3 realization of relative feed movement
When the non-CNC machining of the special rotary milling cutter is carried out, the machined milling cutter only performs the uniform speed rotary motion, and the forming of the spiral groove on the cutter is realized by the axial feed motion of the grinding grinding wheel while rotating at a constant speed. In addition, since the different radius of the circle on the rotary surface is different, and the grinding wheel is usually designed according to the maximum radius of the circle, the radial grinding motion of the grinding wheel must be used to realize the groove grinding of different radii. Therefore, in the non-CNC machining of the special rotary milling cutter, the relative feed motion refers to the combined motion of the axial movement and the radial movement of the grinding wheel relative to the milling cutter.
Axial feed motion
In this paper, the end cam mechanism is used to realize the axial feed motion of the non-CNC machining of the special rotary milling cutter. The cam drive mechanism can generate a movement trajectory for a given function. The cam mechanism displacement function designed in this paper is based on the edge curve equation on the rotary surface. Let the rotational angular velocity of the machined milling cutter be w=dv/dt (v is the angle parameter in the cutting edge curve formula (1)), and the rotational angular velocity of the cam for uniform rotating motion during machining is w, let aw=w ( a>0), the cam displacement function formula can be obtained by the tool edge curve formula (3). The method is to inverse the relationship v=v(u) for the equation of the edge curve equation under the initial condition. =u(v), and substituting it into the axial component z=g(u)=g[ u(v)] in the curve (1) of the surface of the rotary surface, the displacement function of the cam can be obtained. Since the design of the cutting edge curve is based on the smooth continuity of the joint between the two rotating surfaces, the cam displacement function derived therefrom is also smooth and continuous at the joint of the two rotating surfaces.
Radial feed motion
The radial feed motion of the non-CNC machining of the special rotary milling cutter is realized by the cam mechanism of the tool grinding machine, and the radial feed amount varies with the radius of the rotary surface, that is, when the radius of the milling cutter is from R→0, The amount of the core is from the core thickness radius r → 0, so that only the residual rotating surface will appear without overcutting, and the residual rotating surface is easier to compensate by the grinding wheel. Let the feed amount at the point of gyration radius f(u) on the rotary surface be s, then according to the curve equation
s = r
Rf(u) R -0
It can be concluded that the radial feed is solved by
s=r-(r/R)f(u)=r-(r/R)(x2+y2) (4)
Simply substitute the coordinates of any point on the rotary surface into equation (4) to find the radial feed at that point. Since the transition surfaces are smooth and the edge curve is smooth and continuous at the junction of the two surfaces, the profile curve is also smooth and continuous at the intersection of the two surfaces.
4 solution example
The following table gives examples of the solution of the cutting edge curve and the relative motion equation for two special rotary milling cutters (ball-end circular milling cutter and angular circular-cone milling cutter). The meaning of the parameters in the table is shown in Figure 2 and Figure 3. In the table, q is the angle value of the cam displacement curve between different planes of rotation.
Table solver
Ball circularly arcuate cutters with cutter cone
Ball portion arcuate surface of revolution round the turning plane angle conical surface
Figure 2 Ball head arc milling cutter
Figure 3 angular round cone milling cutter
5 Conclusion
The spiral groove of the special rotary milling cutter and the design method of the grinding wheel for grinding have been discussed in many documents, and the paper is omitted. The manufacturing method of the special rotary milling cutter introduced in this paper adopts the non-CNC machining scheme, which is simple in process and low in cost. It is especially suitable for mass production of special rotary milling cutters and has a good market prospect. However, this method is not suitable for experimental tool development or single-piece small batch production.
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