Machine tool

Abstract

This machine tool is provided with an arithmetic control unit that: controls a motor so as to measure the positions of raw material holes in a boom using an imaging camera held on a main shaft (S111-S113); calculates the positions of the center axes of the raw material holes on the basis of the information about the positions of the raw material holes captured by the imaging cameras (S114, S115); calculates distances between two center axes of interest (S116); and, when at least one of the calculated distances does not meet a prescribed value (S117), calculates the most suitable positions for process holes from minimum holes that comply with formulae (1111-1) to (1114-1) and (1141-1) to (1144-1) on the basis of equations (1101), (1111) to (1114), and (1141) to (1144) (S121); and controls the motor so as to form process holes in the positions calculated as the most suitable and cuts raw material holes using a tool held on the main shaft (S122, S123).

Description

TECHNICAL FIELD

The present invention relates to a machine tool.

BACKGROUND ART

The boom of, for example, an excavator sometimes includes a pair of plate members which are disposed in mutually facing postures and in each of which a plurality of holes are formed at predetermined positions for pivotally supporting an arm, a hydraulic cylinder, and the like, and a joint member joining and fixing the plate members to each other. In the case of such a boom, shafts cannot be inserted and supported in the mutually facing holes if the axes of these mutually facing holes are offset from each other. For this reason, after the plate members are disposed in the mutually facing postures and joined and fixed to each other with the joint member, mutually facing blank holes in the plate members are cut to expand their diameters with, for example, a horizontal boring and milling machine with counter spindles or the lie, so that the blank holes are worked and adjusted into worked holes positioned coaxially with each other.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Publication No. 2006-102843

SUMMARY OF INVENTION

Technical Problem

In the case of the boom of an excavator as mentioned above, when the mutually facing blank holes are worked and adjusted into coaxially positioned worked holes, an error greater than or equal to a prescribed value (tolerance) may be present in the distance (pitch) between the axis of one worked hole and the axis of another worked hole. In this case, a hydraulic cylinder or the like cannot be joined between these worked holes, which makes the boom a defective product.

Such a problem is not limited to the case mentioned above where the mutually facing blank holes in the boom of an excavator are worked and adjusted into worked holes by cutting the blank holes to expand their diameters with a horizontal boring and milling machine with counter spindles or the like. The problem possibly occurs like the above case when n blank holes (n is an integer greater than or equal to 3) formed in a workpiece are to be worked and adjusted into worked holes by cutting the blank holes to expand their diameters with a machine tool.

In view of the above, an object of the present invention is to provide a machine tool capable of working and adjusting n blank holes (n is an integer greater than or equal to 3) formed in a workpiece into worked holes by cutting the blank holes to expand their diameters such that the blank holes are worked and adjusted to such optimized positions that the pitch error between the worked holes can be less than or equal to a tolerance.

Solution to Problem

A machine tool according to the present invention for solving the above problem is a machine tool for working and adjusting n blank holes (n is an integer greater than or equal to 3) formed in a workpiece into worked holes by cutting the blank holes to expand diameters thereof, characterized in that the machine tool comprises: a table on which the workpiece is placed; a spindle capable of detachably holding a tool for cutting the blank holes in the workpiece and measurement means for measuring positions of the blank holes in the workpiece such that the tool and the measurement means are capable of being changed from one another; spindle drive means for rotationally driving the spindle; relative movement means for moving at least one of the table and the spindle to move the tool and the measurement means relative to the workpiece in an X-axis direction, a Y-axis direction, and a Z-axis direction; and arithmetic control means for controlling the relative movement means such that the positions of the blank holes in the workpiece are measured with the measurement means held on the spindle, calculating positions of center axes of the blank holes based on information on the positions of the blank holes measured with the measurement means, calculating a distance between each two center axes of interest among the center axes, in a case where at least one of the calculated distances does not satisfy a prescribed value, calculating optimized positions of the worked holes from minimized values satisfying Inequalities (110-1), (120-1), (130-1), (140-1), (150-1) below based on Equations (100), (110), (120), (130), (140), (150) below, and controlling the spindle drive means and the relative movement means to cut the blank holes with the tool held on the spindle such that the worked holes are formed at the calculated optimized positions of the worked holes.

$\begin{array}{cc}\left[\mathrm{Formula}1\right]& \\ \mathrm{Fn}\left({\mathrm{OX}}_1,{\mathrm{OX}}_2,\dots ,{\mathrm{OX}}_n,{\mathrm{OY}}_1,{\mathrm{OY}}_2,\dots {\mathrm{OY}}_n\right)=\frac{1}{2}*\sum _{k=1}^n\sum _{\underset{m\ne k}{m=1}}^n\left({\mathrm{WP}}_{\mathrm{km}}*\Delta P_{\mathrm{km}}^2+{\mathrm{WX}}_{\mathrm{km}}*\Delta X_{\mathrm{km}}^2+{\mathrm{WY}}_{\mathrm{km}}*\Delta Y_{\mathrm{km}}^2\right)+\sum _{k=1}^n\left({\mathrm{WQ}}_k*\Delta Q_k^2+{\mathrm{WT}}_k*\Delta T_k^2\right)& \left(100\right)\\ \Delta P_{\mathrm{km}}=\sqrt{{\left({\mathrm{OX}}_m-{\mathrm{OX}}_k\right)}^2+{\left({\mathrm{OY}}_m-{\mathrm{OY}}_k\right)}^2}-P_{\mathrm{km}}& \left(110\right)\\ \Delta P_{\mathrm{km}}\le {\mathrm{EP}}_{\mathrm{km}}& \left(110\text{-}1\right)\\ \Delta X_{\mathrm{km}}=\left({\mathrm{OX}}_m-{\mathrm{OX}}_k\right)-\left({\mathrm{OX}}_{\mathrm{ms}}-{\mathrm{OX}}_{\mathrm{ks}}\right)& \left(120\right)\\ \Delta X_{\mathrm{km}}\le {\mathrm{EX}}_{\mathrm{km}}& \left(120\text{-}1\right)\\ \Delta Y_{\mathrm{km}}=\left({\mathrm{OY}}_m-{\mathrm{OY}}_k\right)-\left({\mathrm{OY}}_{\mathrm{ms}}-{\mathrm{OY}}_{\mathrm{ks}}\right)& \left(130\right)\\ \Delta Y_{\mathrm{km}}\le {\mathrm{EY}}_{\mathrm{km}}& \left(130\text{-}1\right)\\ \Delta Q_k=\sqrt{{\left({\mathrm{OX}}_k-{\mathrm{MX}}_{\mathrm{ki}}\right)}^2+{\left({\mathrm{OY}}_k-{\mathrm{MY}}_{\mathrm{ki}}\right)}^2}& \left(140\right)\\ \Delta Q_k\le {\mathrm{EQ}}_k& \left(140\text{-}1\right)\\ \Delta T_k=\sqrt{{\left({\mathrm{OX}}_k-{\mathrm{MX}}_{\mathrm{ko}}\right)}^2+{\left({\mathrm{OY}}_k-{\mathrm{MY}}_{\mathrm{ko}}\right)}^2}& \left(150\right)\\ \Delta T_k\le {\mathrm{ET}}_k& \left(150\text{-}1\right)\end{array}$

Here, MX_ki is a position of a center axis of a blank hole G_k in the X-axis direction, MY_ki is a position of the center axis of the blank hole G_k in the Y-axis direction, MX_ko is a position, in the X-axis direction, of a center axis of a circular area where a worked hole H_k is capable of being formed by working and adjusting the blank hole G_k, MY_ko is a position, in the Y-axis direction, of the center axis of the circular area where the worked hole H_k can be formed by working and adjusting the blank hole G_k, OX_k is a position of an axis of the worked hole H_k in the X-axis direction, OY_k is a position of the axis of the worked hole H_k in the Y-axis direction, OX_ks is a designed position of the axis of the worked hole H_k in the X-axis direction, OY_ks is a designed position of the axis of the worked hole H_k in the Y-axis direction, OX_m is a position of an axis of the worked hole H_m in the X-axis direction, OY_m is a position of the axis of the worked hole H_m in the Y-axis direction, OX_ms is a designed position of the axis of a worked hole H_m in the X-axis direction, OY_ms is a designed position of the axis of the worked hole H_m in the Y-axis direction, P_km is a designed pitch between the worked holes H_k, H_m, ΔP_km is a calculated pitch error between the worked holes H_k, H_m, ΔX_km is an axis-to-axis error between the worked holes H_k, H_m in the X-axis direction, ΔY_km is an axis-to-axis error between the worked holes H_k, H_m in the Y-axis direction, ΔQ_k is an amount of offset between the center axis of the blank hole G_k and the calculated axis of the worked hole H_k, ΔT_k is a length between the center axis of the circular area where the worked hole H_k is capable of being formed and the calculated axis of the worked hole H_k, EP_km is a tolerance for the pitch error between the worked holes H_K, H_m, EX_km is a tolerance for the axis-to-axis error between the worked holes H_k, H_m in the X-axis direction, EY_km is a tolerance for the axis-to-axis error between the worked holes H_k, H_m in the Y-axis direction, EQ_k is a tolerance for the amount of offset between the center axis of the blank hole G_k and the axis of the worked hole H_k, ET_k is a tolerance for the length between the center axis of the circular area where the worked hole H_k is capable of being formed and the axis of the worked hole H_k, WP_km is a weight coefficient for ΔP_km, WX_km is a weight coefficient for ΔX_km, WY_km is a weight coefficient for ΔY_km, WQ_k is a weight coefficient for ΔQ_k, and WT_k is a weight coefficient for ΔT_k.

Also, the machine tool according to the present invention may be characterized in that, in the machine tool described above, the workpiece is a boom of an excavator.

Also, the machine tool according to the present invention may be characterized in that, in the machine tools described above, the machine tool is a horizontal boring and milling machine with counter spindles.

Also, the machine tool according to the present invention may be characterized in that, in the machine tools described above, the measurement means is anyone of an imaging camera and a touch sensor.

Advantageous Effects of Invention

Even in the case of a workpiece with a pitch error greater than or equal to its tolerance between worked holes, the machine tool according to the present invention can work and adjust the worked holes to such optimized positions that all the pitch errors can be less than or equal to their respective tolerances. In this way, defective products can be greatly reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view illustrating a schematic configuration of a main part of a first embodiment in which a machine tool according to the present invention is applied to a horizontal boring and milling machine with counter spindles.

FIG. 2 is a front view illustrating a schematic configuration of a main part of the horizontal boring and milling machine with counter spindles in FIG. 1.

FIG. 3 is a control block diagram of the main part of the horizontal boring and milling machine with counter spindles in FIG. 1.

FIG. 4A is a schematic structure view of a boom of an excavator.

FIG. 4B is a schematic structure view of a boom of an excavato.

FIG. 5 is a flowchart of a main part of actuation of the horizontal boring and milling machine with counter spindles in the first embodiment.

FIG. 6 is an explanatory view of the center axes of worked holes.

FIG. 7 is an explanatory view of the position of a worked hole formed in a flange portion.

FIG. 8 is a control block diagram of a main part of a second embodiment in which the machine tool according to the present invention is applied to a horizontal boring and milling machine with counter spindles.

FIG. 9 is a flowchart of a main part of actuation of the horizontal boring and milling machine with counter spindles in the second embodiment.

FIG. 10 is an explanatory view of the center axes of protruding portions.

FIG. 11 is an explanatory view of round portions of flange portions and their center axes.

DESCRIPTION OF EMBODIMENTS

Embodiments of a machine tool according to the present invention will be described with reference to the drawings. However, the present invention is not limited only to the following embodiments to be described with reference to the drawings.

First Embodiment

A first embodiment of the machine tool according to the present invention will be described with reference to FIGS. 1 to 7.

As illustrated in FIGS. 1 and 2, a table 112 is provided on a bed 111 slidably in an X-axis direction (the top-bottom direction of FIG. 1, the direction perpendicular to the plane of the sheet of FIG. 2). Columns 122, 132 are provided upright on beds 121, 131 which are placed by the opposite sides of the table 112 in its width direction (the left-right direction of FIGS. 1 and 2), respectively.

On the surfaces of the columns 122, 132 on the table 112 side, spindle heads 123, 133 are provided movably in an Y-axis direction, which is a vertical direction (the direction perpendicular to the plane of the sheet of FIG. 1, the top-bottom direction of FIG. 2), relative to these surfaces of the columns 122, 132, respectively. On the surfaces of the spindle heads 123, 133 on the table 112 side, spindles 124, 134 are provided, respectively, with their tips facing the table 112 side. The spindles 124, 134 are movable toward and away from their respective spindle heads 123, 133 in a Z-axis direction, which is their axial direction (the left-right direction of FIGS. 1 and 2).

Imaging cameras 125, 135, which serve as measurement means, are detachably attached to the spindles 124, 134, respectively. The spindles 124, 134 are each capable of holding any one of the imaging camera 125, 135 and a tool not illustrated for cutting or the like such as a milling cutter so that the imaging camera 125, 135 and the tool can be changed from one another.

As illustrated in FIG. 3, the imaging cameras 125, 135 are electrically connected to an input part of an arithmetic control unit 140, which serves as arithmetic control means. An output part of the arithmetic control unit 140 is electrically connected to a drive motor 113 that moves the table 112 in the X-axis direction, to drive motors 126, 136 that move the spindle heads 123, 133 in the Y-axis direction, respectively, to drive motors 127, 137 that move the spindles 124, 134 forward and backward in the Z-axis direction, respectively, and to drive motors 128, 138 that rotationally drive the spindles 124, 134, respectively.

An input unit 141 that inputs various instructions is electrically connected to the input part of the arithmetic control unit 140. The arithmetic control unit 140 is capable of controlling the actuation of the drive motors 113, 126 to 128, 136 to 138 based on information from the input unit 141 and information inputted in advance, and of performing arithmetic operation for controlling the actuation of the drive motors 113, 126, 127, 136, 137 based on information from the imaging cameras 125, 135 and information inputted in advance (details will be described later).

As illustrated in FIGS. 4A and 4B, a boom 10 of an excavator, which is a workpiece, includes a pair of plate members 11, 12 disposed in mutually facing postures, and a joint member 13 joining and fixing them to each other. A plurality of (four in this embodiment) blank holes 11A to 11D and a plurality (four in this embodiment) of blank holes 12A to 12D for pivotally supporting an arm, hydraulic cylinders, and the like are formed in the plate members 11, 12 at predetermined positions, respectively.

The blank holes 11A, 11B, 11D, 12A, 123, 12D in the boom 10 are formed in (hollow) cylindrical protruding portions 11a, 11b, 11d, 12a, 12b, 12d, respectively, which protrude outward of the plate members 11, 12 in their thickness direction. The blank holes 11C, 12C in the boom 10 are formed in bracket portions 11c, 12c around their round protruding ends, respectively, the bracket portions 11c, 12c protruding in flush with the surfaces of the plate members 11, 12.

Note that, in this embodiment, components such as the columns 122, 132, the spindle heads 123, 133, the drive motors 113, 126, 127, 136, 137 constitute relative movement means, and components such as the drive motors 126, 138 constitute spindle drive means.

Next, description will be given of actuation of a machine tool 100 according to this embodiment as described above for working and adjusting the blank holes 11A to 11D, 12A to 12D in the boom 10 into worked holes 10A to 10D by cutting the blank holes 11A to 11D, 12A to 12D to expand their diameters.

First, the boom 10 is placed at a prescribed position on the table 112 (S111 in FIG. 5), and the imaging cameras 125, 135 are attached to the spindles 124, 134 (S112 in FIG. 5).

Then, the input unit 141 inputs information into the arithmetic control unit 140 which instructs imaging of the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10 with the imaging cameras 125, 135. In response, the arithmetic control unit 140 actuates the drive motors 113, 126, 127, 136, 137 to move the table 112 in the X-axis direction and move the spindles 124, 134 in the Y-axis direction and the Z-axis direction such that the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10 can be imaged with the imaging cameras 125, 135 (S113 in FIG. 5).

Based on information from the imaging cameras 125, 135, the arithmetic control unit 140 finds the positions of the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10 in the X-axis direction and the Y-axis direction (S114 in FIG. 5).

Then, the arithmetic control unit 140 calculates the positions of such center axes 10ai to 10di in the X-axis direction and the Y-axis direction (see FIG. 6) that the mutually facing blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 can be coaxial with each other with the smallest amounts of movement so that the positions of the mutually facing blank holes 11A to 11D, 12A to 12D in the X-axis direction and the Y-axis direction can coincide with each other, that is, the offset between their axes can be eliminated (S115 in FIG. 5).

Thereafter, the arithmetic control unit 140 calculates the distance (pitch) between each two center axes of interest among the center axes 10ai to 10di, in particular, four pitches in total including the pitch between the center axes 10ai, 10bi, the pitch between the center axes 10bi, 10ci, the pitch between the center axes 10ci, 10di, the pitch between the center axes 10ai, 10di (S116 in FIG. 5). The arithmetic control unit 140 then determines whether or not all of these pitches are less than or equal to their respective prescribed values (tolerances) (S117 in FIG. 5).

If all of the pitches are less than or equal to their respective prescribed values (tolerances), the imaging cameras 125, 135, which are attached to the spindles 124, 134, are changed to tools for cutting or the like such as milling cutters (S118 in FIG. 5).

Then, the arithmetic control unit 140 controls the actuation of the drive motors 113, 126, 127, 136, 137 to move the table 112 in the X-axis direction and move the spindles 124, 134 in the Y-axis direction and the Z-axis direction and controls the actuation of the drive motors 128, 138 to rotationally drive the spindles 124, 134 such that the blank holes 11A to 11D, 12A to 12D are worked and adjusted by cutting cut with the tools into worked holes 10A to 10D having their axes on the center axes 10ai to 10di (S119 in FIG. 5).

On the other hand, if even one of the pitches does not satisfy its prescribed value (tolerance), the arithmetic control unit 140 calculates minimized values satisfying Inequalities (1111-1) to (1114-1) (1141-1) to (1144-1) below based on Equations (1101), (1111) to (1114), (1141) to (1144) below, that is, the arithmetic control unit 140 calculates optimized positions of the center axes 10ai to 10di in the X-axis direction and the Y-axis direction, in other words, optimized positions of the axes of the worked holes 10A to 10D (S121 in FIG. 5).F(OX_a,OX_b,OX_c,OX_d,OY_a,OY_b,OY_c,OY_d)=(WP_AB×ΔP_AB²)+(WP_BC×ΔP_BC²)+(WP_CD×ΔP_CD²)+(WP_AD×ΔP_AD²)+(WQ_A×ΔQ_A²)+(WQ_B×ΔQ_B²)+(WQ_C×ΔQ_C²)+(WQ_D×ΔQ_D²)  (1101)ΔP_AB={(OX_b−OX_a)²+(OY_b−OY_a)²}^1/2−P_AB  (1111)ΔP_SC={(OX_c−OX_b)²+(OY_c−OY_b)²}^1/2−P_BC  (1112)ΔP_CD={(OX_d−OX_c)²+(OY_d−OY_c)²}^1/2−P_CD  (1113)ΔP_AD={(OX_a−OX_d)²+(OY_a−OY_d)²}^1/2−P_AD  (1114)ΔP_AB≤EP_AB  (1111-1)ΔP_BC≤EP_BC  (1111-2)ΔP_CD≤EP_CD  (1111-3)ΔP_DA≤EP_DA  (1111-4)ΔQ_A={(OX_a−MX_ai)²+(OY_a−MY_ai)²}^1/2  (1141)ΔQ_B={(OX_b−MX_bi)²+(OY_b−MY_bi)²}^1/2  (1142)ΔQ_C={(OX_c−MX_ci)²+(OY_c−MY_ci)²}^1/2  (1143)ΔQ_D={(OX_d−MX_di)²+(OY_d−MY_di)²}^1/2  (1144)ΔQ_A≤EQ_A  (1141-1)ΔQ_B≤EQ_B  (1142-1)ΔQ_C≤EQ_C  (1143-1)ΔQ_D≤EQ_D  (1144-1)

Now, the above values will be described.

MX_ai is the position of the center axis 10ai in the X-axis direction. MY_ai is the position of the center axis 10ai in the Y-axis direction. MX_bi is the position of the center axis 10bi in the X-axis direction. MY_bi is the position of the center axis 10bi in the Y-axis direction. MX_ci is the position of the center axis 10ci in the X-axis direction. MY_ci is the position of the center axis 10ci in the Y-axis direction. MX_di is the position of the center axis 10di in the X-axis direction. MY_di is the position of the center axis 10di in the Y-axis direction. These are values calculated by the arithmetic control unit 140 based on the information from the imaging cameras 125, 135 such that the positions of the axes of the mutually facing blank holes 11A to 11D, 12A to 12D can coincide with each other, as described above.

OX_a is the position of the axis of the worked hole 10A in the X-axis direction. OY_a is the position of the axis of the worked hole 10A in the Y-axis direction. OX_b is the position of the axis of the worked hole 103 in the X-axis direction. OY_b is the position of the axis of the worked hole 10B in the Y-axis direction. OX_c is the position of the axis of the worked hole 100 in the X-axis direction. OY_c is the position of the axis of the worked hole 100 in the Y-axis direction. OX_d is the position of the axis of the worked hole 10D in the X-axis direction. OY_d is the position of the axis of the worked hole 10D in the Y-axis direction. These are values calculated by the arithmetic control unit 140 based on Equations (1101), (1111) to (1114), (1141) to (1144) and Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) above.

P_AB is the designed axis-to-axis distance (pitch) between the worked hole 10A and the worked hole 103. P_BC is the designed axis-to-axis distance (pitch) between the worked hole 10B and the worked hole 100. P_CD is the designed axis-to-axis distance (pitch) between the worked hole 100 and the worked hole 10D. P_AD is the designed axis-to-axis distance (pitch) between the worked hole 10A and the worked hole 10D. These are values inputted in advance in the arithmetic control unit 140.

ΔP_AB is the difference (pitch error) between the calculated axis-to-axis distance (pitch) between the axes of the worked hole 10A and the worked hole 10B and P_AB mentioned above. ΔP_BC is the difference (pitch error) between the calculated axis-to-axis distance (pitch) between the axes of the worked hole 10B and the worked hole 10C and P_BC mentioned above. ΔP_CD is the difference (pitch error) between the calculated axis-to-axis distance (pitch) between the axes of the worked hole 10C and the worked hole 10DC and P_CD mentioned above. ΔP_AD is the difference (pitch error) between the calculated axis-to-axis distance (pitch) between the axes of the worked hole 10A and the worked hole 10D and P_AD mentioned above. These are values calculated by the arithmetic control unit 140.

ΔQ_A is the length (amount of offset) between the center axis 10ai and the calculated axis of the worked hole 1-0A. ΔQ_B is the length (amount of offset) between the center axis 10bi and the calculated axis of the worked hole 10B. ΔQ_C is the length (amount of offset) between the center axis 10ci and the calculated axis of the worked hole 100. ΔQ_D is the length (amount of offset) between the center axis 10di and the calculated axis of the worked hole 10D. These are values calculated by the arithmetic control unit 140.

EP_AB is a tolerance for the pitch error between the worked holes 10A, 10B. EP_BC is a tolerance for the pitch error between the worked holes 10B, 10C. EP_CD is a tolerance for the pitch error between the worked holes 10C, 10D. EP_AD is a tolerance for the pitch error between the worked holes 10A, 10D. These are values inputted in advance in the arithmetic control unit 140.

EQ_A is a tolerance for the amount of offset between the center axis 10ai and the axis of the worked hole 10A. EQ_B is a tolerance for the amount of offset between the center axis 10bi and the axis of the worked hole 10B. EQ_C is a tolerance for the amount of offset between the center axis 10ci and the axis of the worked hole 100. EQ_D is a tolerance for the amount of offset between the center axis 10di and the axis of the worked hole 10D. These are values inputted in advance in the arithmetic control unit 140.

WP_AB is a weight coefficient for ΔP_AB mentioned above. WP_BC is a weight coefficient for ΔP_BC mentioned above. WP_CD is a weight coefficient for ΔP_CD mentioned above. WP_AD is a weight coefficient for ΔP_AD mentioned above. These are values greater than or equal to 0 set as appropriate in accordance with various conditions.

WQ_A is a weight coefficient for ΔQ_A mentioned above. WQ_B is a weight coefficient for ΔQ_B mentioned above. WQ_C is a weight coefficient for ΔQ_C mentioned above. WQ_D is a weight coefficient for ΔQ_D mentioned above. These are values greater than or equal to 0 set as appropriate in accordance with various conditions.

Here, assume for example that the tolerances EP_AB, EP_BC, EP_cD, EP_AD for the pitch errors are each set at ±5 mm and the tolerances EQ_A, EQ_B, EQ_C, EQ_D for the amounts of offset are each set at 2.5 mm, and that the pitch errors ΔP_AB, ΔP_BC, ΔP_CD, ΔP_AD and the amounts of offset ΔQ_A to ΔQ_D which do not satisfy their respective Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) are obtained as a result of calculating MX_ai to MX_di, MY_ai to MY_di mentioned above based on the information from the imaging cameras 125, 135 and calculating Equations (1101), (1111) to (1114), (1141) to (1144) mentioned above with the weight coefficients WP_AB, WP_BC, WP_CD, WP_AD, WQ_A to WQ_D each set at “1.” In this case, the above values are calculated by gradually increasing (e.g. by 0.1) the weight coefficients WP_AB, WP_BC, WP_CD, WP_AD, WQ_A to WQ_D for the pitch errors ΔP_AB, ΔP_BC, ΔP_CD, ΔP_AD and amounts of offset ΔQ_A TO ΔQ_D until they satisfy Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) (see Optimization Example 1 in Tables 1 to 4 below).

Also, assume for example that the pitch errors ΔP_AB, ΔP_BC, ΔP_CD, ΔP_AD and the amounts of offset ΔQ_A TO ΔQ_D which do not satisfy their respective Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) are obtained as a result of calculating Equations (1101), (1111) to (1114), (1141) to (1144) mentioned above with the weight coefficients WQ_A to WQ_D for the amounts of offset ΔQ_A to ΔQ_D each set at “1” and the weight coefficients WP_AB, WP_BC, WP_CD, WP_AD for the pitch errors ΔP_AB, ΔP_BC, ΔP_CD, ΔP_AD each set at “0” in an attempt to reduce the amounts of offset ΔQ_A to ΔQ_D as much as possible, that is, to leave the removal stocks as much as possible. In this case, the above values are calculated by gradually increasing (e.g. by 0.1) the weight coefficients WQ_A to WQ_D for the pitch errors ΔP_AB, ΔP_BC, ΔP_CD, ΔP_AD until they satisfy Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) (see Optimization Example 2 in Tables 1 to 4 below).

Also, for example, as illustrated in FIG. 7, if the worked hole 100 is formed in each bracket portion 11c, 12c on a positive side relative to the blank hole 11C, 12C in the X-axis direction and the Y-axis direction (the rightward direction and the upward direction of FIG. 7), strength may possibly decrease. In this case, the above values are calculated such that Inequalities (1143-2), (1143-3) below are also satisfied (see Optimization Example 3 in Tables 1 to 4 below).OX_c≤MX_ci  (1143-2)OY_c≤MY_ci  (1143-3)

TABLE 1
	Calculated	Optimization	Optimization	Optimization
Position	Value	Example 1	Example 2	Example 3
MXai	497.762
MYai	496.657
MXbi	2502.737
MYbi	1502.044
MXci	4497.585
MYci	2002.928
MXdi	7498.608
MYdi	499.319
OXa		498.866	498.471	498.562
OYa		498.004	497.427	497.557
OXb		2501.446	2502.026	2501.937
OYb		1500.698	1501.275	1501.244
OXc		4497.888	4497.732	4497.585
OYc		2002.026	2002.413	2002.128
OXd		7498.492	7498.463	7498.508
OYd		500.221	499.835	500.119
Unit: mm

TABLE 2
Axis-to-Axis	Designed	Calculated	Optimization	Optimization	Optimization
Distance (Pitch)	Value	Value	Example 1	Example 2	Example 3
PAB	2236.068
PBC	2061.553
PCD	3354.102
PAD	7000.000
{(MXbi − MXai)2 +		2242.928
(MYbi − MYai)2}1/2
{(MXci − MXbi)2 +		2056.771
(MYci − MYbi)2}1/2
{(MXdi − MXci)2 +		3356.632
(MYdi − MYci)2}1/2
{(MXai − MXdi)2 +		7000.846
(MYai − MYdi)2}1/2
{(OXb − OXa)2 +			2239.581	2240.808	2240.736
(OYb − OYa)2}1/2
{(OXc − OXb)2 +			2058.424	2057.609	2057.547
(OYc − OYb)2}1/2
{(OXd − OXc)2 +			3355.450	3356.081	3355.826
(OYd − OYc)2}1/2
{(OXa − OXd)2 +			6999.627	6999.946	6999.946
(OYa − OYd)2}1/2
Unit: mm

TABLE 3
Axis-to-Axis
Distance		Calculated	Optimization	Optimization	Optimization
(Pitch) Error	Tolerance	Value	Example 1	Example 2	Example 3
EPAB	±5
EPBC	±5
EPCD	±5
EPAD	±5
{(MXbi − MXai)2 +		6.860
(MYbi − MYai)2}1/2 −
AB
{(MXci − MXbi)2 +		−4.782
(MYci − MYbi)2}1/2 −
BC
{(MXdi − MXci)2 +		2.530
(MYdi − MYci)2}1/2 −
CD
{(MXai − MXdi)2 +		0.846
(MYai − MYdi)2}1/2 −
AD
ΔPAB			3.513	4.740	4.668
ΔPBC			−3.129	−3.944	−4.006
ΔPCD			1.348	1.979	1.724
ΔPAD			−0.373	−0.054	−0.054
Unit: mm

TABLE 4
	Tol-	Optimization	Optimization	Optimization
Amount of Offset	erance	Example 1	Example 2	Example 3
EQA	X-Axis	2.500
	Direction
	Y-Axis	2.500
	Direction
EQB	X-Axis	2.500
	Direction
	Y-Axis	2.500
	Direction
EQC	X-Axis	2.500
	Direction
	Y-Axis	2.500
	Direction
EQD	X-Axis	2.500
	Direction
	Y-Axis	2.500
	Direction
ΔQA	OXa − MXai		1.104	0.709	0.800
	OYa − MYai		1.347	0.770	0.900
ΔQB	OXb − MXbi		−1.290	−0.711	−0.800
	OYb − MYbi		−1.347	−0.770	−0.800
ΔQC	OXc − MXci		0.302	0.146	0.000
	OYc − MYci		−0.902	−0.516	−0.800
ΔQD	OXd − MXdi		−0.116	−0.145	−0.100
	OYd − MYdi		0.902	0.516	0.800
Unit: mm

As can be seen from Tables 1 to 4, even when the pitch error between the worked holes 10A, 10B (6.860 mm) exceeds its tolerance (±5 mm), the amount of offset can be reduced to or below the tolerance (2.5 mm) and the pitch error can also be reduced to or below the tolerance (i.e. to 3.513 mm), as illustrated in Optimization Example 1 above.

Further, as illustrated in Optimization Example 2 above, the pitch error (6.860 mm) between the worked holes 10A, 10B can of course be reduced to or below the tolerance (i.e. to 4.740 mm), and the amount of offset can also be reduced to a greater extent than in Optimization Example 1.

Furthermore, as illustrated in Optimization Example 3 above, the pitch error between the worked holes 10A, 10B (6.860 mm) can be reduced to or below the tolerance (i.e. to 4.668 mm) without positioning the worked hole 10C on the positive side relative to each blank hole 11C, 12C in the X-axis direction and the Y-axis direction (the rightward direction and the upward direction of FIG. 7), that is, without making OX_c−MX_ci, and OY_c−MY_ci positive values. Thus, the decrease in strength of the worked hole 10C can be reduced.

After the arithmetic control unit 140 calculates the optimized positions of the worked holes 10A to 10D as described above, the imaging cameras 125, 135, which are attached to the spindles 124, 134, are changed to tools for cutting or the like such as milling cutters (S122 in FIG. 5).

Then, based on the above calculated results, the arithmetic control unit 140 actuates the drive motors 113, 126, 127, 128, 136, 137, 138 to cut the blank holes 11A to 112, 12A to 12D with the tools to expand their diameters, sc that the blank holes 11A to 11D, 12A to 12D are worked and adjusted into the worked holes 10A to 10D in the boom 10 (S123 in FIG. 5).

The boom 10 with the blank holes 11A to 11D, 12A to 12D worked and adjusted into the worked holes 10A to 10D as described above has all the pitch errors less than or equal to their respective tolerances. Hence, components such as hydraulic cylinders can be joined between the worked holes 10A to 10D without problems at all.

Thus, with the machine tool 100 according to this embodiment, even when the boom 10 has a pitch error greater than or equal to its tolerance, the worked holes 10A to 10D can be worked and adjusted to such optimized positions that all the pitch errors are less than or equal to their respective tolerances. In this way, defective products can be greatly reduced.

Second Embodiment

A second embodiment of the machine tool according to the present invention will be described with reference to FIGS. 8 to 11. Note that, for the same portions as those in the foregoing embodiment, the same reference signs as the reference signs used in the description of the foregoing embodiment will be used, and therefore description overlapping the description in the foregoing embodiment will be omitted.

As illustrated in FIG. 8, the imaging cameras 125, 135 and the input unit 141 are electrically connected to an input part of an arithmetic control unit 240, which serves as arithmetic control means. An output part of the arithmetic control unit 240 is electrically connected to the drive motors 113, 126 to 128, 136 to 138.

The arithmetic control unit 24C is capable of controlling the actuation of the drive motors 113, 126 to 128, 136 to 138 based on information from the input unit 141 and information inputted in advance, and of performing arithmetic operation for controlling the actuation of the drive motors 113, 126, 127, 136, 137 based on information from the imaging cameras 125, 135 and information inputted in advance (details will be described later).

Next, description will be given of actuation of a machine tool according to this embodiment including the above arithmetic control unit 240.

As in the foregoing embodiment, after performing Steps S111, S112 described above, the input unit 141 inputs information into the arithmetic control unit 240 which instructs imaging of the protruding portions 11a, 11b, 11d, 12a, 12b, 12d and the bracket portions 11c, 12c of the plate members 11, 12 of the boom 10 as well as the blank holes 11A to 11D, 12A to 12D with the imaging cameras 125, 135. In response, the arithmetic control unit 240 actuates the drive motors 113, 126, 127, 136, 137 to move the table 112 in the X-axis direction and move the spindles 124, 134 in the Y-axis direction and the Z-axis direction such that the protruding portions 11a, 11b, 11d, 12a, 12b, 12d and the bracket portions 11c, 12c of the plate members 11, 12 of the boom 10 as well as the blank holes 11A to 11D, 12A to 12D can be imaged with the imaging cameras 125, 135 (S213 in FIG. 9).

Based on information from the imaging cameras 125, 135, the arithmetic control unit 240 finds the positions of the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10 in the X-axis direction and the Y-axis direction and the positions of the protruding portions 11a, 11b, 11d, 12a, 12b, 12d in the X-axis direction and the Y-axis direction. The arithmetic control unit 240 further finds the positions of the axes of round portions 11ca, 12ca of the protruding ends of the bracket portions 11c, 12c in the X-axis direction and the Y-axis direction (S214 in FIG. 9).

Then, the arithmetic control unit 240 calculates the positions of the center axes 10ai to 10di in the X-axis direction and the Y-axis direction as in the foregoing embodiment. In addition, the arithmetic control unit 240 calculates the positions, in the X-axis direction and the Y-axis direction, of such center axes that the mutually facing protruding portions 11a, 11b, 11d, 12a, 12b, 12d of the plate members 11, 12 can be coaxial with each other with the smallest amounts of movement, specifically, the positions, in the X-axis direction and the Y-axis direction, of center axes 10ao, 10bo, 10do of circular areas where the worked holes 10A, 10B, 10D can be formed (see FIG. 10). The arithmetic control unit 240 further calculates the positions, in the X-axis direction and the Y-axis direction, of such a center axis that the round portions 11ca, 12ca of the protruding ends of the mutually facing bracket portions 11c, 12c can be coaxial with each other with the smallest amounts of movement, specifically, the positions, in the X-axis direction and the Y-axis direction, of a center axis 10co of a circular area where the worked hole 10C can be formed (see FIG. 11) (S215 in FIG. 9).

Thereafter, as in the foregoing embodiment, the arithmetic control unit 240 calculates the pitch between each two center axes of interest among the center axes 10ai to 10di (S116 in FIG. 9). The arithmetic control unit 240 then determines whether or not all of these pitches are less than or equal to their respective prescribed values (tolerances) (S117 in FIG. 9).

If all of the pitches are less than or equal to their respective prescribed values (tolerances), Steps S118, S119 described above are performed as in the foregoing embodiment.

On the other hand, if even one of the pitches does not satisfy its prescribed value (tolerance), the arithmetic control unit 240 calculates minimized values satisfying Inequalities (1111-1) to (1114-1), (1141-1) to (1144-1) above and Inequalities (2151-1) to (2154-1) below based on Equation (2101) below, Equations (1111) to (1114), (1141) to (1144) above as well as Equations (2151) to (2154) below, that is, the arithmetic control unit 240 calculates optimized positions of the center axes 10ai to 10di in the X-axis direction and the Y-axis direction, in other words, optimized positions of the axes of the worked holes 10A to 10D (S221 in FIG. 9).F(OX_a,OX_b,OX_c,OX_d,OY_a,OY_b,OY_c,OY_d)=(WP_AB×ΔP_AB²)+(WP_BC×ΔP_BC²)+(WP_CD×ΔP_CD²)+(WP_AD×ΔP_AD²)+(WQ_A×ΔQ_A²)+(WQ_B×ΔQ_B²)+(WQ_C×ΔQ_C²)+(WQ_D×ΔQ_D²)+(WT_A×ΔT_A²)+(WT_B×ΔT_B²)+(WT_C×ΔT_C²)+(WT_D×ΔT_D²)  (2101)ΔT_A={(OX_a−MX_ao)²+(OY_a−MY_ao)²}^1/2  (2151)ΔT_B={(OX_b−MX_bo)²+(OY_b−MY_bo)²}^1/2  (2152)ΔT_C={(OX_c−MX_co)²+(OY_c−MY_co)²}^1/2  (2153)ΔT_D={(OX_d−MX_do)²+(OY_d−MY_do)²}^1/2  (2154)ΔT_A≤E_TA  (2151-1)ΔT_B≤E_TB  (2151-2)ΔT_C≤E_TC  (2151-3)ΔT_D≤E_TD  (2151-4)

MX_ao is the position of the center axis 10ao in the X-axis direction. MY_ao is the position of the center axis 10ao in the Y-axis direction. MX_bo is the position of the center axis 10bo in the X-axis direction. MY_bo is the position of the center axis 10bo in the Y-axis direction. MX_co is the position of the center axis 10co in the X-axis direction. MY_co is the position of the center axis 10co in the Y-axis direction. MX_do is the position of the center axis 10do in the X-axis direction. MY_do is the position of the center axis 10do in the Y-axis direction. These are values calculated by the arithmetic control unit 240 based on the information from the imaging cameras 125, 135 such that the positions of the axes of the mutually facing protruding portions 11a, 11b, 11d, 12a, 12b, 12d can coincide with each other and the positions of the axes of the round portions of the protruding ends of the bracket portions 11c, 12c can coincide with each other, as described above.

ΔT_A is the length (amount of eccentricity) between the center axis 10ao and the calculated axis of the worked hole 10A. ΔT_B is the length (amount of eccentricity) between the center axis 10bo and the calculated axis of the worked hole 10B. ΔT_c is the length (amount of eccentricity) between the center axis 10co and the calculated axis of the worked hole 10C. ΔT_D is the length (amount of eccentricity) between the center axis 10do and the calculated axis of the worked hole 10D. These are values calculated by the arithmetic control unit 240.

ET_A is a tolerance for the amount of eccentricity between the center axis 10ao and the axis of the worked hole 10A. ET_B is a tolerance for the amount of eccentricity between the center axis 10bo and the axis of the worked hole 10B. ET_C is a tolerance for the amount of eccentricity between the center axis 10co and the axis of the worked hole 10C. ET_D is a tolerance for the amount of eccentricity between the center axis 10do and the axis of the worked hole 10D. These are values inputted in advance in the arithmetic control unit 240.

WT_A is a weight coefficient for ΔT_A mentioned above. WT_B is a weight coefficient for ΔT_B mentioned above. WT_C is a weight coefficient for ΔT_C mentioned above. WT_D is a weight coefficient for ΔT_D mentioned above. These are values greater than or equal to 0 set as appropriate in accordance with various conditions.

In sum, this embodiment takes into consideration not only the amounts of offset of the worked holes 10A to 10D relative to the blank holes 11A to 11D, 12A to 12D but also the amounts of eccentricity relative to the protruding portions 11a, 11b, 11d, 12a, 12b, 12d and the round portions of the bracket portions 11c, 12c.

After this arithmetic control unit 240 calculates the optimized positions of the worked holes 10A to 10D as in the foregoing embodiment, Steps S122, S123 described above are performed. As a result, the blank holes 11A to 11D, 12A to 12D can be worked and adjusted into the worked holes 10A to 10D in the boom 10.

Thus, for the worked holes 10A, 10B, 10D, the amounts of unevenness in the thicknesses of the protruding portions 11a, 11b, 11d, 12a, 12b, 12d in the radial direction can be optimized. For the worked hole 100, the stock allowances for the protruding ends of the bracket portions 11c, 12c can be optimized.

Hence, with this embodiment, it is possible to achieve similar advantageous effects to those by the foregoing embodiment and, in addition, more effectively reduce the decrease in strength of the protruding portions 11a, 11b, 11d, 12a, 12b, 12d and the bracket portions 11c, 12c due to the formation of the worked holes 10A to 10D.

Other Embodiments

In the foregoing embodiments, the imaging cameras 125, 135 are used to input the information on the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10, the information on the protruding portions 11a, 11b, 11d, 12a, 12b, 12d, the information on the bracket portions 11c, 12c, and other relevant information into the arithmetic control units 140, 240. Note however that, as another embodiment, it is possible to use, for example, touch probes or the like in place of the imaging cameras 125, 135 to input the information on the blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10, the information on the protruding portions 11a, 11b, 11d, 12a, 12b, 12d, the information on the bracket portions 11c, 12c, and other relevant information into the arithmetic control units 140, 240.

Also, the foregoing embodiments have described the cases where the present invention is applied to a table moving-type horizontal boring and milling machine with counter spindles. However, as another embodiment, it is possible to apply the present invention to, for example, a column moving-type horizontal boring and milling machine with counter spindles. In this case, too, similar advantageous effects to those by the foregoing embodiments can be achieved.

Also, the foregoing embodiments have described the cases where the mutually facing blank holes 11A to 11D, 12A to 12D in the plate members 11, 12 of the boom 10 of the excavator are worked and adjusted into the worked holes 10A to 10D by cutting the blank holes 11A to 11D, 12A to 12D to expand their diameters. However, the present invention is not limited to these cases and is applicable just as the foregoing embodiments to cases where n blank holes (n is an integer greater than or equal to 3) formed in a workpiece are to be worked and adjusted into worked holes by cutting the blank holes to expand their diameters.

In the case of such a workpiece, the arithmetic control means calculates optimized positions of the worked holes from minimized values satisfying Inequalities (110-1), (120-1), (130-1), (140-1), (150-1) below based on Equations (100), (110), (120), (130), (140), (150) below.

$\begin{array}{cc}\left[\mathrm{Formula}2\right]& \\ \mathrm{Fn}\left({\mathrm{OX}}_1,{\mathrm{OX}}_2,\dots ,{\mathrm{OX}}_n,{\mathrm{OY}}_1,{\mathrm{OY}}_2,\dots {\mathrm{OY}}_n\right)=\frac{1}{2}*\sum _{k=1}^n\sum _{\underset{m\ne k}{m=1}}^n\left({\mathrm{WP}}_{\mathrm{km}}*\Delta P_{\mathrm{km}}^2+{\mathrm{WX}}_{\mathrm{km}}*\Delta X_{\mathrm{km}}^2+{\mathrm{WY}}_{\mathrm{km}}*\Delta Y_{\mathrm{km}}^2\right)+\sum _{k=1}^n\left({\mathrm{WQ}}_k*\Delta Q_k^2+{\mathrm{WT}}_k*\Delta T_k^2\right)& \left(100\right)\\ \Delta P_{\mathrm{km}}=\sqrt{{\left({\mathrm{OX}}_m-{\mathrm{OX}}_k\right)}^2+{\left({\mathrm{OY}}_m-{\mathrm{OY}}_k\right)}^2}-P_{\mathrm{km}}& \left(110\right)\\ \Delta P_{\mathrm{km}}\le {\mathrm{EP}}_{\mathrm{km}}& \left(110\text{-}1\right)\\ \Delta X_{\mathrm{km}}=\left({\mathrm{OX}}_m-{\mathrm{OX}}_k\right)-\left({\mathrm{OX}}_{\mathrm{ms}}-{\mathrm{OX}}_{\mathrm{ks}}\right)& \left(120\right)\\ \Delta X_{\mathrm{km}}\le {\mathrm{EX}}_{\mathrm{km}}& \left(120\text{-}1\right)\\ \Delta Y_{\mathrm{km}}=\left({\mathrm{OY}}_m-{\mathrm{OY}}_k\right)-\left({\mathrm{OY}}_{\mathrm{ms}}-{\mathrm{OY}}_{\mathrm{ks}}\right)& \left(130\right)\\ \Delta Y_{\mathrm{km}}\le {\mathrm{EY}}_{\mathrm{km}}& \left(130\text{-}1\right)\\ \Delta Q_k=\sqrt{{\left({\mathrm{OX}}_k-{\mathrm{MX}}_{\mathrm{ki}}\right)}^2+{\left({\mathrm{OY}}_k-{\mathrm{MY}}_{\mathrm{ki}}\right)}^2}& \left(140\right)\\ \Delta Q_k\le {\mathrm{EQ}}_k& \left(140\text{-}1\right)\\ \Delta T_k=\sqrt{{\left({\mathrm{OX}}_k-{\mathrm{MX}}_{\mathrm{ko}}\right)}^2+{\left({\mathrm{OY}}_k-{\mathrm{MY}}_{\mathrm{ko}}\right)}^2}& \left(150\right)\\ \Delta T_k\le {\mathrm{ET}}_k& \left(150\text{-}1\right)\end{array}$

In the above equations and inequalities, MX_ki is the position of the center axis of a blank hole G_k in the X-axis direction; MY_ki is the position of the center axis of the blank hole G_k in the Y-axis direction; MX_ko is the position, in the X-axis direction, of the center axis of a circular area where a worked hole H_k is capable of being formed by working and adjusting the blank hole G_k; MY_ko is the position, in the Y-axis direction, of the center axis of the circular area where the worked hole H_k is capable of being formed by working and adjusting the blank hole G_k; OX_k is the position of the axis of the worked hole H_k in the X-axis direction; OY_k is the position of the axis of the worked hole H_k in the Y-axis direction; OX_ks is the designed position of the axis of the worked hole H_k in the X-axis direction; OY_ks is the designed position of the axis of the worked hole H_k in the Y-axis direction; OX_m is a position of an axis of the worked hole H_m in the X-axis direction, OY_m is a position of the axis of the worked hole H_m in the Y-axis direction, OX_ms is the designed position of the axis of a worked hole H_m in the X-axis direction; OY_ms is the designed position of the axis of the worked hole H_m in the Y-axis direction; P_km is the designed pitch between the worked holes H_k, H_m; ΔP_km is the calculated pitch error between the worked holes H_k, H_m; ΔX_km is the axis-to-axis error between the worked holes H_k, H_m in the X-axis direction; ΔY_km is the axis-to-axis error between the worked holes H_k, H_m in the Y-axis direction; ΔQ_k is the amount of offset between the center axis of the blank hole G_k and the calculated axis of the worked hole H_k; ΔT_k is the length between the center axis of the circular area where the worked hole H_k is capable of being formed and the calculated axis of the worked hole H_k; EP_km is a tolerance for the pitch error between the worked holes H_K, H_m; EX_km is a tolerance for the axis-to-axis error between the worked holes H_k, H_m in the X-axis direction; EY_km is a tolerance for the axis-to-axis error between the worked holes H_k, H_m in the Y-axis direction; EQ_k is a tolerance for the amount of offset between the center axis of the blank hole G_k and the axis of the worked hole H_k; ET_k is a tolerance for the length between the center axis of the circular area where the worked hole H_k is capable of being formed and the axis of the worked hole H_k; WP_km is a weight coefficient for ΔP_km; WX_km is a weight coefficient for ΔX_km; WY_km is a weight coefficient for ΔY_km; WQ_k weight coefficient for ΔQ_k; and WT_k is a weight coefficient for ΔT_k.

Here, ΔP_km mentioned above is the error in the axis-to-axis distance between the worked holes H_k, H_m. On the other hand, ΔX_km, ΔY_km mentioned above are the axis-to-axis errors between the worked holes H_k, H_m in the X- and Y-axis directions, and are values employed in a case where the error between the axes of the worked holes H_k, H_m in the X-axis direction and the error between the axes of the worked holes H_k, H_m in the Y-axis direction are considered individually or only one of these errors in the X-axis direction and the Y-axis direction should be considered.

In short, the foregoing first and second embodiments are cases where n is set at “4,” the amount of offset between the worked holes 10A, 100 and the amount of offset between the worked holes 10B, 10D are omitted, WX_km, WY_km are set at “0,” and, in the foregoing first embodiment, WT_k is set at “0.”

As described above, the present invention can handle various cases by optionally selecting, when necessary, those worked holes between which the pitch error is desired to be less than or equal to the tolerance, and optionally selecting various conditions (setting weight coefficients for unnecessary conditions at “0”) in accordance with the state of the workpiece.

INDUSTRIAL APPLICABILITY

Even in the case of a workpiece with a pitch error greater than or equal to its tolerance between worked holes, the machine tool according to the present invention can work and adjust the worked holes to such optimized positions that all the pitch errors can be less than or equal to their respective tolerances. In this way, defective products can be greatly reduced. The machine tool according to the present invention can therefore be utilized significantly beneficially in various working industries.

REFERENCE SIGNS LIST

• 10 boom
• 10 ai to 10di, 10ao to 10do center axis
• 10A to 10D worked hole
• 11, 12 plate member
• 11 a, 11b, 11d, 12a, 12b, 12d protruding portion
• 11 c, 12c bracket portion
• 11 ca, 12ca round portion
• 11A to 11D, 12A to 12D blank hole
• 13 joint member
• 100 machine tool
• 111 bed
• 112 table
• 113 drive motor (for X-axis movement)
• 121, 131 bed
• 122, 132 column
• 123, 133 spindle head
• 124, 134 spindle
• 125, 135 imaging camera
• 126, 136 drive motor (for Y-axis movement)
• 127, 137 drive motor (for Z-axis movement)
• 128, 138 drive motor (for cutting)
• 140, 240 arithmetic control unit
• 141 input unit

Claims

1. A machine tool for working and adjusting n blank holes, n is an integer greater than or equal to 3, formed in a workpiece into worked holes by cutting the blank holes to expand diameters thereof, comprising: a table on which the workpiece is placed;a spindle capable of detachably holding a tool for cutting the blank holes in the workpiece and measurement means for measuring positions of the blank holes in the workpiece where the tool and the measurement means are capable of being changed from one another;a spindle drive means for rotationally driving the spindle;a relative movement means for moving at least one of the table and the spindle to move the tool and the measurement means relative to the workpiece in an X-axis direction, a Y-axis direction, and a Z-axis direction; andarithmetic control unit that controls the relative movement means such that the positions of the blank holes in the workpiece are measured with the measurement means held on the spindle,calculates positions of center axes of the blank holes based on information on the positions of the blank holes measured with the measurement means,calculates a distance between each two center axes of interest among the center axes, andin a case where at least one of the calculated distances does not satisfy a prescribed value, the arithmetic unit calculates optimized positions of the worked holes from minimized values satisfying Inequalities: ΔPkm≤EPkm, ΔXkm≤EXkm, ΔYkm≤EYkm, ΔQk≤EQk, ΔTk≤ETk below based on Equations:

2. The machine tool according to claim 1, wherein the workpiece is a boom of an excavator.

3. The machine tool according to claim 1, wherein the machine tool is a horizontal boring and milling machine with counter spindles.

4. The machine tool according to claim 1, wherein the measurement means is any one of an imaging camera and a touch sensor.