RU120383U1 - WORM MILL FOR CUTTING GEARS - Google Patents

Abstract

A hob cutter for cutting toothed parts, containing teeth with a flat front surface parallel to the cutter axis, and two helically alternating cutting edge profiles, including a tooth tip and one vertex rectilinear cutting edge inclined to a straight line passing through the tooth tip parallel to the milling cutter axis, at an angle of 15-20 ° on odd teeth in one direction, and on even teeth in the other direction, characterized in that the flat front surface of the teeth is made at an angle of 10-15 ° to the axial plane of the cutter passing through the tooth apex.

Description

The utility model relates to the field of gear cutting tools, namely to worm cutters, and can be used in gear hobbing of gear parts.

The closest in technical essence to the claimed utility model is a worm cutter selected as a prototype for cutting gear parts, containing teeth with a flat front surface parallel to the cutter axis, and two cutting edge profiles alternating along a helix, including a tooth tip and one vertex straight-line cutting the edge inclined to a straight line passing through the top of the tooth parallel to the axis of the cutter, at an angle of 15 ... 20 degrees on odd teeth in one direction, and on even teeth in the other direction. Such a profile of the teeth of the worm cutter ensures the separation of the cut-off layer of the workpiece metal into two or three parts and the replacement of undesirable U-shaped forms of the cut layers with simple ones [Pat. 2396152 Russian Federation, IPC B23F 21/16. Worm mill for cutting gear parts / Demidov V.V., Ksenafontov D.S., Demidova E.V .; applicant and patent holder Ulyan. state tech. un-t - No. 2009116316/02; declared 04/28/2009; publ. 08/10/2010, Bull. No. 22].

For the reason that impedes the achievement of the technical result indicated below when using the known worm cutter for cutting gear parts adopted as a prototype, the front angles of this cutter are zero. It is known that at the front angles of any cutting tools, including worm mills, which are equal to zero, increased deformations of the cut metal layers of the workpiece are observed, leading to an increase in forces and temperature in the cutting zone, and therefore to a decrease in the durability period of the worm milling cutter [see Yascheritsyn P.I. Theory of cutting. - Mn .: New edition, 2005. - 512 p. (p. 34)].

The essence of the utility model is as follows.

It is known that increasing the durability period of any cutting tools, including worm mills, is possible by applying rational cutting patterns and positive rake angles [see Yascheritsyn P.I. Theory of cutting. - Mn .: New edition, 2005. - 512 p. (p.34) and Polokhin O.V. Cutting gear profiles with worm type tools. - M.: Mechanical Engineering, 2007 .-- 240 p. (p. 28 and 87)]. In the well-known worm mill adopted for the prototype, only the first of these paths is applied: ensuring a rational cutting pattern. At the same time, the use of positive rake angles in the well-known worm mill adopted as a prototype will lead to an increase in the period of its resistance, since the presence of positive rake angles will significantly reduce the deformation of the cut layers of the workpiece metal and, therefore, reduce the forces and temperature in the cutting zone, [ cm. Yascheritsyn P.I. Theory of cutting. - Mn .: New edition, 2005. - 512 p. (p. 34)]. The value of the positive rake angles of the worm cutters specified in the formula of the utility model, equal to 10 ... 15 degrees, corresponds to well-known recommendations [see Polokhin O.V. Cutting gear profiles with worm type tools. - M.: Mechanical Engineering, 2007 .-- 240 p. (p.28)].

The technical result is an increase in the durability period of the worm cutter.

The specified technical result in the implementation of the utility model is achieved by the fact that the well-known worm cutter for cutting gear parts containing teeth with a flat front surface parallel to the axis of the cutter and two alternating along the helix profiles of the cutting edges, including the top of the tooth and one vertex straight cutting edge , inclined to a straight line passing through the top of the tooth parallel to the axis of the cutter, at an angle of 15 ... 20 degrees on odd teeth in one direction, and on even teeth in the other direction.

The peculiarity lies in the fact that the flat front surface of the teeth is made at an angle of 10 ... 15 degrees to the axial plane of the cutter passing through the top of the tooth.

In the drawings: FIG. 1 shows a tooth profile of a worm-modular cutter with positive rake angles in a plane perpendicular to its axis; figure 2 shows the profile of the cutting edges of the odd teeth of the worm cutter (type A in figure 1); figure 3 shows the profile of the cutting edges of the even teeth of the worm cutter (view B in figure 1).

Information confirming the feasibility of implementing the utility model with obtaining the above technical result is as follows.

A worm cutter for cutting gear parts, contains teeth with a flat front surface parallel to the cutter axis, and two cutting edge profiles alternating along the helix, including the tooth tip (point B in figure 2 and point G in figure 3) and one vertex rectilinear cutting edge 1, inclined to a straight line passing through the top of the tooth parallel to the axis of the cutter, at an angle of 15 ... 20 degrees on odd teeth in one direction (figure 2), and on even teeth in the other direction (figure 3). The flat front surface of the cutter teeth is made at an angle γ _a equal to 10 ... 15 degrees (in accordance with the known recommendations for worm mills [see Polokhin OV Cutting gear profiles with worm type tools. - M .: Engineering, 2007. - 240 p. (p. 28)].

The work of the worm cutter for cutting gear parts is as follows.

When the worm cutter is working, its vertex straight cutting edges 1 cut the layer of the workpiece metal not to the entire width of the bottom of the tooth cavity (as happens with a standard cutter), but to about half of it: one of the cutter teeth (for example, odd) removes the layer of workpiece metal to be cut at the bottom of the tooth cavity, approximately half the width of the bottom of the tooth cavity, and the next tooth of the cutter (even) removes the metal layer remaining in width at the bottom of the tooth cavity. With the proposed location of the vertex rectilinear cutting edges 1, cramped cutting takes place only on one side of the vertex rectilinear cutting edge 1, while its other side is not involved in the cutting, which ultimately reduces the deformation of the cut layers of the workpiece metal. The presence of positive rake angles of the cutter γ _a provides a significant additional reduction in the deformation of the cut layers of the workpiece metal and, therefore, a decrease in the forces and temperature in the cutting zone [see Yascheritsyn P.I. Theory of cutting. - Mn .: New edition, 2005. - 512 p. (p. 34)], which increases the durability of the worm cutter, compared with the cutter adopted as a prototype.

For experimental verification of the influence of the cutting pattern and positive rake angles on the durability period of worm mills, four two-way worm-modular milling cutters with a 2.5 mm module, an outer diameter of 100 mm, and a number of chip grooves of 12 were made of R6M5K5 high-speed steel. The first milling cutter was made with front angles γ _a equal to zero, and without tilting the apical rectilinear cutting edges of the teeth. The second - with positive rake angles γ _a equal to 10 degrees, and without tilting the vertex straight cutting edges of the teeth. The third - with rake angles γ _а equal to zero, and with an inclination of the vertex rectilinear cutting edges of the teeth by 15 degrees on the odd teeth in one direction, and on the even teeth in the other direction. The fourth - with positive rake angles γ _a equal to 10 degrees, and with an inclination of apical rectilinear cutting edges of the teeth by 15 degrees on odd teeth in one direction, and on even teeth in the other direction.

As a result of milling with these cutters gears made of steel 20KHGNM (HB 163) with the number of teeth 37 at a cutting speed of 54.24 m / min and an axial feed of 1.25 mm / rev, the following was established.

The durability period of the first cutter is 60 parts, the second - 180 parts, the third - 180 parts, the fourth - 300 parts. Thus, the feasibility of making worm-modular cutters simultaneously with a rational cutting pattern and with positive rake angles has been experimentally confirmed.

Claims (1)

A worm cutter for cutting gear parts, containing teeth with a flat front surface parallel to the cutter axis, and two alternating along the helix profiles of the cutting edges, including the top of the tooth and one vertex rectilinear cutting edge, inclined to a straight line passing through the top of the tooth parallel to the axis of the cutter, at an angle of 15-20 ° on odd teeth in one direction, and on even teeth in the other direction, characterized in that the flat front surface of the teeth is made at an angle of 10-15 ° to the axial plane of the cutter, passing through cut the top of the tooth.