SU552138A1 - The method of obtaining the roots of chips - Google Patents

Description

where Гп is the current radius corresponding to a given slice thickness, it is determined by the dependence

52./g

where S is the straight-line tangential feed;

n is the number of revolutions remaining until the cutter reaches the final sample diameter of the 2nd;

bp is the thickness of the web between the hole and the cutting blade at the place of chip separation.

The thickness of the web is determined from the condition of tensile strength with sufficient accuracy by the formula

6-ar

where PZ is the tangential cutting force; b - cut width; ar - permissible tensile stress.

When turning with a rectilinear tangential feed S, the cutter blade 3 describes in the body of part 1 a cycloidal curve 4, the distance between adjacent turns of which is measured in the radial direction to the center of the part corresponds to the thickness of the slice on the radius of the smaller turn.

The largest slice thickness a1 amake is formed after the first turn of sample 1 on the radius ri. Any intermediate thickness flg corresponds to the current radius rz. Therefore, the separation of chips 5 begins with the greatest slice thickness ai and occurs in a sequence of progressively decreasing thicknesses Og ... a "on the corresponding decreasing current radii rz ... g" of the trajectory 4. Cutting forces in three X coordinates , Y, Z are fixed simultaneously with the separation of the chips by the dynamometric table 6. The electric signal from the dynamometric table is transmitted through the amplifier 7 to the oscilloscope 8.

To obtain free orthogonal shavings of the roots, a cylindrical protrusion 9 of a given width and height t is made on the sample (see Fig. 2). In the process of removing the allowance, the cutter 10 goes through the entire range of slice thicknesses, decreasing from ymax to a „shown in FIG. 3, discretely for each revolution of the part. The change in the slice thickness during tangential turning occurs steplessly, which allows to obtain chip root of any thickness by choosing the radius p of the location of the plug 2.

Shaving roots, corresponding to turning with a straight through cutter, are obtained by installing a tangential cutter 10 to the cutting width along the main cutting edge 11 and contacting the cutter width with the end face 12 of the sample (see Fig. 3). The direction of the radial movement of the cutting edge 11 is equivalent to

longitudinal feed cutter. The separation of chips with a fixed cut occurs when the jumper breaks under the main cutting edge I and the wall equal to the thickness of the cut along the end 12.

When simulating longitudinal turning with a through cutter 13 with an angle in terms of f (see Fig. 4), the holes for the plugs in the test sample are inclined to the axis of rotation of the sample and parallel to the main cutting edge of the cutter. As in the previous case, the radial movement of the cutter

13 equivalent longitudinal feed through cutter. The separation of the roots of chips in a given place is accompanied by a break in the lintel along the inclined surface and the end

14 in the sample.

When slotting groove cutter 15 (see Fig. 5), corresponding to the non-free cutting,

the separation of the chips is accompanied by a break in the lintel along the front edge of the incisor and along the side surfaces. These increased tensile forces are taken into account by choosing the appropriate lintel thickness between the hole and the incisor at the output of the calculated shear thickness.

The method was tested under the conditions of a free tangential cutter with a straight-line feed of 5 0.5 mm / about 4 mm wide washers, in which six plugs were installed on radii from r to Gu, corresponding to the cut thicknesses at this feed ai 0.14 mm; , 12 mm; , 1 mm; 04 0.075 mm; 05 0.05 mm; , 03 mm (see

FIG. 12). Outer diameter of 178 mm, processed - 168 mm. Allowance on the side of t 5 mm. The material to be processed is steel 60, the cutter material is TT 20 K 9 alloy. Cutting speeds varied in the range

from 25 to 150 m / min at 25 m / min. Cutting without cooling. Under these conditions, 36 shingle roots were obtained in 2 hours of working time, which is about 10 times faster than with separate turning for a given slice thickness. It should be noted, a significant simplification of the blank for research, high accuracy of the results, due to the stability of the material on the physicochemical properties for a series of thicknesses, the speed of changeover to the new thickness of the slice. It is enough to increase the tangential feed by 2 times in order to obtain a new row of thicknesses: a 0.28 / 0.24 / 0.2 / 0.15 / 0.1 / 0.06 mm.

The method is suitable for obtaining the roots of shavings of machining processes corresponding to turning, planing, pulling, drilling. The method is particularly effective for separating

the roots of chips of very small thickness, close to zero, which cannot be obtained by conventional means due to the instability of the mechanical feed of the machine. Perhaps the implementation of the method with a circular tangential feed cutter.