JP7259645B2 - Numerical controller and control method - Google Patents

Description

The present invention relates to a numerical controller and control method.

Patent Literature 1 discloses a numerical control device that controls a machine tool that can replace tools provided on a spindle. The spindle has a holder clamp and a drawbar. A holder clamping portion clamps the tool holder, and the spindle mounts the tool. A spindle head that rotatably supports the spindle can be vertically moved by a Z-axis motor. When the spindle head moves downward from the origin, the holder clamping section is driven by the drawbar to clamp the tool holder and mount the tool on the spindle. In this process, the torque of the Z-axis motor increases due to the drag force of the clamp spring that urges the drawbar. When the mounting of the tool on the spindle is completed, the clamp spring resistance ceases to act. Therefore, the torque of the Z-axis motor remains unchanged. Here, when the tool is not normally attached to the spindle due to chips or the like interposed between the tool holder and the holder clamping portion, the timing at which the torque of the Z-axis motor remains unchanged changes. Therefore, when the difference between the torque of the Z-axis motor when the tool is normally attached to the spindle and the actual torque of the Z-axis motor is equal to or greater than a predetermined threshold value, the numerical control device can correctly attach the tool to the spindle. Decide not to.

JP 2018-205891 A

Motor torque sometimes fluctuates depending on temperature, humidity, and the like. In addition, noise due to mechanical vibration may be superimposed on the torque of the motor. At this time, the above-described method of comparing the torque difference with the threshold value may not be able to determine whether or not the machine tool operates normally in response to the motor drive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a numerical controller and a control method capable of accurately determining the state of a machine tool according to the driving of a motor.

A numerical control device according to a first aspect of the present invention is provided with a motor, and controls a machine tool that relatively moves a tool attached to a spindle and a work material fixed to a workbench to machine the work material. A numerical controller, comprising: an acquisition unit that acquires the torque of the motor in time series; and the torque value acquired in time series by the acquisition unit is differentiated by a rotation angle of a drive shaft that rotates when the motor is driven. a calculating unit that calculates the differential value obtained by calculating the differential value, and further calculates the center of gravity of the calculated differential value in a rotation angle section of the drive shaft corresponding to a predetermined period including a period that indicates a predetermined state of the machine tool; Based on a center-of-gravity timing corresponding to the rotation angle indicated by the center of gravity calculated by the calculating unit and a predetermined timing corresponding to the predetermined rotation angle within the rotation angle interval , the and a judging unit for judging the state of the machine tool, wherein the relationship G=Σθt/Σt is satisfied, where G is the center of gravity, t is the torque, and θ is the rotation angle of the drive shaft. do.

The center-of-gravity timing indicated by the center-of-gravity calculated by the numerical control device according to the first aspect is less susceptible to temperature, humidity, instantaneous noise, and the like. Therefore, the numerical controller can accurately determine the state of the machine tool based on the center-of-gravity timing.

In the first aspect, the determination unit may determine whether or not the tool is attached to the spindle based on a relationship between a predetermined timing within the predetermined period and the center-of-gravity timing. At this time, the numerical controller can accurately determine whether or not the tool is attached to the spindle based on the relationship between the predetermined timing and the center-of-gravity timing.

In the first aspect, the acquisition unit acquires the torque of the motor when the tool attached to the spindle is replaced and when the tool attached to the spindle is detached, Whether or not the tool is attached to the spindle before detachment may be determined based on the relationship between the timing and the center-of-gravity timing. At this time, the numerical controller can determine whether or not the tool is attached to the main spindle before detachment at the time of tool replacement.

In the first aspect, the acquisition unit acquires the torque of the motor when the tool attached to the spindle is replaced or when a new tool is attached to the spindle, and the determination unit receives the torque at the predetermined timing. and the center-of-gravity timing, it may be determined whether or not the tool is attached to the spindle after attachment. The numerical control device can determine whether or not the tool is mounted on the spindle after mounting when the tool is replaced.

In the first aspect, the predetermined timing may be a timing according to the rotation angle of the center of the rotation angle section . At this time, the numerical controller can easily determine whether or not the tool is attached to the spindle.

In the first aspect, a drawbar is provided on the main shaft and the tool can be attached to and detached from the main shaft by the elastic force of a spring; by driving the drawbar, the tool is attached to the main shaft; may be provided with a lever for switching between a detached state in which the motor is not attached to the main shaft, and the motor may switch between the attached state and the detached state by driving the lever. At this time, the torque of the motor when driving the lever differs between the attached state and the detached state. Therefore, the numerical controller can determine whether or not the tool is attached to the spindle based on the center-of-gravity timing calculated according to the torque of the motor.

In the first aspect, an arm for exchanging the tool attached to the spindle is provided, and the arm has two arms that hold the tool detached from the spindle and the tool newly attached to the spindle. Holding portions may be provided at both ends, and the motor may drive the lever to switch between the attached state and the detached state, and rotate the arm to replace the tool on the spindle. . At this time, the numerical control device can determine whether or not the tool is attached to the spindle in a so-called arm-type machine tool.

A control method according to a second aspect of the present invention provides a numerical value for controlling a machine tool that includes a motor and relatively moves a tool mounted on a spindle and a work material fixed to a workbench to machine the work material. A control method for controlling a control device, comprising: an acquisition step of acquiring the torque of the motor in time series; calculating a differential value differentiated by a rotation angle , and further calculating the center of gravity of the calculated differential value in a rotation angle section of the drive shaft corresponding to a predetermined period including a period indicating a predetermined state of the machine tool. a center-of-gravity timing that is a timing corresponding to the rotation angle indicated by the center of gravity calculated in the calculation step and a predetermined timing that is a timing corresponding to the predetermined rotation angle within the rotation angle section, in the predetermined period. satisfies the relationship G=Σθt/Σt, where the center of gravity is G, the torque is t, and the rotation angle of the drive shaft is θ. It is characterized by According to the second aspect, the same effects as those of the first aspect can be obtained.

2 is a perspective view of the machine tool 1; FIG. 2 is a plan view of the machine tool 1; FIG. 2 is a front view of the machine tool 1; FIG. 2 is a right side view of the machine tool 1; FIG. FIG. 4 is a cross-sectional view taken along the line II shown in FIG. 3; FIG. 2 is a partially enlarged view within the W region shown in FIG. 1; FIG. 4 is a cross-sectional view around the turning shaft 43 and the ATC drive shaft 46 in the main body 401; 2 is a block diagram showing electrical configurations of a numerical controller 50 and a machine tool 1; FIG. Flowchart of tool change processing. Explanatory drawing of tool exchange processing. Timing diagram of tool change operation. FIG. 5 is a diagram showing the relationship between the tilt angle of the swing arm member 60 and the position of the drawbar 70; 4 is a graph showing the torque and differential value of the ATC motor 45; Flowchart of main processing. 4 is a flowchart of first abnormality detection processing; 4 is a flowchart of second abnormality detection processing; The flowchart of the main process in a modification. 9 is a graph showing the torque and differential value of the magazine motor 42 in the modified example;

Embodiments of the present invention will be described. In the following description, left and right, front and rear, and top and bottom indicated by arrows in the drawings are used. The horizontal direction, the front-rear direction, and the vertical direction of the machine tool 1 shown in FIG. 1 are the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. The machine tool 1 is a vertical machine tool having a spindle 7 (see FIG. 5) extending in the Z-axis direction. A machine tool 1 rotates a spindle 7 on which a tool is mounted. The work material is fixed to the turntable 11 . The machine tool 1 relatively moves the spindle head 6 in the X-, Y-, and Z-axis directions, and rotates the spindle 7 to machine the work material. The operation of the machine tool 1 is controlled by a numerical controller 50 (see FIG. 8).

<Overview of machine tool 1>
The structure of the machine tool 1 will be described with reference to FIGS. 1 to 5. FIG. The machine tool 1 includes a base portion 2, a vertical column 5, a spindle head 6, a spindle 7, a workbench device 10, a tool changer 40 (hereinafter referred to as an ATC device 40), and the like.

The base portion 2 is an iron member having a substantially rectangular shape in plan view, and has a base portion 20 (see FIG. 4) on the rear side of the upper surface. The pedestal 20 has a substantially rectangular parallelepiped shape, and has an X-axis movement mechanism 101 (see FIG. 4) on its upper surface. The X-axis moving mechanism 101 supports the carrier 12 (see FIGS. 1 and 4) so as to be movable in the X-axis direction. The X-axis movement mechanism 101 includes a pair of X-axis tracks (not shown), an X-axis ball screw (not shown), an X-axis motor 21 (see FIG. 8), and the like. A pair of X-axis tracks extend in the X-axis direction and are provided on the upper surface of the base portion 20 . The X-axis ball screw extends in the X-axis direction and is provided between a pair of X-axis tracks. Vehicle 12 moves along a pair of X-axis tracks. The carrier 12 has a nut (not shown) on the bottom, and the nut is screwed onto the X-axis ball screw. The X-axis motor 21 rotates the X-axis ball screw, and the carrier 12 moves in the X-axis direction together with the nut.

The carrier 12 has a Y-axis movement mechanism (not shown) on its upper surface. The Y-axis movement mechanism supports the upright column 5 so as to be movable in the Y-axis direction. The Y-axis movement mechanism includes a pair of Y-axis tracks, a Y-axis ball screw, a Y-axis motor 24 (see FIG. 8), and the like. A Y-axis ball screw extends in the Y-axis direction and is provided between a pair of Y-axis tracks. The vertical column 5 moves along a pair of Y-axis tracks. The upright column 5 has a nut (not shown) at its bottom, and the nut is screwed onto the Y-axis ball screw. The Y-axis motor 24 rotates the Y-axis ball screw, and the vertical column 5 moves in the Y-axis direction together with the nut. The vertical column 5 moves in the X-axis direction via the carrier 12 . The vertical column 5 is moved in the X-axis direction and the Y-axis direction by the X-axis movement mechanism 101, the carrier 12, the Y-axis movement mechanism, and the like.

The vertical column 5 has a Z-axis movement mechanism 103 (see FIGS. 2, 3, and 5) on its front surface. A Z-axis moving mechanism 103 supports the spindle head 6 so as to be movable in the Z-axis direction. The Z-axis movement mechanism 103 includes a pair of Z-axis tracks 35 (see FIG. 3), a Z-axis ball screw 36 (see FIG. 5), a Z-axis motor 19, and the like. The Z-axis track 35 extends in the Z-axis direction. The Z-axis ball screw 36 extends in the Z-axis direction and is provided between the pair of Z-axis tracks 35 . The spindle head 6 is movable along a pair of Z-axis tracks 35 . The spindle head 6 has a nut 68 (see FIG. 5) on its rear surface, and the nut 68 is screwed onto the Z-axis ball screw 36 . The Z-axis motor 19 is supported on the upper front surface of the upright column 5 . The Z-axis motor 19 rotates the Z-axis ball screw 36, and the spindle head 6 moves in the Z-axis direction together with the nut 68.

The workbench device 10 is provided in front of the pedestal portion 20 of the base portion 2 . The workbench device 10 has a turntable 11 on its upper part. The turntable 11 is a turntable motor (not shown), and is provided rotatably around a rotation axis parallel to the Z-axis direction. The turntable 11 has pallets P1 and P2 on its upper surface. The work material is fixed to one or both of the pallets P1 and P2 using a jig (not shown) or the like.

<Spindle head 6>
As shown in FIG. 5, spindle head 6 rotatably supports spindle 7 therein. The main shaft 7 extends in the Z-axis direction. The spindle head 6 has a spindle motor 8 fixed thereon. The main shaft 7 and the drive shaft 81 of the main shaft motor 8 are connected by a coupler 25 . The drive shaft 81 extends downward. The spindle 7 includes a mounting hole (not shown), a clamping mechanism (not shown), a draw bar 70, and the like. A mounting hole is provided at the lower end of the spindle 7 . The lower end of the main shaft 7 has a convex key (not shown) at a predetermined position. The key is engageable with a key groove (not shown) provided in a tool holder that holds the tool. The clamping mechanism is provided inside a shaft hole (not shown) passing through the center of the main shaft 7 and above the mounting hole. The drawbar 70 is coaxially inserted into the shaft hole of the main shaft 7 . The draw bar 70 is always biased upward by a spring. The tool holder is mounted in the mounting hole of the spindle 7. As shown in FIG. When the tool holder is mounted in the mounting hole, the clamping mechanism section mounts the tool holder (hereinafter referred to as a clamp) by a mechanism to be described later. When the draw bar 70 presses the clamping mechanism downward, the clamping mechanism detaches the tool holder (hereinafter referred to as unclamping). In this embodiment, for convenience of explanation, the "tool holder" may be abbreviated as "tool".

The spindle head 6 is provided with a swing arm member 60 on the inner side of the rear upper portion. The swinging arm member 60 is substantially L-shaped and swingable around a support shaft 61 . The support shaft 61 extends in the left-right direction inside the spindle head 6 and is fixed to both left and right side walls of the spindle head 6 . The swing arm member 60 has a vertical arm portion 63 and a lateral arm portion 62 . The vertical arm portion 63 extends obliquely upward from the support shaft 61 toward the vertical column 5 side. The lateral arm portion 62 extends substantially horizontally forward from the support shaft 61 . The pin 71 protrudes perpendicularly to the drawbar 70 . The distal end portion 62A of the lateral arm portion 62 is bifurcated, and the drawbar 70 is arranged between the distal end portions 62A. The tip portion 62A can be engaged with the pin 71 from above. When the rocking arm member 60 is viewed from the left side, a tension spring (not shown) always biases the rocking arm member 60 counterclockwise. Therefore, the swing arm member 60 always releases the downward pressure of the pin 71 by the lateral arm portion 62 .

As shown in FIGS. 5 and 6, the spindle head 6 has a rod support portion 91 on the upper portion thereof on the ATC device 40 side. The rod support portion 91 supports the push rod 92 so as to be movable in the front-rear direction. The push rod 92 extends in the front-rear direction. The vertical arm portion 63 of the swing arm member 60 has a contact portion 63A on the right side surface of the upper end portion (tip portion). The contact portion 63A contacts the front end portion of the push rod 92, and is always urged rearward by a tension spring. Therefore, the rear end portion of the push rod 92 always protrudes rearward from the rod support portion 91 by a predetermined distance. When the rear end of the push rod 92 is pushed forward, the swing arm member 60 swings clockwise (left side view) about the support shaft 61 to push down the draw bar 70 against the biasing force of the tension spring. A clamping mechanism unclamps the tool holder. The tool holder can be removed from the mounting hole of the spindle 7.

Hereinafter, a state in which the clamping mechanism clamps the tool holder is referred to as a clamped state, and a state in which the clamping mechanism unclamps the tool holder is referred to as an unclamped state. The angle of the swing arm member 60 with respect to the vertical direction of the vertical arm portion 63 when the clamping mechanism completes unclamping is referred to as the inclination angle of the swing arm member 60, and is assumed to be 0°. At this time, the inclination angle of the swinging arm member 60 when the clamping mechanism clamps is 3.7°.

<ATC device 40>
As shown in FIGS. 1 and 4, the ATC device 40 is supported on the right side of the spindle head 6 by columns 31 and 32 . The struts 31 and 32 are provided on the right side of the upper surface of the base portion 2 . The struts 31 and 32 are separated from each other in the front-rear direction and extend upward from the upper surface of the base portion 2 . The ATC device 40 receives a control signal from the numerical control device 50, and replaces the tool mounted in the mounting hole of the spindle 7 with another tool designated by the NC program described later. The ATC device 40 includes a main body 401, a tool magazine 41, and the like.

As shown in FIGS. 1 to 3, the main body 401 is a substantially rectangular parallelepiped metal box and supported by columns 31 and 32 . As shown in FIGS. 1 to 7, the main body 401 includes an operating member 47, a turning shaft 43, a tool changing arm 44, an ATC motor 45, an ATC driving shaft 46 (see FIG. 7), rocking levers 22 and 23 (see FIG. 7). See), etc. As shown in FIGS. 1, 2, and 4 to 6, the operating member 47 is a rod-shaped member provided inside the main body 401 and extending substantially parallel to the Z-axis direction. An upper end portion of the operation member 47 protrudes upward from an opening (not shown) provided on the upper surface of the main body portion 401 . A lower end portion of the operation member 47 is supported so as to be capable of swinging around a swing shaft 49 (see FIG. 4). The swing shaft 49 extends in the left-right direction inside the body portion 401 and is fixed to both left and right side walls of the body portion 401 . Therefore, the upper end portion of the operating member 47 can move in the front-rear direction around the pivot shaft 49 . The posture in which the operating member 47 extends parallel to the Z-axis direction is the basic posture. The operation member 47 has a contact portion 48 (see FIG. 2) on the left side surface of the upper end portion. The contact portion 48 has a substantially cylindrical shape that protrudes leftward. As shown in FIG. 6, when the spindle head 6 is moved to a predetermined tool changing position (see FIGS. 2 and 3) for tool changing, the rear end of the push rod 92 contacts the contact portion 48 of the operating member 47. located forward.

As shown in FIG. 7, the swivel shaft 43 is formed in a cylindrical shape protruding downward from the lower portion of the main body portion 401, and the main body portion 401 supports the swivel shaft 43 so as to be rotatable about its axis. The swivel shaft 43 extends parallel to the Z-axis direction and has a spline 15 and a spline countershaft 17 at its upper end. Splines 15 are provided with stepped holes 16 . Stepped hole 16 has a predetermined depth along the axis of spline 15 . The support member 39 is formed in the shape of a long shaft and is inserted through the through hole 38A of the upper machine frame 38 fixed to the upper portion of the main body portion 401 . Support member 39 has an outer diameter less than the inner diameter of stepped hole 16 and is secured to upper machine frame 38 . The support member 39 is inserted into the stepped hole 16 via a bush (not shown) arranged at the upper stage of the stepped hole 16 .

The spline subshaft 17 is cylindrically formed and mounted on the outside of the spline 15 . The spline 15 is vertically movable inside the spline subshaft 17 . The bearings 75 and 76 are fixed above the body portion 401 and rotatably support the spline subshaft 17 . Therefore, the swivel shaft 43 rotates around the support member 39 with respect to the main body portion 401 . The spline countershaft 17 has a flange portion 17A on its outer circumference. The flange portion 17A fixes the shafts of the driven rollers 18A and 18B on its upper and lower surfaces. The swivel shaft 43 is coaxially provided with a cylindrical portion 34 in the central portion in the axial direction. The cylindrical portion 34 has a circumferential groove 34A on its outer peripheral surface. When the cylindrical portion 34 is vertically moved, the swivel shaft 43 is vertically moved along the support member 39 .

An outer shaft gear 431 is provided at the lower part inside the main body part 401 . The outer shaft gear 431 has an opening in the center, into which the turning shaft 43 is inserted. The swivel shaft 43 is vertically movable with respect to the outer shaft gear 431 . When the turning shaft 43 moves to a top dead center, which will be described later, the outer shaft gear 431 is engaged with the tool changing arm 44, and the tool changing arm 44 rotates as the outer shaft gear 431 rotates. When the turning shaft 43 moves downward from the top dead center, the outer shaft gear 431 is separated from the tool changing arm 44, and even if the outer shaft gear 431 rotates, the tool changing arm 44 does not rotate. The outer shaft gear 431 has teeth 432 on the outer circumference of the upper end. The lower part inside the main body part 401 rotatably supports the segment gear 66 . The tooth portion 432 meshes with the segment gear 66 . Segment gear 66 supports oscillator 571 . The oscillator 571 follows the planar grooved cam 33 provided on the lower surface of the cylindrical portion 37 .

The tool changer arm 44 extends horizontally perpendicular to the lower end of the pivot shaft 43 . The tool exchange arm 44 rotates according to the rotation of the turning shaft 43 or the rotation of the outer shaft gear 431, and moves vertically between the top dead center and the bottom dead center according to the vertical movement of the turning shaft 43. . The tool change arm 44 has grips 44A and 44B at both ends. Although not described in detail, the gripping portions 44A and 44B are formed, for example, in a C shape in plan view, and fit into grooves (not shown) formed in the tool holder to grip the tool holder. The tool exchange arm 44 has a lock mechanism (not shown) that fixes the tool holders gripped by the gripping portions 44A and 44B, and fixes and unlocks the tool holders according to the rotation angle of the ATC motor 45, which will be described later. Therefore, the gripping portions 44A and 44B detachably grip the tool holder.

The main body part 401 has a box 450 fixed on its upper surface at the approximate center in the front-rear direction. The box 450 has an open bottom wall and the bearing 27 is fixed around the opening. The ATC motor 45 is fixed to the upper part of the box 450, and the output shaft 451 of the ATC motor 45 protrudes downward from an opening provided in the upper wall. The ATC drive shaft 46 extends vertically behind the turning shaft 43 and in parallel with the turning shaft 43. A bearing 27 and a bearing 28, which will be described later, rotatably support the ATC drive shaft 46. As shown in FIG. The bearing 28 is fixed to the bottom wall of the body portion 401 . The upper end of the ATC drive shaft 46 is connected to the output shaft 451 of the ATC motor 45 via a coupling 45C inside the box 450 . The ATC drive shaft 46 is coaxially provided with a cylindrical portion 37 in the center portion in the axial direction. The cylindrical portion 37 has a grooved cam 371 and a grooved cam 372 on its outer peripheral surface.

The body portion 401 internally supports a support point 221 provided at one end of the swing lever 22 so as to be swingable. The rocking lever 22 is formed in the shape of a long shaft, and the engaging element 222 provided in the center thereof engages with the grooved cam 372 . A contact 223 provided at the other end of the swing lever 22 is engaged with a circumferential groove 34A provided in the cylindrical portion 34. As shown in FIG. Therefore, when the ATC drive shaft 46 rotates once, the swing lever 22 swings following the grooved cam 372, and the swing shaft 43 and the tool exchange arm 44 reciprocate once in the axial direction. The rocking lever 23 is formed in the shape of a long shaft, and one end in the length direction is engaged with the grooved cam 371 . The other end of the swing lever 23 is rotatably supported by the operating member 47 . Therefore, when the ATC drive shaft 46 rotates, the swing lever 23 swings following the rotating grooved cam 371, swinging the operation member 47 forward from the basic posture. As described above, when the operation member 47 pushes the rear end of the push rod 92 forward, the tool holder can be removed from the mounting hole of the spindle 7 .

The ATC drive shaft 46 is coaxially provided with a columnar parallel cam 59 on the upper part in the axial direction. The parallel cam 59 is a compound cam having flange-shaped plate cams 591 and 592 . The plate cams 591 and 592 abut on the driven rollers 18A and 18B of the spline subshaft 17, respectively. Therefore, when the ATC drive shaft 46 rotates and the plate cams 591, 592 abut against the driven rollers 18A, 18B, the spline auxiliary shaft 17, the swivel shaft 43, and the tool change arm 44 rotate.

As shown in FIGS. 1 and 4, the tool magazine 41 is fixed to the right side of the main body 401 and has a substantially elliptical shape elongated in the Y-axis direction when viewed from the side. The tool magazine 41 has a substantially elliptical tool passage inside, and stores a plurality of tool pots 41A along the inside of the tool passage. The tool pot 41A detachably mounts a tool holder. The tool magazine 41 has a tool changer (not shown) on the lower front side. The tool changer opens downward. The tool changer has a shutter (not shown). The shutter uses a shutter cylinder 89 (see FIG. 8) as a drive source to open and close the opening. The magazine motor 42 is fixed to the upper front side of the tool magazine 41 . A plurality of tool pots 41A are driven by a magazine motor 42 to move within the tool passage. The numerical controller 50 drives the magazine motor 42 to convey the tool pot 41A to which the next tool is to be attached to the tool changer. In this embodiment, the current tool means the tool that is currently mounted on the spindle 7, and the next tool means the tool that will be mounted on the spindle 7 after tool replacement.

<Electrical configuration>
The electrical configuration of the numerical controller 50 and the machine tool 1 will be described with reference to FIG. The numerical controller 50 includes a CPU 51, a ROM 52, a RAM 53, a storage device 54, an input interface 55, an output interface 56, and the like. The CPU 51 centrally controls the numerical control device 50 . The ROM 52 stores various programs. The RAM 53 stores various data during execution of various processes. The storage device 54 is a non-volatile memory and stores various data in addition to the NC program. The NC program consists of a plurality of blocks, each block containing at least one command such as a tool change command.

The machine tool 1 further includes an input section 82, an identification sensor 58, an air cylinder 88, a shutter cylinder 89, a display section 90, and the like. The air cylinder 88 , the shutter cylinder 89 and the identification sensor 58 are provided in the ATC device 40 . The input section 82 and the display section 90 are provided on an operation panel (not shown). The input unit 82 receives various inputs. The display unit 90 displays various screens. The air cylinder 88 is a driving source of a pot elevating mechanism (not shown) that elevates the tool pot 41A between a vertical posture and a horizontal posture, which will be described later. When the tool pot 41A is in the vertical position, it is positioned leftward with respect to the spindle 7 when the spindle head 6 is in the tool change position. The shutter cylinder 89 is a drive source for a shutter opening/closing mechanism (not shown) that opens and closes the shutter. The input section 82 is electrically connected to the input interface 55 . The air cylinder 88 , shutter cylinder 89 and display section 90 are electrically connected to the output interface 56 .

The Z-axis motor 19 , spindle motor 8 , X-axis motor 21 , Y-axis motor 24 , magazine motor 42 and ATC motor 45 are electrically connected to the output interface 56 . The Z-axis motor 19 , main shaft motor 8 , X-axis motor 21 , Y-axis motor 24 , magazine motor 42 , and ATC motor 45 are servo motors that rotate according to pulse signals output by the output interface 56 . The Z-axis motor 19 has an encoder 19A. The encoder 19A detects the rotation angle of the Z-axis motor 19. FIG. The spindle motor 8 has an encoder 8A. The encoder 8A detects the rotation angle of the spindle motor 8. FIG. The X-axis motor 21 has an encoder 21A. Encoder 21A detects the rotation angle of X-axis motor 21 . The Y-axis motor 24 has an encoder 24A. The encoder 24A detects the rotation angle of the Y-axis motor 24. FIG. The magazine motor 42 has an encoder 42A. The encoder 42A detects the rotation angle of the magazine motor 42. FIG. The ATC motor 45 has an encoder 45A. The encoder 45A detects the rotation angle of the ATC motor 45. FIG. Encoders 19 A, 8 A, 21 A, 24 A, 42 A, 45 A are electrically connected to input interface 55 .

<Tool change processing>
The tool changing process will be described with reference to FIGS. 9 to 12. FIG. When the CPU 51 interprets the NC program block by block and generates a tool change command, the program stored in the ROM 52 is read out and executed to execute tool change processing. As shown in FIG. 9, the CPU 51 moves the spindle head 6 to the tool change position (see FIGS. 2 and 3) (S111). A rear end portion of the push rod 92 is positioned in front of the contact portion 48 of the operating member 47 with a space therebetween (see FIG. 5). The rotation angle of the ATC drive shaft 46 at this time is called 0°. At this time, the tool change arm 44 is positioned at the top dead center in the vertical direction and positioned at the standby position in the rotational direction. The standby position is a position where the gripping portions 44A and 44B are arranged between the spindle 7 and the tool changing portion.

The CPU 51 drives the magazine motor 42 to convey the next tool 202 to the tool changing section (S113). The CPU 51 opens the shutter (S115). As shown in FIGS. 10(1) and 10(2), the CPU 51 lowers the next tool 202 from the opening of the tool changing section by tilting the tool pot 41A, in which the next tool 202 is mounted, by 90 degrees vertically downward from the horizontal state ( S117). The tool pot 41A is in a vertical state. The CPU 51 starts driving the ATC motor 45 (S119).

As shown in FIG. 11, the ATC motor 45 starts driving at time T0, and the ATC drive shaft 46 shown in FIG. 7 rotates forward. The planar groove cam 33 rotates forward, and the segment gear 66 and the outer shaft gear 431 rotate via the oscillator 571 . The turning shaft 43 starts rotating in the first direction (counterclockwise in plan view) at time T1. The rotation of the pivot shaft 43 causes the tool changing arm 44 to rotate in the first direction from the standby position. Hereinafter, the angle when the tool exchange arm 44 rotates in the first direction from the standby position is referred to as a turning angle.

As the ATC drive shaft 46 rotates, the swing lever 23 swings, and the operating member 47 swings forward. Therefore, the contact portion 48 of the operating member 47 contacts the rear end portion of the push rod 92 and presses it forward. The push rod 92 moves forward and urges the contact portion 63A of the vertical arm portion 63 of the swing arm member 60 forward. The swinging arm member 60 starts to rotate clockwise around the support shaft 61 against the biasing force of the tension spring. The tilt angle of the swing arm member 60 changes from 3.7° to 0° (time T2). At this time, the lateral arm portion 62 engages the pin 71 from above and presses the draw bar 70 downward against the biasing force of the spring provided inside the main shaft 7 . The drawbar 70 urges the clamping mechanism downward, and the clamping mechanism begins to move from the clamped state to the unclamped state.

When the rotation angle of the ATC drive shaft 46 reaches 60° (timing T3), the turning angle of the tool change arm 44 reaches 70°. As shown in FIG. 10(3), the gripping portion 44A grips the current tool 201 mounted on the spindle 7, and the gripping portion 44B grips the next tool 202 positioned in the tool changing portion. As shown in FIG. 11, between times T3 to T6 (see FIG. 11), the plate cams 591 and 592 of the parallel cam 59 shown in FIG. to maintain.

When the rotation angle of the ATC drive shaft 46 reaches 80° (timing T4), the clamping mechanism enters a substantially unclamped state, and as shown in FIG. Exit. The tool change arm 44 starts to descend from the top dead center toward the bottom dead center. When the rotation angle of the ATC drive shaft 46 reaches the 90° position (timing T5), the tilt angle of the swing arm member 60 becomes 0°, and the clamping mechanism enters the unclamped state. At this time, the current tool 201 and the next tool 202 are separated downward from the spindle 7 and the tool pot 41A.

At time T6, the plate cams 591 and 592 of the parallel cam 59 shown in FIG. 7 come into contact with the driven rollers 18A and 18B, and the pivot shaft 43 starts rotating again in the first direction from the pivot angle of 70°. The tool change arm 44 rotates while descending toward the bottom dead center. When the rotation angle of the ATC drive shaft 46 is 130° (timing T7), the tool change arm 44 reaches the bottom dead center. ATC drive shaft 46 continues to rotate. When the rotation angle of the ATC drive shaft 46 is 230° (timing T8), the tool change arm 44 starts to rise while rotating from the bottom dead center toward the top dead center. When the rotation angle of the ATC drive shaft 46 is 260° (timing T9), the turning angle of the tool change arm 44 is 250°. As shown in FIG. 10(5), the positions of the current tool 201 and the next tool 202 are interchanged. The next tool 202 is arranged below the spindle 7, and the current tool 201 is arranged below the tool pot 41A of the tool changing section. The plate cams 591 and 592 of the parallel cam 59 shown in FIG. 7 are separated from the driven rollers 18A and 18B, and the turning angle of the tool change arm 44 is maintained at 250°. The tool change arm 44 continues to rise toward the top dead center. At this time, the next tool 202 is inserted into the mounting hole of the spindle 7, and the current tool 201 is inserted into the tool pot 41A.

When the rotation angle of the ATC drive shaft 46 reaches 270° (timing T10), the operation member 47 shown in FIG. 5 begins to swing rearward, and the push rod 92 moves rearward. The oscillating arm member 60 starts to rotate counterclockwise in a right side view around the support shaft 61 by the biasing force of the tension spring, and the inclination angle changes from 0° to 3.7°. The clamping mechanism begins to move from the unclamped state to the clamped state.

When the rotation angle of the ATC drive shaft 46 reaches the 280° position (timing T11), the tool change arm 44 reaches the top dead center as shown in FIG. 10(6). The next tool 202 is mounted in the mounting hole of the spindle 7, and the current tool 201 is mounted in the tool pot 41A. The key groove of the tool holder is engaged with the key at the lower end of the spindle 7, and the next tool 202 is mounted in the mounting hole of the spindle 7. As shown in FIG.

When the rotation angle of the ATC drive shaft 46 reaches 300° (timing T12), the oscillator 571 shown in FIG. The segment gear 66 driven by the oscillator 571 rotates, and the outer shaft gear 431 meshing with the segment gear 66 through the tooth portion 432 rotates. As the outer shaft gear 431 rotates, the tool exchange arm 44 reverses and rotates in the second direction (clockwise in plan view) integrally with the outer shaft gear 431 . When the rotation angle of the ATC drive shaft 46 reaches 330° (timing T13), the tilt angle of the swing arm member 60 returns to 3.7°, and the clamping mechanism enters the clamping state. When the rotation angle of the ATC drive shaft 46 reaches 350° (timing T14), the tool change arm 44 shown in FIG. 7 stops rotating with the turning angle of 180°.

As shown in FIG. 9, the CPU 51 determines whether the rotation angle of the ATC drive shaft 46 has reached 360 degrees (S121). Until the rotation angle of the ATC drive shaft 46 reaches 360° (S121: NO), the CPU 51 returns to S121 and waits. When the rotation angle of the ATC drive shaft 46 reaches 360° (S121: YES), the CPU 51 stops the ATC motor 45 (S123). As shown in FIG. 10(8), the CPU 51 moves the tool pot 41A located in the tool changing portion of the tool magazine 41 from the vertical position back to the horizontal position and lifts it up (S125). The CPU 51 closes the shutter (S127) and ends the tool changing process.

<Specifying the state of the clamping mechanism>
There are times when the current tool 201 is not attached to the main spindle 7 before the tool is removed in the above tool changing process, or attachment of the next tool 202 to the main spindle 7 fails. Based on the torque of the ATC motor 45, the CPU 51 of the numerical controller 50 detects the state (clamped state/unclamped state) of the clamping mechanism of the spindle 7 by the following method. As a result, the CPU 51 determines whether or not the tool is attached to the spindle 7 before removing the tool in the tool changing process, and whether or not the tool is attached to the spindle 7 after attaching the tool in the tool changing process. judge appropriately.

As shown in FIG. 12, the vertical position of the pin 71 provided on the draw bar 70 of the spindle 7 is determined by the clamping mechanism in the unclamped state (see FIGS. 12A and 12C) and the clamped state (see FIG. 12B). (D) reference). The pin 71 is positioned higher when the clamping mechanism is in the unclamped state than in the clamped state. Therefore, the tilt angle of the swing arm member 60 engaging the pin 71 is larger when the clamping mechanism is in the unclamped state than when it is in the clamped state. At this time, the position of the contact portion 63A of the swing arm member 60 in the front-rear direction is positioned more rearward when the clamping mechanism is in the unclamped state than when it is in the clamped state.

When the tool is detached from the spindle 7, the ATC drive shaft 46 is rotated by driving the ATC motor 45, so that the contact portion 48 (see FIG. 5, etc.) of the operating member 47 pushes the push rod 92 forward ( 12 (A) and (B), arrow Y1). Hereinafter, drive control of the ATC motor 45 that is executed to detach the tool from the spindle 7 will be referred to as detachment control. During detachment control, the timing at which the front end of the push rod 92 contacts the contact portion 63A of the swing arm member 60 varies according to the tilt angle of the swing arm member 60. FIG. Torque fluctuation of the ATC motor 45 increases when the push rod 92 comes into contact with the swing arm member 60 . Therefore, the time when the torque fluctuation of the ATC motor 45 increases during detachment control differs between when the clamping mechanism is in the unclamped state and when it is in the clamped state.

Similarly, when a tool is mounted on the spindle 7, the ATC drive shaft 46 is rotated by driving the ATC motor 45, so that the contact portion 48 of the operating member 47 moves rearward, and the clamping mechanism is in the clamped state. The push rod 92 is separated from the swing arm member 60 at an angle that depends on the amp ramp state (FIGS. 12(C) and 12(D), arrow Y2). The drive control of the ATC motor 45 executed to mount the tool on the spindle 7 is hereinafter referred to as mounting control. During mounting control, the timing at which the contact portion 63A of the swing arm member 60 separates from the front end portion of the push rod 92 varies according to the tilt angle of the swing arm member 60. FIG. Torque fluctuation of the ATC motor 45 increases when the push rod 92 is separated from the swing arm member 60 . Therefore, the timing when the torque fluctuation of the ATC motor 45 increases during mounting control differs between when the clamping mechanism is in the clamped state and when it is in the unclamped state.

13A is a graph showing the relationship between the rotation angle of the ATC drive shaft 46 and the torque of the ATC motor 45. FIG. A curve p11 represents the torque when the clamping mechanism is in the unclamped state during detachment control and the clamping mechanism is in the unclamped state during attachment control. A curve p12 indicates the torque when the clamping mechanism is in the unclamped state during detachment control and in the clamped state during attachment control. A curve p13 represents the torque when the clamping mechanism is in the clamped state during detachment control and in the unclamped state during mounting control. A curve p14 indicates the torque when the clamping mechanism is in the clamped state during detachment control and in the clamped state during mounting control.

FIG. 13B shows the torque of the ATC motor 45 during desorption control. Between the curves p11 and p12 when the clamping mechanism is in the unclamped state and the curves p13 and p14 when the clamping mechanism is in the clamped state during detachment control, there are times when the slopes increase, in other words, when torque fluctuations increase. differ. More specifically, when the clamping mechanism is in the unclamped state (curves p11 and p12), the torque fluctuation increases when the clamping mechanism is in the clamped state (curves p13 and p14). The rotation angle of the corresponding ATC drive shaft 46 becomes smaller than when it becomes large. The reason for this is that, as shown in FIGS. 12A and 12B, when the front end of the push rod 92 comes into contact with the contact portion 63A of the swing arm member 60 during detachment control, the unclamped state (see FIG. 12) (A)) is earlier than the clamped state (FIG. 12(B)). When the clamping mechanism is in the unclamped state (curves p11 and p12) during detachment control, either the attachment of the tool to the spindle 7 failed in attachment control in the previous tool change process, or the tool There was no problem with the installation of the tool, but after that, the tool fell off during machining of the work material. At this time, the CPU 51 determines that the tool is not attached to the spindle 7 before the tool is removed in the tool changing process.

FIG. 13D shows the torque of the ATC motor 45 during mounting control. The curves p11 and p13 when the clamping mechanism is in the unclamped state during mounting control and the curves p12 and p14 when the clamping mechanism is in the clamped state differ in timing at which torque fluctuations increase. More specifically, when the clamping mechanism is in the unclamped state (curves p11 and p13), the torque fluctuation increases when the clamping mechanism is in the clamped state (curves p12 and p14). The rotation angle of the corresponding ATC drive shaft 46 is larger than the time when it becomes large. This is because, as shown in FIGS. 12(C) and 12(D), when the front end of the push rod 92 separates from the contact portion 63A of the swing arm member 60 during mounting control, the unclamped state (see FIG. 12 ( C)) is slower than the clamped state (FIG. 12(D)). When the clamping mechanism is in the unclamped state (curves p12 and p14) during mounting control, it indicates that the mounting of the tool on the spindle 7 has failed in the mounting control in the current tool changing process. At this time, the CPU 51 determines that the tool is not attached to the spindle 7 after the tool has been attached in the tool replacement process. Hereinafter, the time when the clamping mechanism is in the unclamped state during detachment control and the time when the clamping mechanism is in the unclamped state during mounting control are collectively referred to as tool mounting abnormality.

The CPU 51 of the numerical control device 50 identifies the state of the clamping mechanism according to the time when the torque fluctuation of the ATC motor 45 becomes large by the following method. The CPU 51 controls the torque of the ATC motor 45 during a period in which the rotation angle of the ATC drive shaft 46 is 40° to 75° (hereinafter referred to as a detachment period) in order to specify the time when the torque fluctuation becomes large during the detachment control. and calculate the differential value (see FIG. 13(C)). The CPU 51 further calculates the center of gravity of the calculated differential value of the torque. Similarly, the CPU 51 controls the rotation of the ATC motor 45 during a period in which the rotation angle of the ATC drive shaft 46 is between 285° and 320° (hereinafter referred to as the mounting period) in order to specify when torque fluctuations increase during mounting control. A torque is obtained and a differential value is calculated (see FIG. 13(E)). The CPU 51 further calculates the center of gravity of the calculated differential value of the torque. The timing corresponding to the rotation angle of the ATC drive shaft 46 corresponding to the calculated center of gravity corresponds to the timing at which the torque fluctuation of the ATC motor 45 increases.

The center of gravity calculated above satisfies the relationship of the following equation. The center of gravity is denoted by G, the torque by t, and the rotation angle of the ATC drive shaft 46 by θ.
G = Σθt/Σt

In FIG. 13C, the rotation angles of the ATC drive shaft 46 corresponding to the centers of gravity of the differential values of the torque calculated based on the curves p11 to p14 are indicated by the centers of gravity G11 to G14. The timing indicated by the rotation angle of the center of the desorption period is referred to as predetermined desorption timing C1. At this time, the rotation angles corresponding to the centers of gravity G11 and G12 are both smaller than the rotation angle corresponding to the detachment predetermined timing C1. That is, when the clamping mechanism is in the unclamped state during detachment control, the timing indicated by the centers of gravity G11 and G12 (hereinafter referred to as the center of gravity timing) is earlier than the predetermined detachment timing C1. On the other hand, the rotation angles corresponding to the centers of gravity G13 and G14 are both larger than the rotation angle corresponding to the detachment predetermined timing C1. That is, when the clamping mechanism is in the clamped state during detachment control, the center-of-gravity timings of the centers of gravity G13 and G14 are later than the predetermined detachment timing C1. Therefore, the CPU 51 can identify the state of the clamping mechanism during detachment control based on the relationship between the center-of-gravity timing of the centers of gravity G11 to G14 and the predetermined detachment timing C1. Furthermore, when the state of the identified clamping mechanism is in the unclamped state, the CPU 51 determines whether the mounting of the tool on the spindle 7 failed in the mounting control in the previous tool changing process, or there was a problem in the mounting of the tool in the previous tool changing process. However, after that, it can be identified that the tool fell off during machining of the work material or the like.

Similarly, in FIG. 13E, the respective rotation angles of the ATC drive shaft 46 corresponding to the centers of gravity of the differential values of the torque calculated based on the curves p11 to p14 are indicated by the centers of gravity G21 to G24. The timing indicated by the rotation angle of the center of the mounting period is referred to as predetermined mounting timing C2. At this time, the rotation angles corresponding to the centers of gravity G21 and G23 are both larger than the rotation angle corresponding to the predetermined mounting timing C2. That is, when the clamping mechanism is in the unclamped state during mounting control, the center-of-gravity timings of the centers of gravity G21 and G23 are later than the predetermined mounting timing C2. On the other hand, the rotation angles of the centers of gravity G22 and G24 corresponding to the center-of-gravity timing are both smaller than the rotation angles corresponding to the predetermined mounting timing C2. That is, when the clamping mechanism is in the clamped state during mounting control, the center-of-gravity timings of the centers of gravity G22 and G24 are earlier than the predetermined mounting timing C2. Therefore, the CPU 51 can specify the state of the clamping mechanism during mounting control based on the relationship between the center-of-gravity timing of the centers of gravity G21 to G24 and the predetermined mounting timing C2. Furthermore, when the specified state of the clamping mechanism is in the unclamped state, the CPU 51 can specify that the tool is not attached to the spindle 7 in the attachment control in the current tool replacement process.

<Main processing>
Main processing executed by the CPU 51 of the numerical controller 50 will be described with reference to FIGS. 14 to 16. FIG. When starting to drive the ATC motor 45 in S119 of the tool change process (see FIG. 9), the CPU 51 executes the main process in parallel with the tool change process. As shown in FIG. 14, the CPU 51 determines whether or not the detachment control is started based on the rotation angle of the ATC drive shaft 46 which rotates forward (S11). When the rotation angle of the ATC drive shaft 46 is outside the angular range of 40° to 75° corresponding to the desorption period, the CPU 51 determines that desorption control has not started (S11: NO). At this time, the CPU 51 advances the process to S17. The CPU 51 determines that desorption control has started when the rotation angle of the ATC drive shaft 46 is within the angle range of 40° to 75° corresponding to the desorption period (S11: YES). At this time, the CPU 51 advances the process to S13.

The CPU 51 determines whether the desorption control has ended (S13). When the rotation angle of the ATC drive shaft 46 is within the angle range of 40° to 75° corresponding to the desorption period, the CPU 51 determines that desorption control has not ended (S13: NO). At this time, the CPU 51 acquires the torque of the ATC motor 45 based on the pulse signal output to the ATC motor 45 and the rotation angle of the ATC motor 45 detected by the encoder 45A (S15). The CPU 51 stores the acquired torque in the storage device 54 (S15). The CPU 51 advances the process to S17. When the rotation angle of the ATC drive shaft 46 is out of the angle range of 40° to 75° corresponding to the detachment period, the CPU 51 determines that detachment control has ended (S13: YES). At this time, the CPU 51 advances the process to S17.

Based on the rotation angle of the ATC drive shaft 46, the CPU 51 determines whether mounting control has started (S17). When the rotation angle of the ATC drive shaft 46 is outside the angular range of 285° to 320° corresponding to the mounting period, the CPU 51 determines that mounting control has not started (S17: NO). At this time, the CPU 51 advances the process to S23. The CPU 51 determines that mounting control has started when the rotation angle of the ATC drive shaft 46 is within the angle range of 285° to 320° corresponding to the mounting period (S17: YES). At this time, the CPU 51 advances the process to S19.

The CPU 51 determines whether the mounting control has ended (S19). When the rotation angle of the ATC drive shaft 46 is within the angle range of 285° to 320° corresponding to the detachment period, the CPU 51 determines that the attachment control has not ended (S19: NO). At this time, the CPU 51 acquires the torque of the ATC motor 45 based on the pulse signal output to the ATC motor 45 and the rotation angle of the ATC motor 45 detected by the encoder 45A (S21). The CPU 51 stores the acquired torque in the storage device 54 (S21). The CPU 51 advances the process to S23. When the rotation angle of the ATC drive shaft 46 is out of the angle range of 285° to 320° corresponding to the mounting period, the CPU 51 determines that mounting control has ended (S19: YES). At this time, the CPU 51 advances the process to S23.

The CPU 51 determines whether the detachment control and the mounting control have ended (S23). When the CPU 51 determines that at least one of the detachment control and the attachment control has not ended (S23: NO), the process returns to S11. When the detachment control is executed (S11: YES, S13: NO), the CPU 51 acquires the torque until the rotation angle of the ATC drive shaft 46 is out of the angle range of 40° to 75° corresponding to the detachment period. The process of storing the data in the storage device 54 is periodically repeated. As a result, the CPU 51 acquires the torque of the ATC motor 45 during detachment control in time series. When the mounting control is executed (S17: YES, S19: NO), the CPU 51 acquires the torque until the rotation angle of the ATC drive shaft 46 is out of the angle range of 285° to 320° corresponding to the mounting period. The process of storing in the storage device 54 is repeated periodically. Thereby, the CPU 51 acquires the torque of the ATC motor 45 during the mounting control in time series. When the CPU 51 determines that both the detachment control and the attachment control have ended (S23: YES), the process proceeds to S25.

The CPU 51 executes the first abnormality detection process (see FIG. 15) in order to detect the mounting abnormality before the detachment control (S25). The first abnormality detection process will be described with reference to FIG. The CPU 51 reads time-series data of the torque of the ATC motor 45 during the detachment period from the storage device 54 . The CPU 51 differentiates the read time series data of torque to calculate a differential value (S41). The CPU 51 calculates the center of gravity of the calculated differential value (S41). The CPU 51 compares the calculated center-of-gravity timing with the detachment predetermined timing C1 (see FIG. 13C) (S43). When the center-of-gravity timing is earlier than the predetermined detachment timing C1 (S43: YES), the CPU 51 determines that the clamping mechanism prior to detachment control is in the unclamped state (S45). At this time, the CPU 51 determines that the tool is not attached to the spindle 7 before the tool is removed in the tool changing process. More specifically, the CPU 51 determines whether a tool mounting error occurred in the mounting control in the previous tool changing process, or whether there was no problem with the tool mounting in the previous tool changing process, but the work material is being machined after that. (S45). On the other hand, when the center-of-gravity timing is later than the predetermined detachment timing C1 (S43: NO), the CPU 51 determines that the clamping mechanism prior to detachment control is in the clamped state (S47). At this time, the CPU 51 determines that the tool was attached to the spindle 7 before the tool was detached in the tool changing process. The CPU 51 ends the first abnormality detection process and returns the process to the main process (see FIG. 14).

As shown in FIG. 14, after executing the first abnormality detection process (S25), the CPU 51 executes the second abnormality detection process (see FIG. 16) in order to detect mounting abnormality after mounting control (S27). The second abnormality detection process will be described with reference to FIG. The CPU 51 reads time-series data of the torque of the ATC motor 45 during the mounting period from the storage device 54 . The CPU 51 differentiates the read time series data of torque to calculate a differential value (S51). The CPU 51 calculates the center of gravity of the calculated differential value (S51). The CPU 51 compares the calculated center-of-gravity timing with the predetermined mounting timing C2 (see FIG. 13E) (S53). When the center-of-gravity timing is later than the predetermined mounting timing C2 (S53: YES), the CPU 51 determines that the clamping mechanism after mounting control is in the unclamped state (S55). At this time, the CPU 51 determines that the tool is not attached to the spindle 7 after the tool has been attached in the tool replacement process. More specifically, the CPU 51 determines that the attachment of the tool to the spindle 7 has failed in the attachment control in the current tool replacement process (S55). On the other hand, when the center-of-gravity timing is earlier than the predetermined mounting timing C2 (S53: NO), the CPU 51 determines that the clamping mechanism after mounting control is in the clamping state (S57). At this time, the CPU 51 determines that the tool is attached to the spindle 7 after the tool has been attached in the tool change process. The CPU 51 ends the second abnormality detection process and returns the process to the main process (see FIG. 14).

As shown in FIG. 14, the CPU 51 determines whether or not it is determined in the first abnormality detection process (S25) or the second abnormality detection process (S27) that a mounting abnormality has occurred (S45, S55) (S29). When the CPU 51 determines that a mounting error has occurred (S29: YES), it displays a notification screen for reporting the occurrence of the error on the display unit 90 (S31). The CPU 51 stops the operation of the machine tool 1 (S31). The CPU 51 terminates the main processing. When the CPU 51 determines that neither the detachment abnormality nor the attachment abnormality has occurred (S29: NO), the main process is terminated.

<Actions and effects of the present embodiment>
The numerical controller 50 calculates the center of gravity of the differential value of the time series data of the torque of the ATC motor 45 (S41). The numerical controller 50 determines the state of the clamping mechanism based on the center-of-gravity timing (S43). Note that the calculated center-of-gravity timing is not easily affected by noise caused by temperature, humidity, and mechanical vibrations, unlike torque difference values and the like. Therefore, the numerical controller 50 can accurately determine the state of the clamping mechanism based on the center-of-gravity timing.

The numerical controller 50 determines whether the clamping mechanism is in a clamped state or not, based on the relationship between the center-of-gravity timing and the predetermined detachment timing C1 during the detachment period and the relationship between the center-of-gravity timing and the predetermined mounting timing C2 during the mounting period. It is determined whether it is in an unclamped state (S43, S53). At this time, the numerical controller 50 can accurately determine whether or not the tool is attached to the spindle 7 based on the relationship between the center of gravity timing and the predetermined timing (detachment predetermined timing C1 or mounting predetermined timing C2).

The numerical controller 50 calculates the center-of-gravity timing based on the torque of the ATC motor 45 during the desorption period during the desorption control, and compares it with the predetermined desorption timing C1. At this time, the numerical controller 50 can determine whether the clamping mechanism before the detachment control is in the clamped state or in the unclamped state during the tool changing process. Therefore, the numerical control device 50 can determine whether a tool is attached to or detached from the spindle 7 before the detachment control of the tool in the tool changing process.

During mounting control, the numerical controller 50 calculates the center-of-gravity timing based on the torque of the ATC motor 45 during the mounting period, and compares it with the predetermined mounting timing C2. At this time, the numerical control device 50 can determine whether the clamping mechanism after mounting control is in the clamped state or the unclamped state during the tool changing process. Therefore, the numerical controller 50 can determine whether the tool is attached to or detached from the spindle 7 after the tool attachment control in the tool change process.

The numerical controller 50 compares the center timing of the detachment period as the predetermined detachment timing C1 with the center-of-gravity timing (S43), and compares the center timing of the mounting period with the center-of-gravity timing as the predetermined mounting timing C2 (S53). ). At this time, the numerical controller 50 can easily determine whether or not the tool is attached to the spindle 7 .

In the machine tool 1, the tilt angle of the swing arm member 60 differs between when the clamping mechanism is in the clamped state and in the unclamped state. At this time, the torque of the ATC motor 45 when driving the swing arm member 60 also differs between the clamped state and the unclamped state. Therefore, the numerical controller 50 can determine whether or not the tool is attached to the spindle 7 based on the center-of-gravity timing calculated according to the torque of the ATC motor 45 . Further, the numerical controller 50 can determine whether or not a tool is attached to the spindle 7 in the so-called arm type machine tool 1 .

<Modification>
The present invention is not limited to the above embodiments, and various modifications are possible. The above processing is not limited to specifying the state of the clamping mechanism in the arm-type machine tool 1 . For example, it may be applied to a so-called turret type machine tool 1 in which a drum-shaped magazine holding a plurality of circular tools is rotationally driven by a motor.

The state of the machine tool 1 that can be specified by the numerical controller 50 is not limited to the state of the clamping mechanism of the spindle 7 (clamped state or unclamped state). For example, the numerical controller 50 determines the degree of backlash of gears connected to various motors (Z-axis motor 19, spindle motor 8, X-axis motor 21, Y-axis motor 24, magazine motor 42, ATC motor 45) of the machine tool 1. may be specified as the state of the machine tool 1 . A modification will be described with reference to FIGS. 17 and 18. FIG. In the modified example, the degree of backlash of the gear group interposed between the plurality of tool pots 41A of the tool magazine 41 and the magazine motor 42 is determined as the state of the machine tool 1. FIG.

As shown in FIG. 17A, a case is illustrated in which rotation is started when the rotary shaft (called magazine shaft) of the magazine motor 42 has a rotation angle of A0. At this time, after the magazine motor 42 rotates by the amount corresponding to the gap (backlash) between the gear groups, the gear groups come into contact with each other, and the plurality of tool pots 41A of the tool magazine 41 start rotating. In FIG. 17A, the gear groups come into contact with each other when the magazine shaft rotates at angles A1 to A2. Therefore, from when the magazine shaft of the magazine motor 42 starts rotating at the rotation angle A0 until the gear groups come into contact with each other at the rotation angles A1 to A2, even if the magazine motor 42 rotates, the plurality of tool pots 41A rotate. do not.

Therefore, when the CPU 51 of the numerical controller 50 controls the magazine motor 42 to transport the tool pot 41A for supporting the next tool to the tool changer and position it, the magazine motor 42 is controlled based on the degree of backlash of the gear group. It is necessary to correct the amount of rotation of More specifically, the CPU 51 controls the amount of rotation of the magazine motor 42 (referred to as the target amount of rotation) required to transport and position the tool pot 41A that supports the next tool to the tool changer. Then, it is necessary to correct by adding the amount of rotation (referred to as a correction value) until the plurality of tool pots 41A start rotating.

Here, the torque of the magazine motor 42 increases (rotational angles A1 to A2) as the gear groups come into contact with each other, and then changes at a constant level (rotational angles A2 to A4). Therefore, the CPU 51 acquires the torque of the magazine motor 42 from when the magazine shaft of the magazine motor 42 starts rotating at the rotation angle A0 until the rotation angle A3, which is sufficiently larger than the rotation angle A2. As shown in FIG. 17B, the CPU 51 calculates the differential value of the acquired torque. The CPU 51 further calculates the center of gravity G31 of the calculated differential value of the torque. The CPU 51 calculates the amount of rotation C between the rotation angle A0 and the rotation angle Ag corresponding to the center of gravity G31 as a correction value. The CPU 51 corrects the target rotation amount by adding the specified correction value to the target rotation amount.

The main processing in the modified example will be described with reference to FIG. When the next tool 202 is transported to the tool changing section in S113 (see FIG. 9), the CPU 51 reads out and executes the program stored in the ROM 52 to execute main processing. The CPU 51 reads the correction values stored in the storage device 54 (S71). When the CPU 51 first executes the main process, the correction values are not stored in the storage device 54, so the initial set values stored in the ROM 52 are read out as correction values. The CPU 51 adds the read correction value to the target amount of rotation, which is the amount of rotation of the magazine motor 42 required to convey the next tool 202 to the tool changing section, to correct the target amount of rotation (S71).

The CPU 51 starts rotating the magazine motor 42 . The rotation angle of the magazine shaft at the start is A0 (see FIG. 17). This rotation angle is hereinafter referred to as the starting angle. The CPU 51 determines whether the current rotation angle of the magazine shaft of the magazine motor 42 (referred to as the current angle) is smaller than the rotation angle A3 (see FIG. 17, hereinafter referred to as the detected angle) (S75). When the CPU 51 determines that the current angle is smaller than the detected angle (S75: YES), the CPU 51 rotates the magazine motor 42 based on the pulse signal output to the magazine motor 42 and the rotation angle of the magazine motor 42 detected by the encoder 42A. Torque is acquired (S77). The CPU 51 stores the acquired torque in the storage device 54 (S77). The CPU 51 advances the process to S79.

The CPU 51 determines whether the current angle of the magazine motor 42 is smaller than the rotation angle A4 (see FIG. 17, hereinafter referred to as the end angle) corresponding to the target rotation amount (S79). When the CPU 51 determines that the current angle is smaller than the end angle (S79: YES), the process returns to S75. The CPU 51 periodically repeats the process of acquiring the torque and storing it in the storage device 54 until the current angle becomes equal to or greater than the detected angle. Thereby, the CPU 51 acquires the torque of the magazine motor 42 in time series. On the other hand, when the CPU 51 determines that the current angle is greater than or equal to the detected angle (S75: NO), the process proceeds to S79. The CPU 51 determines that the current angle of the magazine motor 42 is greater than or equal to the end angle (S79: NO), and since the transfer of the next tool 202 to the tool exchange section has been completed, the process returns to S81.

The CPU 51 reads the time-series data of the torque of the magazine motor 42 from the storage device 54 . The CPU 51 differentiates the read time series data of torque to calculate a differential value (S81). The CPU 51 calculates the center of gravity G31 (see FIG. 17) of the calculated differential value (S81). The CPU 51 calculates, as a correction value, a rotation amount C (see FIG. 17) corresponding to the difference between the rotation angle Ag (see FIG. 17) corresponding to the calculated center of gravity G31 and the start angle (rotation angle A0). The CPU 51 stores the calculated correction value in the storage device 54 (S83). The CPU 51 terminates the main process. The CPU 51 corrects the target rotation amount using the correction value stored in the storage device 54 in S83 when executing the main process from the next time onwards (S71).

At this time, the numerical control device 50 can appropriately determine the degree of backlash of the gear group interposed between the tool pots 41A of the tool magazine 41 and the magazine motor 42, and accurately correct the target rotation amount.

<Other Modifications>
The numerical controller 50 may determine the state of the machine tool 1 in more detail based on the degree of difference between the prescribed detachment timing C1 and the prescribed mounting timing C2 and the center of gravity timing. Furthermore, the numerical control device 50 may apply different predetermined periods and predetermined timings for each state of the machine tool 1 to be determined. The numerical controller 50 may execute either the first abnormality detection process (see FIG. 15) or the second abnormality detection process (see FIG. 16) without executing the other. The predetermined desorption timing C1 may not be the center of the desorption period. The predetermined mounting timing C2 may not be the center of the mounting period.

<Others>
The ATC motor 45 is an example of the "motor" of the present invention. The turntable 11 is an example of the "workbench" of the present invention. The swing arm member 60 is an example of the "lever" of the present invention. The gripping portions 44A and 44B are examples of the "holding portion" of the present invention. The CPU 51 that performs S15, S21, and S71 is an example of the "acquisition unit" of the present invention. CPU51 which processes S41 and S51 is an example of the "calculation part" of the present invention. The detachment period and the attachment period are examples of the "predetermined period" of the present invention. The CPU 51 that performs the processes of S43, S53, and S77 is an example of the "determining section" of the present invention. The processing of S15, S21, and S71 is an example of the "acquisition step" of the present invention. The processing of S41 and S51 is an example of the "calculation step" of the present invention. The processing of S43, S53, and S77 is an example of the "determining step" of the present invention.

Reference Signs List 1: machine tool 7: spindle 11: turntable 40: tool changer 41: tool magazine 44: tool changer arm 45: ATC motor 50: numerical controller 51: CPU
60: Swing arm member 70: Drawbar C1: Detachment predetermined timing C2: Mounting predetermined timing

Claims (8)

A numerical control device for controlling a machine tool having a motor and for relatively moving a tool mounted on a spindle and a work material fixed to a workbench to machine the work material,
an acquisition unit that acquires the torque of the motor in time series;
calculating a differential value obtained by differentiating the torque value acquired in time series by the acquiring unit with respect to the rotation angle of the drive shaft rotated by the drive of the motor ; a calculation unit that further calculates the center of gravity in the rotation angle section of the drive shaft corresponding to the predetermined period including the period indicating
Based on a center-of-gravity timing corresponding to the rotation angle indicated by the center of gravity calculated by the calculating unit and a predetermined timing corresponding to the predetermined rotation angle within the rotation angle interval , A determination unit that determines the state of the machine tool ,
A numerical controller, wherein G=Σθt/Σt, where G is the center of gravity, t is the torque, and θ is the rotation angle of the drive shaft. The determination unit is
2. A numerical controller according to claim 1, wherein whether or not said tool is attached to said spindle is determined based on the relationship between said predetermined timing and said center-of-gravity timing. The acquisition unit
Acquiring the torque of the motor when replacing the tool attached to the spindle and when detaching the tool attached to the spindle;
The determination unit is
3. A numerical controller according to claim 2, wherein whether or not the tool is attached to the spindle before detachment is determined based on the relationship between the predetermined timing and the center-of-gravity timing. The acquisition unit
obtaining the torque of the motor when replacing the tool mounted on the spindle and when mounting the new tool on the spindle;
The determination unit is
4. A numerical controller according to claim 2, wherein whether or not the tool is attached to the spindle after attachment is determined based on the relationship between the predetermined timing and the center-of-gravity timing. 5. A numerical controller according to claim 2, wherein said predetermined timing is a timing according to said rotation angle of the center of said rotation angle section . a drawbar provided on the main shaft and capable of attaching and detaching the tool to and from the main shaft by the elastic force of a spring;
a lever for switching between an attached state in which the tool is attached to the spindle and a disengaged state in which the tool is not attached to the spindle by driving the drawbar;
6. The numerical controller according to claim 2, wherein the motor switches between the mounted state and the detached state by driving the lever. An arm for exchanging the tool attached to the spindle,
The arm is
having two holding portions at both ends for holding the tool detached from the spindle and the tool to be newly attached to the spindle,
The motor is
7. The numerical controller according to claim 6, wherein the lever is driven to switch between the mounted state and the detached state, and the arm is rotated to replace the tool on the spindle. A control method for controlling a numerical control device that controls a machine tool that is equipped with a motor and that relatively moves a tool mounted on a spindle and a work material fixed to a workbench to machine the work material,
an acquiring step of acquiring the torque of the motor in time series;
A differential value is calculated by differentiating the torque value obtained in time series by the obtaining step with respect to the rotation angle of the drive shaft rotated by the drive of the motor, and the calculated differential value is used in a predetermined state of the machine tool. a calculating step of further calculating the center of gravity in the rotation angle section of the drive shaft corresponding to the predetermined period including the period indicating
Based on the center-of-gravity timing, which is the timing corresponding to the rotation angle indicated by the center of gravity calculated in the calculation step, and the predetermined timing, which is the timing corresponding to the predetermined rotation angle within the rotation angle interval, within the predetermined period, a determination step of determining the state of the machine tool ;
A control method characterized by satisfying a relationship of G=Σθt/Σt, where G is the center of gravity, t is the torque, and θ is the rotation angle of the drive shaft.

Images