| 摘要 |
The plate is applied in precast constructions, metal cutting instruments for manipulation of openings such as drills and countersinks. Its construction ensures stable fastening and a simplified grounding. It is possible to use plates with a variable rear angle and various pairs of cutting edges of the plate in its two positions. It is formed as a reclined prism, the top (2) and bottom (2) bases of which have a regular six-angle form. Three neighbouring lateral planes (4,5 and 6) cross the top base (2) in cutting edges (19,20 and 18), while the bottom base (3) - in non-cutting edges (36,37 and 35). The other three neighbouring lateral planes (8,9 and 7) cross respectively the top base (2) in non-cutting edges (38,39 and 40) and the bottom base (3) - in cutting edges (21,23 and 22). At least one of the neighbouring lateral planes (4) is made of a basic rear plane (12) and an auxiliary rear plane (13). At least two of the obtuse angles of the non-cutting edges (36,37 and 35) of the bottom base (3) are equal to the respective obtuse angles of the non-cutting edges (40, 39 and 38) of the top base (2). At least one of the angles closed between the auxiliary rear planes (11 and 13) and between each of them and their neighbouring lateral plane (6), closing a sharp angle with the top base (2) is respectively equal to the angles, closed between the auxiliary rear planes (15 and 17) and between each of them and their neighbouring lateral plane (9), closing an obtuse angle with the top base (2).
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