JPH11105149A - Method of manufacturing cross-coil instrument casing - Google Patents

Abstract

(57) [Problem] To provide an inexpensive instrument casing, respond flexibly to a change in casing specification, and effectively prevent the magnetic chip from being detached from the casing. A cross-coil type in which a disc-shaped magnet that rotates by an angle corresponding to the amount of current supplied to a cross coil is built in, and a magnetic chip that moves the magnet back when power is stopped is accommodated in a small hole 11a provided on the surface. In the method of manufacturing the instrument casing, a magnetic chip is accommodated by injecting a paste containing a synthetic resin or rubber and a magnetic powder into the small hole 11a and then hardening or injecting and then cooling and solidifying. Casing 11
Is transported by the conveyor 21 and the casing 11 is moved by the paste injecting device 22 provided above the conveyor 21.
When the paste reaches a predetermined position, it is preferable to inject the paste into the small holes 11a provided on the surface of the casing and to heat the paste by the heating device 23 provided downstream of the paste injecting device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a casing of a cross-coil type instrument incorporating a disk-shaped magnet which rotates by an angle corresponding to the amount of current supplied to a cross coil. More specifically, the present invention relates to a method of manufacturing a casing for a cross-coil instrument in which a magnetic tip for returning a disk-shaped magnet is accommodated in a small hole provided on the surface of the casing.

[0002]

2. Description of the Related Art As shown in FIG. 3, a crossed coil type instrument is provided with bearing holes 2, 3 on the upper and lower surfaces of a synthetic resin casing 1 made of a nonmagnetic material. The rod 4 is pivoted. A disc-shaped magnet 5 is integrally provided at an intermediate portion of the shaft 4, and a pointer 6 is attached to a tip of the shaft 4. Although not shown, a cross coil is wound around the outer periphery of the casing 1, and when the cross coil is energized, the disc-shaped magnet 5 rotates by an angle corresponding to the amount of energized current and is integrally attached thereto. When the hands 6 rotate, the vehicle speed, fuel remaining amount, various temperatures and the like are displayed.

[0003] The casing of the coil-type instrument is provided with a magnetic tip 7 for returning the pointer 6 to a predetermined position (for example, a zero point) when energization of the cross coil is stopped. The magnetic chip 7 is made of synthetic resin or rubber containing a magnetic powder. The magnetic chip 7 is strongly magnetized, and the magnetic chip 7 and the N-pole or S-pole of the disk-shaped magnet 5 attract each other, thereby causing a crossing. The pointer 6 is configured to return when the power supply to the coil is stopped. Conventionally, the magnetic chip 7 is manufactured by punching a sheet of a synthetic resin or rubber containing a magnetic powder. The mounting of the magnetic chip 7 is performed by forming the magnetic chip into a small donut shape (not shown), This is performed by tightly fitting the protrusion into the projection or by forming a small hole 8 in the surface of the casing 1 and housing the magnetic chip 7 in the small hole 8 as shown in FIG.

[0004]

However, the magnetic chip 7
In order to manufacture by punching, a die for punching is required, and the manufacturing equipment is relatively expensive, so that the unit price of the magnetic chip itself is increased. If the size or shape of the small projections or small holes 8 on which the magnetic chip 7 is mounted is changed, it is necessary to change the mold accordingly, and it is possible to respond to the specification change of the casing 1 flexibly. Some problems cannot be achieved. On the other hand, punching out a sheet of synthetic resin or rubber has the disadvantage that burrs and chips are generated at the time of punching, and dimensional errors are likely to occur. If a dimensional error occurs, the magnetic chip 7 must be tightly fitted into the small projections or small holes 8. If the magnetic chip 7 is loosely fitted, there is another problem that the magnetic chip 7 is easily removed. When the disk-shaped magnet 5 rotates, the disk-shaped magnet 5 and the magnetic chip 7 face each other at the same polarity, and a repulsive force is generated between the two. In the chip 7, it is necessary to effectively prevent the magnetic chip 7 from coming off the casing 1 due to repeated repulsion.

An object of the present invention is to provide an inexpensive instrument casing by eliminating the need for a unique mold for manufacturing a magnetic chip, and to provide a cross-coil instrument casing that can flexibly respond to changes in casing specifications. It is to provide a manufacturing method of. It is another object of the present invention to provide a method of manufacturing a casing for a cross-coil instrument which can ensure that the magnetic chip is housed in the casing and effectively prevent the magnetic chip from coming off the casing.

[0006]

The invention according to claim 1 is
As shown in FIG. 2, a disk-shaped magnet 13 that rotates by an angle corresponding to the amount of current flowing through the cross coil wound around the outer periphery is rotatably built in, and the magnet 13 is moved back when power to the coil is stopped. This is an improvement in a method for manufacturing a cross-coil instrument casing made of a non-magnetic material in which a magnetic chip 16 is accommodated in a small hole 11a provided on the surface of a casing 11 facing the peripheral portion of a magnet 13. The characteristic configuration is that the magnetic chip 16 is accommodated by injecting a paste containing a synthetic resin or rubber and a magnetic powder into the small hole 11a and then hardening or by injecting and then cooling and solidifying.

The synthetic resin or rubber constituting the matrix of the paste is preferably a thermoplastic resin such as vinyl chloride, a thermosetting resin such as epoxy, or NBR rubber. The magnetic powder is generally soft, such as iron-based soft magnetic alloy powder, permalloy powder, sendust powder, pure iron powder, Mn-Zn ferrite powder or Ni-Zn ferrite powder having an average particle diameter of 1 to 100 m and a maximum diameter of 200 m or less. Powders called ferrites are preferable, but hard ferrites such as Ba ferrite and Sr ferrite, and Sm-Co
Hard magnetic powders, such as magnetic powders, such as magnetic powders, alnico-based, and neodymium-based magnet powders, and magnetite powders can be used. Note that the powder is not limited to the above range as long as the powder exhibits the same effect magnetically. After injecting the paste into the small holes 11a, the paste is hardened or solidified to form the magnetic chip 16, so that a unique mold for manufacturing the magnetic chip 16 becomes unnecessary. By hardening or solidifying the paste injected into the small hole 11a, the magnetic chip 16
Is securely accommodated in the small hole 18 irrespective of the shape of the small hole 18.

The invention according to claim 2 is the invention according to claim 1, wherein the casing 11 is conveyed by a conveyor 21 and is supplied by a paste injection device 22 provided above the conveyor 21 as shown in FIG. Manufacture of a cross-coil instrument casing for injecting paste into small holes 11a provided on the casing surface when casing 11 reaches a predetermined position and heating the paste by heating device 23 provided downstream of the paste injecting device. Is the way. After the casing 11 is conveyed by the conveyor 21 and the paste is injected into the small holes 11a by the paste injection device 22, the paste is heated by the heating device 23 provided on the downstream side, thereby automating the production of the cross-coil instrument casing. It becomes possible to do.

A third aspect of the present invention is the method according to the first or second aspect, wherein the magnetic powder is a soft magnetic powder, and is a method for manufacturing a casing for a cross-coil instrument. When a soft magnetic powder is used as the magnetic powder, a soft magnetic magnetic chip 17 is manufactured, and the magnetic chip 17 attracts the disc-shaped magnet 13 of the cross-coil instrument to move the pointer back. When the soft magnetic tip 17 is used, no repulsive force is applied to the magnetic tip 17 from the disc-shaped magnet 13 of the meter, and the error of the pointer due to the magnetic force of the magnetic tip 17 is reduced.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIG. 2, a casing 11 manufactured by the method of the present invention is used for a cross-coil instrument 10. The casing 11 is made by molding a non-magnetic material synthetic resin. The casing 11 has a rotatable disk-shaped magnet 13 provided on a shaft rod 12. A pointer 14 is attached to the tip of the shaft 12,
A cross coil (not shown) is wound around the outer periphery of the casing 11. A scale plate 15 is fixedly attached between the pointer 14 and the casing 11. In such a cross-coil instrument 10, when a cross coil (not shown) is energized, the disc-shaped magnet 13 rotates by an angle corresponding to the amount of energized current. Since the pointer 14 integrally attached to the magnet 13 also rotates, the scale of the vehicle, the remaining fuel amount, various temperatures, and the like are displayed by reading the scale on the scale plate 15 pointed by the pointer 14. You. On the other hand, the magnetic chip 16 for returning the magnet 13 when the power supply to the cross coil (not shown) is stopped is accommodated in a small hole 11 a provided on the surface of the casing 11 facing the periphery of the magnet 13. The magnetic chip 16 is accommodated in the small hole 11a by injecting a paste containing a synthetic resin or rubber and a magnetic powder into the small hole 11a, and hardening the paste by heating or the like, or cooling and solidifying the paste.

As shown in FIG. 1, when the paste is a synthetic resin, it is preferable that the injection of the paste into the small holes 11a and the curing be performed automatically through the conveyor 21.
In this manufacturing method, the casing 11 is arranged at a predetermined interval on the conveyor 21 on which the paste injecting device 22 is provided. The casing 11 is conveyed by the movement of the conveyor 21 in the direction of the solid arrow, and when the casing 11 reaches a predetermined position, the paste is injected into the small holes 11a provided on the surface of the casing 11 by the paste injection device 22. Further, a heating device 23 is provided downstream of the paste injecting device 22, and the casing 11 in which the paste has been injected into the small holes 11a is further conveyed to the heating device 23 by the conveyor 21, and the paste is heated by the heating device 23. After hardening or heating, it is cooled and solidified to obtain the casing 11 in which the magnetic chip 16 is accommodated in the small hole 1a.

[0012]

【Example】

<Example 1> A cross-coil instrument casing 11 was manufactured according to the method of the present invention. First, Fe80wt%, S
i 10 wt% and Cr 10 wt% average particle size 10
A paste composed of 76 parts by weight of a soft magnetic alloy powder having a particle diameter of 76 μm, 16 parts by weight of a vinyl chloride resin paste sol, and 8 parts by weight of a dioctyl phthalate solvent (DOP) was prepared. . On the other hand, they are arranged at equal intervals on the belt conveyor 21 shown in FIG.
When the casing 11 arrives immediately below the injection device 22, a predetermined amount of paste is supplied from the injection device 22 to an inner diameter of 3 mm.
It was injected into the small hole 11a of the casing 11 having a depth of 1.5 mm. Thereafter, the casing 11 was heated for 3 minutes through a heating device 23 maintained at 150 ° C. Heating device 23
After passing through, the paste was solidified by natural air cooling. Thus, 1,000 casings 11 in which the magnetic chips 16 were accommodated in the small holes 11a were obtained. Approximately 1000 casings 11 in which the magnetic chips 16 are accommodated in the small holes 11a as described above.
When the presence or absence of the magnetic chip 16 falling out of the small hole 11a due to its own weight was confirmed by inverting, no casing 11 in which the magnetic chip 16 was dropped from the small hole 11a was confirmed.

<Example 2> A cross-coil instrument casing 11 was manufactured according to the method of the present invention. First, a paste comprising 70 parts by weight of a soft magnetic powder using Sr ferrite powder having an average particle size of 1.05 μm, 20 parts by weight of a vinyl chloride resin paste sol, and 10 parts by weight of a dioctyl phthalate solvent (DOP) was prepared. Then, this paste was filled in a paste injecting device 22. On the other hand, when the casing 11 arrives directly below the injection device 22 and is conveyed side by side at equal intervals to the belt conveyor 21 shown in FIG.
2 to a predetermined amount of paste 3 mm in inner diameter and 1.5 m in depth
m of the casing 11. Thereafter, the casing 11 was heated for 3 minutes through a heating device 23 maintained at 150 ° C. After passing through the heating device 23, the paste was solidified by natural air cooling. Thus, 1,000 casings 11 in which the magnetic chips 16 were accommodated in the small holes 11a were obtained. When about 1,000 casings 11 in which the magnetic chips 16 are accommodated in the small holes 11a are turned upside down to check whether the magnetic chips 16 have fallen out of the small holes 11a due to their own weight, the magnetic chips 16 fall out of the small holes 11a. No casing 11 was found.

Comparative Example 1 A rubber plate having a thickness of 1.5 mm was prepared by kneading 80 parts by weight of Ba ferrite powder having an average particle diameter of 1.5 μm and 20 parts by weight of NBR rubber and kneading them. This rubber plate was prepared by punching out 900 magnetic chips having a diameter of 3 mm using a dedicated punching die. This 9
The appearance of the 00 magnetic chips was visually observed using a magnifying glass. As a result, about 100 burrs or chips were confirmed, and it was recognized that the burrs could not be mounted in the small holes of the casing. Next, 800 pieces that were determined to be non-defective were mounted in small holes in the casing. Approximately 100 of the 800 pieces were dropped into the small holes due to the repulsive force of the magnetic chip after being mounted in the small holes. Furthermore,
When about 700 casings having the magnetic chips mounted in the small holes were turned upside down and the presence or absence of the magnetic chips falling out of the small holes due to their own weight was confirmed, it was confirmed that about 50 magnetic chips were dropped from the small holes.

[0015]

As described above, according to the present invention, after the paste is injected into the small hole of the casing, the paste is hardened or solidified to form a magnetic chip. Since a mold is not required, a cost for the mold is not required, and an inexpensive instrument casing can be obtained. In addition, since the magnetic chip is obtained by hardening or solidifying the paste injected into the small hole, a magnetic chip according to the shape of the small hole can be obtained, and the specification of the casing accompanying the change in the shape of the small hole can be obtained. Can respond to changes. Furthermore, by hardening or solidifying the paste injected into the small hole to form a magnetic chip and forming a magnetic chip according to the shape of the small hole, the magnetic chip can be securely housed in the casing, and the magnetic chip is removed from the casing. Departure can be effectively prevented. Further, if the casing is conveyed by a conveyor and the paste is injected into the small holes by the paste injection device, and then the paste is heated by the heating device provided on the downstream side, the manufacture of the casing for the cross-coil instrument can be automated. . If soft magnetic powder is used as the magnetic powder, the relationship between the angle of the pointer and the current flowing through the cross coil becomes constant over time, and a repulsive force is applied to the magnetic chip from the disc-shaped magnet of the instrument. Absent.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a conveyor line illustrating a production method of the present invention.

FIG. 2 is a perspective view of an instrument using the casing.

FIG. 3 is a sectional view showing a conventional casing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Casing 11a Small hole 13 Disc-shaped magnet 16 Magnetic chip 21 Conveyor 22 Paste injection device 23 Heating device

Claims (3)

[Claims] 1. A disc-shaped magnet (13) that rotates by an angle corresponding to the amount of current flowing through a cross coil wound around the outer periphery so as to be rotatable, and the magnet (13) is turned off when power to the coil is stopped. Manufacture of a cross-coil instrument casing made of a non-magnetic material for accommodating a magnetic chip (16) for returning the magnet in a small hole (11a) provided on the surface of the casing (11) facing the peripheral portion of the magnet (13). In the method, a paste containing a synthetic resin or rubber and a magnetic powder is injected into the small hole (11a), and then the magnetic chip (16) is accommodated by being hardened or injected and then cooled and solidified. Of manufacturing a cross-coil type instrument casing. 2. When the casing (11) is conveyed by a conveyor (21) and the casing (11) reaches a predetermined position by a paste injecting device (22) provided above the conveyor (21), the paste is applied. 2. The manufacturing of a casing for a cross-coil instrument according to claim 1, wherein the paste is injected into a small hole (11a) provided on the surface of the casing, and the paste is heated by a heating device (23) provided downstream of the paste injecting device. Method. 3. The method for producing a cross-coil instrument casing according to claim 1, wherein the magnetic powder is a soft magnetic powder.