楕圓罐用ダイアル檢罐器

Abstract

The authors have designed two dial vacuum indicators of the β type(1) for oval cans, one of which has two ellipses of seat rail for both 1 lb and 1/2 lb cans, and the other has only one elliptic seat rail for 0•7lb cans, the one as shown in Fig. 1 is the former kind. For the present study we have measured with the instruments both the top and bottom end depths of the following cans, i. e. a 4 doz. box of 1 lb and a 8 doz. box of 1/2 lb tomato-sardine cans, and a 4 doz. box of 0•7 lb tunny-steak cans. The, vacuum in the cans were also measured by an ordinal vacuum testor of Bourdon tube type, and the results of both the measurements were plotted in the υ-β (Vacuum-end depth) diagrams as shown in Figs. 2, 3 and 4. The mean straight lines in the diagrams were drawn by the least square method, the mean values of deviations of the measured points from the mean lines of the diagrams are as shown in Table 1. The values for 1/2 lb tomato-sardine cans were a little larger than those of the other two, the reason of which is considered that the size of 1/2 lb can ends is the smallest among the three and accordingly the depth of them due to the vacuum in the can is the smallest, there-fore the least irregularity of thickness of tin-plate and can shape, or the injury of which has greater effect on the vacuum indication of the can end depth. In both the 1/2 lb and 0.7 lb cans the mean deviations of the measured points for the top ends were greater than those for their bottom en1s, especially for the 1/2 1b cans the value being as large as 2•7 inch in vacuum, and not so large but slightly in the case of the 0•7 lb cans; this was because the maker marks of the cans were pressed out very close, and more closer in the case of 1/2 lb cans, to the just centre of the top ends where the measuring point of the dial indicator spindle touched and the measurements were made irregular. If the marks bad been shifted away slightly from the centre, then the mean errors for these cases would also have been made smaller than those for the bottom ends, therefore it may be said that the mean error of the vacuum indication of the dial indicator with the scale calibrated by the mean straight line for the top end depth, which is obtained by such a method as described here, is always less than 1.8 inch vacuum in every case of the three kinds of oval cans tested in this experiment.