EA020077B1 - Rotary cutter - Google Patents

Abstract

The invention relates to machine building and can be used for machining shafts made from different construction materials. The invention is aimed at designing technological construction of rotary cutter at grinding of which falls away the need to use special grinding machines and also to increase the accuracy of cutter edges in plane. A rotary cutter represents a polygonal body having a tool bore and a cutting part comprising N teeth, each has front and rear surfaces forming a rectilinear cutting edge therebetween. The cutting edges formed at each tooth are arranged in plane perpendicular to the rotational axis of the rotary cutter, forming a cutting polygon. The tooth front is made at angle γ to cutting plane varying from 2 to 5 degrees. Separation grooves are made at the polygonal body vertice with width a. Polygonal body vertices may be rounded to r=0.1-0.4 mm.

Description

The invention relates to the field of engineering and can be used in the processing of shafts from various structural materials.

Known rotary cutting insert [application for invention KI No. 2008148805, IPC VV 27/06, publ. 07/20/2010], with the first and second surfaces of the plate, generally having a triangular shape, three side surfaces and at least one cutting protrusion located in the region of the angle between the first and second side surfaces, the cutting protrusion is generally M-shaped the shape and includes at least the first and second cutting teeth, and at least on the first cutting tooth, a first cutting edge is formed, located in the transition area to the first surface of the plate, and at least on the second cutting tooth formed in a second cutting edge located in the transition area to the second surface of the insert, wherein the first chip removal direction related to the first cutting edge forms an angle α with the second direction for chip removal relating to the second cutting edge, the first and second cutting edges are associated with the first and a second guide for removing chips in the direction of removal of chips, the first guide for removing chips includes at least a first groove on the first surface of the plate, which is held generally endikulyarno first direction of chip discharge between the first and second side surfaces, and second guide chip discharge includes at least a second groove on a second surface of the plate, which is held generally perpendicular to the second chip removal direction between the first and second side surfaces.

The disadvantages of the known design are the difficulty in manufacturing and rapid wear due to the fact that the cutting edge consists of a large number of intermittent sections. In addition, the low quality of processing the workpiece, since the profile of the cutting edge during processing of the workpieces will give a kinematic undulation due to intermittent cutting.

The closest technical solution to the claimed is a method of blade processing of shafts with an equiaxed contour profile [A.S. 1,126,375; MKI ³ V23V 1/00, publ. November 30, 1984], in which the rotation of the machined shaft is reported, and the tool is informed of the longitudinal feed and harmonic transverse movement, the rotation axes of the tool and shaft being set intersecting at right angles, a rotary cutter is used as a tool, the cutting edge of which has a polygonal shape in the plane perpendicular to the axis of its rotation, the linear speed of rotation of the tool set at least an order of magnitude greater than the linear speed of rotation of the work shaft. Processing with the specified cutter is performed in such a way that the main direction of chip deformation occurs along the cutting edge of the cutter. Cutting due to the constructive feed occurs in the profile section with an increasing radius vector.

The disadvantage of this design of the cutter is that due to the arc shape of the edges of the cutting edge when it is formed during sharpening along the front and rear surfaces, a significant deviation from the flatness of the arrangement of the edges of the cutting edge occurs. In addition, when sharpening the cutter, special grinding machines with the planetary movement of the grinding wheel or workpiece are required.

The objectives of the invention are the creation of a technological design of a rotary cutter, the sharpening of which eliminates the need for special grinding machines, as well as improving the accuracy of the location of the edges of the cutter in the plane.

The tasks are solved in that in a rotary cutter, the cutting edge of which has a polygonal shape in a plane perpendicular to the axis of rotation, according to the invention, the cutting part of the polyhedral body of the cutter consists of N teeth, the cutting edge of each tooth is straight, the front surface of the tooth is made at an angle γ to cutting planes from 2 to 5 °, dividing grooves are made on the vertices of the polyhedral body of the cutter.

The vertices of the separation grooves are made with a radius of fillet g from 0.1 to 0.4 mm

The accuracy of the location of the cutter faces in the plane is increased due to the fact that the cutting edge of each tooth is made rectilinear. Performing on the vertices of the multifaceted body of the cutter of the separation grooves allows you to grind the tool on universal grinding machines with the output of the tool through the separation groove. The implementation of the top of the separation grooves with a radius of fillet g from 0.1 to 0.4 mm allows to increase the durability of the rotary cutter.

The invention is illustrated by drawings, which depict:

in FIG. 1 - the proposed cutter;

in FIG. 2 - the proposed cutter, top view;

in FIG. 3 is a section along AA in FIG. 2;

in FIG. 4 - embodiment of the proposed cutter, top view;

in FIG. 5 is a diagram of a shaft processing;

in FIG. 6 is a diagram of a shaft processing, left view.

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Symbols adopted in the drawings:

a is the width of the separation groove;

ν _Β - rotation speed of the processed shaft;

ν _ρ is the speed of rotation of the cutter;

K - polygonal cutting edge in the form of a cutting polygon;

_GR - total feed per tooth incisor;

_PR - longitudinal feed;

8 _K - constructive feed;

N is the number of teeth of the cutter;

r _t1P - the minimum radius vector of the cutting edge;

p _max - the maximum radius vector of the cutting edge;

g is the fillet radius;

γ is the rake angle.

The rotary cutter is a polyhedral body 1, for example trihedral (see Fig. 1), with a landing hole 2 and a cutting part consisting of N teeth. Each tooth contains a rear 3 and front 4 surfaces that form a straight cutting edge 5. The cutting edges 5 formed on each tooth and placed on a plane perpendicular to the axis of rotation of the rotary cutter (Fig. 2) form a cutting polygon between each other. The front 4 tooth surface (Fig. 3) is made at an angle γ to the cutting plane from 2 to 5 °. On the vertices of the polyhedral body 1 of the incisor, dividing grooves 6 of width a are made.

For the embodiment (Fig. 4), the tops of the dividing grooves 6 are made with a fillet radius r from 0.1 to 0.4 mm.

Sharpening of the cutter is carried out on the front 4 or rear 3 surfaces of the teeth, depending on the type of wear.

The work of the proposed rotary cutter is as follows.

The machined shaft 7 rotates at a speed of ν _Β , and the cutter 8, having a polygonal cutting edge K, rotates at a speed of ν _ρ towards the rotation of the shaft 7. The axis of rotation of the cutter 8, installed with the help of the mounting hole 2 on the spindle of the machine tool assembly, is perpendicular to the axis of rotation of the machined shaft 7, in addition, the axis of rotation of the tool should be at the same height as the axis of rotation of the shaft.

The cutting conditions are determined by the design parameters of the cutter, as well as the type of tool and processed material.

The cutter 8 makes a harmonic transverse movement according to a sinusoidal or cone-shaped law and has a longitudinal feed of 8 PR. Periodically, when the cutter 8 rotates in the cutting zone, the working tooth is replaced, due to which the working cutting edge 5 is updated, while the remaining teeth of the cutter cool down. With this mode of operation, COTS (cutting lubricants) is not required.

Cutting due to the constructive feed of 8 _K occurs due to a change in the radius vector p of the cutting edge 5, while the cut chip formed in the form of separate sections of the wedge type descends along the front surface of the tooth 4 with sliding along the cutting edge 5 of the tool.

The dividing groove 6 serve to increase the manufacturability of the cutter, simplifying the regrinding of the cutting edge 5 due to the possibility of the grinding tool exit through the dividing groove 6.

The experimental verification was carried out on a model 16K20 screw-cutting lathe using a tool drive consisting of an electrospindle, an arm, and a frequency converter. Specially ground polyhedral plates together with the mandrel are mounted on the shaft of the electrospindle. When processing a batch of shafts (S = 50 mm, L = 70 mm) with a polygonal rotary cutter (p _max = 9.63 mm; p _mp = 7.94 mm; N = 3), the cutting depth varied in the range from 0.1 to 2 mm Shaft feed (circular feed) 0.2 to 3 mm / rev. The cutting speed ranged from 12,000 to 18,000 rpm. Verification showed that the treated surfaces with cutters with an arc polygonal cutting edge [A.S. 1126375 USSR; MKI ³ V23B 1/00] and the proposed one have the same surface quality parameters (roughness) Κ.α = 1.25-2.5 μm. In addition, there is no formation of kinematic undulation. When sharpening a tool with straight cutting edges, it was possible to achieve a much smaller deviation from the plane of the cutting edges than with arc edges. It was revealed that the cutting depth does not significantly affect the surface roughness. In the course of the research it was revealed that guaranteed chip crushing is ensured. In addition, there is no build-up, due to the lack of heating of the cutting tool and the gathering of chips with relative sliding along the cutting edge.

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Claims (2)

CLAIM 1. A rotary cutter, the cutting edge of which has a polygonal shape in a plane perpendicular to its axis of rotation, characterized in that the cutting part of the multi-faceted cutter body consists of N teeth, the cutting edge of each tooth is straight, the front surface of the tooth is made at an angle γ to the plane of cutting 2 to 5 °; separation grooves are made on the tops of the multi-faceted cutter body. 2. Rotary cutter according to claim 1, characterized in that the tops of the separation grooves are made with a rounding radius g from 0.1 to 0.4 mm.