Patent Application
20170095863
The present invention relates to a cutting method for an inner circumferential face and an outer circumferential face of a work using a cutting tool of a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, the cutting being performed by summating a cutting velocity of the cutting tool.
The “turning of the main shaft” is not limited to rotation of the main shaft along a central axis thereof but refers to rotations including revolution of the main shaft around the predetermined position serving as a center.
What is called an orbit machining that a main shaft turns around a predetermined center has been adopted as a method for forming an inner circumferential face and an outer circumferential face of a work into curved faces variously shaped like cylinders, tapered shapes, flanges, or the like, as disclosed in Patent Literature 1. This machining method is technically advantageous in that machining can be achieved at whatever position a table supporting the work is located.
However, in the orbit machining method according to the related art, the work is not rotated, and cutting is performed only by turning the main shaft. Thus, the cutting velocity is limited.
For cutting of the work, Patent Literature 2 proposes a cutting method involving movement of a table supporting a tool in addition to rotation of the main shaft.
However, in the method in prior arts, the table moves linearly by using ball screw, and no summation of the turning angular velocity of the main shaft is configured (see
Furthermore, the rotation of the main shaft and the movement of the table need to be controlled based on complicated expressions (for example, expressions (5)-(99) shown in sections [0023]-[0073]).
Patent Literature 3 proposes a configuration in which the rotation of the main shaft be reinforced by circular arc motion of the work. However, the configuration needs to be controlled based on complicated operations in which the number of rotations of the main shaft is synchronized with the relative circular-arc complemental motion of the work in a predetermined ratio.
Thus, for the cutting of the inner circumferential face or the outer circumferential face of the work, no cutting method has been proposed to summate the cutting velocity of the cutting tool and to provide a simple control for summation.
According to the present invention, there is provided a cutting method in which, in cutting an inner circumferential face or an outer circumferential face of a work based on turning of a main shaft around a predetermined position serving as a center, a cutting velocity is summated and this summation is simply controlled to enable quick cutting of the inner circumferential face and the outer circumferential face of the work.
According to the present invention, there are further provided a basic configuration (1); a cutting method for an inner circumferential face or an outer circumferential face of a work using a cutting tool projecting from a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, wherein a table that supports the work is set in a rotating central axis that is coaxial with a turning central axis of the main shaft, and the table is rotated in a direction opposite to a turning direction of the main shaft to summate a cutting velocity of the cutting tool, and
a basic configuration (2) the cutting method for an inner circumferential face or an outer circumferential face of the work of the basic configuration (1), in which a position of a turning center of the main shaft is movable in an orthogonal direction or an oblique direction to a plane orthogonal to the turning central axis, and when the position of the turning center of the main shaft is movable in the oblique direction, a rotating central position of the table is also moved in association with the movement in the oblique direction to maintain the coaxial state.
In the aspect of the present invention based on the basic configurations (1) and (2), the table supporting the work rotating in a direction opposite to the turning direction of the main shaft allows summation of the cutting velocity without any special control, while the inner circumferential face or the outer circumferential face of the work can be formed into any of various curved faces by controlling a small number of parameters, that is, a turning angular velocity of the main shaft and/or a rotating angular velocity of the table (in the case of the basic configuration (1)) and a turning radius of the main shaft and a moving position and a moving velocity of a turning center of the main shaft in the orthogonal direction or the oblique direction to the plane orthogonal to the turning central axis of the main shaft (in the case of the basic configuration (2)).
That is, the aspect of the present invention eliminates the need for control based on complicated calculations or operations as disclosed in Patent Literature 2 and 3.
As is denoted in
In the present invention, elements to be controlled are parameters indicative of the turning angular velocity of the main shaft 1 with respect to the turning center and/or the rotating angular velocity of the table 4, the turning radius of the main shaft 1 (above-described elements correspond to the basic configuration (1)), and further the moving position and the moving velocity of the turning center in the orthogonal direction or the oblique direction with respect to a plane orthogonal to a central axis 6 for turning of the main shaft 1 (the above-described elements correspond to the basic configuration (2)). For the basic configuration (1), the number of the parameters is only two or three, and for the basic configuration (2), the number of the parameters is only three or four.
Moreover, the turning angular velocity and the rotating angular velocity act in the opposite directions and are thus naturally summated together. Since the need for special control to summate the cutting velocity is eliminated, a control method is very simple.
The main shaft 1 and the cutting tool 2 make turning motion around a predetermined central position. A tip of the cutting tool 2 cuts an inner circumferential face of the work 3 as is denoted in
That is, circumferential curved faces in
The cutting velocity of the cutting tool 2 needs to be constant in order to provide an even cutting face.
In view of such a demand, for the basic configurations (1) and (2), an embodiment is often adopted in which the total of the turning angular velocity of turning of the main shaft 1 and the rotating angular velocity of the work 3 is set to be large with decreasing distance from the turning center to the tip of the cutting tool 2.
In particular, the use of simple expressions as is described below enables the cutting velocity of the tip of the cutting tool 2 to be set to a constant value C.
As is denoted in
{dot over (X)}={dot over (R)} cos θ−R{dot over (θ)} sin θ,{dot over (Y)}={dot over (R)} sin θ+R{dot over (θ)} cos θ
is formulated (dots over reference characters indicate time differentials).
Therefore, when the cutting velocity is represented as V,
V
2
={dot over (X)}
2
+{dot over (Y)}
2
={dot over (R)}
2
+R
2{dot over (θ)}2
is formulated.
According to the above-described relational expressions, wherein, in the case that the turning angular velocity of the main shaft 1 is represented as ω1 and the rotating angular velocity of the table 4 is represented as ω2, the constant value C may be preset and controlled to formulate
in association with the distance R and {dot over (R)} that is a time differential of the distance R, in order to allow the tip of the cutting tool 2 to operate at a constant cutting velocity V.
In the present invention, to form each of the inner and outer circumferential faces into any of various cutting shapes, the following embodiment may be adopted. That is, as shown in the basic configuration (2), the position of the turning center of the main shaft 1 is movable in an orthogonal direction or an oblique direction to the plane orthogonal to the turning central axis 6. When the position of the turning center of the main shaft 1 is movable in the oblique direction, a rotating central position of the table 4 is also moved in association with this movement to maintain the coaxial state.
When the turning center of the main shaft 1 is movable in the oblique direction as is described above, the turning central axis 6 of the main shaft 1 moves by itself. Thus, the rotating central position of the table 4 is forced to move with synchronized state to the position of the turning center in order to maintain the coaxial state.
When the tapered shape has circumferential curved faces at opposite ends thereof, the turning radius may be approximately constant at an initial stage and a final stage of turning as is denoted in
As is apparent from
The above-described drawings all denote that the turning center of the main shaft 1 is moved in the direction orthogonal to the plane orthogonal to the turning central axis 6, that is, in the same direction as that of the turning central axis 6. When the turning center is moved in the direction oblique to the plane, a tapered shape is obtained which generally changes in the oblique direction.
Alternatively to the embodiments denoted in
(1) In an inner region of the work 3 that is close to the turning center, the distance from the turning center to the tip of the cutting tool 2 is sequentially increased to move the tip along a helical locus, in the case that the distance reaches a maximum state, the maximum state is maintained to form an inner wall in a ring shape.
(2) In an outer region of the work 3 that is away from the turning center, the distance from the turning center to the tip of the cutting tool 2 is sequentially reduced to move the tip along a helical locus, in the case that the distance reaches a minimum state, the minimum state is maintained to form an outer wall in a ring shape.
In the above-described embodiment, the ring shape can be quickly obtained.
Thus, in the present invention, the work 3 is cut with a summation of the cutting velocity to allow the inner circumferential face and the outer circumferential face to be quickly formed. The need for special control for the summation is not required to achieve simple control.
In an example, at least one of the turning angular velocity of the main shaft 1 and the rotating angular velocity of the work 3 is made constant.
In this example, at least one of the turning angular velocity of the main shaft 1 and the rotating angular velocity of the table 4 need not be controlled.
Therefore, when the turning center of the main shaft 1 is moved in the orthogonal direction or the oblique direction with respect to the plane, control with three parameters can be performed. When the turning center of the main shaft 1 is not moved in the orthogonal direction or the oblique direction with respect to the plane, control with two parameters can be performed. Consequently, very simple control can be achieved.
As is described above, the present invention enables the inner circumferential face and the outer circumferential face of the work to be quickly cut into any of various shapes under simple control with a small number of parameters. Thus, the present invention has enormous applicability.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-196514 | Oct 2015 | JP | national |
