Machine tool

Abstract

A machine tool includes a movement device, which has a first feed shaft and a second feed shaft that mutually intersect, and a plurality of tools, which are driven by the movement device and respective blade edges of which are staggered stepwise. The blade edges of the tools are aligned with the second axis due to the inclination of the tools as a unit. The machine tool is capable of executing center level adjustment of a plurality of tools mounted on a tool post against a workpiece having a larger diameter, and is also capable of reducing wasted time in non-cutting operation via equal stroke lengths of the tools.

Claims

1. A machine tool comprising: movement means having a first feed axis and a second feed axis that mutually intersect; and a tool post movable with the movement means, the tool post including a plurality of tools mounted thereon, each of said tools having a respective work-engaging edge, and said plurality of tools being movable as a unit along with movement of the tool post with the movement means; the tool post having a predetermined cut-in direction along which said plurality of tools mounted on the tool post are moved to adjust the depth of cut-in in a turning operation; said plurality of tools being mounted on the tool post so that machining of a workpiece is executed by movement of the tool post in the cut-in direction; machining of the workpiece being executed by a selected one of said plurality of tools by moving the tool post in the cut-in direction; each of said plurality of tools mounted on the tool post being selectively switchable by movement of said plurality of tools in a direction of a selection axis, said selection axis intersecting said cut-in direction; the tools of said plurality of tool being arranged side by side in the direction of said selection axis; each of said plurality of tools having a respective longitudinal axis that is inclined with respect to a predetermined reference plane; the respective work-engaging edges of said plurality of tools being staggered in a stepwise fashion in the cut-in direction; and said plurality of tools being arranged such said work-engaging edges thereof are substantially aligned with a straight line, said straight line extending through each of said work-engaging edges and being perpendicular to said predetermined reference plane.

2. The machine tool according to claim 1, wherein one of the first feed axis and the second feed axis is the selection axis of said plurality of tools.

3. The machine tool according to claim 2, wherein said first feed axis extends in a horizontal direction and said second feed axis extends in a vertical direction, and said first feed axis and said second feed axis are orthogonal to each other.

4. The machine tool according to claim 3, wherein said plurality of tools is arranged in said vertical direction, whereby said plurality of tools comprises plural pairs of adjacent tools of said plurality of tools, each of said pairs consisting of an upper tool and an adjacent lower tool, the upper tool of each of said pairs being located above the lower tool of the same one of said pairs in said vertical direction.

5. The machine tool according to claim 4, wherein, for each of said plural pairs of adjacent tools of said plurality of tools, the work-engaging edge of the upper tool of each of said pairs of tools projects with respect to the work-engaging edge of the lower tool of the same one of said pairs of tools by an amount sufficient that cutting chips generated in the turning operation using the upper tool of each of said pairs of tools do not fall on the lower tool of the same one of said pairs of tools.

6. The machine tool according to claim 2, wherein, with respect to the one of the first feed axis and the second feed axis that is the selection axis, the other of the first feed axis and the second feed axis is inclined and extends parallel to the longitudinal axes.

7. The machine tool according to claim 1, wherein each tool of said plurality of tools mounted on the tool post has the same cut-in direction; and movement of said tool post in the turning operation is limited to said same cut-in direction.

8. The machine tool according to claim 7, wherein one of the first feed axis and the second feed axis is the selection axis of said plurality of tools.

9. The machine tool according to claim 8, wherein said first feed axis extends in a horizontal direction and said second feed axis extends in a vertical direction, and said first feed axis and said second feed axis are orthogonal to each other.

10. The machine tool according to claim 9, wherein said plurality of tools is arranged in said vertical direction, whereby said plurality of tools comprises plural pairs of adjacent tools of said plurality of tools, each of said pairs consisting of an upper tool and an adjacent lower tool, the upper tool of each of said pairs being located above the lower tool of the same one of said pairs in said vertical direction.

11. The machine tool according to claim 10, wherein, for each of said plural pairs of adjacent tools of said plurality of tools, the work-engaging edge of the upper tool of each of said pairs of tools projects with respect to the work-engaging edge of the lower tool of the same one of said pairs of tools by an amount sufficient that cutting chips generated in the turning operation using the upper tool of each of said pairs of tools do not fall on the lower tool of the same one of said pairs of tools.

12. The machine tool according to claim 8, wherein, with respect to the one of the first feed axis and the second feed axis that is the selection axis, the other of the first feed axis and the second feed axis is inclined and extends parallel to the longitudinal axes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a machine tool in accordance with an embodiment of the invention.

(2) FIG. 2 is an internal front view of the machine tool in accordance with the embodiment of the invention as seen from an interior to a front spindle side.

(3) FIG. 3 is a main part schematic front view of the machine tool in accordance with the embodiment of the invention.

(4) FIG. 4 is a conceptual diagram describing an inclined state of a plurality of tools with respect to a second feed shaft.

(5) FIG. 5 is a conceptual diagram describing one step of a center level adjustment method.

(6) FIG. 6 is a conceptual diagram describing a state in which a tool cuts into a workpiece.

(7) FIG. 7 is a conceptual diagram describing a state in which tools are switched.

(8) FIG. 8 is a conceptual diagram describing another inclined state of the plurality of tools with respect to the second feed axis.

(9) FIG. 9 is a schematic front view of the main part of a machine tool in accordance with another embodiment of the invention.

(10) FIG. 10A is a conceptual diagram illustrating a first relative positional relationship between a plurality of tools and a workpiece in a conventional machine tool.

(11) FIG. 10B is a conceptual diagram illustrating a second relative positional relationship between a plurality of tools and a workpiece in a conventional machine tool.

(12) FIG. 11 is a conceptual diagram illustrating a third relative positional relationship between a plurality of tools and a workpiece in a conventional machine tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) The machine tool 100 shown in FIGS. 1 and 2 is a machine tool such as an NC automatic lathe, and includes a plurality of tools 120 such as cutting tools, supported on a tool post 112, a front spindle 130, a back spindle 140, a back tool post 150, and a turret 160. The machine tool 100 is capable of machining a workpiece by gripping and rotating the workpiece by the front spindle 130 and the back spindle 140 at different times.

(14) The tool post 112 is movably supported via a feed mechanism 110A on a first feed axis A and a feed mechanism 110B on a second feed axis B, the first feed axis A and the second feed axis B being mutually orthogonal. The feed mechanisms 110A and 110B constitute a movement device 110 for the tool post 112. The first feed axis A and the second feed axis B are orthogonal to the axis Z1 (FIG. 3) of the front spindle 130.

(15) As shown in FIGS. 1 to 3, the feed mechanism 110A on the first feed axis A includes a first slide stand 110A-1 that is slidably supported on a slide rail 110A-2 along the first feed axis A and that is driven by a first feed screw 111A (FIG. 3) along the first feed axis A. The first feed screw 111A is rotationally driven by a first motor 113A. The driving force of the first motor 113A moves the first slide stand 110A-1 along the first feed axis A. The feed mechanism 110B on the second feed axis B includes a second slide stand 110B-1 that is slidably supported on a slide rail 110B-2 along the second feed axis B and that driven by a second feed screw 111B along the second feed axis B. The second feed screw 111B is rotationally driven by a second motor 113B. The driving force of the second motor 113B moves the second slide stand 110B-1 along the second feed axis B. The tool post 112 is mounted on the second slide stand 110B-1 and moves along the first feed axis A via the rotation of the first feed screw 111A and along the second feed axis B via the rotation of the second feed screw 111B.

(16) The tools 120 are mounted on the tool post 112 as a unit. The movement device 110 can move the tool post 112 in any direction with the combined action of the first feed screw 111A and the second feed screw 111B. The machine tool 100 can machine a round, bar-shaped workpiece W held by the front spindle 130 shown in FIGS. 1 and 2 while switching between the tools 120 by moving the tools 120 in any direction via the movement device 110.

(17) The tools 120 are arranged in parallel to one another along a Y1 axis direction that is inclined with respect to the first feed axis A and the second feed axis B. As shown in FIG. 4, with a broken line illustrating the Y1 axis direction as a horizontal direction, the tools 120, shown in broken lines, are arranged so that the blade edges thereof are staggered stepwise in an X1 axis direction perpendicular to the Y1 axis direction. The blade edges of the respective tools 120 are proportionally staggered, and are positioned on a straight line L. As shown in FIG. 4 with solid lines, the tools 120 are inclined as a unit so that the straight line L is aligned with the first feed axis B.

(18) Thus, an X1-Y1 coordinate system consisting of the X1 axis direction and the Y1 axis direction is rotated through a predetermined angle with respect to an A-B coordinate system consisting of the first feed axis A and the second feed axis B. With this configuration, each of the blade edges comes into contact with the workpiece W at a top of the workpiece W in the X1 axis direction in machining operation, and the X1 axis direction becomes a cut-in direction of the tools 120.

(19) Because each of the blade edges comes into contact with the workpiece W at a top of the workpiece W in the X1 axis direction in machining operation, the blade edge position adjustment is executed, as shown in FIG. 5, by first contacting a blade edge of a particular tool 120 with a top of the workpiece W in the Y1 axis direction, and then, as in conventional machining, determining a Y1 coordinate value (as an absolute value) of a center, or rotational axis, of the workpiece W by using the Y1 coordinate value of the contacting position and a premeasured radius of the workpiece W. Even though the blade edges of the respective tools 120 are positioned along and aligned with the second feed axis B, the blade edges are staggered in the X1 axis direction in a stepwise fashion. Thus, the blade edge position adjustment can be executed against a workpiece W having an outer diameter larger than the distance between two adjacent tools 120.

(20) As shown in FIG. 6, the blade edge of the particular tool 120 is then moved to the Y1 coordinate value (Y0) of the rotational axis of the workpiece W and is subsequently moved in the X1 axis direction to cut into and machine the workpiece W. Because the blade edges of the respective tools 120 are aligned with the second feed axis B, the tools 120 can be switched by moving the tool post 112 along the second feed axis B regardless of the staggering of the blade edges in the X1 axis direction, as shown in FIG. 7.

(21) For example, as shown in FIG. 7, in order to switch between the tools 120, a particular tool 120 that has been used in machining operation is moved from the surface of the workpiece W to an escape position, or a tool standby position, which is a small distance d away from the surface of the workpiece W in the X1 axis direction, or the cut-in direction of the tool 120. Because the blade edges of the respective tools 120 are aligned with a straight line that is along the second feed axis B and that passes through the tool standby position, next machining operation can be started by simply moving the tool post 112 along the second feed axis B to position another tool 120 that will be used in next machining operation to the standby position, regardless of the staggering of the blade edge, and then moving the another tool 120 by the distance d, which is a minimum moving distance common to all the tools 120, without considering the amount of stagger of the blade edges. Also, because the stroke length needed for starting the machining operation is common to all the tools 120, a processing stroke does not need to be made longer in accordance with the amount of stagger of the blade edges in the X1 axis direction.

(22) Thus, because the blade edges of the plurality of tools 120 are aligned with a straight line along the selection axis for selecting between the tools 120, such as the second feed axis B, the respective tools 120 can be directly moved to the tool standby position to reduce wasted time in non-cutting operation. In addition, by selecting the second feed axis B as the selection axis and inclining the tools 120 as a unit so that the blade edges of the respective tools 120 are aligned with the second feed axis B, the strokes of the first feed screw 111A and the second feed screw 111B can be determined in accordance with the rotation (inclination) angle of the X1-Y1 coordinate system with respect to the A-B coordinate system without depending on the amount of stagger of the blade edges of the respective tools 120. Thus, the strokes of the first feed screw 111A and the second feed screw 111B do not need to be made longer by a length corresponding to the amount of stagger of the blade edges, and the first feed screw 111A and the second feed screw 111B can be made compact. Particularly, because the tools 120 are arranged in the vertical direction, the stroke length in the horizontal direction does not need to be made longer and the machine tool 100 can thus be made compact in the horizontal direction. Furthermore, in the present embodiment, because the stroke lengths of the first feed screw 111A and the second feed screw 111B do not need to be made longer, the machine tool 100 can be made compact both in the horizontal and in the vertical direction.

(23) Although in the above embodiment the second feed axis B is selected as the selection axis and the blade edges of the respective tools 120 are aligned with the second feed axis B, it is also possible to select the first feed axis A as the selection axis and to align the blade edges with the first feed axis A. In this case, the tools 120 are switched by moving the tool post 112 along the first feed axis A.

(24) In the present embodiment, the wording that the blade edges of the plurality of tools are aligned with a straight line along the selection axis of the tools includes a situation in which a blade edge of an upper tool 120 of any two adjacent tools of the plurality of tools 120 projects with respect to a blade edge of a lower tool 120 of the two adjacent tools for only a certain length with which cutting chips generated in machining operation with the upper tool 120 do not fall on the lower tool 120, as shown in FIG. 8.

(25) In other words, as long as the projection of the upper tool 120 with respect the lower tool 120 is restricted to a certain length with which cutting chips generated in machining operation with the upper tool 120 do not fall on the lower tool 120, the straight line L passing through the blade edges of the plurality of tools 120 is not required to coincide with the second feed axis B and may be simply along the second feed axis B, as shown in FIG. 8. With this arrangement of the tools 120, cutting chips generated in the machining operation with the upper tool 120 do not fall on the lower tool 120. Thus, adhesion of the cutting chips to the tools 120 can be prevented. The straight line L may be used as the selection axis.

(26) Although in the above embodiment the first feed axis A and the second feed axis B are orthogonal to each other and the tools 120 (the tool post 112) are moved in the X1 axis direction with the combined action of the first feed screw 111A and the second feed screw 111B, the second feed screw 111B may be provided along the X1 axis direction so that the second feed axis B is in the X1 axis direction, as shown in FIG. 9.

(27) In this case, the tool post 112 can be moved along the first feed axis A by driving only the first feed screw 111A and can be moved along the X1 axis direction by driving only the second feed screw 111B. This enables easy and low-load movement of the tool post 112.