Method for manufacture stress detector

Details Method for manufacture stress detector Method for manufacture stress detector

1989-05-05

1990-09-04

Powell, William A.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

29605, 156634, 156643, 156656, 1566591, 21912169, 21912185, B44C 122, B23K 900, C23F 102, C03C 1500

Patent

active

049542150

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a method for manufacturing a stress detector, which is used in manufacturing a torque detector or the like for the non-contact measuring of the axle torque on the driven shaft such as a rotary shaft widely used in the industrial equipments such as an automotive steering shaft, a propeller shaft, an axle as well as electric motors and compressors.


BACKGROUND ART

FIG. 1 is a schematic diagram showing a torque detector disclosed in Japanese Patent Laid-Open No. 61-178627 for example, in which figure, (1) is a driven shaft to which a torque is applied, (3) are coils for detecting the amount of change in magnetic permeability, (4) are magnetic elements of which magnetic permeability change in accordance with the amount of the internal strain generated by the torque applied to the driven shaft (1). A plurality of magnetic elements in the form of strip pieces cut from a thin sheet of magnetic material are arranged in symmetry around the driven shaft (1) at an angle of .+-.45.degree. for example.
The operation will now be described When a Lorque is applied from the exterior to the driven shaft (1), a main stress having a main axis along the longitudinal direction of a group of the rectangular magnetic elements is generated. When it is assumed that this stress is a tensile force in the magnetic element group on the left side of the driven shaft (1) as viewed in FIG. 1, then the stress on the right side element group is a compression force. In general, when a stress is applied to a magnetic material of which constant of magneto-restriction is not zero, its magnetic property varies and accordingly the magnetic permeability changes as well known. This phenomenon is utilized in a magnetoristriction transducer for converting mechanical energy into electrical energy, and corresponds to Villari effect according to which the magnetic permeability of a magnetic material varies in accordance with the amount of deforming of the material. Also, when the magnetoristriction constant, which is an amount quantitably indicating the amount of magnetoristriction, is positive, the magnetic permeability increases when a tensile force is applied, and the magnetic permeability decreases when a compressive force is applied. It is also known that a quite opposite result is obtained when the constant of magnetoristriction is negative. Therefore, since the magnetic permeability of the magnetic elements (4) changes as they deform in accordance with the amount of the externally applied torque, the amount of the torque applied to the driven shaft (1) can be determined by detecting the change in magnetic permeability as the change in magnetic impedance by the sensor coils (3) wound around the driven shaft (1).
As a method for securely attaching the magnetic elements (4) on the driven shaft (1) of the torque detector of the above-described construction, a method in which the magnetic elements are formed from a thin sheet of a magnetic material and the magnetic elements (4) are bonded one by one to the driven shaft (1) at a predetermined angle thereto, or a method in which the magnetic elements (4) are bonded to a nonmagnetic film by a bonding agent or the like and then this film is wound around the driven shaft (1) and secured thereto by an epoxy thermo-setting bonding agent or the like.
FIG. 2 is a flow chart showing where the magnetic elements are bonded by a bonding agent onto a conventional non magnetic film. As seen from the figure, a strip of thin magnetic sheet material is cut into a plurality of magnetic elements (Step 41). Then, a bonding agent is applied on the plastic film (Step 42). The magnetic elements are placed on the bonding agent applied to the plastic film (Step 43), and the plastic film is wound around the driven shaft (1) (Step 44). The plastic film is secured by caulking at its periphery and thermally set to firmly attach the magnetic elements (4) around the driven shaft (1) (Step 45).
According to the conventional manufacturing method, a careful attention must be paid to arrange

REFERENCES:
patent: 4566936 (1986-01-01), Bowlin
patent: 4639708 (1987-01-01), Weatherly

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