Patent Description:
In a machine tool such as an automatic lathe that machines an object to be machined, and includes a plurality of spindle headstocks, a spindle headstock is moved by superposition control in accordance with movement of a tool post that machines an object to be machined, which is held by a main spindle of a predetermined spindle headstock, with a tool, so as to simultaneously machine an object to be machined, which is held by the spindle headstock, with the tool of the tool post (see Patent Literature <NUM>, for example). Patent Literature <NUM> discloses a machine tool that comprises a spindle headstock movable in an X axis direction. The machine tool further comprises a tool post that includes a movement axis in the X axis direction and a movement axis in a direction which is inclined relative to the X axis and intersects with the X axis without being orthogonal to the X axis, and is movable relative to the spindle headstock. Patent Literature <NUM> discloses a numeric controlled (NC) lathe which includes a first spindle and a second spindle, and a tool rest having tools for processing works held by these. The tool rest is freely movable in the direction of the Z1-axis and the X1-axis. The second spindle is freely movable in the direction of the X2-axis and the Z2-axis. An NC unit controls the movement in the direction of the X1-axis and the Z1-axis of the tool rest, and controls the movement in the direction of the X2-axis and the Z2-axis of the second headstock. The NC unit makes it possible to superpose the movement in the direction of the X2-axis necessary for processing the work by the second tool on the movement in the direction of the X1-axis of the tool rest. Furthermore, the movement in the direction of the Z2-axis necessary for processing the work by the second tool is superposed on the movement in the direction of the Z1-axis of the tool rest.

On the other hand, when the tool post is movable along an X axis (for example, horizontal direction) and an inclined Ys axis, which is inclined relative to the X axis and intersects with the X axis without being orthogonal to the X axis, it is necessary to combine the movement in the X axis direction and the movement in the Ys axis direction, in order to move the tool post in a Y axis direction (for example, vertical direction) orthogonal to the X axis direction.

However, with the above superposition control, the tool post is moved in the X axis direction along with the movement of the tool post in the Y axis direction, resulting in the movement of the spindle headstock to be superposition-controlled in the X axis direction. As the spindle headstock moves in the X axis direction under the superposition control, the positional relationship between the tool post and the spindle headstock may not be maintained appropriately.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a machine tool that includes a movement axis in the X axis direction and a movement axis in a direction inclined but not orthogonal to the X axis, and regulates the movement of the spindle headstock in the superposition control when the tool post is moved in the Y axis direction due to the combination of both of the movement axis.

The invention is defined by the independent claim <NUM>, defining a machine tool. The preferred embodiments are defined in the appended claims.

According to the machine tool of the present disclosure, the positional relationship between the spindle headstock and the tool post which includes a movement axis in the X axis direction and a movement axis in a direction inclined but not orthogonal to the X axis can be maintained by regulating the movement of the spindle headstock in the superposition control when the tool post is moved in the Y axis direction due to the combination of both of the movement axes.

Hereinafter, an embodiment of a machine tool according to the present disclosure is described. <FIG> is a plan view illustrating a machine tool <NUM> as one embodiment of the present disclosure. The machine tool <NUM> is an NC automatic lathe, and includes two main spindles <NUM>, <NUM> as illustrated in <FIG>. One main spindle <NUM> (hereinafter referred to as first main spindle <NUM>) is provided in a fixed spindle headstock <NUM>. The first main spindle <NUM> holds, for example, a rod like workpiece (object to be machined) to be feedable in an axis center direction of the first main spindle <NUM>.

The other main spindle <NUM> (hereinafter, referred to as second main spindle <NUM>) is provided in a spindle headstock <NUM> to face the first main spindle <NUM>. The second main spindle <NUM> is arranged such that its Z3 axis as an axis center direction becomes parallel to an axis center direction Z1 of the first main spindle <NUM>. The spindle headstock <NUM> is provided to be movable in the Z3 axis direction and in a horizontal direction (X3 axis direction) orthogonal to the Z3 axis.

The machine tool <NUM> includes a Z3 axis moving device <NUM> that moves the spindle headstock <NUM> in the Z3 axis direction and an X3 axis moving device <NUM> that moves the spindle headstock <NUM> in the X3 axis direction. Each of the Z3 axis moving device <NUM> and the X3 axis moving device <NUM> includes an electric motor and a ball screw that rotates in synchronization with rotation of an axis of the electric motor. The ball screws extend in the Z3 axis direction and the X3 axis direction, respectively.

A turret tool post <NUM> (hereinafter referred to as turret <NUM>) is provided between the first main spindle <NUM> and the second main spindle <NUM> to be rotatable about an axis C and to be freely positioned. In the turret <NUM>, a plurality of turret surfaces (in present embodiment, twelve turret surfaces as one example) provided in a circumference surface about the axis C hold tools such as bytes and drills. As illustrated in <FIG>, the turret <NUM> is provided to be movable with respect to the first main spindle <NUM> and the second main spindle <NUM> with a turret moving device <NUM>.

The turret moving device <NUM> includes a rail 146a extending in an X2 axis direction parallel to the X3 axis, a base 146b movable in the X2 axis direction on the rail 146a, a middle base 146c movable in a Z2 axis direction parallel to a Z1 axis on the base 146b, and a supporting base 146d movable in a Ys axis direction, which is orthogonal to the Z2 axis and is not orthogonal to the X2 axis, on the middle base 146c. The turret <NUM> is provided in the supporting base 146d to be rotatable about the axis C parallel to the Z2 axis. In addition, the Ys axis extends in a direction inclined relative to the Y axis direction as the vertical direction orthogonal to the Z2 axis, inclines in the X axis direction, and intersects with the X axis.

The turret moving device <NUM> also includes an X2 axis moving device <NUM> that moves the turret <NUM> in the X2 axis direction, a Z2 axis moving device <NUM> that moves the turret <NUM> in the Z2 axis direction, and a Ys axis moving device <NUM> that moves the turret <NUM> in the Ys axis direction. Accordingly, the turret <NUM> includes three movement axes in the Z2 axis direction, the X2 axis direction, and the Ys axis direction, and is movable relative to the spindle headstocks <NUM>, <NUM> along each movement axis. Each of the X2 axis moving device <NUM>, the Z2 axis moving device <NUM>, and the Ys axis moving device <NUM> includes an electric motor and a ball screw that rotates in synchronization with rotation of an axis of the electric motor. The ball screws extend in the X2 axis direction, the Z2 axis direction, and the Ys axis direction, respectively.

The Z2 axis moving device <NUM> is placed on the base 146b that is moved in the X2 axis direction by the X2 axis moving device <NUM>, and the Ys axis moving device <NUM> is placed on the middle base 146c that is moved in the Z2 axis direction by the Z2 axis moving device <NUM>. The turret <NUM> is placed on the supporting base 146d that is moved in the Ys axis direction by the Ys axis moving device <NUM>.

The machine tool <NUM> also includes a controller <NUM> that controls the respective operations of the Z3 axis moving device <NUM>, the X3 axis moving device <NUM>, the X2 axis moving device <NUM>, the Z2 axis moving device <NUM>, and the Ys axis moving device <NUM> in addition to the rotation of the turret <NUM>. Similar to the conventional one, the controller <NUM> turns the turret <NUM> in a predetermined rotation position, and moves the second main spindle <NUM> and the turret <NUM> in specific positions.

In the machine tool <NUM>, the controller <NUM> turns the turret <NUM> about the axis C, selects the tool held on a specific turret surface, and moves the second main spindle <NUM> and the turret <NUM> in specific positions. The workpiece held by the first main spindle <NUM> and the workpiece held by the second main spindle <NUM> can be thereby machined by the selected tool.

The turret <NUM> is equipped with a tool that machines the workpiece held by the first main spindle <NUM> and a tool that machines the workpiece held by the second main spindle <NUM>. Both of the tools can be arranged such that one of the tools is selected relative to the second main spindle <NUM> or the first main spindle <NUM> by selecting the other tool relative to the corresponding first main spindle <NUM> or second main spindle <NUM> by the rotation of the turret <NUM>.

In the machine tool <NUM>, the workpiece held by the first main spindle <NUM> and the workpiece held by the second main spindle <NUM> can be simultaneously machined by performing the superposition control to the movement of the second main spindle <NUM> and the movement of the turret <NUM> with the controller <NUM> when the controller <NUM> controls the movement of the turret <NUM> for performing preset machining to the workpiece held by the first main spindle <NUM>.

The turret <NUM> is equipped with each tool through a tool holder <NUM>. For example, as illustrated in <FIG>, the tool holder <NUM> is equipped with the tools <NUM>, <NUM> that machine the workpiece of the first main spindle <NUM>, and also is equipped with the tools <NUM>, <NUM> that machine the workpiece of the second main spindle <NUM>.

In the present embodiment, tool edges of the tools <NUM>, <NUM> and tool edges of the tools <NUM>, <NUM> are the same in positions in the X axis direction (direction parallel to X2 axis and X3 axis) and in the Y axis direction, and differ in positions in the Z axis direction (direction parallel to Z2 axis and Z3 axis). The tool edge of the tool <NUM> relative to the tool edge of the tool <NUM> and the tool edge of the tool <NUM> relative to the tool edge of the tool <NUM> are the same in positions in the X axis direction, and differ in positions in the Y axis direction.

When the tool <NUM> is switched with the tool <NUM> while the superposition control is maintained, the turret <NUM> moves the tool edge of the tool <NUM> to a position P2a of the tool edge of the tool <NUM>.

The tool <NUM> can be switched with the tool <NUM> by moving the turret <NUM> in the Y axis direction. The tool <NUM> is switched with the tool <NUM> by switching the tool <NUM> with the tool <NUM>. The turret <NUM> is moved in the Y axis direction by combining the movement in the Ys axis direction with the Ys axis moving device <NUM> and the movement in the X2 axis direction with the X2 axis moving device <NUM>.

When the turret <NUM> is moved in the Y axis direction, the X2 axis moving device <NUM> operates according to the operation of the Ys axis moving device <NUM>, and the turret <NUM> is moved in the X2 axis direction. When the turret <NUM> is moved in the Y axis direction while the superposition control is maintained, the controller <NUM> regulates the movement of the second main spindle <NUM> with the X3 axis moving device <NUM>, which corresponds to the operation of the X2 axis moving device <NUM>, associated with the movement of the turret <NUM> in the Y axis direction according to the superposition control.

As a result, even though the machining with the tools <NUM>, <NUM> arranged in the Y axis direction are switched, and the machining with the tools <NUM>, <NUM> are switched, the X3 axis moving device does not follow the movement of the turret <NUM> in that switching. The second main spindle <NUM> is thereby prevented from being displaced to the tool <NUM> switched to be arranged in a new reference position, and the second man spindle <NUM> can be appropriately moved in the superposition control. Accordingly, the controller <NUM> operates as a regulator that regulates the movement of the spindle headstock <NUM> in the superposition control, which corresponds to the movement of the turret <NUM> in the X axis direction associated with the movement of the turret <NUM> in the Y axis direction.

When the controller <NUM> operates as the regulator to move the turret <NUM> in the Y axis direction, the second main spindle <NUM> in the superposition control can be moved with the coordinate position of the turret <NUM> in the X axis direction as the reference. As the tool edge of the tool <NUM> is previously positioned to the turret <NUM>, the position of the tool edge of the tool <NUM> mounted on the turret <NUM> is set to the reference position of the movement of the second main spindle <NUM> in the superposition control. By setting the reference position for the superposition control to the position of the tool edge of the tool <NUM>, the movement of the second main spindle <NUM> associated with the movement of the turret <NUM> in the Y axis direction can be simply regulated in the superposition control.

When the controller <NUM> operates as the regulator, the movement amount (distance and coordinate) of the second main spindle <NUM> in the direction opposite to the direction of the movement of the second main spindle <NUM> in the X axis direction in the superposition control in response to the movement of the turret <NUM> in the Y axis direction is added to the movement amount of the second main spindle <NUM> in the X axis direction in the superposition control, so as to regulate the movement of the second main spindle <NUM>. In this case, such control is a process inside the controller <NUM>, and can be achieved by the same process as the relative movement of the second main spindle <NUM> to the turret <NUM> for machining.

A time constant of the moving device for each axis in the machine tool <NUM> is preset to a small value (minimum value) for quickly moving the moving device. A time constant TX2 of the X2 axis direction is set to be smaller than a time constant TYs of the Ys axis direction, and a constant moving velocity VX2 in the X2 axis direction is set to be larger than a constant moving velocity VYs.

The time constant TX2 in the movement in the X2 axis direction with the X2 axis moving device <NUM> is meant to be a time in which the moving velocity of the turret <NUM> in the X2 axis direction reaches the constant moving velocity VX2 from <NUM>. The smaller the time constant TX2, the shorter the time required to reach the constant moving velocity VX2. The larger the time constant TX2, the longer the time required to reach the constant moving velocity.

Similarly, the time constant TYs in the movement in the Ys axis direction with the Ys axis moving device <NUM> is meant to be a time in which the moving velocity of the turret <NUM> in the Ys axis direction reaches the constant moving velocity VYs. The smaller the time constant TYs, the shorter the time required to reach the constant moving velocity VYs. The larger the constant time TYs, the longer the time required to reach the constant moving velocity VYs.

Accordingly, when the X2 axis moving device <NUM> and the Ys axis moving device <NUM> are simultaneously operated while maintaining the preset time constants (time constant TX2 set to value smaller than time constant TYs), as illustrated in <FIG>, the moving velocity VX2 in the X2 axis direction with the X2 axis moving device <NUM> reaches the moving velocity VX2 earlier than the moving velocity VYs in the Ys axis direction with the Ys axis moving device <NUM> reaches the moving velocity VYs.

The moving velocity VYs in the Ys axis direction reaches the moving velocity VYs later than the moving velocity VX2 in the X2 axis direction reaches the moving velocity VX2. Accordingly, when the two axes are simultaneously operated, the moving velocity in the Y axis direction (shown by thick broken line in <FIG>) obtained by combining (vector sum) the moving velocity VX2 in the X2 axis direction and the moving velocity VYs in the Ys axis direction increases along with the increase of the moving velocity in the X2 axis direction till a time t1, and reaches a constant moving velocity V1 at a time t2.

In the machine tool <NUM> of the present embodiment, when the turret <NUM> is moved in the Y axis direction by combining the movement in the X2 axis direction and the movement in the Ys axis direction, the controller <NUM> sets the time constants TX2, TYs to the same value, and adjusts both of the moving velocity VX2 in the X2 axis direction with the X2 axis moving device <NUM> and a X2 axis direction component VYs (X2) of the moving velocity VYs with the Ys axis moving device <NUM> to have the opposite vectors from each other and the same absolute values. As a result, the movement in the X2 axis direction is cancelled and the turret <NUM> is moved along the Y axis direction.

More specifically, the time constant TX2 is increased to be the same as the time constant TYs, and the moving velocity VX2 in the X2 axis direction with the X2 axis moving device <NUM> and the X2 axis direction component VYs (X2) of the moving velocity VYs with the Ys axis moving device <NUM> are adjusted to be the same, such that the movement in the X2 axis direction is cancelled.

As described above, the two time constants TX2, TYs are set to the same value, and both of the moving velocities of the moving devices <NUM>, <NUM> for both axes are adjusted, such that the movement in the X2 axis direction is cancelled by the simultaneous movement. Accordingly, when the X2 axis moving device <NUM> and the Ys axis moving device <NUM> are simultaneously operated, as illustrated in <FIG>, the moving velocity VX2 and the moving velocity VYs are reached at the same time of the time t1 and the time t2, and the combination of the movement in the Ys axis direction and the movement in the X2 axis direction achieves the movement along the Y axis direction.

In the machine tool <NUM> of the present disclosure, when the turret <NUM> is moved in the Y axis direction by combining the movement in the X2 axis direction and the movement in the Ys axis direction, in a period during which the moving velocity in the Y axis direction reaches a constant moving velocity, the combination of the moving velocity in the Ys axis direction and the moving velocity in the X2 axis direction reaches a constant moving velocity V2 without generating a moving component in the X2 axis direction, so as to achieve the movement along the Y axis direction.

When the controller <NUM> independently operates the Ys axis moving device <NUM> and the X2 axis moving device <NUM> without moving the turret <NUM> in the Y axis direction, the controller <NUM> sets the time constant TX2 to the minimum time constant TX2 to reach the moving velocity VX2 in a short time, so as to quickly move the X2 axis moving device <NUM>.

In the machine tool <NUM> of the present embodiment, the time constant TX2 is set to a value smaller than the time constant TYs. On the other hand, when the time constant TYs is set to a value smaller than the time constant TX2, the controller <NUM> increases the relatively small time constant TYs to be the same as the relatively large time constant TX2 for moving in the Y axis direction.

Similar to the machine tool <NUM> of the present embodiment, the time constant TX2 in the movement in the X2 axis direction and the time constant TYs in the movement in the Ys axis direction, and the moving velocity VX2 in the X2 axis direction and the moving velocity VYs in the Ys axis direction can be switched according to a type of machining, in addition to the operation which moves the turret <NUM> in the Y axis direction.

For example, in turning, the controller <NUM> sets the time constant TX2 to the previously set minimum time constant, and in machining with a rotating tool (for example, milling), the controller <NUM> may adjust the moving velocity in each axis direction, and set the time constant TX2 to the same value as the time constant TYs.

While the main spindle rotates, the controller <NUM> sets the time constant TX2 to the previously set minimum time constant. While the rotating tool provided in the turret <NUM> rotates without rotating the main spindle, the controller <NUM> may adjust the moving velocity in each axis direction, and set the time constant TX2 to the same value as the time constant TYs.

The controller <NUM> may switch the time constant TX2 in the movement in the X2 axis direction to the previously set minimum time constant or to the same value as the time constant TYs, and may adjust the moving velocity in each axis direction according to the information on the type of the holder that holds the tool to be attached to the turret <NUM>.

More specifically, when the information on the type of the tool holder is a byte holder for machining external diameter or a byte holder for machining internal diameter, the machining is meant to be the turning or grinding. In this case, the controller <NUM> sets the time constant TX2 to the previously set minimum time constant. When the information is on the rotating tool unit, the machining is meant to be the machining with the rotating tool such as the milling. In this case, the controller <NUM> may adjust the moving velocity in each axis direction, and set the time constant TX2 to the same value as the time constant TYs.

The turning or the machining with the rotating tool is determined in accordance with a machining mode for a machining operation. When a machining mode for the turning is set, the controller <NUM> sets the time constant TX2 to the previously set minimum time constant. When a machining mode for the machining with the rotating tool is set, the controller <NUM> may adjust the moving velocity in each axis direction, and may set the time constant TX2 to the same value as the time constant TYs.

Claim 1:
A machine tool comprising:
a spindle headstock (<NUM>) movable in an X axis direction (X3);
a tool post (<NUM>) that includes a movement axis (X2) in the X axis direction and a movement axis (Ys) in a direction which is inclined relative to the X axis and intersects with the X axis without being orthogonal to the X axis, and is movable relative to the spindle headstock (<NUM>); and
a controller (<NUM>), wherein
the tool post (<NUM>) is movable in a Y axis direction orthogonal to the X axis by combining movements along the two movement axes (X2, Ys),
characterized in that
the controller (<NUM>) performs superposition control of movement of the tool post (<NUM>) and movement of the spindle headstock (<NUM>),
the controller (<NUM>) includes a regulator that regulates movement of the spindle headstock (<NUM>) in the superposition control, which corresponds to the movement of the tool post (<NUM>) in the X axis direction associated with movement of the tool post (<NUM>) in the Y axis direction, and wherein when the tool post (<NUM>) is moved in the Y axis direction, the controller (<NUM>) sets respective moving velocities along both of the movement axes (X2, Ys) to cancel the movement in the X axis direction by the movement in a same time.