface of the bolt 5. When a magnetic sensor 1 composed of a secondary coil (output secondary voltage coil) 4 is wound and placed in contact with the magnetic sensor 1 and the primary coil 3 is excited with alternating current, the magnetic flux from the iron core 2 moves along the surface of the head of the bolt 5 as shown in the arrow. The magnetic flux flows in the direction of , forming a closed magnetic path that returns to the iron core 2 again.

In this case, by controlling the excitation current of the primary coil 3 of the magnetic sensor 1 and keeping the output secondary voltage induced in the secondary coil 4 constant equal to a preset setting voltage, the magnetic flux generated in the iron core is is constant, and the excitation current of the primary coil 3 and the secondary coil 4
If the output secondary voltage of
The iron loss of the head can be measured.

This measured iron loss is introduced into the calculator of the axial force meter (not shown), and the stress acting on the bolt 5 is determined from the relationship shown in FIG. 1 or FIG. The axial force of the bolt 5 can be determined from the stress.

Please note that the bolt head surface has irregularities (surface undulations in the former case, surface roughness in the latter case) due to forging or machining, and there may be unevenness between the bolt head surface and the contact surface of the magnetic sensor. For example, if there is a gap of 0.01mm, the magnetic flux density inside the bolt will decrease by about 2.1%.Since iron loss is approximately proportional to the square of the magnetic flux density, the gap due to unevenness on the bolt head surface will be reduced by approximately 2.1%. There were some drawbacks that greatly affected accuracy.

In view of the above-mentioned points, the present invention has been proposed in place of the above-mentioned conventional axial force detection method and axial force meter sensor, which have many drawbacks.
The present invention provides a magnetic sensor for an axial force meter that has excellent measurement accuracy and reliability, is easy to operate, and can be easily used in the field, and a method for manufacturing the same.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the magnetic sensor for an axial force meter and its manufacturing method of the present invention will be described below with reference to the drawings.

FIG. 4a is a front sectional view of a main part of an embodiment of the magnetic sensor for an axial force meter according to the present invention, and FIG. 4b is an A of FIG. 4a.
4c is a sectional view taken along line BB in FIG. 4a, FIG. 5a is a front view of another embodiment of the magnetic sensor for an axial force meter of the present invention, and FIG. 6 is an explanatory diagram of the method for manufacturing the magnetic sensor for an axial force meter shown in FIGS. 4 and 9 of the present invention, and FIG. 9 is an explanatory diagram of another method of manufacturing a magnetic sensor for an axial force meter, and FIG. 8a is an explanatory diagram of a method of manufacturing a magnetic sensor for an axial force meter shown in FIGS. FIG. 8b is a view taken in the direction of arrow D in FIG. 12 is an enlarged cross-sectional view taken along the line FF in FIG. 9, and FIG. 13 is an explanatory diagram of the flow of the axial bundle in the iron loss measuring section of the embodiment shown in FIG. 9.

As shown in FIG. 4a, the magnetic sensor 8 for an axial force meter of the present invention is manufactured by casting a liquid synthetic resin such as epoxy (polymerizing and solidifying the liquid synthetic resin in a mold).
A main body 9 made of
The plug 12 is connected to the plug 12. Although the main body 9 is not limited to a cylindrical shape, for convenience of explanation, the main body 9 will be described below as having a cylindrical shape.

The iron loss measurement unit 10 is constructed by winding a primary coil (excitation coil) 14 and a secondary coil (output secondary voltage coil) 15 around an iron core 13 having a substantially U-shaped cross section. It is coated with a wear-resistant non-magnetic insulator (eg, ceramic) by thermal spraying, and polished to form a thin coating 43 of a certain thickness (eg, about 0.1 mm). As shown in FIG. 4b, the surface of this thin coating 43 is on the same plane as the bottom surface of the main body 9, and the iron core 13 is embedded in the lower part of the main body 9 so as to be exposed to the outside.

The receptacle 11, as shown in FIG. 4c,
It has a plurality of pins 40, and the lead wires 16 of the primary coil 14 and secondary coil 15 of the iron loss measuring section 10 are connected to the lower end of each pin, and the plug 1 is connected to the upper part of the main body 9.
It is embedded so that the part to be combined with 2 is exposed. Plug 12 mates with receptacle 11 and is connected via cable 17 to an external power source (not shown) that includes a controller.

Since the magnetic sensor 8 for an axial force meter of the present invention has the above configuration, the cable 17 of the plug 12
is connected to an external power source, the main body 9 is grasped by hand, and the bottom surface is placed in contact with the head surface of the bolt whose iron loss is to be measured.
Since it has substantially the same configuration as the magnetic sensor 1 shown in the figure, the iron loss of the bolt can be measured in the same manner as in the case shown in FIG.

By introducing the measured iron loss into an axial force meter, the axial force of the bolt can be measured as described above.

In this case, a thin coating 43 of a constant thickness of, for example, 0.1 mm, made of a wear-resistant non-magnetic insulator is formed on the magnetic pole end surface of the iron core 13 of the magnetic sensor 8 for an axial force meter according to the present invention.
is formed, so no eddy current or wear occurs on the pole end surface, and even if the free length changes by 0.01 mm depending on how the magnetic sensor 8 for the axial force meter is applied to the bolt head surface, the bolt The change in magnetic flux density within the member is approximately 0.3%, which is approximately 1/7 times as much as when no air is provided in advance. Therefore, since the iron loss is approximately proportional to the square of the magnetic flux density, the influence on the measured value is reduced to about 1/50. Therefore, the iron loss to be measured is extremely unlikely to change due to irregularities on the surface of the bolt head, so that the iron loss of the bolt can be accurately measured.

Further, the lead wires 16 of the primary coil 14 and the secondary coil 15 of the iron loss measuring section 10 are connected to the receptacle 11.
Since it is connected to the main body 9 and is integrally cast with synthetic resin such as epoxy, there is no fear of disconnection.

As described above, the magnetic sensor for an axial force meter of the present invention measures the iron loss of the bolt by simply holding the main body by hand, placing it in contact with the head surface of the bolt, and energizing the iron loss measurement part. It is easy to operate since it can be measured, and since a thin coating 43 of wear-resistant non-magnetic insulator is formed on the magnetic pole end face of the iron core of the iron loss measuring section, the iron loss of the bolt can always be measured correctly.

In addition, it has excellent measurement accuracy and reliability, and the pole end face of the iron core in the iron loss measuring section has wear resistance, and
Since there is no fear of disconnection of the lead wires of the primary coil and the secondary coil, there are advantages such as being able to withstand long-term use.

Figure 5 shows another embodiment of the magnetic sensor for an axial force meter according to the present invention, in which the direction of the maximum or minimum core loss of the magnetic material, that is, the direction of the principal stress acting on the magnetic material, is determined. In order to easily determine the direction in which the magnetic flux flows without having to turn the magnetic sensor 18 for an axial force meter and see the position of the iron core, a Two grooves 20, 2 indicating the longitudinal direction of the iron core 13 passing through the center of the iron core 13 of the iron loss measuring section 10 are provided on the periphery.
0' and two grooves 21 pointing in a direction perpendicular thereto,
21' is provided.

Therefore, the magnetic sensor 18 for an axial force meter according to the present invention has the same functions and effects as the magnetic sensor 8 shown in FIG.
21 and 21', the direction in which the magnetic flux flows can be clearly seen, so there is no need to turn the magnetic sensor 18 over each time to check the position of the iron core 13.

Further, the iron loss measuring section 10b of the magnetic sensors 46, 47 for axial force meter shown in FIG. 9 and FIG.
As shown in FIGS. 1 and 12, two notches 48 and 49 are provided in the two legs of the iron core 13b, which has a substantially U-shaped cross section, passing through the two legs.
Three iron core parts 50, 51, 52 are formed on each leg, a thin wear-resistant non-magnetic insulating coating 43 is formed on the end surfaces of the iron core parts 50, 51, 52, and a central iron core is formed. The secondary coil 15 is wound around the part 51,
A primary coil 14 is commonly wound around all the iron core parts 50, 51, and 52.

Therefore, the flow of magnetic flux in the iron loss measuring section 10b is the first
As shown in FIG. 3, the magnetic flux φ ₁ flowing through the iron core portion 51 as a magnetic path is approximately uniform, but the magnetic flux φ ₂ flowing through the iron core portions 50 and 52 on both sides as magnetic paths.
spreads out and becomes non-uniform as it goes outward, so the secondary coil 15 wound around the iron core 51 detects only the uniform magnetic flux φ ₁ with the iron core 51 as a magnetic path, and always provides a stable secondary output. Can output voltage.

The number of notches in the legs of the iron core 13b is not limited to two, but at least two or more may be provided, and therefore the number of core portions formed is also at least three.

Of these, the secondary coil may be wound around at least the core portions excluding the core portions at both ends.

The axial force meter magnetic sensors 46 and 47 shown in FIGS. 9 and 10 are the same as the axial force meter shown in FIG. 4 or 5, respectively, except for using the iron loss measuring section 10b having the above configuration. It has approximately the same configuration as the magnetic sensor for use in other applications.

Therefore, the axial force meter magnetic sensors 46 and 47 shown in FIGS. 9 and 10 have substantially the same functions and effects as the axial force meter magnetic sensors 8 and 18 shown in FIGS. 4 and 5, respectively. In addition, since the number of iron core parts is at least three or more, there is an effect that a stable secondary output voltage can be output at all times.

Next, a method of manufacturing the above-described magnetic sensor for an axial force meter according to the present invention will be explained.

FIG. 6 shows a cross-sectional view of the manufacturing apparatus 22 for explaining the method of manufacturing the magnetic sensors 8 and 46 for axial force gauges shown in FIGS. 4 and 9. FIG.

That is, the manufacturing apparatus 22 includes a mold 32 and a floating prevention magnet 41.

The mold 32 consists of a lower mold 23 and an upper mold 24. The lower mold 23 is made of a heat-resistant elastic material such as silicone rubber, and has a magnetic sensor 8 for an axial force meter in the center, and a magnetic sensor 8 having the same shape as the main body 9 of 46. The upper mold 24 has a space 33, fits into the opening of the lower mold 23, and has a mounting hole 25 for the receptacle 11 and an injection port 26 for liquid synthetic resin.

The floating prevention magnet 41 is made up of a magnet 29 and magnetic poles 30 and 31, and the primary coil 1 of the iron loss measuring section 10 or 10b connected to the receptacle 11.
4 and the lead wire 16 of the secondary coil 15, etc., to prevent the iron loss measuring section 10 or 10b from tilting and floating.

Of course, instead of the floating prevention magnet 41, a magnet having a U-shaped cross section may be used.

An axial force meter magnetic sensor 8 is placed in the space 33 of the lower die 23 of the mold die 32 having the above configuration.
and made of the same mold resin as the main body 9 of 46,
A collar 28 whose inner dimension is in close contact with the maximum outer dimension of the iron loss measuring device 10 or 10b and whose outer dimension fits into the inner surface of the space 33 of the lower mold 23 is fitted. The iron loss measuring part 10 or 10b is placed inside the iron core 13 or 1.
The surface of the non-magnetic insulator 43 coated on the end face of the magnetic pole 3b or the end face of the iron core is pushed in so that it comes into close contact with the bottom face of the space 33, and the iron loss measuring part 10 or 10 is
The receptacle 11 to which the lead wires 16 of the primary coil 14 and secondary coil 15 are connected is attached to the mounting hole 25 of the upper mold 24 with a lock nut 27, and the lower mold 23
The upper mold 24 is fitted into the opening of the lower mold 23, and the floating prevention magnet 41 is brought into contact with the bottom surface of the lower mold 23.
When the liquid synthetic resin is injected through the injection port 26 and polymerized and solidified, the iron loss measuring section 1
The center of 0 or 10b and the center of the space 33 of the lower mold 23 coincide.

In addition, since the collar 28 is made of the same molded resin as the main body 9, it is integrated with the main body 9 without any discomfort, and since the lower mold 23 is made of a heat-resistant elastic material such as silicone rubber, the lower mold 28 is made of the same molded resin as the main body 9. This has the advantage that magnetic sensors 8 and 46 for axial force gauges can be easily removed from the mold 23 and have clean outer surfaces.

Moreover, FIG. 7 shows the magnetic sensors 8 and 4 for axial force meter.
Manufacturing device 42 for explaining another manufacturing method of No. 6
FIG. Instead of the collar 28 in FIG. 6 and the iron loss measuring part 10 or 10b pushed inside the collar 28, a polyester film 34 having the shape of the bottom of the space 33 of the lower die 23 is placed on the upper surface of the polyester film 34 for iron loss measurement. The surface of the non-magnetic insulator 43 coated on the iron core 13 of part 10 or 10b, or the magnetic pole end face of 13b or the end face of the iron core part is adhered with an adhesive that can be easily peeled off after casting so that the centers of both coincide. The material is placed in the space 33 of the lower mold 23 with the polyester film 34 at the bottom, and then the injection port 26 of the upper mold 24 is placed in the same manner as in FIG.
Inject more liquid synthetic resin, polymerize and solidify,
The magnetic sensors 8 and 46 for axial force gauges are manufactured.

Therefore, in the manufacturing method of the present invention, the center of the iron loss measuring part 10 or 10b is aligned with the center of the polyester film, and the center of the iron loss measuring part 10 or 10b is aligned with the magnetic pole end face of the iron core 13 or 13b or the end face of the iron core part. The surface of the coated non-magnetic insulator 43 is adhered to the upper surface of the polyester film 43 with adhesive, and the lower mold 2
By simply placing it at the bottom of the space 33 of No. 3, the lower mold 2
3 and the center of the iron loss measuring part 10 or 10b coincide with each other, and the main body 9 can be easily taken out from the lower mold 23 after casting.

Furthermore, in order to manufacture the magnetic sensors 18 and 47 shown in FIGS. 5 and 10, the mold 38 shown in FIGS. 8a and 8b may be used. That is, the mold 38 consists of a lower mold and an upper mold 24, and the lower mold 3
A space 39 provided at the center of the space 39 has protrusions 36, 36' that rise from the bottom and face each other at the lower part of the inner surface thereof.
and 37, 37' are provided so that a straight line connecting the centers of the protrusions 36, 36' and a straight line connecting the centers of the protrusions 37, 37' are perpendicular to each other.

In this case, if the collar 28 is used as shown in FIG.
and 37, 37' should be provided with a groove for escaping.
When using the polyester film 34 as shown in FIG.
6, 36' and 37, 37' may be cut away.

And the protrusions 36, 36' or the protrusions 37, 3
7' and the iron core 13 or 13 that passes through the center of the iron core 13 or 13b of the iron loss measuring section 10 or 10b.
The iron loss measuring section 10 or 10b may be placed in the lower part of the space 39 so that the straight lines in the longitudinal direction b coincide with each other.

Therefore, the grooves 20, 20', 21, 21' can be easily provided on the lower peripheral edge of the main body 19 of the magnetic sensor 18, 47 for an axial force meter manufactured by the manufacturing method of the present invention. be.

As described above, the magnetic sensor for an axial force meter manufactured by the manufacturing method of the present invention is easy to operate, and a wear-resistant non-magnetic insulator is used on the pole end face of the iron core or the end face of the iron core in the iron loss measurement part. Because a thin coating is formed, it can withstand long-term use, and provides high measurement accuracy and excellent reliability.

Further, according to the method of manufacturing a magnetic sensor for an axial force meter of the present invention, the process is simple, and by using a polyester film or collar, the center of the iron loss measuring part and the center of the main body of the magnetic sensor for an axial force meter are shifted. In order to prevent the iron loss measuring section from floating, a floating prevention magnet is used, so the pole end surface of the iron core of the iron loss measuring section and the bottom of the main body of the magnetic sensor for the axial force meter are always kept close to each other. Since it can be made with an air gap, it is possible to obtain a magnetic sensor for an axial force meter that can accurately measure iron loss even if the bolt head has an uneven surface.

Further, by providing a groove in the lower peripheral edge of the main body of the magnetic sensor for an axial force meter using a protrusion, the effect is great, such as the direction in which the magnetic flux flows can be clearly seen.

[Brief explanation of the drawing]

Figure 1 is a characteristic curve diagram showing the relationship between stress and iron loss in magnetic materials, Figure 2 is a characteristic curve diagram showing the relationship between stress and iron loss change rate in magnetic materials, and Figure 3 is a diagram showing the relationship between stress and iron loss in magnetic materials. FIG. 4a is a front cross-sectional view of an embodiment of the present invention, FIG. 4b is a view taken in the direction of arrow A in FIG. 4a, and FIG. 4a is a sectional view taken along line B-B, FIG. 5a is a front view of another embodiment of the present invention, FIG. 5b is a view taken along arrow C in FIG. 9 is an explanatory diagram of a manufacturing method according to an embodiment of the present invention, FIG. 7 is an explanatory diagram of another manufacturing method according to an embodiment of the present invention shown in FIGS. 4 and 9, and FIG. 10 are explanatory diagrams of the manufacturing method of another embodiment of the present invention, FIG. 8b is a view taken along arrow D in FIG. 8a, and FIG. 9 is a front view of still another embodiment of the present invention. ,
FIG. 10 is a front view of still another embodiment of the present invention, FIG. 11 is a view taken along arrow E in FIG. 9, FIG. 12 is an enlarged cross-sectional view taken along line FF in FIG. FIG. 3 is an explanatory diagram of the flow of magnetic flux in the iron loss measuring section of the illustrated embodiment. 8, 18, 46, 47... Magnetic sensor for axial force meter, 9, 19... Main body, 10, 10b... Iron loss measuring section, 11... Receptacle, 12... Plug,
13, 13b... Iron core, 14... Primary coil, 1
5... Secondary coil, 16... Lead wire, 20,2
0', 21, 21'... Groove, 22, 42... Manufacturing equipment, 23, 35... Lower mold, 24... Upper mold, 26...
...Inlet, 28...Color, 29...Magnet, 3
0,31...Magnetic pole, 32,38...Mold type,
33, 39...Space, 34...Polyester film, 36, 36', 37, 37'...Protrusion, 4
1...Magnet for preventing floating, 43...Coating.

Claims (1)

[Claims] 1. By controlling the excitation current of the primary coil and keeping the output secondary voltage induced in the secondary coil constant equal to a preset voltage, the magnetic flux generated in the iron core can be kept constant. In a magnetic sensor for an axial force meter, which measures an iron loss in a surface layer of a bolt head that is related to an axial force acting on the bolt from the excitation current of the primary coil and the output secondary voltage of the secondary coil,
The upper part of the main body, which is cast from synthetic resin, is embedded with a receptacle with the connecting part to the plug exposed, and the lower part has a roughly U-shaped cross section with thin wear-resistant magnets on the end faces of the two poles. A thin wear-resistant non-magnetic insulating coating is formed on the magnetic pole end surface, and an iron loss measuring section is formed of an iron core having a non-magnetic insulating coating formed thereon, and a primary coil and a secondary coil wound around this iron core. the surface of which is on the same plane as the bottom surface of the main body,
A magnetic sensor for an axial force meter, further comprising a plug that is embedded and arranged so as to be exposed to the outside, connects the lead wire of each coil of the receptacle and the iron loss measuring section, and is coupled to the receptacle. 2. The magnetic sensor for an axial force meter according to claim 1, characterized in that the main body is provided with a plurality of opposing grooves around its lower part. 3. By controlling the excitation current of the primary coil and keeping the output secondary voltage induced in the secondary coil constant equal to a preset voltage, the magnetic flux generated in the iron core is made constant, and the magnetic flux of the primary coil is kept constant. In a magnetic sensor for an axial force meter that measures iron loss in the surface layer of the bolt head, which is related to the axial force acting on the bolt, from the excitation current and the output secondary voltage of the secondary coil,
A receptacle with an exposed connection part to the plug is embedded in the upper part of the main body, which is cast from synthetic resin, and the two legs of the iron core, which has a roughly U-shaped cross section, are placed in the lower part. At least two notches are formed through the legs of the base to form at least three cores in each leg, and a thin wear-resistant non-magnetic insulating coating is formed on the end surface of each core. , a secondary coil is wound around the core excluding at least the cores at both ends, and an iron loss measuring section is formed by winding a primary coil in common around all the cores, and is formed on the end face of each of the cores. The surface of the coating of an abrasive non-magnetic insulator is on the same plane as the bottom surface of the main body and is embedded and arranged so as to be exposed to the outside, and the lead wire of each coil of the receptacle and the iron loss measuring section A magnetic sensor for an axial force meter, comprising a plug connected to the receptacle and coupled to the receptacle. 4. The magnetic sensor for an axial force meter according to claim 3, characterized in that the main body is provided with a plurality of opposing grooves around its lower part. 5. A lower mold made of a heat-resistant elastic material such as silicone rubber and having a space in the center that has the same shape as the outer shape of the main body of the magnetic sensor for axial force meter, and a receptacle that fits into the opening of this lower mold. Using a mold consisting of an upper mold with a hole and an injection port for liquid synthetic resin,
At the bottom of the space of the lower mold, a mold made of the same resin as the molding resin of the main body of the magnetic sensor for the axial force meter,
The inside is in close contact with the maximum external dimension of the iron loss measuring section,
On the outside, insert a collar that fits into the inner surface of the space of the lower mold, and insert an iron loss measuring section inside this collar.
The primary coil of the iron loss measuring part is arranged so that the surface of the thin wear-resistant non-magnetic insulating film formed on the magnetic pole end face of the iron core or the end face of the iron core part is in close contact with the bottom face of the space of the lower die. and a receptacle to which the lead wire of the secondary coil is connected is fixed to the upper mold, the upper mold is fitted into the opening of the lower mold, and both magnetic poles of a magnet for lifting prevention are attached to the lower end of the lower mold. A method for manufacturing a magnetic sensor for an axial force meter, characterized in that a liquid synthetic resin is injected from the injection port of the upper mold to polymerize and solidify the resin in contact with the upper mold. 6 Claims characterized in that the lower mold is provided with projections on the inside of the lower part of the space for providing a plurality of grooves facing around the lower part of the main body of the magnetic sensor for an axial force meter. 5. A method for manufacturing a magnetic sensor for an axial force meter according to item 5. 7. A lower mold made of a heat-resistant elastic material such as silicone rubber and having a space in the center with the same shape as the outer shape of the main body of the magnetic sensor for axial force meter, and a receptacle that fits into the opening of this lower mold. Using a mold consisting of an upper mold with a hole and an injection port for liquid synthetic resin,
On the upper surface of the polyester film having the shape of the bottom surface of the space of the lower die, the surface of the thin wear-resistant non-magnetic insulator formed on the pole end surface of the iron core or the end surface of the iron core portion of the iron loss measuring section is glued. The polyester film is placed in the space of the lower mold with the polyester film at the bottom, the receptacle to which the lead wires of the primary coil and secondary coil are connected is fixed to the upper mold, and the receptacle is fixed to the opening of the lower mold. The upper mold is fitted into the upper mold, and both magnetic poles of a lifting prevention magnet are brought into contact with the lower end of the lower mold, and the liquid synthetic resin is injected from the injection port of the upper mold and polymerized and solidified. A method for manufacturing a magnetic sensor for an axial force meter. 8. Claims characterized in that the lower mold is provided with protrusions on the inside of the lower part of the space for forming a plurality of grooves facing around the lower part of the main body of the magnetic sensor for an axial force meter. 8. A method for manufacturing a magnetic sensor for an axial force meter according to item 7.