Toolpath indicator device for displaying a toolpath

Abstract

Toolpath indicator device (20) which indicates a path of a tool of a machine tool, wherein a workpiece is machined by reciprocal and relative movement between the tool and the workpiece by at least one drive axis using a numerical control device (16), characterized in that it comprises the following: a position information acquisition unit (21) that acquires position information generated in the numerical control unit (16) in a predetermined control cycle and / or position information of at least one drive axle from a position sensor (11 to 15), a tool coordinate calculation unit (22) that calculates coordinate values ​​of the tool based on the position information of at least one drive axis and information regarding the mechanical structure of the machine tool, a display attribute modification unit (23) that modifies a display attribute of the toolpath according to the direction of movement of the tool, a display unit (24) that displays the path of the tool based on the coordinate values ​​of the tool calculated by the tool coordinate calculation unit and the display attribute modified by the display attribute modification unit; and a reversal position detection unit (25) that detects a reversal position at which the direction of movement of the tool (5) is reversed by the numerical control unit (16) or the operating program of the machine tool (1), and at which a change of the tip point of the tool from a forward path to a return path or from the return path to the forward path takes place, wherein the display attribute modification unit modifies the display attribute of the tool path according to the reversal position.

Description

BACKGROUND OF THE INVENTION 1. Technical field of the invention

[0001] The present invention relates to a tool path display device that displays a path of a tool for a machine tool that machines a workpiece while reciprocating the tool and / or the workpiece through at least one drive axis using a numerical control (NC) device. 2. Description of the state of the art

[0002] Conventionally, there are path display devices in which a path of a tool is displayed in various display attributes for checking the cause of an error occurring in the actual path.

[0003] In Japanese patent JP 3 834 268 B2, the tool path is displayed by a set of minute line segments. The inclination of each minute line segment with respect to a specific axis is assessed, and the tool path consisting of a set of minute line segments is displayed using a display attribute determined according to the assessed inclination. In this case, the unevenness occurring in the tool path can be easily determined.

[0004] In a machine tool that performs machining by controlling multiple servo shafts, there are cases where a workpiece is machined while a tool is reciprocating with respect to the workpiece. In such a machining operation, if a commanded curve for the tool consists of multiple curves with different curvatures, the normal acceleration changes gradually at the joints between the curves. As a result, the influence of the acceleration change changes depending on the tool movement direction, so the position at which a path deviation between the commanded path and the actual path increases and the amount of the path deviation change.

[0005] Therefore, even if the profile of the commanded path is the same, the path deviation differs between the forward path and the return path. However, with conventional path display devices, the commanded path and the actual path are displayed as they are, without distinguishing between the forward path and the return path. As a result, it is impossible to correlate the path deviation with the direction of travel, and accordingly, it is difficult to determine whether a path deviation has occurred based on the servo setting or the direction of travel.

[0006] It should be noted that in Japanese Patent Publication No. 3834268 B2, the tool path is displayed based on NC data created by CAD, etc. Accordingly, it is impossible to display the NC-commanded path and the actual path of the tool tip point movement. Therefore, in Japanese Patent Publication No. 3834268, it is impossible to confirm the path deviation between the commanded path and the actual path, and accordingly, appropriate servo control for eliminating the path deviation cannot be performed.

[0007] Furthermore, although Japanese Patent JP 3 834 268 B2 allows the display attribute to be modified according to the inclination of the minute line segments, it is impossible to modify the display attribute depending on the direction of movement (forward movement or return movement). Therefore, it cannot be correctly determined whether the path deviation is caused by the servo control or the direction of movement.

[0008] Under these circumstances, it is an object of the present invention to provide a tool path display device capable of correlating the path deviation and the movement direction for effectively performing servo control.

[0009] DE 10 2013 016 489 A1 describes a tool trajectory display device with a function for displaying a position at which the polarity of the speed of a servo axis changes. DE 10 2013 106 076 A1 describes a tool path display device with a display unit that displays a target path and an actual path of a tool. SUMMARY OF THE INVENTION

[0010] To achieve the above-mentioned object, according to the present invention, a tool path display device having the features of claim 1 is provided. Advantageous developments of the invention emerge from the dependent claims.

[0011] The above objects, features and advantages and other objects, features and advantages of the present invention will become more apparent from the detailed description of the illustrative embodiments of the present invention shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a machine tool with a tool path display device according to the present invention mounted thereon; Fig. 2 is a block diagram of a tool path display device according to the present invention; Fig. 3 is a schematic view of an example of a movement path of a tool along which a machine tool having a tool path display device according to the present invention attached thereto machines a workpiece; Fig. 4A is an enlarged partial view of a forward path curve shown in Fig. 3 is shown; Fig. 4B is an enlarged partial view of a return path curve shown in Fig. 3 is shown; Fig. 5 is a diagram showing a commanded path and an actual path consisting of a forward path and a return path; Fig. 6 is a flowchart showing the operation of a tool path display device according to the present invention; Fig. 7A is a schematic view showing a first display attribute; Fig. 7B is a schematic view showing a second display attribute; and Fig. Figure 7C is a schematic view showing a third display attribute. DETAILED DESCRIPTION

[0012] In the drawings, the same reference symbols are assigned to corresponding components. For the sake of clarity, the scale of the drawings has been adjusted.

[0013] Fig. Fig. 1 is a perspective view of a machine tool to which a tool path display device according to the invention is mounted. The machine tool 1 shown in Fig. 1 as an example, is a five-axis machine tool. The machine tool 1 is formed of a table 2 on which a workpiece (not shown) can be placed, and a support column 3 that is relatively movable in three orthogonal directions (X-axis, Y-axis, Z-axis) perpendicular to the table 2. As can be seen from Fig. As can be seen in Figure 1, a head 4 extends laterally from the support column 3 and is rotatable about the axis B parallel to the surface of the table 2. In addition, a tool 5, which is rotatable about the axis "A", which is perpendicular to both the axis B and the surface of the table 2, is attached to the head 4.

[0014] Therefore, the machine tool 1 machines the workpiece on the table 2 by controlling the position and posture of the tool 5 using the three linear motion shafts (X-axis, Y-axis, Z-axis) and the two rotary shafts (A-axis and B-axis). Note that an alternative arrangement in which the tool 5 is fixed to the table 2 and the workpiece (not shown) is attached to the front end of the head 4 is within the scope of the present invention. The X-axis, Y-axis, Z-axis, A-axis, and B-axis may hereinafter be referred to as "drive axes."

[0015] Fig. 2 shows a block diagram of the tool path display device according to the present invention. As in Fig. As shown in Figure 2, the tool path display device 20 is connected to the machine tool 1 via a numerical control (NC) device 16. The machine tool 1 includes motors M1 to M5 that drive the respective drive axes. The motors M1 to M5 are each equipped with position sensors 11 to 15 that detect the actual positions of the drive axes in a predetermined control cycle. The NC device 16 generates a position command for each drive axis in the predetermined control cycle in accordance with the operating program of the machine tool 1.

[0016] As from Fig. As shown in Figure 2, the tool path display device 20 includes a position information acquisition unit 21 that acquires the position commands generated in the NC device 16 in a predetermined control cycle as position information. Furthermore, the position information acquisition unit 21 acquires the detected position values ​​detected by the position sensors 11 to 15 as position information. The position information is temporarily stored in the tool path display device 20 in chronological order.

[0017] The tool path display device 20 includes a tool coordinate calculation unit 22 that calculates commanded tool coordinate values ​​of the tip point of the tool 5 according to the position information of the position command and the structure of the machine tool 1. Furthermore, the tool coordinate calculation unit 22 calculates the actual tool coordinate values ​​of the tip point of the tool 5 according to the position information of the position detection value and the structure of the machine tool 1. The commanded tool coordinate values ​​and the actual tool coordinate values ​​represent the commanded path and the actual path of the tip point of the tool 5, respectively. Note that the structure of the machine tool 1 mainly relates to its size.

[0018] In addition, the tool path display device 20 includes a display attribute modification unit 23 that modifies the display attribute of the tool path according to the movement direction of the tool 5, as discussed below. Furthermore, the tool path display device 20 includes a display unit 24 that displays the path of the tool 5 based on the coordinate values ​​of the tool 5 calculated by the tool coordinate calculation unit 22 and the display attribute modified by the display attribute modification unit 23.

[0019] In addition, the tool path display device 20 includes a reversal position detection unit 25 that detects a reversal position at which the movement direction of the tool 5 is reversed by the NC device 16 or the operation program of the machine tool 1. As can be seen from Fig. 2, a reversal position input unit 26, such as a keyboard, a mouse, a touch screen, through which an operator can externally assign the reversal position at which the direction of movement of the tool 5 is reversed, is connected to the tool path display device 20.

[0020] Fig. 3 shows, as an example, the machining route along which the machine tool to which the tool path display device according to the present invention is attached machines the workpiece. In the embodiment shown in Fig. As shown in Figure 3, machining by the tool 5 of the machine tool 1 begins at the machining start point X1 and proceeds along the forward curved path P1. The tool 5 is moved by the amount represented by a line segment XA in the X direction at the terminal end of the forward path P1 and then moves along the curved return path Q1 to machine the workpiece. The tool 5 is stopped at the point spaced from the machining start point X1 by a distance of the line segment XA in the X direction.

[0021] Next, the tool 5 is moved by the amount represented by a line segment XB in the X direction at the terminal end of the return path Q1, and then moved along the forward curved path P2 to machine the workpiece. The tool 5 is moved by the amount represented by a line segment XC in the X direction at the terminal end of the forward path P2, and then moved along the curved return path Q2 to machine the workpiece. The tool 5 is stopped at the machining terminal point X2. As understood from the above, the workpiece is machined by the tool reciprocating along the machining route consisting of the forward curved paths P1 and P2 and the curved return paths Q1 and Q2.

[0022] As from Fig. As can be seen in Figure 3, the forward paths P1 and P2 and the return paths Q1 and Q2, each consisting of several line segments, have the same shape. In other words, Fig. 3 assuming that the workpiece is repeatedly machined along the same route while the tool and / or the workpiece are moved relative to each other in the direction X. Note that the length of the line segments XA, XB, XC can be zero.

[0023] Fig. 4A and Fig. 4B are enlarged partial views of the curved forward paths and the curved return paths shown in Fig. 3 are shown. In Fig. 4A, Fig. 4B shows two circles C1 and C2 that touch each other externally at a tangent point C0. The curved forward paths P1, P2 and the curved return paths Q1, Q2 are defined by a portion of each of the circles C1 and C2. Fig. 4A and Fig. 4B also show normal accelerations, which are represented by line segments extending towards the centers of circles C1 and C2, respectively.

[0024] As from Fig. As can be seen in Figure 4A, when the tool passes the tangent point C0 while moving along the forward paths P1, P2, the direction of the normal acceleration is reversed from the left direction to the right direction. Similarly, as in Fig. As shown in Figure 4B, when the tool passes the tangent point C0 during movement along the return paths Q1 and Q2, the direction of normal acceleration is reversed from the right direction to the left direction. As stated above, if the direction in which the normal acceleration is reversed differs between the forward path and the return path, even if the commanded path is the same, the position at which the path deviation occurs and the deviation amount differ between the forward path and the return path.

[0025] Fig. Figure 5 shows the commanded path and the actual paths in the forward and return directions as an example. Fig. In Figure 5, the central smooth solid curve S represents the commanded path common to the forward paths P1, P2 and the return paths Q1, Q2. The dashed curve P` represents the actual path in the forward path P1 or P2, and the solid curve Q` represents the actual path in the return path Q1 or Q2.

[0026] As from Fig. As can be seen in Figure 5, each of the dashed curve P' and the solid curve Q` has a projection. The projection occurs in the vicinity of the tangent point C0, which is Fig. 4A, Fig. 4B. The protrusions correspond to the sections where the path deviation between the commanded path and the actual path is large. However, the directions of the protrusions differ between the dashed curve P' and the solid curve Q'. Furthermore, the positions where the protrusions appear differ between the dashed curve P' and the solid curve Q'.

[0027] In conventional tool path display devices, the path in the forward path and the path in the return path are displayed indistinguishably. In other words, in the prior art, the path deviation is not correlated with the movement direction. As a result, it is impossible to determine whether the path deviation, if any, occurs between the commanded path and the actual path in the forward path or the return path. Furthermore, it is impossible to determine whether the cause of the path deviation is based on the movement direction or servo control. It is an object of the present invention to eliminate these deficiencies of the prior art.

[0028] Fig. 6 shows a flowchart of the operation of the tool path display device according to the present invention. First, at step S1, the position information acquisition unit 21 acquires the position commands created in the numerical control device 16 in a predetermined control cycle as position information. The position information acquisition unit 21 can acquire position detection values ​​of the drive axes detected by the respective position sensors 11 to 15 as position information. The position information of the position commands is used to calculate the commanded path, and the position information of the position detection values ​​is used to calculate the actual paths. Note that if only the actual paths should be referred to, it is sufficient that only the position information of the position detection values ​​is used.

[0029] Thereafter, at step S2, the tool coordinate calculation unit 22 calculates the commanded tool coordinate value Pcn of the tip point of the tool 5 according to the position information of the position commands based on the position information of the position commands and the structure of the machine tool 1. In addition, the tool coordinate calculation unit 22 calculates the actual tool coordinate value Pfn of the tip point of the tool 5 according to the position information of the position detection values ​​based on the position information of the position detection values ​​and the structure of the machine tool 1.

[0030] The commanded tool coordinate value Pcn and the actual tool coordinate value Pfn are calculated as follows.

[0031] With reference to Fig. 1 are the coordinates of the five drive axes x(t), y(t), z(t), a(t) and b(t).

[0032] The coordinates of the intersection point M between the axes A and B are represented by (x(t), y(t), z(t)). Assuming that the distance from the intersection point M to the tip end of the tool 5 is L, and that the position where the tool 5 is oriented vertically downward is a reference position (origin) of the axes A and B, the coordinates of the tip point of the tool 5 are represented as follows. Px(t)=X(t)+L×cos(a(t))×sin(b(t)) Py(t)=y(t)−L×sin(a(t)) Pz(t)=z(t)−L×cos(a(t))×cos(b(t))

[0033] This allows the coordinates of the tip point of the tool 5 to be calculated based on the position information of the five drive axes and the conditions of the mechanical structure.

[0034] At step S3, the reversal position detecting unit 25 detects a reversal position in which the movement direction of the tool 5 is reversed by the NC device 16 or the operation program of the machine tool 1. The reversal position refers to a position at which a change of the tip point of the tool 5 from the forward path to the return path or from the return path to the forward path takes place, and corresponds to each of both ends of each of the line segments XA, XB, and XC shown in Fig. 3 are shown.

[0035] Specifically, the reversal position detection unit 25 detects the reversal position by referring to the position commands of the NC device 16 or the machining program of the machine tool 1. For example, program numbers or block numbers on the machining program where changes from the forward path to the return path occur, or signals representing the reversal positions output from the NC device 16, are detected. When the reversal position detection unit 25 is used, the sections where the display attributes of the tool path change can be made distinguishable.

[0036] Alternatively, the reversal positions can be input externally by an operator using a reversal position input unit 26. The reversal position input unit 26 can be used, for example, when the reversal positions are assigned numerically using coordinates, or when the reversal positions are assigned based on the tool path displayed on the display unit 24. It should be understood that when the reversal position input unit 26 is used, the position at which the display attributes of the tool path change can be easily distinguished.

[0037] Thereafter, at step S4, a display attribute modification unit 23 modifies the display attribute of the tool path according to the moving direction of the tool 5.

[0038] After modification, the detected reversal positions are used appropriately. The display attribute may include a color, a line type, and the path thickness. The display attribute modification unit 23 selects any one of the first to third display attributes discussed below according to the operator's input procedure. Other display attributes (not shown) may be selected. In step 5, the tool path is displayed on the display unit 24 according to the tool coordinate values ​​Pcn, Pfn and the selected display attribute.

[0039] Fig. 7A to / C show the first to third display attributes, respectively. In these figures, for the sake of clarity, the return path Q2 and the line segment XC in the direction X, which Fig. 3 are omitted, and only the curved forward paths P1 and P2 and the curved return paths Q1 and Q2 are shown. As can be seen from Fig. As can be seen in Figures 7A to 7C, the first forward paths P1, P2 and the curved return paths Q1, Q2 are shown superimposed.

[0040] In the first display attribute, which is Fig. As shown in Figure 7A, each of the forward paths P1 and P2 is assigned the word "Forward Path" along with the arrow, and the return path Q1 is assigned the word "Backward Path" along with the arrow. Furthermore, in the first display attribute shown in Fig. 7A, the movement directions are indicated by the arrows along the curved forward paths P1 and P2 and the curved return path Q1. Furthermore, in the first display attribute, the curved forward paths P1, P2, the curved return path Q1, and the line segments XA, XB are indicated by different colors or different color gradations. For example, the curved forward paths P1 and P2 may be colored blue, and the return path Q1 may be colored red.

[0041] In the second display attribute, which is Fig. As shown in Figure 7B, each of the forward paths P1 and P2 is assigned the word "Forward Path" along with the arrow, and the return path Q1 is assigned the word "Backward Path" along with the arrow. Furthermore, in the second display attribute shown in Fig. 7B, the movement directions are indicated by the arrows along the curved forward paths P1 and P2 and the curved return path Q1. Furthermore, in the second display attribute, the curved forward paths P1, P2, the curved return path Q1, and the line segments XA, XB are indicated by different line types. Fig. 7B, the curved forward paths P1 and P2 are indicated by solid lines, and the return path Q1 is indicated by a dashed line, and the line segments XA and XB are indicated by dotted lines.

[0042] In the third display attribute, which is Fig. As shown in Figure 7C, each of the forward paths P1 and P2 is assigned the word "Forward Path" along with the arrow, and the return path Q1 is assigned the word "Backward Path" along with the arrow. Furthermore, in the third display attribute, which is shown in Fig. 7C, the movement directions are indicated by the arrows along the curved forward paths P1 and P2 and the curved return path Q1. Furthermore, in the third display attribute, the curved forward paths P1, P2, the curved return path Q1, and the line segments XA, XB are indicated by lines of different thicknesses. Fig. 7C, the forward curved paths P1 and 2 are indicated by medium-thickness lines, the return curved path Q1 is indicated by a thick line, and the line segments XA and XB are indicated by thin lines.

[0043] As can be seen from the above, according to the present invention, the path of the forward path and the path of the return path are displayed in different attributes. Therefore, in the present invention, at least the forward path and the return path are displayed distinguishably according to the display attributes. Therefore, in the present invention, the path deviation is correlated with the movement direction. As a result, it is possible for the operator to easily recognize the movement direction of the tool 5 and easily understand whether the displayed path is the forward path or the return path.

[0044] In addition, since the commanded path and the actual paths are displayed superimposed, the operator can easily understand the path deviation between the commanded path and the actual paths. When a large path deviation occurs, it is possible to determine whether the path deviation occurs in the forward path or the return path. Furthermore, it is possible to determine whether the cause is based on the movement direction or servo adjustment. Therefore, it is understood that according to the present invention, servo adjustment can be effectively performed. FAVORABLE EFFECTS OF THE INVENTION

[0045] According to the first embodiment of the present invention, since the display attributes of the tool path are changed according to the moving direction of the tools, it is possible to correlate the path deviation with the moving direction, and accordingly, the servo adjustment can be effectively performed.

[0046] According to the second embodiment of the present invention, the portions where the display attribute of the tool path changes can be made obvious by the reversal position detecting unit.

[0047] According to the third embodiment of the present invention, the portions where the display attribute of the tool path changes can be easily made obvious by the reversal position input unit.

[0048] According to the fourth embodiment of the present invention, the path deviation between the instructed path and the actual path is easily understood.

[0049] According to the fifth embodiment of the present invention, the forward path and the return path are easily distinguishable from each other.

[0050] According to the sixth embodiment of the present invention, the direction of movement of the tools is easy to understand.

[0051] Although the present invention has been discussed above with reference to the representative embodiments, it should be understood that the above-noted modifications and other various modifications can be made by those skilled in the art without departing from the spirit of the invention.

Claims

[1] A tool path display device (20) which displays a path of a tool of a machine tool, wherein a workpiece is machined by reciprocal and relative movement between the tool and the workpiece by at least one drive axis using a numerical control device (16), characterized by that it includes: a position information acquisition unit (21) which acquires position information generated in the numerical control unit (16) in a predetermined control cycle and / or position information of the at least one drive axis from a position sensor (11 to 15), a tool coordinate calculation unit (22) which calculates coordinate values ​​of the tool on the basis of the position information of the at least one drive axis and information regarding the mechanical structure of the machine tool, a display attribute modification unit (23) that modifies a display attribute of the tool path according to the movement direction of the tool, a display unit (24) that displays the path of the tool based on the coordinate values ​​of the tool calculated by the tool coordinate calculation unit and the display attribute modified by the display attribute modification unit; and a reversal position detecting unit (25) that detects a reversal position at which the movement direction of the tool (5) is reversed by the numerical control device (16) or the operation program of the machine tool (1), and at which a change of the tip point of the tool from a forward path to a return path or from the return path to the forward path takes place, wherein the display attribute modifying unit modifies the display attribute of the tool path according to the reversal position. [2] The tool path display device according to claim 1, wherein the display unit displays the instructed path of the tool obtained from the position information acquired from the numerical control device superimposed on the actual path obtained from the position information acquired from the position sensor. [3] The tool path display device according to claim 1 or 2, wherein the display attribute modification unit modifies the display attribute of the tool path between the forward path and return path of the reciprocal movement. [4] The tool path display device according to any one of claims 1 to 3, wherein the display attribute modification unit additionally displays symbols, characters or character strings corresponding to the forward path and the return path of the reciprocal movement on the display unit.

Images