Turret control device and turret lathe

Abstract

In order to improve the accuracy of the stop position of a turret after rotation, a turret lathe (100) comprises: a drive unit (25) to which a tool holder (T) including a tool (t) is attached and which rotates a turret (22) having 12 turret surfaces (23) about an axis (C2); a control unit (34) that controls operation of the drive unit (25); a reception unit (31) that receives an input of information regarding a tool layout specifying an arrangement state where the tool holder (T) is attached; a center-of-mass position calculation unit (32) that calculates the center-of-mass position (M') of the turret (22) in the tool layout on the basis of the inputted information regarding the tool layout, information regarding the weight and the center-of-mass position of the attached tool holder (T), and information regarding the weight and the center-of-mass position of the turret (22) alone; and an eccentricity calculation unit (33) that calculates the eccentricity amount (δ) of the center-of-mass position (M') with respect to the axis (C2). The control unit (34) controls the rotation speed of the turret (22) on the basis of the eccentricity amount (δ).

Description

Turret control device and turret lathe

[0001] The present invention relates to a turret control device and a turret lathe.

[0002] Some machine tools, such as automatic lathes, are equipped with a turret tool post. The turret of the turret tool post is formed in a rectangular column shape, and tool holders, each with a tool such as a drill or reamer, are attached to the turret faces, which are the peripheral surfaces of the column.

[0003] A tool holder selected according to the type of machining of the workpiece to be machined is attached to each turret face, but since the workpiece is machined sequentially using the tool holders attached to the different turret faces, it is necessary to rotate the turret and switch tool holders to perform an indexing operation as the machining process progresses.

[0004] Here, in order to shorten the time required to switch between tool holders, a layout may be adopted in which multiple tool holders used for machining are arranged on turret faces adjacent in the rotation direction.

[0005] In particular, when the number of tool holders attached to a turret is small, the tool holders are concentrated in a specific angular range of the turret, which causes the weight balance around the center of rotation to become unbalanced, and when the turret is rotated and an indexing operation is performed on a specific tool holder, an overshoot occurs in which the turret passes over the intended stopping position, making it impossible to accurately control the stopping position.Furthermore, after this overshoot, an overshoot also occurs in the operation to return to the correct stopping position, which can result in hunting.

[0006] Furthermore, even a slight deviation in the stop position causes a phase shift in the engagement when the curvic coupling is engaged when the turret is rotated, resulting in a deviation in the stop position.

[0007] Therefore, a turret rotation speed determination device has been proposed that increases the speed at which the turret rotates while ensuring the accuracy of the stopping position (see, for example, Patent Document 1).

[0008] Japanese Patent Application Laid-Open No. 2000-218470

[0009] However, the turret rotation speed determination device described in the above-mentioned Patent Document 1 determines the turret rotation speed based on the tool layout or based on the tool layout and the tool weight, but does not specifically disclose the tool layout, and the process for determining the turret rotation speed is unclear.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a turret control device and a turret lathe that can improve the accuracy of the stopping position of the turret after rotation.

[0011] A first aspect of the present invention is a turret control device comprising: a drive unit that rotates about a predetermined center of rotation, the turret having a plurality of turret faces on which tool holders including tools are attached, and that causes the turret to rotate about the center of rotation; a control unit that controls the operation of the drive unit; a reception unit that receives input of information related to a tool layout that specifies the arrangement of the tool holders attached to the turret faces; a center of gravity position calculation unit that calculates the position of the center of gravity of the turret in the tool layout based on the information related to the tool layout input to the reception unit, information related to the weights and positions of the centers of gravity of the tool holders attached to the turret faces, and information related to the weight and position of the center of gravity of the turret alone; and an eccentricity amount calculation unit that calculates the amount of eccentricity of the position of the center of gravity of the turret calculated by the center of gravity position calculation unit, relative to the position of the center of rotation, wherein the control unit controls the rotation speed of the turret by the drive unit based on the amount of eccentricity.

[0012] A second aspect of the present invention is a turret lathe comprising: a turret device including a turret that rotates around a predetermined center of rotation and has a plurality of turret faces to which tool holders containing tools are attached; a spindle that holds a workpiece to be machined by the tools attached to the turret; and a control device that controls the spindle and the turret, wherein the control device has the turret control device according to the present invention.

[0013] The turret control device and turret lathe according to the present invention can improve the accuracy of the stopping position of the turret after rotation.

[0014] 1 is a perspective view schematically showing the main external appearance of a turret lathe; FIG. 2 is a front view schematically showing the turret as viewed in the direction of the turret axis C2; FIG. 3 is a block diagram showing the configuration of a control device 30 that controls the operation of the turret lathe; FIG. 4 is a view showing the position m1 of the center of gravity of the tool holder T1 alone in a local coordinate system; FIG. 5 is a view showing the position m4 of the center of gravity of the tool holder T4 alone in a local coordinate system; FIG. 6 is a schematic diagram showing the position M' (X', Y') of the center of gravity of the turret in a global coordinate system and the amount of eccentricity δ from the center of rotation (axis C2) according to an example layout of the tool holders, showing a layout in which the tool holders are concentrated in an angular range θ1; FIG. 7 is a schematic diagram showing the position M' (X', Y') of the center of gravity of the turret in a global coordinate system and the amount of eccentricity δ from the center of rotation (axis C2) according to an example layout of the tool holders, showing a layout in which the tool holders are distributed over an angular range θ2 (>θ1); and FIG. 8 is a flowchart showing the detailed operation of the control device.

[0015] An embodiment of a turret control device and a turret lathe according to the present invention will be described below with reference to the drawings.

[0016] Fig. 1 is a perspective view showing a schematic view of the main exterior of a turret lathe 100, Fig. 2 is a front view showing a schematic view of the turret 22 as viewed in the direction of the axis C2 of the turret 22, and Fig. 3 is a block diagram showing the configuration of a control device 30 that controls the operation of the turret lathe 100. The turret lathe 100 is one embodiment of a turret lathe according to the present invention.

[0017] The turret lathe 100 includes the spindle 10 and turret device 20 shown in Fig. 1, and the control device 30 shown in Fig. 3. In addition to the spindle 10, turret device 20, and control device 30, the turret lathe 100 also includes a cutting fluid device that sprays cutting fluid onto a workpiece W to be machined when the workpiece W is cut, but a description of these will be omitted. The turret lathe 100 may also include a second spindle (back spindle), a second turret device, etc.

[0018] The spindle 10 has a holding mechanism, such as a collet chuck, at its tip, which holds a workpiece W, which is mainly a bar material. The spindle 10 is rotatable around an axis C1 parallel to the z-axis direction, which is the longitudinal direction of the spindle 10, under the control of the control device 30. The spindle 10 is also capable of moving forward and backward parallel to the z-axis under the control of the control device 30.

[0019] The turret device 20 includes a main body 21 and a turret 22. As an example, the turret 22 is formed in the shape of a regular dodecagonal prism. The shape of the turret 22 is not limited to a regular dodecagonal prism, but may be a regular decagonal prism, a regular octagonal prism, or another regular polygonal prism. Furthermore, the shape of the turret 22 is not limited to a regular polygonal prism having a regular polygonal cross section, but may be a polygonal prism having a non-regular polygonal cross section. In other words, the turret 22 may have any shape as long as multiple turret surfaces 23, which are peripheral surfaces around axis C2, the central axis of the polygonal prism, are planes parallel to axis C2.

[0020] The turret 22 of this embodiment is configured to be rotatable around axis C2, which is the central axis of a regular dodecagonal prism. The circumferential surface of the turret 22 around axis C2 is formed by flat surfaces parallel to axis C2. Each of these flat surfaces is a turret surface 23 to which a tool holder T, which will be described later, is attached. The turret 22 of this embodiment is formed with 12 turret surfaces 23, and when the individual turret surfaces 23 are to be individually described, they are referred to as turret surfaces 23a, 23b, 23c, 23d, 23e, 23f, 23g, 23h, 23j, 23k, 23m, and 23n, as shown in FIG. 2 (the reference numerals 23i (lowercase English letter i) and 23l (lowercase English letter l) have been omitted to prevent confusion with other characters).

[0021] 1 and 2, a tool holder T can be attached to each turret face 23. When the turret 22 rotates about the axis C2, the tool holder T attached to each turret face 23 pivots about the axis C2.

[0022] The tool holder T holds a tool t for machining a workpiece W held by the spindle 10, and fixes the tool t to the turret face 23. Depending on the type of tool t held, the tool holder T can transmit a driving force supplied from the main body 21 through the turret 22 to the tool t to rotate the tool t.

[0023] The main body 21 supports the turret 22 rotatably about the axis C2 of the turret 22. The main body 21 also includes a drive unit 25. The drive unit 25 rotates the turret 22 about the axis C2, rotates the tool t in the tool holder T fixed to the turret face 23 about the axis of the tool holder T, and turns the tool holder T itself.

[0024] The control device 30 controls the overall operation of the turret lathe 100. Specifically, the control device 30 controls the operation of the spindle 10, such as the opening and closing operation of the holding mechanism for the spindle 10, the rotation operation of the workpiece held by the spindle 10 about the axis C1, and the movement operation of the spindle 10 itself in the z-axis direction, as well as the operation of the turret device 20. In addition to controlling the operation of the spindle 10 and the turret device 20, the control device 30 also controls the operation of components such as a cutting fluid device provided in the turret lathe 100.

[0025] The control device 30 shown in Figure 3 is a block diagram showing only the configuration related to the control of the operation of the turret device 20, as one embodiment of a turret control device according to the present invention, out of the control of the components of the turret lathe 100 described above.

[0026] In addition to the configuration related to controlling the operation of the turret device 20 shown in Figure 3, the control device 30 also includes a memory unit that stores a program that defines the operation of the entire turret lathe 100 including the main spindle 10, an operation panel for inputting instructions related to the operation of the entire turret lathe 100, a display unit (monitor), etc., but explanations of the configuration other than those related to controlling the operation of the turret device 20 will be omitted.

[0027] 3, the control device 30 includes a receiving unit 31, a center-of-gravity position calculation unit 32, an eccentricity amount calculation unit 33, and a control unit 34 as components related to the control of the operation of the turret device 20. Insofar as the control device 30 is related to the control of the operation of the turret device 20, it is one embodiment of a turret control device according to the present invention.

[0028] The reception unit 31 receives input of information (tool layout information) relating to the tool layout that specifies the arrangement state in which the tool holders T are attached on the turret surfaces 23, i.e., which of the 12 turret surfaces 23 of the turret 22 has which tool holder T is attached to which turret surface 23.

[0029] In other words, the turret lathe 100 does not always have tool holders T attached to all 12 turret faces 23 (23a, ..., 23n) regardless of the type of machining to be performed on the workpiece W, but rather, depending on the type of machining to be performed on the workpiece W, tool holders T containing tools t of the type selected depending on the type of machining are attached only to turret faces 23 at one or more selected positions among the 12 turret faces 23.

[0030] The receiving unit 31 receives tool layout information input by a user. The tool layout information input by the user to the receiving unit 31 is information that associates information specifying the turret surface 23 to which the tool holder T is attached (turret surface 23a, ..., 23n) among the twelve turret surfaces 23a, ..., 23n, with information specifying the tool holder T attached to the specified turret surface 23a, ..., 23n (T1, T2, T3, T4, ...). The tool layout information may include information specifying the tool t (t1, t2, t3, t4, ...).

[0031] For example, in the turret 22 shown in FIG. 2, a tool holder T1 is attached to the turret surface 23a, a tool holder T2 is attached to the turret surface 23b, a tool holder T3 is attached to the turret surface 23c, a tool holder T4 is attached to the turret surface 23d, and no tool holder T is attached to the other turret surfaces 23e, ..., 23n.

[0032] In this case, the user inputs to the reception unit 31 the combination of turret surface 23a (information identifying turret surface 23; the same applies hereinafter) and tool holder T1 (information identifying tool holder T; the same applies hereinafter), the combination of turret surface 23b and tool holder T2, the combination of turret surface 23c and tool holder T3, and the combination of turret surface 23d and tool holder T4.

[0033] The information obtained by combining the information specifying these turret faces 23 and the information specifying the tool holders T for all turret faces 23 to which the tool holders T are attached is tool layout information that specifies the arrangement state (tool layout) of the turret faces 23 to which the tool holders T are attached in the turret 22. Therefore, the receiving unit 31 receives an input of the tool layout information.

[0034] The center of gravity position calculation unit 32 calculates the center of gravity position of the turret 22 in a plane perpendicular to the axis C2 in a state in which a tool holder T is attached to the turret surface 23. Specifically, the center of gravity position calculation unit 32 stores, for each tool holder T prepared to be attached to the turret surface 23, the weight of the turret 22 alone and the center of gravity position m of the turret 22 alone in the local coordinate system (x-y coordinate system), and the weight of the turret 22 alone and the center of gravity position M0 of the turret 22 alone in the global coordinate system (x-y coordinate system) in a state in which no tool holder T is attached to the turret surface 23.

[0035] Fig. 4 is a diagram showing the position m1 of the center of gravity of the tool holder T1 alone in the local coordinate system, and Fig. 5 is a diagram showing the position m4 of the center of gravity of the tool holder T4 alone in the local coordinate system. For example, the tool holder T1 having a tool t1 has a predetermined weight by itself, and as shown in Fig. 4, assuming that the tool holder T1 is attached to the turret face 23, the position of the center of gravity of the tool holder T1 alone is specified as m1(x1, y1) in the local coordinate system (xy coordinate system) with the turret face 23 as the y-axis and the center line of the tool holder T1 as the x-axis. In this way, the weight and position m1 of the center of gravity of the tool holder T1 alone, which have been determined in advance, are stored in the center of gravity position calculation unit 32.

[0036] Similarly, the tool holder T4 having the tool t4 has a predetermined weight by itself, and as shown in Fig. 5, when it is assumed that the tool holder T4 is attached to the turret face 23, the position of the center of gravity of the tool holder T4 by itself is specified as m4(x4, y4) in a local coordinate system (xy coordinate system) with the turret face 23 as the y-axis and the center line of the tool holder T4 as the x-axis. In this way, the weight of the tool holder T4 by itself and the position m1 of its center of gravity of the tool holder T4 by itself, which have been determined in advance, are stored in the center of gravity position calculation unit 32.

[0037] The center of gravity position calculation unit 32 also stores the weight of the turret 22 alone, which has been determined in advance, and the center of gravity position M of the turret 22 alone in a plane perpendicular to the axis C2, with the axis C2, which is the center of rotation, being the origin (0,0) of the global coordinate system (XY coordinate system).

[0038] Then, based on the tool layout information input to the receiving unit 31, information relating to the weight and center of gravity position in the local coordinate system of the tool holder T attached to the turret surface 23 in the tool layout information, and information relating to the weight and center of gravity position in the global coordinate system of the turret 22 alone, the center of gravity calculation unit 32 calculates the center of gravity position M′ of the turret 22 in the global coordinate system in a state in which the tool holder T is attached in the arrangement of the tool layout information.

[0039] 6 and 7 are schematic diagrams showing the position M′ (X′, Y′) of the center of gravity of the turret 22 in the global coordinate system and the amount of eccentricity δ from the center of rotation (axis C2) according to an example of a tool layout of the tool holder T. FIG. 6 shows a tool layout in which the tool holders T are concentrated and arranged in an angular range θ1, and FIG. 7 shows a layout in which the tool holders T are dispersed and arranged in an angular range θ2 (>θ1).

[0040] In this case, when the tool holder T1, which has a center of gravity m1(x1, y1) in the local coordinate system, is attached to the turret surface 23a that is parallel to the Y-axis in the global coordinate system as shown in Fig. 6, and the origin of the local coordinate system is set to the center position of the turret surface 23a in the global coordinate system, the center of gravity M1'(X1', Y1') of the tool holder T1 alone in the global coordinate system can be calculated by adding the distance r from the axis C2 to the turret surface 23a to the x-coordinate value of the center of gravity m1(x1, y1) in the local coordinate system (see Fig. 4). In other words, the center of gravity M1'(X1', Y1') is the center of gravity M1'(x1+r, y1).

[0041] Furthermore, in a state in which the tool holder T4, having a center of gravity position m4 (x4, y4) in the local coordinate system, is attached to the turret face 23d parallel to the X-axis in the global coordinate system as shown in Fig. 6, when the origin in the local coordinate system is set to the center position of the turret face 23d in the global coordinate system, the center of gravity position M4' (X4', Y4') of the tool holder T4 alone in the global coordinate system can be calculated by adding the distance r from the axis C2 to the turret face 23a to the y coordinate value of the center of gravity position m4 (x4, y4) in the local coordinate system (see Fig. 5). In other words, the center of gravity position M4' (X4', Y4') is the center of gravity position M4' (x4, y1 + r).

[0042] For the tool holders T2 and T3 on the other turret faces 23b and 23c that are not parallel to either the X axis or the Y axis, the origin in the local coordinate system can be set to the center position of each of the turret faces 23b and 23c in the global coordinate system, and the center of gravity positions M2' (X2', Y2'), M3' (X3', Y3') of the tool holders T2 and T3 alone in the global coordinate system can be calculated in accordance with the inclination of each of the turret faces 23b and 23c.

[0043] The position M′ of the center of gravity of the turret 22 in the global coordinate system when one or more tool holders T are attached can be calculated by applying a method for calculating the position of the center of gravity of a combination of multiple members, which is a general formula in physics, based on the position and weight of the center of gravity of each tool holder T alone in the global coordinate system and the position and weight of the center of gravity of the turret 22 alone in the global coordinate system.

[0044] The eccentricity calculation unit 33 calculates the amount of eccentricity δ of the center of gravity M′ in the global coordinate system of the turret 22 attached in the arrangement of the tool layout information, calculated by the center of gravity position calculation unit 32, relative to the axis C2 that is the center of rotation of the turret 22. The position of the axis C2 in the global coordinate system is the position of the origin (0,0), and is stored in advance in the eccentricity calculation unit 33.

[0045] Here, for example, when comparing the layout shown in Fig. 6 with the layout shown in Fig. 7, the tool holders T attached to the turret 22 are arranged in an angular range θ about the axis C2 of the turret 22, and are concentrated in an angular range θ1 in the layout of Fig. 6, whereas they are dispersed over a wide angular range θ2 (>θ1) in the layout of Fig. 7. Moreover, the number of tool holders T attached to the layout of Fig. 7 is smaller than that of the layout of Fig. 6.

[0046] 6 has a larger eccentricity δ with respect to the axis C2, which is the center of rotation, than the center of gravity M' in the layout of FIG. 7. A layout with a larger eccentricity δ results in an imbalanced weight balance when the turret 22 rotates around the axis C2, resulting in a larger moment of inertia. The drive unit 25 rotates the turret 22 at the rated maximum speed and performs an indexing operation to stop the tool t attached to the tool holder T at a position where the workpiece W is machined (for example, a position facing the axis C1 of the spindle in FIG. 2). However, in a layout with a large moment of inertia, the tool holder T may not stop at the intended stopping position and may stop past the intended stopping position, resulting in overshoot.

[0047] The control unit 34 controls the operation of the drive unit 25 provided in the main body 21 of the turret device 20 based on the eccentricity δ calculated by the eccentricity calculation unit 33. Specifically, when the eccentricity δ is greater than a predetermined threshold value δ0, the control unit 34 controls the drive unit 25 to slow the rotation speed of the turret 22 below a preset rated maximum speed. The threshold value δ0, which is compared with the eccentricity δ, is stored in the control unit 34.

[0048] The threshold value δ0 to be compared with the eccentricity δ is a value that corresponds to the amount of eccentricity that causes overshoot, that is, the tool holder T does not stop at the targeted stopping position but passes over it, during an indexing operation in which the eccentricity δ is calculated in advance for each of a large number of various tool layouts of one or more tool holders T illustrated in FIGS. 6 and 7 , and the turret 22 is rotated at the rated maximum speed corresponding to each tool layout, and the tool t provided in the tool holder T is stopped at a position where the workpiece W is machined (for example, a position facing the axis C1 of the spindle in FIG. 2 ).

[0049] In other words, the threshold value δ0 is set as a value that is the boundary between the amount of eccentricity when overshooting occurs and the amount of eccentricity when overshooting does not occur, by conducting experiments in which the tool holder T is rotated at the rated maximum speed and stopped by an indexing operation for each of a large number of different tool layouts.

[0050] In other words, when the eccentricity δ is greater than the threshold value δ0, the control unit 34 controls the drive unit 25 so that the rotational speed of the turret 22 during the indexing operation is slower than the preset rated maximum speed and at a speed at which overshoot does not occur.

[0051] On the other hand, when the eccentricity δ is not greater than the threshold value δ0, the control unit 34 controls the drive unit 25 so that the rotation speed of the turret 22 during the indexing operation becomes the preset rated maximum speed.

[0052] 8 is a flowchart showing the detailed operation of the control device 30. The more detailed operation of the control device 30 will be described below with reference to FIG.

[0053] When the indexing operation processing of the turret device 20 is started, first, the reception unit 31 waits for the user to input information identifying the tool holders T (such as tool holder numbers T1, T2, ...) and information identifying the turret faces 23 to which those tool holders T are attached (such as turret face numbers 23a, 23b, ...) (S1). When this information is input, the arrangement of the tool holders T on the turret 22 (tool layout information) is specified, and the specified tool layout information is input to the center of gravity position calculation unit 32.

[0054] The center of gravity position calculation unit 32 calculates the center of gravity position M' of the turret 22 in the global coordinate system in a state in which the tool holder T is attached in the arrangement of the tool layout information, based on the input tool layout information and information on the weight and center of gravity position in the local coordinate system of each tool holder T attached to the turret face 23 in the tool layout information, which information is stored in the center of gravity position calculation unit 32, and information on the weight and center of gravity position in the global coordinate system of the turret 22 alone (S2). The calculated center of gravity position M' is input to the eccentricity calculation unit 33.

[0055] The eccentricity calculation unit 33 calculates the eccentricity δ of the center of gravity M' relative to the axis C2 based on the input center of gravity M' in the global coordinate system and the position of the axis C2 in the global coordinate system that is stored in advance in the eccentricity calculation unit 33 (S3). The eccentricity δ is input to the control unit 34.

[0056] The control unit 34 compares the input eccentricity amount δ with a threshold value δ0 stored in advance in the control unit 34 (S4). When the control unit 34 determines that the eccentricity amount δ does not exceed the threshold value δ0 (NO in S4), it controls the drive unit 25 to perform a trial run of an indexing operation in which the turret 22 rotates at the rated maximum speed (S5). In this trial run, the tool holder T, which is positioned at a position where the rotation angle around the axis C2 is the largest from the position of the workpiece W (the position of the axis C1 in FIGS. 2, 6, and 7), is rotated and stopped so as to index the workpiece W positioned on the axis C1.

[0057] The control unit 34 or the drive unit 25 detects the amount of overshoot from the position where the tool holder T, which is positioned at the largest rotation angle around the axis C2, is indexed to the workpiece W, which is positioned on the axis C1, during the indexing operation of this trial run (S6). The amount of overshoot is set to 0 when the tool holder T stops without overshooting, and when the tool holder T overshoots and stops, the amount of overshoot is set to the rotation angle from the original stopping position.

[0058] In addition, when the drive unit 25 rotates the turret under the control of a servo motor, the amount of overshoot can be detected by an encoder used when feedback controlling the rotation angle with the servo motor, and the encoder can function as an overshoot amount detection means for detecting the amount of overshoot.

[0059] When the drive unit 25 is a drive means other than a servo motor, for example, when the drive means is a stepping motor, the turret device 20 may be provided with an overshoot amount detection means that detects the rotation angle of the turret 22, and the overshoot amount may be detected by the overshoot amount detection means.

[0060] The control unit 34 determines whether the detected amount of overshoot is greater than a pre-stored threshold (S7). The threshold, which is used to compare the detected amount of overshoot, is, for example, 0. In other words, if the threshold is 0, the control unit 34 determines whether an overshoot exists (S7).

[0061] When the control unit 34 determines that there was no overshoot (did not exceed threshold value 0) (NO in S7), it controls the drive unit 25 to set the rotation speed of the turret 22 to the rated maximum speed, performs the actual indexing operation (S8), and ends the indexing operation.

[0062] On the other hand, when the control unit 34 determines that an overshoot has occurred (exceeded threshold value 0) (YES in S7), it controls the drive unit 25 to set the rotation speed of the turret 22 to a speed slower than the rated maximum speed at which it is assumed that no overshoot will occur, and performs the actual indexing operation (S13), thereby ending the indexing operation.

[0063] The rotation speed when the control unit 34 controls the drive unit 25 so that the rotation speed of the turret 22 is slower than the rated maximum speed (S13) is a rotation speed that has been experimentally set in advance. This experimentally set rotation speed may be a single rotation speed or a plurality of different rotation speeds.

[0064] When multiple predetermined rotation speeds are set, the control unit 34 can select one of the multiple predetermined rotation speeds depending on the magnitude of the overshoot detected in step 6 (S6). In this case, multiple thresholds for comparison in step 7 (S7) are set, and the control unit 34 compares the amount of overshoot with each threshold, and the control unit 34 can select one rotation speed from the multiple rotation speeds depending on whether the amount of overshoot is larger or smaller than each threshold. Specifically, the control unit 34 can select a slower rotation speed the greater the amount of overshoot detected in step 6.

[0065] The threshold value to be compared with the detected amount of overshoot in step 7 (S7) does not have to be 0, but may be a positive value greater than 0. Furthermore, in step 13 (S13) described above, a plurality of threshold values ​​may be set so as to correspond to a plurality of rotation speeds that are set in advance through experiments, and in step 13 (S13), the control unit 34 may set the rotation speed in stages corresponding to the range of the plurality of threshold values.

[0066] In step 4 (S4), when the control unit 34 determines that the eccentricity δ exceeds the threshold value δ0 (YES in S4), it displays a message on the display unit of the control device 30 urging the user to reconsider the tool layout (S9). That is, when the eccentricity δ exceeds the threshold value δ0, there is a high possibility that an overshoot will occur during the indexing operation in which the turret 22 is rotated at the rated maximum speed. Therefore, the control unit 34 notifies the user by displaying on the display unit that the tool layout should be changed so that an overshoot will not occur. In this case, the display unit functions as a notification unit.

[0067] On the other hand, if the user wants to change the tool layout (YES in S10), the process returns to before step 1 (S1).

[0068] On the other hand, if the user does not change the tool layout (NO in S10), for example, if tool holders T are attached to all of the turret faces 23 and the arrangement of the tool holders T cannot be changed, the control unit 34 controls the drive unit 25 to perform a trial run of the indexing operation of the turret 22 at a rotational speed that is lower than the rated maximum speed and that is preset in accordance with the eccentricity δ detected in step 3 (S3) (S11).

[0069] In this trial run indexing operation, the tool holder T, which is positioned at the position where the rotation angle around the axis C2 is greatest from the position of the workpiece W (the position of the axis C1 in Figures 2, 6, and 7), is rotated and stopped so as to index the workpiece W positioned on the axis C1.

[0070] The control unit 34 or the drive unit 25 detects the amount of overshoot from the position where the tool holder T, which is positioned at the largest rotation angle around the axis C2, is indexed to the workpiece W, which is positioned on the axis C1, during the indexing operation of this trial run (S12). The amount of overshoot is set to 0 when the tool holder T stops without overshooting, and when the tool holder T overshoots and stops, the amount of overshoot is set to the rotation angle from the original stopping position.

[0071] The control unit 34 controls the drive unit 25 to rotate the turret 22 at a speed slower than the rated maximum speed, at which no overshoot is expected to occur, according to the detected amount of overshoot, and causes the actual indexing operation to be performed (S13), thereby terminating the indexing operation.

[0072] The rotation speed when the control unit 34 controls the drive unit 25 so that the rotation speed of the turret 22 is slower than the rated maximum speed (S13) is a rotation speed that has been experimentally set in advance. This experimentally set rotation speed may be a single rotation speed or a plurality of different rotation speeds.

[0073] When a plurality of predetermined rotation speeds are set, the control unit 34 can select one of the plurality of predetermined rotation speeds according to the magnitude of the overshoot amount detected in step 6 (S6). In this case, the control unit 34 selects a slower rotation speed as the amount of overshoot detected in step 6 increases.

[0074] As described above in detail, the control device 30 for the turret 22 and the turret lathe 100 of this embodiment can improve the accuracy of the rotation stop position of the turret 22 by rotating the turret at a rotational speed that corresponds to the tool layout of the tool holder T.

[0075] In the turret 22 control device 30 and turret lathe 100 of this embodiment, the control unit 34 slows the rotational speed of the turret 22 in accordance with the amount of overshoot so as to reduce the amount of overshoot (processing of S13 in Figure 8), but the turret control device and turret lathe of the present invention do not need to go as far as performing the process (S13) in which the control unit 34 slows the rotational speed of the turret 22 in accordance with the amount of overshoot so as to reduce the amount of overshoot.

[0076] That is, in the turret control device and turret lathe according to the present invention, when the eccentricity δ exceeds the threshold value δ0 in the process of S4 in FIG. 8 (YES in S4), the control unit 34 at that time may perform a process (S13) of controlling the drive unit 25 so as to make the rotation speed of the turret 22 slower than the rated maximum speed.

[0077] Furthermore, in the control device 30 for the turret 22 and the turret lathe 100 of this embodiment, the user manually inputs information specifying the tool holder T and information specifying the turret surface 23 on which the tool holder T is attached to the receiving unit 31. However, the turret control device and turret lathe according to the present invention are not limited to those in which the receiving unit 31 manually receives input of information specifying the tool holder T and information specifying the turret surface 23 on which the tool holder T is attached.

[0078] That is, a turret control device and a turret lathe configured such that each tool holder T is provided with a storage means (such as an RFID tag) that stores information for identifying the tool holder T, and each turret face 23 is provided with an identifiable reading means (such as an RFID reader) that reads the information for identifying the tool holder T from the storage means of the tool holder T attached to that turret face 23 can also be an embodiment of the turret control device and the turret lathe according to the present invention.

[0079] In the turret control device and turret lathe of this embodiment, the reception unit 31 identifies the reading means provided on each turret surface 23 and obtains information specifying the tool holder T read by each reading means, thereby identifying the tool holder T attached to each turret surface 23 and automatically recognizing the tool layout of the turret 22, thereby eliminating the need for the user to manually input information. CROSS-REFERENCE TO RELATED APPLICATIONS

[0080] This application claims priority based on Japanese Patent Application No. 2023-107638, filed with the Japan Patent Office on June 30, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A turret control device comprising: a drive unit that rotates about a predetermined center of rotation, and that has a plurality of turret faces on which tool holders including tools are attached, and that rotates the turret around the center of rotation; a control unit that controls the operation of the drive unit; a reception unit that receives input of information relating to a tool layout that specifies the arrangement state of the tool holders attached to the turret faces; a center of gravity position calculation unit that calculates the position of the center of gravity of the turret in the tool layout based on the information about the tool layout input to the reception unit, information relating to the weight and center of gravity of the tool holders attached to the turret faces, and information relating to the weight and center of gravity of the turret alone; and an eccentricity calculation unit that calculates the amount of eccentricity of the position of the center of gravity of the turret calculated by the center of gravity position calculation unit relative to the position of the center of rotation, wherein the control unit controls the rotation speed of the turret by the drive unit based on the amount of eccentricity.

2. A turret control device as described in claim 1, further comprising an alarm unit that displays information encouraging a change in the tool layout, and when the amount of eccentricity is greater than a preset threshold value, the control unit controls the alarm unit to issue the information encouraging a change in the tool layout.

3. A turret control device as described in claim 1, further comprising an overshoot amount detection unit that detects the amount of overshoot when an indexing operation is performed in which the turret is rotated at a predetermined rotational speed and the tool holder is stopped at an index position, and when the amount of overshoot is greater than a predetermined threshold value, the control unit controls the drive unit to reduce the rotational speed.

4. A turret lathe comprising: a turret device including a turret which rotates around a predetermined center of rotation and has a plurality of turret faces to which a tool holder including a tool is attached; a main spindle which holds a workpiece to be machined by the tool attached to the turret; and a control device which controls the main spindle and the turret, wherein the control device has the turret control device according to any one of claims 1 to 3.

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