Laminated core producing apparatus

Details Laminated core producing apparatus Laminated core producing apparatus

1982-11-30

1985-06-25

Briggs, William R.

Metal working

Plural diverse manufacturing apparatus including means for...

Separate tool stations for selective or successive operation...

29 33Q, 29736, 29738, B23Q 1500

Patent

active

045245070

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an apparatus for producing laminated cores forming stators for electric machines, and provides a laminated core producing apparatus capable of punching out core sheets from a long strip of core sheet material by metal dies and concurrently fitting and crimping together already punched-out core sheets in the same metal dies to thereby provide a laminated core of predetermined thickness.


BACKGROUND ART

FIG. 1 is a schematic view, in longitudinal section, of a conventional laminated core producing apparatus, and FIG. 2 is a plan view showing how a core sheet is formed. A strip 1 of a material for a laminated core product is guided to upper and lower metal dies 3 and 4 through guide rollers 2. When the upper metal die 3 lowers, the core sheet 1 is punched at first and second stations, as shown in FIG. 2; at a third station it is formed with crimp projections 11 or holes and at a fourth station contour punching-out and crimping are performed. Each time the upper metal die 3 moves up and down, the strip 1 is fed a predetermined pitch by the guide rollers 2, and with this operation repeated, punched out core sheets are laminated in the fourth station of a lower metal die 4. On the other hand, at a timing obtained by a microswitch 6 for detecting the up and down movement of the upper die 3, the thickness of the strip 1 is measured by a sheet thickness sensor 7 before it enters the metal dies, the data being successively shifted until the thickness-measured portion of the core sheet reaches the third station of metal die and being then stored in a control device 8. The control device 8 successively adds the sheet thickness at the third station of metal die, to find the sum. A punch 10 at the third station is movable by a solenoid 9, as shown in FIGS. 3 and 4. The control device 8 controls the solenoid 9 in such a manner that when said sum of sheet thicknesses is below a preset target value for the laminated core, the punch 10 is caused to project to form a crimping projection 11 on the strip 1, as shown in FIG. 3, but when said sum reaches the target value, it is caused to project to form a throughgoing hole, as shown in FIG. 4, whereupon said sum is set to zero. Then, the punched out core sheets 5 in the metal die at the fourth station are in an unbound state for the preset target value and become a laminated core product of predetermined thickness.
The usual laminated core product is formed by laminating 40-100 core sheets, and the preset value for lamination thickness is 20-50 mm in the case of a core sheet having a thickness of 0.5 mm. The dimensional accuracy of the product depends on lamination thickness, but increasingly high accuracy is being demanded year by year. For example, for a specification lamination thickness of 50 mm, it is 50.+-.0.5 mm or thereabouts, and if the nominal value of sheet thickness is 0.5 mm, 100 sheets will be assembled. In this case, the point of time when the control device 8 controls the solenoid 9 (referred to as the throughgoing hole making solenoid) to form a throughgoing hole is when the aforesaid sum is not less than the target value T, which is defined by the following formula. ##EQU1##
Substituting the lamination thickness preset value of 50 mm and the sheet thickness of 0.5 mm gives T=49.750 mm, and the total lamination thickness H of the laminated core product obtained is 49.75 mm.ltoreq.H<50.25 mm.
However, since the allowable lamination thickness of the core product is 50 mm.+-.0.5 mm, as described above, the allowable lamination thickness measurement error is .+-.0.25 mm. Therefore, the sheet thickness measurement error for a single core sheet is obtained by dividing said value by 100, or .+-.0.0025 mm. That is, there is a need for a sheet thickness sensor 7 capable of measuring 0.5-mm thick core sheets with an absolute accuracy of .+-.2.5 .mu.m. A similar calculation shows that when the core product thickness specification is 100.+-.0.5 mm and the standard sheet thickness is 0.5 mm, the accuracy per sheet is .+-

REFERENCES:
patent: 3203077 (1965-08-01), Zimmerle
patent: 4073373 (1978-02-01), Crowley et al.
patent: 4110895 (1978-09-01), Mitsui
patent: 4294006 (1981-10-01), Fair et al.

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