the Greatest use of the types of scans received native helical scan, and therefore somewhat more focus on the consideration of their structures.
manufacturing Tolerance and the diameter of the sweep shall be appointed on the basis of class precision machined holes with account of the phenomena of breakdown PLI shrinkage.
it Should be noted that for the free entrance of the reamer in the hole, the smaller diameter cutting portion with an angle f must be smaller than the diameter of the sweep is approximately 1.5 seam allowance and can be determined according to the following formula :
Zach = 0,99 D — 0.2 mm.
To remove, excessive allowance, as well as a smoother transition between the cutting blade to the end of the sweep at the end of the cutting portion is chamfered and a = 1,4—2,4 mm at an angle of 45°. In this case, the minimum diameter of the conical bearing portion due to the presence of cylindrical ribbons carries out the direction of the sweep during the cutting process and also provides the appropriate dimensional accuracy and surface finish of the hole. The width f of the guides of the ribbons, like drill, is assigned depending on the hole diameter and workpiece material, which unfolds the hole, and the accuracy of the processing. In the processing of ferrous metals, it is 0.1—0.3 mm, and when processing very viscous metals to eliminate sticking its width is reduced to 0.05—0.08 mm. At the same time, processing high precision holes in cast iron and steel pieces on machines with automatic feed and relatively low cutting speeds to reduce the surface roughness to rationally increase the width of the ribbon f to 0.4—0.5 mm.
Because the regrinding reamers are only available on the back tooth surface of the cutting portion, the increasing length of the latter as a result of regrinding must be compensated for by reducing the length of the control part. However, the smaller the length of the control part, the less friction, but the worse the direction of the sweep. At the same time, the small length of the control part enables more efficient use of tool materials.
the value of the inverse taper on the conical length of the phase control part is in the range of from 0.035 to 0.06 mm in fixing pitch and from 0.06 to 0.1 min when mounting it in bobble cartridge. This value also influence the physico-mechanical properties of the workpiece material.
Number of teeth of the sweep, its circumferential step and the direction of the flutes is appointed in accordance with the method discussed below.
thus, the number z of teeth of the reamers with a diameter of 10 to 50 mm, made of high speed steel, equal to in the range of 6 to 11, and equipped with hard alloy to ensure more stiffness and strength of teeth.
the value of the angle of the screw grooves is normally equal to zero. When processing the same intermittent openings, as well as at increased requirements to the surface roughness used reamers spiral direction of the teeth. In this case, the angle of the screw grooves are assigned mainly depending on the material being processed and is in the range from 7 to 45 degrees.
Form chip grooves for the whole scan is done mainly two types. The reamers with a diameter of 3-20 mm is used the most simple registration form, when the front surface and the back of the tooth, defined by straight lines, fillet radius. The same scans with a diameter of 21 to 50 mm with the aim of increasing the flute back of the tooth decorated on radius.
According to: Gigalo N. I., Kiselev V. V. designing and manufacturing cutting tools