JPH057572B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The present invention provides a pressure adjustment method for a spring molded body formed from a thin metal plate used as a magnetic disk head assembly member, for example, a load spring molded body that supports a slider in a cantilever configuration. According to this method, bending deformation (plasticity) due to thermal stress generated by scanning a laser beam in a direction perpendicular to the length direction of the spring is utilized and applied to adjust the spring pressure.

[Industrial application field]

The present invention relates to a method of adjusting spring pressure using a laser beam, which is effective when applied to a spring molded body such as a head support spring for supporting a slider used as an assembly member of a magnetic head for a magnetic disk.

[Prior Art] A method of adjusting the spring pressure of a magnetic head will be explained with reference to the perspective view of FIG.

In the figure, the head support spring 25 formed from a thin metal plate is a stainless steel spring with a spring plate thickness of about 0.3 mm, which is punched and formed.A magnetic head 27 is attached to the free end 26 of the spring. The other end of the head support spring 25 is a screw fixed end 28
It is.

The screw fixed end 28 is fixed to the block 29 of the spring pressure adjustment jig 32, and the spring pressure adjustment jig 32
A strain gauge 30 for detecting the pressure of the head support spring 25 is provided at the free end of the spring that the magnetic head 27 comes into contact with. In the figure, 31 is an output indicator of a strain gauge 30 that supports spring pressure. That is, the pressure of the cantilever-shaped head support spring 25, one end of which is fixed to the block 29 of the spring pressure jig 32, is detected by the strain gauge 30 attached to the free end of the spring.

The detected spring pressure varies due to variations in processing conditions and plate thickness of the spring material, and dimensional variations after punching and forming. In particular, in the case of formed springs such as stainless steel springs, which have a thin material spring plate thickness and high spring elasticity, the spring pressure fluctuates greatly after forming. The spring had been adjusted.

When the spring pressure of the spring molded body is greater than a predetermined value, the arrow 3 shown in FIG.
The spring is pushed up from the back side in the direction 3 to forcibly deform it plastically, thereby reducing the pressure on the head support end side.

On the other hand, when the spring pressure is lower than a predetermined value, the spring is forced down along the arrow 34 shown in the figure to plastically deform the spring and increase the spring pressure at the head support end. .

[Problem that the invention seeks to solve]

Such a method of adjusting the spring pressure for the spring molded body 25 relies largely on the operator's skill or intuition, and the accuracy of the desired spring pressure adjustment is unstable, and the number of man-hours for adjustment work increases. There is a problem. In particular, recently, spring materials used as floating slider load springs for magnetic heads have a high spring elasticity value but are extremely thin, so it is difficult to mold them into head support springs, etc. Therefore, there was a need for a stable, highly reliable, and highly accurate spring pressure adjustment method that met strict design standards.

[Means for solving problems]

FIG. 1 is a diagram showing the principle of the spring pressure adjusting method of the present invention. According to the present invention, the longitudinal end portion of the spring molded body 1 formed from a thin metal plate spring is the fixed end 3, and the spring molded body 1
Between the fixed end 3 and the free end 2 of the spring molded body 1, which is placed on a spring pressure adjustment jig with a strain gauge 10 in contact with the other free end, there is a long length on either the front or back side of the spring molded body 1. By scanning a focused laser beam 4 or 4' with an appropriate energy density and irradiating it in a direction perpendicular to the horizontal direction,
This is a spring pressure adjustment method that plastically deforms the spring surface on the scanning surface side.

[Effect]

Figure 2a shows a spring pressure adjustment method in which a laser beam is scanned in a direction perpendicular to the length direction of the spring molded body.
This will be explained with reference to the basic spring bending characteristics of the spring molded body shown in FIG. 3A and FIG.

Figure 2a shows the case where a spot 4 with a light diameter φ is irradiated onto the spring molded body 1 according to a linear scanning line.The surface of the scanned spring molded body rapidly rises in temperature and thermal expansion occurs , during the irradiation, it bends upward in a convex state.

However, if the irradiation is stopped while the state shown in Figure A is maintained, the surface of the spring molded body will be rapidly cooled, and plastic deformation as shown in Figure B, which is in the opposite direction to Figure A, will occur due to thermal stress from the periphery. The angle θ shown in Figure b is the bending angle of the spring molded body after the laser beam irradiation is stopped.

FIG. 3 shows comprehensive experimental data for applying the plastic deformation characteristics of the spring due to laser beam scanning explained in FIG. 2 as a spring pressure adjusting means.
However, the spring material used for measurement is a stainless steel (SUS-304) flat spring material with a thickness of 0.3 mm specified by the Japanese Industrial Standards, and the width dimension of the plate material that scans the material surface. is 10mm long.

Figure a shows the finely adjusted light irradiation energy density per unit area mm ² (horizontal axis of the figure, Joule/mm ² unit) when a single scan is performed between the widthwise dimensions of the spring molded body.
The bending angle θ of the spring with respect to (vertical axis in the figure; degree
unit) is a relational property.

Figure 3b shows the number of times the light spot is scanned (horizontal axis of the figure)
and the bending angle θ of the spring (vertical axis in the figure, unit;
It is a relationship characteristic diagram of degree).

However, the numerical values written together with each characteristic in Figure b are the parameters of the light irradiation energy, and the spot diameter φ of the laser beam 4 (Figure 2 a) is 0.3 and 0.4 mm, and
Joule's heat equivalent parameter J/P (0.144, 0.075 and 0.02 three types).

〔Example〕

Hereinafter, the principle diagram in FIG. 1 and the side view of the device in FIG. 4 which is an embodiment of the laser beam irradiation device of the present invention,
The present invention will be explained in detail with reference to a float chart of spring pressure detection control shown in FIG.

In FIG. 1, the cantilever structure spring in which the longitudinal end of the spring molded body 1 attached to the pressure adjustment jig 32 is the fixed end 3, and the other free end is the head support end 2, is shown in the principle diagram. The spring molded body 1 as shown in
A pair of irradiation units 7 and 8 are arranged on both upper and lower sides with the irradiation unit in between. The irradiation units 7 and 8 are scanned in the direction of the arrow 21 by the irradiation unit drive section 11 (in FIG. 4, they are scanned in the front-rear direction in the drawing perpendicular to the longitudinal direction of the spring).

The laser beam irradiation device shown in FIG. 4 includes a laser beam oscillator 13, a reflector 16 (half mirror 16) and a total reflector 17 that distribute the oscillated laser beam to both the front and back surfaces, and the light of these reflectors 16 and 17. A light control section 14 consisting of shutter mechanism sections 9 and 9' that open and close the
and irradiation units 7 and 8 with built-in focusing lenses connected from the light control unit 14 via the optical cable 6.
Consisting of

The laser beam from the half mirror 16 passes through the shutter mechanism 9 and the optical cable 6, and is led out from the irradiation unit 7. The light spot 4 is focused on the surface side of the spring molded body 1.

On the other hand, a light spot 4' led out from the irradiation unit 8 connected via the total reflector 17, the shutter mechanism 9', and the optical cable 6 is focused on the back side of the spring molded body 1.

The switching of the light spot 4 or 4' irradiating the front or back surface of the spring molded body 1 is controlled by the spring pressure detection control unit 12 which determines whether the pressure level detected by the strain gauge 10 of the spring pressure sensor is large or small. Specifically, it is performed by the opening/closing drive section 18 of the shutters 9, 9'.

The opening/closing of the shutter by the opening/closing drive unit 18 is such that, for example, when the shutter on the 9th side is open, the shutter on the 9' side is closed, and conversely, when the shutter on the 9' side is open, the shutter on the 9th side is closed. Control takes place.

The spring pressure detection control unit 12 includes a pressure reference value for the spring molded body, and upper and lower allowable limit values for pressure adjustment are set above and below the reference value, and the above-mentioned upper and lower allowable limit values are set in advance. A comparator is built in to compare the pressure detected by the strain gauge 10.

Of course, if the pressure detected by the strain gauge 10 is between the upper and lower allowable limit values, the spring pressure adjustment has been completed. However, if the detected pressure of the strain gauge 10 exceeds the upper permissible limit, for example, a signal is sent from the spring pressure detection control section 12 to the opening/closing drive section 18 for opening and closing the shutter, and at the same time the shutter 9 is opened, the irradiation unit 7 The spring pressure is reduced as the light spot 4 is irradiated from the spring.

On the other hand, if the detected pressure of the strain gauge 10 is below the lower allowable limit, the light spot 4' from the irradiation unit 8 on the back side of the spring molded body 1 will be irradiated, and as a result, the spring pressure will be increased.

The signal for driving the shutter to open and close is also sent to the irradiation unit drive section 11, and the light spot 4 or 4' is scanned, which causes the light spot 4 or 4' to alternately reciprocate between the spring ends in the width direction of the spring molded body 1.

The control process by the spring pressure detection control section 12 described above will become clearer with reference to the flowchart shown in FIG. In addition, the numbers on the upper right side of the flowchart that are written together with the judgment signals and processing signals are the same as those written on the main control device in the same figure to facilitate relative comparison with the example diagram in Figure 4. This is the citation number.

In the illustrated flowchart, the start of adjustment means
This is the stage of setting initial conditions for spring pressure adjustment control for the spring molded body 1 and setting of irradiation energy conditions necessary for laser beam processing, such as irradiation pulse width and pulse repetition rate for the laser beam oscillator 13.

After the initial conditions are set, the process continues until the detection output by the strain gauge 10 for pressure detection becomes appropriate, that is,
Until the detected pressure falls between the preset upper and lower allowable limit values, the system starts with the "spring pressure?" message shown in the diagram, drives the shutter to open and close, starts laser irradiation, and drives the unit (scans the light spot with the irradiation unit).
Laser light scanning is repeated, with each stage of ON, OFF, and laser irradiation stopping as a single operation cycle. When the detection output from the strain gauge 10 becomes appropriate, it means that the spring pressure adjustment has been completed.

The preset upper and lower allowable limit values are, for example, when the design standard value of the head support spring is
If it is 30〓, an allowable limit value of about 30±2.5% will be set.

〔Effect of the invention〕

As described above, according to the spring pressure adjustment method using laser beam irradiation of the present invention, the detected pressure of the strain gauge arranged so as to be in contact with the spring free end side with respect to the spring molded body attached to the spring pressure adjustment jig is Therefore, since the thermal deformation of the spring body is used by scanning the front and back surfaces of the molded spring body with a laser beam whose energy can be easily controlled minutely, the spring pressure can be adjusted accurately, quickly, and automatically. It will be enforced.

[Brief explanation of drawings]

FIG. 1 is a diagram of the principle of the spring pressure adjustment method of the present invention, FIG. 2a is a diagram of spring deformation when a spring molded body is irradiated with laser light, and FIG.
Figure 3 is a characteristic diagram of spring plastic deformation caused by laser light, and figure a is a characteristic diagram of the relationship between energy density and bending angle.
Figure b is a characteristic diagram of the relationship between the number of scans and the bending angle, Figure 4 is an embodiment of the laser beam irradiation device of the present invention (device side view), Figure 5 is a flowchart of spring pressure detection control, and Figure 6 is a diagram of the relationship between the number of scans and the bending angle. FIG. 2 is a diagram (perspective view) illustrating a conventional spring pressure adjustment method. In the figure, 1 and 25 are spring molded bodies, 2 and 26 are spring free ends (head support ends), 3 and 28 are fixed ends, 4
is a laser beam or optical spot, 6 is an optical cable,
7 and 8 are irradiation units on the front or back side of the spring molded body 1, 9 and 9' are shutters, 10 and 30 are strain gauges, 11 is a drive unit for 7 and 8, 12 is a pressure detection control unit, and 14 is a light The control section and 32 are spring pressure adjustment tools.

Claims (1)

[Claims] 1 One lengthwise end of a spring molded body 1 formed from a thin metal spring material is fixed on a spring pressure adjustment jig 32 with a fixed end 3, and a strain gauge 10 is brought into contact with the spring free end 2 on the other end side. Tightened spring molded body 1
Scanning a focused laser beam 4 of an appropriate energy density along the direction orthogonal to the length direction on either the front or back surface between the fixed end 3 and the spring free end 2, and plastically deforming the scanned surface. A method of adjusting spring pressure using laser light.