feeding device

Abstract

Provided are two guide rails (15, 16) arranged in parallel along a feed direction, sliders (17, 19, 21, 23) provided on the guide rails (15, 16), a moving table (3) on which the sliders (17, 19, 21, 23) are mounted and which moves along the feed direction, and a driving mechanism (11) that moves the moving table (3). Further, provided are a scale arranged on the guide rails (15, 16) along the feed direction, reading heads (18, 20, 22, 24) provided on the sliders (17, 19, 21, 23) respectively and reading information provided to the scale, detecting positions in the feed direction and positions in a direction orthogonal to the feed direction, and a motion error calculation unit (70) that calculates a motion error of the moving table (3) based on position information in the two directions detected by the reading heads (18, 20, 22, 24).

Description

Technical Field

[0001] This invention relates to a feeding device that forms a linear feed axis, and more particularly to a feeding device capable of measuring its own motion error. Background Technology

[0002] Conventionally, for example, there is a known machine tool configured such that a tool-holding spindle and a worktable with a workpiece mounted on it can move relative to each other along three orthogonal axes: the X-axis, Y-axis, and Z-axis. This machine tool includes three feed devices: an X-axis feed device (for the X-axis), a Y-axis feed device (for the Y-axis), and a Z-axis feed device (for the Z-axis). Furthermore, in this type of machine tool, the machining accuracy is affected by the motion accuracy of these feed devices; therefore, it is necessary to appropriately correct these errors by accurately measuring them and controlling them within a certain allowable range.

[0003] In recent years, considering the motion error (positioning error) of working machinery in three-dimensional space, such as... Figure 5 As shown, the errors manifest themselves in the interplay of translational motion errors of each feed axis, angular errors of each feed axis, and errors related to the perpendicularity between each feed axis. Therefore, by calculating these individual errors, the precise motion errors can be identified.

[0004] Previously, as a method for measuring this error, a method using... Figure 6 as well as Figure 7 The measurement method of the measuring device shown. As... Figure 6 The machine tool 100 shown in one example consists of a bed 101 with a workpiece mounting surface (so-called a worktable) on its upper surface, a door-shaped frame 102, and a saddle 103. The frame 102 is arranged such that its horizontal portion is located above the bed 101, and the two vertical portions of the frame 102 are respectively engaged with the sides of the bed 101, allowing the whole machine to move in the Y-axis direction.

[0005] Furthermore, the saddle 103 engages with the horizontal portion of the frame 102, allowing it to move along this horizontal portion in the X-axis direction. The main shaft 104 is held on the saddle 103 in a manner that allows it to move in the Z-axis direction and rotate around an axis parallel to the Z-axis. The X-axis, Y-axis, and Z-axis are mutually orthogonal reference axes, and each feed axis corresponding to these reference axes is constituted by an X-axis feed device (not shown), a Y-axis feed device (not shown), and a Z-axis feed device (not shown).

[0006] The aforementioned errors are measured using a laser length measuring device 105 mounted on the bed 101 and a mirror 110 mounted on the spindle 104. Specifically, firstly, the laser length measuring device 105 is positioned at a predetermined location, for example, in... Figure 6 Four points are shown in solid lines, and the mirror 110 is mounted on the main spindle 104. Next, the X-axis feed device, Y-axis feed device, and Z-axis feed device are positioned at certain intervals, thereby positioning the mirror 110 at each grid point that divides the three-dimensional space into a grid pattern at certain intervals. At each grid point, a laser beam is irradiated onto the mirror 110 from each laser length measuring device 105, and the reflected light is received by the laser length measuring device 105. The distance between the laser length measuring device 105 and the mirror 110 is measured by the laser length measuring device 105.

[0007] Furthermore, based on the measurement data obtained by the above method, according to the principle of trilateration, the position of the mirror 110 at each grid point in three-dimensional space is calculated, and the above errors are calculated by analyzing the calculated position data.

[0008] Furthermore, the laser length measuring device 105 is configured to be capable of using Figure 7 Centering on the reference sphere 106, the laser interferometer 107 rotates and moves, and the laser interferometer 105 rotates and moves along with the mirror 110, thereby automatically tracking the mirror 110.

[0009] However, such a laser length measuring device 105 is very expensive, and it is impractical to use four laser length measuring devices 105 in the above measurement. Therefore, in the past, a single laser length measuring device 105 was used, which was moved and positioned in four locations in sequence. At each location, the mirror 110 was positioned at the respective grid point, and the distance between the laser length measuring device 105 and the mirror 110 was measured.

[0010] However, while using a single laser length measuring device 105 to measure motion errors reduces the cost of the device, it requires repeatedly positioning the mirror 110 at each of the device's locations. This results in a longer measurement time and is also complex and cumbersome. Compared to measurements using four laser length measuring devices 105, measurements using a single device require four times the computation time alone.

[0011] Therefore, the applicant of this application proposed a motion error identification method in the following patent document 1, which uses a laser length measuring device but can identify motion errors in a single operation.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 2019-206043 Summary of the Invention

[0015] The technical problem that the invention aims to solve

[0016] However, in recent years, in the field of machine tools, high-precision scales such as magnetic scales or optical scales have been used in the feeding device to control the feeding device with high precision.

[0017] Therefore, if it is not necessary to prepare an expensive measuring instrument like the laser length measuring device 105, it is not costly to use the existing scale configured in the feeding device to measure the motion error of the feeding device. In addition, the measurement does not require complicated and troublesome preparation work and can measure the motion error of the feeding device with high accuracy, which is very beneficial.

[0018] Furthermore, even if it is not possible to detect all errors of the machine tool, such as translational errors of each feed axis, angular errors of each feed axis, and errors related to the perpendicularity between each feed axis, as long as the minimum required motion error can be easily detected, the machine tool's operating performance over time can be evaluated at appropriate times without significantly reducing its operating rate. Moreover, based on the evaluation results, necessary maintenance and other necessary treatments can be performed on the machine tool in advance.

[0019] The present invention was made in view of the above circumstances, and its object is to provide a feeding device that can efficiently measure its own motion error in a short time.

[0020] Solutions for solving technical problems

[0021] The present invention, which addresses the above-mentioned technical problems, relates to a feeding device comprising:

[0022] Two guide rails are set parallel to each other along the specified feed direction;

[0023] At least four sliders, with at least two of them disposed on each of the guide rails, are freely movable and engage with each of the guide rails along the feed direction.

[0024] A movable stage, on which the sliders are mounted, moves along the feed direction; and

[0025] A drive mechanism that moves the moving stage along the feed direction.

[0026] The feed device is configured by incorporating a scale, a reading head, and a motion error calculation unit.

[0027] The scale is disposed on at least one of the guide rails along the feed direction.

[0028] The reading heads are respectively disposed on the sliders to read the information provided to the scale, detect the position in the feed direction and the position in the direction orthogonal to the feed direction, and the sliders are at least two sliders selected from the at least four sliders and engage with the guide rail on which the scale is disposed.

[0029] The motion error calculation unit calculates the motion error of the mobile station based on the position information detected in two directions by each of the reading heads.

[0030] According to the feeding device of this method (first method), the moving stage is driven by the drive mechanism, and moves along the feeding direction due to the engagement relationship between the guide rail and the slider. Moreover, when the moving stage moves by a predetermined distance, the motion error of the moving stage is calculated by the motion error calculation unit based on the position information in two directions detected by the reading heads provided on the at least two sliders.

[0031] In this way, with this feeding device, it is not necessary to use an expensive measuring instrument such as the laser length measuring device mentioned above. Instead, the existing scale configured on the feeding device can be used to measure the motion error of the feeding device, which will not lead to excessive costs. In addition, the measurement does not require complicated and troublesome preparation work, and the motion error of the feeding device can be measured with high accuracy.

[0032] Furthermore, since the motion performance of the feed device can be easily detected, the operating performance of the machine over time can be evaluated at the appropriate time without significantly reducing the machine's operating rate. Based on the evaluation results, necessary maintenance and other necessary treatments can be performed on the machine in advance.

[0033] Furthermore, in the first type of feeding device, by appropriately setting the guide rail for the scale and the slider for the reading head, the motion error calculation unit can not only derive the collimation and positioning error in the feeding direction, but also various motion errors of the feeding device.

[0034] For example, in the feeding device of the first method, the following method (second method) can be adopted: the scale is arranged on the two guide rails, and the reading head is respectively arranged on the four sliders.

[0035] The motion error calculation unit is configured to calculate the motion error of the mobile station based on the position information detected in two directions by the four reading heads.

[0036] In addition, the feeding device of the second method can be configured in the following manner (third method): two reading heads provided on at least one of the guide rails are configured to detect the position in the first axial direction which is the feeding direction and the position in the second axial direction orthogonal to the first axis in the plane including the two guide rails; and two reading heads provided on another guide rail are configured to detect the position in the first axial direction and the position in the third axial direction orthogonal to the first axis and the second axis.

[0037] Alternatively, in the feeding device of the second method described above, the following method (fourth method) can be adopted: one of the two reading heads disposed on at least one of the guide rails is configured to detect the position in a first axial direction which is the feeding direction and the position in a second axial direction orthogonal to the first axis in a plane including the two guide rails, and the other reading head is configured to detect the position in the first axial direction and the position in a third axial direction orthogonal to the first axis and the second axis.

[0038] Two reading heads are configured on another guide rail to detect the position in the first axis and the position in the third axis.

[0039] Furthermore, in the third and fourth embodiments described above, the following method (fifth embodiment) can be adopted: the motion error calculation unit is configured to calculate at least one error selected from the positioning error (collimation positioning accuracy) on the first axis and the collimation error (collimation) on the second axis in the first axis-second axis plane, the collimation error (collimation) on the third axis in the first axis-third axis plane, the angle error (tilt) about the first axis, the angle error (pitch) about the second axis, and the angle error (yaw) about the third axis.

[0040] In addition, the present invention relates to a working machine having a feeding device of any of the first to fifth embodiments described above.

[0041] Invention Effects

[0042] According to the feeding device of the present invention, it is not necessary to use an expensive measuring device such as the laser length measuring device described above. The motion error of the feeding device can be measured using the existing scale configured on the feeding device, which will not lead to excessive costs. In addition, the measurement does not require complicated and troublesome preparation work, and the motion error of the feeding device can be measured with high accuracy.

[0043] Furthermore, since the motion performance of the feed device can be easily detected, the operating performance of the machine over time can be evaluated at the appropriate time without significantly reducing the machine's operating rate. Based on the evaluation results, necessary maintenance and other necessary treatments can be performed on the machine in advance. Attached Figure Description

[0044] Figure 1 This is a perspective view showing a working machine according to one embodiment of the present invention.

[0045] Figure 2 This is an explanatory diagram showing the general structure of the feeding device involved in this embodiment.

[0046] Figure 3 This is a cross-sectional view showing the guide rail, slider, and scale involved in this embodiment. Figure 2 AA section view in the middle.

[0047] Figure 4 This is a cross-sectional view showing the guide rail, slider, and scale involved in this embodiment. Figure 2 BB section view in the middle.

[0048] Figure 5 This is an explanatory diagram used to illustrate the motion error of a working machine with an orthogonal triaxial feed device.

[0049] Figure 6 This is an explanatory diagram used to illustrate existing methods for measuring motion errors.

[0050] Figure 7 This is an explanatory diagram used to illustrate existing methods for measuring motion errors. Detailed Implementation

[0051] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0052] First, the general structure of the machine tool 1 involved in this embodiment will be described. For example... Figure 1 As shown, the machine tool 1 in this example includes a bed 2 that is T-shaped when viewed from above, a column 3 disposed on one side of the bed 2, a worktable 6 disposed on the other side of the same bed 2, a saddle 4 disposed on the side (front surface) of the column 3 near the worktable 6, a spindle 5 rotatably supported on the saddle 4, a spindle motor (not shown) that rotates the spindle 5, an X-axis feed unit 10 that moves the column 3 along the X-axis (indicated by the arrow), a Y-axis feed unit 30 that moves the saddle 4 along the Y-axis (indicated by the arrow), and a Z-axis feed unit 50 that moves the worktable 6 along the Z-axis (indicated by the arrow). Furthermore, the X-axis, Y-axis, and Z-axis are mutually orthogonal reference axes.

[0053] In addition, such as Figure 2 As shown, the machine tool 1 in this example, in addition to the structure described above, includes a motion error calculation unit 70, an output unit 71, and a control device 75. Furthermore, in this example, the X-axis feed unit 10, the Y-axis feed unit 30, the Z-axis feed unit 50, the column 3, the saddle 4, the worktable 6, the motion error calculation unit 70, and the output unit 71 constitute a single feed device. The detailed structure of each part will be described below.

[0054] First, the X-axis feed unit 10, Y-axis feed unit 30, and Z-axis feed unit 50, which are the motion mechanism units, will be explained. Furthermore, in Figure 2 as well as Figure 3 The diagram shows the X-axis feed section 10 as a representative example, but the Y-axis feed section 30 and the Z-axis feed section 50 have the same structure. The symbols for the same structures are marked with parentheses.

[0055] [X-axis feed unit]

[0056] The X-axis feed unit 10 consists of a pair of guide rails 15 and 16 arranged parallel to the X-axis on the bed 2, two sliders 17 and 19 moving freely along the guide rail 15 and engaging with it, a scale 15a fixed to the upper surface of the guide rail 15 and a scale 15b fixed to the side, reading heads 18 and 20 respectively fixed to the sliders 17 and 19, two sliders 21 and 23 moving freely along the guide rail 16 and engaging with it, a scale 16a fixed to the upper surface of the guide rail 16 and a scale 16b fixed to the side, reading heads 22 and 24 respectively fixed to the sliders 21 and 23, and an X-axis drive mechanism 11 for driving the column 3.

[0057] The scales 15a and 15b, along with the read heads 18 and 20, constitute a linear encoder. Similarly, the scales 16a and 16b, along with the read heads 22 and 24, constitute a linear encoder. This linear encoder can be either magnetic or optical, but a magnetic type is used in this example. Furthermore, each read head 18 and 20 detects the position of sliders 17 and 19 in the X-axis direction and their displacement in the Y and Z-axis directions by reading the scales 15a and 15b. Similarly, read heads 22 and 24 detect the position of sliders 21 and 23 in the X-axis direction and their displacement in the Y and Z-axis directions by reading the scales 16a and 16b.

[0058] The X-axis drive mechanism 11 consists of an X-axis feed motor 12 (which functions as a servo motor), a ball screw 13 driven by the X-axis feed motor 12, a ball nut (not shown) threadedly connected to the ball screw 13 and fixed to the lower surface of the column 3, and bearings 14 (another bearing not shown) that support the two ends of the ball screw 13 for free rotation. The X-axis drive mechanism 11 drives the X-axis feed motor 12 to rotate the ball screw 13, and the column 3 is guided by guide rails 15 and 16 to move along the X-axis.

[0059] [Y-axis feed section]

[0060] The Y-axis feed unit 30 comprises a pair of guide rails 35 and 36 arranged parallel to the Y-axis on the front surface of the column 3, two sliders 37 and 39 moving along the guide rail 35 and engaging with it, a scale 35a fixed to the upper surface of the guide rail 35 and a scale 35b fixed to the side, reading heads 38 and 40 respectively fixed to the sliders 37 and 39, two sliders 41 and 43 moving along the guide rail 36 and engaging with it, a scale 36a fixed to the upper surface of the guide rail 36 and a scale 36b fixed to the side, reading heads 42 and 44 respectively fixed to the sliders 41 and 43, and a Y-axis drive mechanism 31 for driving the column 3.

[0061] The scales 35a and 35b, along with the read heads 38 and 40, constitute a linear encoder. Similarly, the scales 36a and 36b, along with the read heads 42 and 44, constitute a linear encoder. This linear encoder can be either magnetic or optical, but a magnetic type is used in this example. Furthermore, each read head 38 and 40 detects the position of sliders 37 and 39 in the Y-axis direction and their displacement in the Z and X-axis directions by reading the scales 35a and 35b. Similarly, read heads 42 and 44 detect the position of sliders 41 and 43 in the Y-axis direction and their displacement in the Z and X-axis directions by reading the scales 36a and 36b.

[0062] The Y-axis drive mechanism 31 consists of a Y-axis feed motor 32 (which functions as a servo motor), a ball screw 33 driven by the Y-axis feed motor 32, a ball nut (not shown) threadedly connected to the ball screw 33 and fixed to the rear surface of the saddle 4, and bearings 34 (another bearing not shown) that support the two ends of the ball screw 33 for free rotation. The Y-axis drive mechanism 31 drives the Y-axis feed motor 32 to rotate the ball screw 33, and the saddle 4 is guided by guide rails 35 and 36 to move along the Y-axis.

[0063] [Z-axis feed unit]

[0064] The Z-axis feed unit 50 consists of a pair of guide rails 55 and 56 arranged parallel to the Z-axis on the bed 2, two sliders 57 and 59 moving along the guide rails 55 and engaging with them, a scale 55a fixed to the upper surface of the guide rails 56 and a scale 55b fixed to the side, reading heads 58 and 60 fixed to the sliders 57 and 59 respectively, two sliders 61 and 63 moving along the guide rails 56 and engaging with them, a scale 56a fixed to the upper surface of the guide rails 56 and a scale 56b fixed to the side, reading heads 62 and 64 fixed to the sliders 61 and 63 respectively, and a Z-axis drive mechanism 51 that drives the worktable 6.

[0065] The scales 55a and 55b, along with the read heads 58 and 60, constitute a linear encoder. Similarly, the scales 56a and 56b, along with the read heads 62 and 64, constitute a linear encoder. This linear encoder can be either magnetic or optical, but a magnetic type is used in this example. Furthermore, each read head 58 and 60 detects the position of sliders 57 and 59 in the Z-axis direction and their displacement in the Y and X-axis directions by reading the scales 55a and 55b. Similarly, read heads 62 and 64 detect the position of sliders 61 and 63 in the Z-axis direction and their displacement in the Y and X-axis directions by reading the scales 56a and 56b.

[0066] The Z-axis drive mechanism 51 consists of a Z-axis feed motor 52 (which functions as a servo motor), a ball screw 53 driven by the Z-axis feed motor 52, a ball nut (not shown) threadedly connected to the ball screw 53 and fixed to the lower surface of the worktable 6, and bearings 54 (another bearing not shown) that support the two ends of the ball screw 53 for free rotation. The Z-axis drive mechanism 51 drives the Z-axis feed motor 52 to rotate the ball screw 53, and the worktable 6 is guided by guide rails 55 and 56 to move along the Z-axis.

[0067] Next, the motion error calculation unit 70, the output unit 71, and the control device 75 will be described. Furthermore, the motion error calculation unit 70 and the control device 75 are configured as a computer including a CPU, RAM, ROM, etc.

[0068] [Control Device]

[0069] The control device 75 is a known control device that performs numerical control on the movements of the spindle motor (not shown), X-axis feed motor 12, Y-axis feed motor 32, and Z-axis feed motor 52. Furthermore, the control device 75 performs the following control according to a pre-prepared motion error measurement procedure: it drives the X-axis feed motor 12, Y-axis feed motor 32, and Z-axis feed motor 52 respectively, causing the column 3, saddle 4, and worktable 6 to move at predetermined intervals and position them along their respective feed axes.

[0070] [Motion Error Calculation Department]

[0071] Under the control of the control device 75, the motion error calculation unit 70 performs the action of moving the column 3, saddle 4, and worktable 6 at predetermined intervals according to the motion error measurement action program, thereby positioning them in each feed axis. At this time, based on the data detected by the reading heads 18, 20, 22, and 24 of the X-axis feed unit 10, the data detected by the reading heads 38, 40, 42, and 44 of the Y-axis feed unit 30, and the data detected by the reading heads 58, 60, 62, and 64 of the Z-axis feed unit 50, the motion error of the X-axis feed unit 10, the Y-axis feed unit 30, and the Z-axis feed unit 50 is calculated and processed in the following manner.

[0072] [Motion error of the X-axis feed unit]

[0073] The motion error calculation unit 70 calculates each motion error of the X-axis feed unit 10 in the following manner, for example.

[0074] The collimation and positioning error in the X-axis direction of the X-axis feed unit 10, i.e., E XX :

[0075] As error E XX The average value of the difference between the movement command value in the X-axis direction and the movement value in the X-axis direction detected by each read head 18, 20, 22, 24 is calculated.

[0076] The collimation error (Y-axis direction) in the X-axis-Y-axis plane of the X-axis feed unit 10, i.e., E YX :

[0077] As error E YX Calculate any one of the displacements in the Y-axis direction detected by each of the reading heads 18, 20, 22, and 24, or their average value.

[0078] The collimation error (Z-axis direction) in the X-axis-Z-axis plane of the X-axis feed unit 10, i.e., E ZX :

[0079] As error E ZXCalculate any one of the displacements in the Z-axis direction detected by each of the reading heads 18, 20, 22, and 24, or their average value.

[0080] The angular error of the X-axis feed unit 10 around the X-axis, i.e., E AX :

[0081] As error E AX Calculate the difference in displacement in the Y-axis direction detected by reading heads 18 and 22, or reading heads 20 and 24.

[0082] The angular error of the X-axis feed unit 10 around the Y-axis, i.e., E BX :

[0083] As error E BX Calculate the difference in position in the X-axis direction detected by reading heads 18 and 22, or reading heads 20 and 24, or the difference in displacement in the Z-axis direction detected by reading heads 18 and 20, or reading heads 22 and 24.

[0084] The angular error of the X-axis feed unit 10 around the Z-axis, i.e., E CX :

[0085] As error E CX Calculate the difference in displacement in the Y-axis direction detected by reading heads 18 and 20, or reading heads 22 and 24.

[0086] [Motion error of the Y-axis feed unit]

[0087] The motion error calculation unit 70 calculates each motion error of the Y-axis feed unit 30 in the following manner, for example.

[0088] The alignment and positioning error in the Y-axis direction of the Y-axis feed unit 30, i.e., E YY :

[0089] As error E YY The average value of the difference between the movement command value in the Y-axis direction and the movement value in the Y-axis direction detected by each read head 38, 40, 42, 44 is calculated.

[0090] The collimation error (X-axis direction) in the Y-axis-X-axis plane of the Y-axis feed unit 30, i.e., E XY :

[0091] As error E XY Calculate any one of the displacements in the X-axis direction detected by each of the reading heads 38, 40, 42, and 44, or their average value.

[0092] The collimation error (Z-axis direction) in the Y-axis-Z-axis plane of the Y-axis feed unit 30, i.e., EZY :

[0093] As error E ZY Calculate any one of the displacements in the Z-axis direction detected by each of the reading heads 38, 40, 42, and 44, or their average value.

[0094] The angular error of the Y-axis feed section 30 around the X-axis, i.e., E AY :

[0095] As error E ZY Calculate the difference in displacement in the Z-axis direction detected by reading heads 38 and 40, or reading heads 42 and 44.

[0096] The angular error of the Y-axis feed section 30 around the Y-axis, i.e., E BY :

[0097] As error E BY Calculate the difference in displacement in the Z-axis direction detected by reading heads 38 and 42, or reading heads 40 and 44.

[0098] The angular error of the Y-axis feed section 30 around the Z-axis, i.e., E CY :

[0099] As error E CY Calculate the difference in position in the Y-axis direction detected by reading heads 38 and 42, or reading heads 40 and 44, or the difference in displacement in the X-axis direction detected by reading heads 38 and 40, or reading heads 42 and 44.

[0100] [Motion error of the Z-axis feed unit]

[0101] The motion error calculation unit 70 calculates each motion error of the Z-axis feed unit 50 in the following manner, for example.

[0102] The alignment and positioning error of the Z-axis feed unit 50 in the Z-axis direction, i.e., E ZZ :

[0103] As error E ZZ The average difference between the movement command value in the Z-axis direction and the movement value in the Z-axis direction detected by each read head 58, 60, 62, 64 is calculated.

[0104] The collimation error (X-axis direction) in the Z-axis-X-axis plane of the Z-axis feed unit 50, i.e., E XZ :

[0105] As error E XZ Calculate any one of the displacements in the X-axis direction detected by each of the reading heads 58, 60, 62, and 64, or their average value.

[0106] The alignment error (Y-axis direction) in the Z-axis-Y-axis plane of the Z-axis feed unit 50, i.e., E YZ :

[0107] As error E YZ Calculate any one of the displacements in the Y-axis direction detected by each of the reading heads 58, 60, 62, and 64, or their average value.

[0108] The angular error of the Z-axis feed section 50 around the X-axis, i.e., E AZ :

[0109] As error E AZ Calculate the difference in displacement in the Y-axis direction detected by reading heads 58 and 60, or reading heads 62 and 64.

[0110] The angular error of the Z-axis feed section 30 around the Y-axis, i.e., E BZ :

[0111] As error E BZ Calculate the difference in position in the Z-axis direction detected by reading heads 58 and 62, or reading heads 60 and 64, or the difference in displacement in the X-axis direction detected by reading heads 58 and 60, or reading heads 62 and 64.

[0112] The angular error of the Z-axis feed section 50 around the Z-axis, i.e., E CZ :

[0113] As error E CZ Calculate the difference in displacement in the Y-axis direction detected by reading heads 58 and 62, or reading heads 60 and 64.

[0114] [Output Department]

[0115] The output unit 71 is, for example, a display device such as a touch screen, and displays the motion errors of the X-axis feed unit 10, Y-axis feed unit 30 and Z-axis feed unit 50 calculated by the motion error calculation unit 70.

[0116] According to the machine tool 1 of this example with the above structure, under the control of the control device 75, the X-axis drive mechanism 11, the Y-axis drive mechanism 31, the Z-axis drive mechanism 51 and the spindle motor (not shown) are appropriately driven, thereby the spindle 5 and the worktable 6 move relatively in three-dimensional space. Through this relative movement, the workpiece placed on the worktable 6 is processed by the tool mounted on the spindle 5.

[0117] Furthermore, as needed, under the control of the control device 75, a pre-prepared motion error measurement procedure is executed, and the column 3, saddle 4 and worktable 6 are positioned on each feed axis at specified intervals by the X-axis feed motor 12, Y-axis feed motor 32 and Z-axis feed motor 52.

[0118] Furthermore, in this operation, based on the data detected by the reading heads 18, 20, 22, and 24 of the X-axis feed unit 10, the data detected by the reading heads 38, 40, 42, and 44 of the Y-axis feed unit 30, and the data detected by the reading heads 58, 60, 62, and 64 of the Z-axis feed unit 50, the motion error calculation unit 70 calculates the aforementioned motion errors of the X-axis feed unit 10, the Y-axis feed unit 30, and the Z-axis feed unit 50, respectively. Moreover, the motion errors calculated in this way are displayed on the output unit 71.

[0119] In this way, according to the machine tool 1 in this example, it is not necessary to use the expensive laser length measuring device of the existing example. Instead, the existing scales 15a, 15b, 16a, 16b and reading heads 18, 20, 22, 24 arranged in the X-axis feed section 10, the existing scales 35a, 35b, 36a, 36b and reading heads 38, 40, 42, 44 arranged in the Y-axis feed section 30, and the existing scales 55a, 55b, 56a, 56b and reading heads 58, 60, 62, 64 arranged in the Z-axis feed section 50 can be used to measure the motion errors of the X-axis feed section 10, Y-axis feed section 30 and Z-axis feed section 50. This will not lead to excessive costs. In addition, the measurement does not require complicated and troublesome preparation work, and the motion errors of the X-axis feed section 10, Y-axis feed section 30 and Z-axis feed section 50 can be measured with high precision.

[0120] Furthermore, since the motion error (motion performance) of the X-axis feed unit 10, Y-axis feed unit 30 and Z-axis feed unit 50 can be easily detected, the operating performance of the machine tool 1 can be evaluated at the appropriate time without significantly reducing the operating rate of the machine tool 1, and necessary maintenance and other necessary treatments can be performed on the machine tool 1 in advance based on the evaluation results.

[0121] The foregoing has described one embodiment of the present invention, but the specific methods that the present invention can take are not limited to any of the examples above.

[0122] For example, in the above example, a horizontal machining center is exemplified as machine tool 1, but it is not limited thereto. The present invention can be used with vertical machining centers or all existing known machine tools such as horizontal lathes and vertical lathes.

[0123] Furthermore, regarding the structure of the aforementioned machine tool 1, in the example above, the motion error calculation unit 70 calculates the motion errors of the three feed units: the X-axis feed unit 10, the Y-axis feed unit 30, and the Z-axis feed unit 50. However, it is not limited to this structure. If the machine tool has only one feed unit, the motion error calculation unit 70 can be configured to calculate the motion error of that one feed unit. If the machine tool has two or more feed units, the motion error calculation unit 70 can also be configured to calculate the motion errors of these feed units.

[0124] In addition, in the example above, the reading heads 18, 20, 22, and 24 provided in the X-axis feed section 10 are configured to detect the position in the X-axis direction and the displacement in the Y-axis and Z-axis directions, but are not limited to this.

[0125] For example, it can be configured as follows: one of the two reading heads disposed on at least one guide rail detects the position along a first axial direction, which is the feed direction, and the position along a second axial direction orthogonal to the first axis in a plane including the two guide rails; the other reading head detects the position along the first axial direction and the position along a third axial direction orthogonal to both the first and second axes; and two reading heads disposed on another guide rail detect the positions along the first and third axial directions. According to this configuration, the aforementioned six motion errors can also be detected.

[0126] Alternatively, it can be configured as follows: one of the two reading heads mounted on at least one guide rail detects the position along a first axial direction (the feed direction) and the position along a second axial direction orthogonal to the first axis in a plane including the two guide rails; the other reading head detects the position along the first axial direction and the position along a third axial direction orthogonal to both the first and second axes; and the two reading heads mounted on the other guide rail detect the positions along the first and third axial directions. This configuration also enables the detection of the aforementioned six motion errors.

[0127] Furthermore, in the example above, the motion error calculation unit 70 is configured to calculate six motion errors for each feed unit, but it is not limited to this structure. For example, the motion error calculation unit 70 may also be configured to calculate the positioning error (collimation positioning accuracy) on the first axis and at least one error selected from the following: the collimation error (collimation) of the second axis in the first axis-second axis plane, the collimation error (collimation) of the third axis in the first axis-third axis plane, the angle error (tilt) about the first axis, the angle error (pitch) about the second axis, and the angle error (yaw) about the third axis.

[0128] Furthermore, in this case, it is not necessary to install scales for detecting the position along both axes on each guide rail. Alternatively, only the scales required for error calculation can be installed on each guide rail or any single guide rail. Correspondingly, the reading head on the slider can also be configured only with the reading head required for error calculation.

[0129] In addition, in the example above, two sliders are set on each guide rail, but it is not limited to this. More than three sliders can also be set on each guide rail.

[0130] Although the description is reiterated, all aspects of the above-described embodiments are illustrative and not restrictive. Modifications and alterations will be possible for those skilled in the art. The scope of the invention is shown by the claims rather than by the above-described embodiments. Furthermore, the scope of the invention includes modifications according to the embodiments that are equivalent to the scope of the claims.

[0131] [Explanation of Labels in the Attached Image]

[0132] 1. Working machinery

[0133] 2 beds

[0134] 3-column

[0135] 4 saddles

[0136] 6 workbenches

[0137] 10 X-axis feed section

[0138] 11 X-axis drive mechanism

[0139] 15 and 16 guide rails

[0140] Sliders 17, 19, 21, and 23

[0141] 18, 20, 22, 24 read heads

[0142] 30 Y-axis feed section

[0143] 31 Y-axis drive mechanism

[0144] 35 and 36 guide rails

[0145] Sliders 37, 39, 41, and 43

[0146] 38, 40, 42, 44 Read Heads

[0147] 50 Z-axis feed unit

[0148] 51 Z-axis drive mechanism

[0149] 55, 56 guide rails

[0150] Sliders 57, 59, 61, and 63

[0151] 58, 60, 62, 64 read heads

[0152] 70 Motion Error Calculation Department

[0153] 71 Output Section

[0154] 75 Control device

Claims

1. A feeding device, characterized in that, Possessing: two guides which are arranged in parallel along a prescribed feed direction; at least four sliders which are provided on each of the guides with at least two each and which are engaged with the guides so as to be movable along the feed direction, a moving table which is mounted with the sliders and which is movable along the feed direction; and a drive mechanism which moves the moving table along the feed direction, a scale, a reading head, and a motion error calculation section are provided in the feed device to constitute, the scale is arranged on at least one of the guides along the feed direction, the reading head is provided on the sliders selected from at least two of the at least four sliders and engaged with the guide on which the scale is arranged, and reads information supplied to the scale to detect a position in the feed direction and a position in a direction orthogonal to the feed direction, the motion error calculation section calculates a plurality of motion errors of the moving table based on position information in two directions detected by the reading heads.

2. The feed device according to claim 1, wherein the scale is arranged on both of the guides, and the reading head is arranged on each of the four sliders, the motion error calculation section is constituted so as to be able to calculate a plurality of motion errors of the moving table based on position information in two directions detected by the four reading heads.

3. The feed device according to claim 2, wherein the two reading heads arranged on at least one of the guides are constituted so as to detect a position in a first axis direction which is the feed direction and a position in a second axis direction which is orthogonal to the first axis in a plane including the two guides, and the two reading heads arranged on the other guide are constituted so as to detect a position in the first axis direction and a position in a third axis direction which is orthogonal to the first axis and the second axis.

4. The feed device according to claim 2, wherein one of the two reading heads arranged on at least one of the guides is constituted so as to detect a position in a first axis direction which is the feed direction and a position in a second axis direction which is orthogonal to the first axis in a plane including the two guides, and the other reading head is constituted so as to detect a position in the first axis direction and a position in a third axis direction which is orthogonal to the first axis and the second axis, the two reading heads arranged on the other guide are constituted so as to detect a position in the first axis direction and a position in the third axis direction.

5. The feed device according to claim 3, wherein the motion error calculation section is constituted so as to calculate at least one error selected from a positioning error in the first axis direction, a collimation error in the second axis direction in the first axis-second axis plane, a collimation error in the third axis direction in the first axis-third axis plane, an angle error around the first axis, an angle error around the second axis, and an angle error around the third axis.

6. The feed device according to claim 4, wherein The motion error calculation unit is configured to calculate at least one error selected from the positioning error in the first axis and the collimation error in the second axis in the first axis-second axis plane, the collimation error in the third axis in the first axis-third axis plane, the angular error about the first axis, the angular error about the second axis, and the angular error about the third axis.

7. A machine tool, characterized in that, The feeding device comprising any one of claims 1 to 6.

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