JP7677099B2 - Machine tool, machining path generation method, and computer program - Google Patents

Description

This technology relates to a machine tool that generates a machining path for a spindle on which a tool is attached, a machining path generation method, and a computer program.

When removing burrs that have occurred on the surface of a workpiece, for example the outer periphery of the workpiece or the inner periphery of a hole in the workpiece, a tool is attached to the spindle of a machine tool, and the spindle moves along the outer or inner periphery of the workpiece to remove the burrs. The machine tool generates a machining path before the spindle moves. The spindle moves along the machining path.

The machining path of the spindle can be generated by offline teaching. Offline teaching can automatically generate the machining path of the spindle to avoid interference between the workpiece and the spindle based on the CAD data of the workpiece (see, for example, Patent Document 1).

JP 2019-150864 A

However, the machining path is only a rough path, and after generating the machining path, the operator must correct the machining path while checking the operation of the spindle in order to create a highly accurate machining path.

This disclosure has been made in consideration of these circumstances, and aims to provide a machine tool, a machining path generation method, and a computer program that can reduce the correction work required by the operator to generate a highly accurate machining path.

A machine tool according to one embodiment of the present disclosure includes a spindle on which a tool is attached, a moving unit that moves the spindle toward and away from the peripheral portion of a master workpiece along a reference path on the outer or inner side of the master workpiece that is determined based on a plurality of reference points, a separation contact determination unit that determines whether the tool comes into contact with the master workpiece during the separation operation, a change unit that changes the separation direction in the separation operation when the separation contact determination unit determines that the tool comes into contact with the master workpiece, an approach contact determination unit that determines whether the tool comes into contact with the peripheral portion during the approach operation by the moving unit, an acquisition unit that acquires coordinates of the spindle each time the approach contact determination unit determines that contact has occurred, and a generation unit that generates a machining path for the spindle based on the plurality of coordinates acquired by the acquisition unit.

In the present disclosure, the spindle repeats an approach operation to the peripheral portion of the master workpiece and an operation of moving away from the peripheral portion along a reference path. If the tool comes into contact with the peripheral portion during the approach operation, the machine tool acquires the coordinates of the spindle and generates a machining path based on the coordinates. In addition, the direction in which the spindle can move away without interfering with the master workpiece differs depending on, for example, whether the spindle is located on the outer or inner side of the master workpiece. When passing the reference point, it is determined whether the tool will come into contact with the master workpiece during the moving away operation, and if it is determined that the tool will come into contact, the moving away direction is changed, automatically preventing the spindle from interfering with the master workpiece during the moving away operation.

In a machine tool according to an embodiment of the present disclosure, the separation contact determination unit determines that the tool is in contact with the master workpiece when the torque acting on the spindle is equal to or greater than a predetermined threshold value.

In this disclosure, during the separation operation, it is determined whether the torque acting on the spindle is equal to or greater than a predetermined threshold value, and whether or not the tool interferes with the master workpiece is confirmed.

In a machine tool according to an embodiment of the present disclosure, the moving unit performs the separation operation to one of a first region and a second region whose boundary is a line connecting the center of the spindle and the reference point located closest to the spindle in the direction of travel of the spindle, and when the separation contact determination unit determines that the tool has come into contact with the master workpiece, the change unit changes the separation direction so as to perform the separation operation to the other of the first region and the second region.

In the present disclosure, when a separation operation is performed to one of the first and second regions, and it is determined that the tool will come into contact with the master workpiece, the separation direction is changed so that the separation operation is performed to the other of the first and second regions, thereby preventing interference with the master workpiece during the separation operation.

A machining path generation method according to an embodiment of the present disclosure is a machining path generation method for generating a machining path for a spindle on which a tool is mounted, which performs an approaching operation of the spindle on which the tool is mounted to the peripheral portion of the master workpiece and a moving operation of the spindle from the peripheral portion along a reference path on the outer or inner side of the master workpiece determined based on a plurality of reference points, determines whether the tool will come into contact with the master workpiece during the moving operation, changes the moving direction in the moving operation when it is determined that the tool will come into contact with the master workpiece during the approaching operation, determines whether the tool will come into contact with the peripheral portion during the approaching operation, obtains coordinates of the spindle, and generates the machining path based on the obtained plurality of coordinates.

In the present disclosure, the spindle alternately repeats an approach operation to the peripheral portion of the master workpiece and an action of moving away from the peripheral portion along a reference path. If the tool comes into contact with the peripheral portion during the approach operation, the machine tool acquires the coordinates of the spindle and generates a machining path based on the coordinates. In addition, the direction in which the spindle can move away without interfering with the master workpiece differs depending on, for example, whether the spindle is located on the outer or inner side of the master workpiece. When passing the reference point, it is determined whether the tool will come into contact with the master workpiece during the moving away operation, and if it is determined that the tool will come into contact, the moving away direction is changed, automatically preventing the spindle from interfering with the master workpiece during the moving away operation.

A computer program according to an embodiment of the present disclosure is a computer program executable by a machine tool that generates a machining path for a spindle on which a tool is attached, and causes the machine tool to perform an approaching operation of the spindle on which a tool is attached to the peripheral portion of the master workpiece and a moving operation of the spindle from the peripheral portion along a reference path on the outer or inner side of the master workpiece that is determined based on a plurality of reference points, determine whether the tool will come into contact with the master workpiece during the moving operation, change the moving direction in the moving operation if it is determined that the tool will come into contact with the master workpiece during the approaching operation, determine whether the tool will come into contact with the peripheral portion during the approaching operation, obtain coordinates of the spindle each time it is determined that the tool will come into contact with the peripheral portion during the approaching operation, and execute a process of generating the machining path based on the obtained plurality of coordinates.

In the present disclosure, the spindle alternately repeats an approach operation to the peripheral portion of the master workpiece and an action of moving away from the peripheral portion along a reference path. If the tool comes into contact with the peripheral portion during the approach operation, the machine tool acquires the coordinates of the spindle and generates a machining path based on the coordinates. In addition, the direction in which the spindle can move away without interfering with the master workpiece differs depending on, for example, whether the spindle is located on the outer or inner side of the master workpiece. When passing the reference point, it is determined whether the tool will come into contact with the master workpiece during the moving away operation, and if it is determined that the tool will come into contact, the moving away direction is changed, automatically preventing the spindle from interfering with the master workpiece during the moving away operation.

In the machine tool, machining path generation method, and computer program according to an embodiment of the present disclosure, the spindle repeats an approach operation to the peripheral portion of the master workpiece and an action of moving away from the peripheral portion along the reference path. If the tool comes into contact with the peripheral portion during the approach operation, the machine tool acquires the coordinates of the spindle, and generates a machining path with high accuracy based on the coordinates, thereby reducing the operator's correction work. In addition, the direction in which the spindle can move away without interfering with the master workpiece differs depending on whether the spindle is located on the outer or inner side of the master workpiece, for example. When passing the reference point, it is determined whether the tool will come into contact with the master workpiece during the moving away operation, and if it is determined that the tool will come into contact, the moving away direction in the moving away operation is changed, so that the spindle can automatically be prevented from interfering with the master workpiece during the moving away operation, and the operator's correction work can be reduced.

FIG. 1 is a schematic perspective view of a machine tool. FIG. 2 is a block diagram showing the configuration of a machine tool. FIG. 11 is an explanatory diagram for explaining generation of a reference trajectory. FIG. 11 is an explanatory diagram for explaining generation of a processing path. FIG. 11 is an explanatory diagram for explaining machining based on a machining path. 4 is an example of a display screen of a display unit. FIG. 11 is an explanatory diagram for explaining a method for generating a processing path. FIG. 8 is a partially enlarged view of FIG. 7 . FIG. 11 is a schematic perspective view of a master work for explaining a change in the separation direction of the spindle. 11 is a flowchart illustrating a machining path generation process by a CPU.

The present invention will be described below based on the drawings showing a machine tool 1 according to an embodiment. Figure 1 is a simplified perspective view of the machine tool 1, and Figure 2 is a block diagram showing the configuration of the machine tool 1. In the following description, the directions up, down, front, back, left and right shown in the drawings will be used.

The machine tool 1 is equipped with a base 2 that is rectangular in plan view. On the top surface of the base 2, multiple reinforcing cylinders 2a are formed parallel to the top of the base 2. A holding table 3 is provided on the reinforcing cylinder 2a in the center of the base 2. The holding table 3 is in the shape of a flattened cylinder and holds a workpiece.

Three uprights 4 are provided around the periphery of the support base 3. The uprights 4 extend upward from the reinforcing tube 2a. The three uprights 4 are arranged with a phase interval of approximately 120 degrees in a plan view. A track 5 is provided on the side of each upright 4 facing the support base 3. The track 5 extends in the vertical direction.

A moving unit 6 is provided on the track 5. A drive source, for example, a ball screw 14 and a moving axis motor 13 (see FIG. 2), is provided on the track 5. The moving unit 6 can be moved up and down along the track 5 by the ball screw 14 driven by the moving axis motor 13. In other words, the moving unit 6 can be moved in a direction intersecting with a first support plate 10 described later.
A mounting portion for mounting a first link 11 and a second link 21, which will be described later, is provided on the side surface of the moving portion 6 facing the support base 3. The mounting portion is, for example, a hole or a protrusion.

A first support plate 10 is disposed above the holding base 3. The first support plate 10 has a triangular shape in a plan view and is approximately parallel to the upper surface of the holding base 3. The three sides of the first support plate 10 face the three uprights 4, respectively. That is, the three sides correspond to the three moving parts 6, respectively. Each side and each moving part 6 are connected by two parallel first links 11. The first links 11 are rod-shaped. One end of each of the two first links 11 is connected to both ends of the side via a rotatable joint 7, respectively. The other end of each of the two first links 11 is connected to the moving part 6 via a rotatable joint 7, respectively. The joints 7 are, for example, universal joints.

The first support plate 10 holds a main shaft 30 that protrudes upward and downward. The main shaft 30 grips a tool 30a at its end. The second support plate 20 is disposed above the first support plate 10, and a connecting tube 8 is provided between the first support plate 10 and the second support plate 20, with the axial direction being the up-down direction. The connecting tube 8 connects the first support plate 10 and the second support plate 20. The connecting tube 8 integrates the first support plate 10 and the second support plate 20.

The upper part of the main shaft 30 is inserted inside the connecting tube 8 and penetrates the second support plate 20. The second support plate 20 has a triangular shape in a plan view and is approximately parallel to the first support plate 10. The three sides of the second support plate 20 face the three uprights 4, respectively. That is, the three sides correspond to the three moving parts 6, respectively. Each side and each moving part 6 are connected by two parallel second links 21. The second links 21 are rod-shaped. One end of each of the two second links 21 is connected to both ends of the side via a rotatable joint 7, respectively. The other end of each of the two second links 21 is connected to the moving part 6 via a rotatable joint 7, respectively. The joints 7 are, for example, universal joints.

The connecting tube 8 has a hexagonal shape in a plan view, and of the six sides at the upper end of the connecting tube 8, three adjacent sides spaced apart in the circumferential direction are connected to three sides of the second support plate 20. Of the six sides at the lower end of the connecting tube 8, three adjacent sides spaced apart in the circumferential direction are connected to three sides of the first support plate 10.

When the three moving parts 6 are at the same height, the main shaft 30 is located approximately directly above the center of the holding table 3. When two moving parts 6 are at the same vertical position and another moving part 6 moves lower than the other two moving parts 6, the main shaft 30 moves horizontally toward the opposite side of the moving part 6 that moves downward, without changing its vertical position.

When two moving parts 6 are in the same vertical position and one other moving part 6 moves higher than the other two moving parts 6, the spindle 30 moves horizontally toward the moving part 6 that is moving upward without changing its vertical position. When all three moving parts 6 move the same distance in the vertical direction, the spindle 30 moves in the vertical direction. By combining these movements, the machine tool 1 positions the spindle 30 at the desired vertical, front-back, left-right position.

The spindle 30 is equipped with a spindle motor 12. The spindle 30 positioned at the desired position is rotated by the drive of the spindle motor 12, and the tool 30a attached to the spindle 30 machines the workpiece held on the holding table 3.

2, the control device 40 includes a CPU 41, a storage unit 42, a RAM 43, an input/output interface 44, an operation unit 45, and a display unit 46. The CPU 41 controls the operation of each unit of the machine tool 1. The storage unit 42 is a rewritable memory, such as an EPROM or EEPROM. The storage unit 42 stores a program product, and in this embodiment, stores a control program (not shown) for controlling the machine tool 1, a processing program DB 421 that stores multiple processing programs for processing the workpiece 95, and a processing path generation program 422. The program 422 is a program for executing a process for generating a processing path, and is provided in a state stored in a computer-readable recording medium 423 such as a CD-ROM, DVD-ROM, or USB memory, and is stored in the storage unit 42 by installing it in the control device 40. The program 422 may also be acquired from an external computer (not shown) connected to a communication network and stored in the storage unit 42.

The memory unit 42 stores a threshold value for comparison with the torque of the spindle motor 12 described later, a flag indicating the direction of separation, i.e., a flag "1" indicating the direction toward the first area A1 or a flag "2" indicating the direction toward the second area A2, etc.

When an operator operates the operation unit 45, a signal is input from the operation unit 45 to the input/output interface 44. The operation unit 45 is, for example, a keyboard, a button, a touch panel, etc. The input/output interface 44 outputs a signal to the display unit 46. The display unit 46 is, for example, a liquid crystal display panel, and displays characters, figures, symbols, etc.

The control device 40 further includes a torque detector 12a for detecting the torque of the spindle motor 12, a spindle control circuit 47 corresponding to the spindle motor 12, a servo amplifier 48, a moving axis control circuit 49 corresponding to the moving axis motor 13, and a servo amplifier 50. Based on a command from the CPU 41, the spindle control circuit 47 outputs a command indicating target values such as the rotation direction and rotation speed of the spindle motor 12 to the servo amplifier 48. The servo amplifier 48 supplies power to the spindle motor 12 based on the command. The torque detector 12a detects the torque of the spindle motor 12, and the CPU 41 acquires the torque via the input/output interface 44. The encoder 18 detects the rotation position and speed of the spindle motor 12 and sends a detection signal to the servo amplifier 48. The servo amplifier 48 compares the detection signal with the target value and controls the output power.

The moving axis control circuit 49 outputs commands indicating target values such as the moving direction and speed of the three moving parts 6 to the servo amplifier 50 based on instructions from the CPU 41. The servo amplifier 50 supplies power to the moving axis motor 13 based on the commands. The encoder 19 detects the rotational position and speed of the moving axis motor 13 and sends a detection signal to the servo amplifier 50. The servo amplifier 50 compares the detection signal with the target values and controls the output power.

FIG. 3 is an explanatory diagram for explaining generation of a reference path, FIG. 4 is an explanatory diagram for explaining generation of a machining path, and FIG. 5 is an explanatory diagram for explaining machining based on the machining path.
In the machining path generating method of this embodiment, a deburred master workpiece 9 is held on the holder 3 of the machine tool 1. A tool 30a is attached to the tip of the spindle 30.
3, a reference path _L0 is generated on the outer periphery of a master workpiece 9 by a method such as online teaching using conventional CAM software. The reference path _L0 is taught by a plurality of teaching points _Pn (n is a natural number) on the reference path _L0 . The teaching points correspond to the reference points.
Based on the program 422, the spindle 30 alternately moves toward and away from the peripheral edge of the master workpiece 9 along the reference path _L0 . The peripheral edge includes the outer peripheral edge and the inner peripheral edge. The approaching movement is a movement toward the master workpiece 9, and the moving away movement is a movement away from the master workpiece 9.

The CPU 41 determines whether or not the tool 30a has come into contact with the peripheral portion during the approaching operation, and each time it determines that the tool 30a has come into contact, acquires the coordinates of the center P of the spindle 30. The CPU 41 acquires the rotational position of the moving axis motor 13 using the encoder 19, and calculates the coordinates of the center P of the spindle 30 using the acquired rotational position.
As shown in FIG. 4, the CPU 41 generates a machining path _L1 based on the coordinates of a plurality of centers P obtained.
When a workpiece 95 having burrs is to be deburred, the workpiece 95 is held on the holder 3. Based on a corresponding machining program, the spindle 30 having the tool 30a attached thereto is moved along the machining path _L1 as shown in FIG.

6 is an example of a display screen of the display unit 46. To generate the machining path _L1 , the CPU 41 displays the master work, the teaching points _Pn (n=1, 2, 3, ...), and the reference path _L0 as a perspective view or a plan view on the right side of the display screen. The perspective view or the plan view may be switched by an operation of the operator. The CPU 41 displays input fields for the search pitch, the separation amount, and the movement amount during measurement on the left side of the display screen. The details of the search pitch, the separation amount, and the movement amount during measurement will be described later.

The operator checks the reference path _L0 displayed by the CPU 41 on the display unit 46, and indicates with an arrow any portion of the reference path _L0 that he or she wishes to correct using the operation unit 45. The operator inputs the search pitch, the distance, and the movement amount during measurement. Candidates for the search pitch, the distance, and the movement amount during measurement may be displayed so that the operator can select one of them.

The CPU 41 acquires the search pitch, the distance, and the amount of movement during measurement input by the operator, and inputs the correction portion if acquired, and sets the search conditions by reducing the search pitch, etc. Based on the set conditions, the CPU 41 generates the machining path _L1 .

FIG. 7 is an explanatory diagram for explaining a method for generating the machining path _L1 , and FIG. 8 is a partially enlarged view of FIG. 7. The reference path _L0 is a path initially stored in the machining program DB 421. There are a plurality of teaching points _Pn (n=1, 2, 3, ...) on the reference path _L0 . The CPU 41 generates a search path T along which the spindle 30 moves in a zigzag pattern based on the set search pitch, separation amount, and measurement-time movement amount along the reference path _L0 . In FIG. 7, point P _a is the center point of the spindle 30 when it is separated, and points _P1a , _P1b , _P1c , _P2a , _P2b , ... are the center points of the spindle 30 when it contacts the master workpiece 9 during the approaching operation. The broken lines connecting point P _a and center points P _1a , P _1b , P _1c , P _2a , P _2b , . . . of main axis 30 are search paths T.

As shown in Fig. 8, the center point of the spindle 30 moves from _P0 to _P1 , approaches the master workpiece 9, and comes into contact with the master workpiece 9. The center point of the spindle 30 at the time of contact is _P1a . The CPU 41 calculates a first vector a having a first length from the center point _P1a of the spindle ₃₀ toward the teaching point P2, and a second vector b having a second length and perpendicular to the first vector a. The first length is equal to the search pitch in Fig. 7, and is the distance from the center point of the spindle 30 at the time of contact during the approaching operation. The second length is the separation amount in Fig. 7, and is the distance by which the spindle 30 separates from the peripheral portion of the master workpiece 9 after contacting the peripheral portion.

The CPU 41 calculates a third vector c, which is the sum of the first vector a and the second vector b, and moves the main shaft 30 away based on the third vector c. Note that the angle θ _a may be stored in the storage unit 42 in advance or may be calculated in advance, and the third vector c may be calculated so as to form the angle θ _a with respect to the vector a.

Next, the spindle 30 is moved closer based on a fourth vector d having a third length obtained by adding a measurement movement amount (see FIG. 7) to the second length and having a direction opposite to that of the second vector b. The measurement movement amount is a distance added to the second length for the approaching operation. The approaching operation is performed toward the end point _Pb of the fourth vector d inside the master workpiece 9 until contact with the master workpiece 9 is detected. In reality, the spindle 30 comes into contact with the master workpiece 9 before reaching the end point _Pb , and after the contact, the spindle 30 does not move, and the moving axis motor 13 rotates an amount necessary to reach the end point _Pb .

When the distance D between the center _P1c of the spindle 30 at the time of contact and the teaching point _P2 becomes less than the search pitch, the spindle 30 is moved away from _P1c toward the next teaching point _P3 based on a third vector c which is the sum of a first vector a having a first length and a second vector b perpendicular to the first vector a and having a second length. In this way, the CPU 41 alternately performs the moving away operation and the contact operation, and the CPU 41 stores the coordinates of the center point of the spindle 30 every time the spindle 30 contacts the master workpiece 9 during the approach operation. The CPU 41 generates a machining path for the spindle 30 based on the stored multiple coordinates.

As shown in Fig. 8, when a line connecting a center point _P1a of the spindle 30 and a teaching point (reference point) _P2 located closest to the spindle 30 in the moving direction of the spindle 30 is used as a boundary, the region can be divided into a first region A1 and a second region A2. In Fig. 8, the spindle 30 performs a moving away operation to the first region A1.

FIG. 9 is a schematic perspective view of the master work 9 for explaining the change of the separation direction of the spindle 30. The small circles in FIG. 9 are teaching points P _n (n=1, 2, ...). As shown in FIG. 9, the master work 9 has a base 9d, a tubular portion 9a protruding from the base 9d, and a hole portion 9b penetrating the base 9d. The tubular portion 9a and the hole portion 9b are adjacent to each other. The arrow in FIG. 9 indicates the moving direction of the spindle 30 when the machining path is generated. As shown by the arrow in FIG. 9, the spindle 30 goes around the outer periphery of the tubular portion 9a, then moves along the path 9c and goes around the inner periphery of the hole portion 9b. The path 9c is the path that connects the teaching point of the tubular portion 9a and the teaching point of the hole portion 9b in the shortest time.

When the spindle 30 moves along the outer periphery of the tube 9a, the direction in which it can move away is to the left of the direction of travel. On the other hand, when it moves along the inner periphery of the hole 9b, the direction in which it can move away is to the right of the direction of travel. The area to the left of the direction of travel corresponds to the first area A1 in FIG. 8, and the area to the right of the direction of travel corresponds to the second area A2 in FIG. 8. In other words, when generating the machining path, it is necessary to change the direction in which the spindle 30 moves away from the master workpiece 9. When moving along path 9c, the spindle 30 moves away to the left, but it may also move to the right.

The CPU 41 executes a process to check whether or not it is necessary to change the separation direction each time the spindle 30 passes the teaching point. The CPU 41 separates the spindle 30 in the same direction as the previous separation direction, and rotates the spindle motor 12 at a low speed. It determines whether or not the torque of the spindle motor 12 is equal to or greater than a threshold value stored in the memory unit 42, and if it is equal to or greater than the threshold value, it determines that the tool 30a will come into contact with the master workpiece 9 during the separation operation, and changes the separation direction.

10 is a flow chart for explaining the machining path generation process by the CPU 41. The CPU 41 acquires the reference path _L0 , the search teaching point, the correction teaching point, and the like (S1). The CPU 41 acquires the number of the machining program by the operator's operation, refers to the machining program DB 421, and acquires the reference path _L0 in the machining path column of the machining program with the corresponding number. Or, the spindle 30 is moved to bring the tool 30a into contact with the master work 9, and the coordinates of the point indicating the corner of the master work 9 and the point where the attitude of the tool 30a changes are acquired, and the reference path _L0 is acquired based on these teaching points _Pn . In addition, the search teaching point, which is a teaching point used for calculating the search path, and the changed teaching point, which is a teaching point used for changing the separation direction, are acquired. In the initial state, both the search teaching point and the changed teaching point are the teaching point _P2 .

The CPU 41 displays the reference path _L0 and input fields for the conditions of the search pitch, the amount of separation, and the amount of movement during measurement on the display unit 46 (S2, see FIG. 6). The CPU 41 acquires the search pitch, the amount of separation, and the amount of movement during measurement input by the operator, and inputs a correction portion if acquired, and sets the search conditions by reducing the search pitch, etc. for the correction portion (S3).

The CPU 41 executes an approaching operation of the spindle 30 (S4) and determines whether the tool 30a has come into contact with the master workpiece 9 (S5). The CPU 41 moves the spindle 30 closer to the master workpiece 9 while rotating the spindle motor 12 at a low speed (forward or reverse). The low speed is, for example, 100 to 1000 rpm. The CPU 41 determines whether the torque of the spindle motor 12 is equal to or greater than a threshold value stored in the memory unit 42, and if the torque of the spindle motor 12 is equal to or greater than the threshold value, determines that the tool 30a has come into contact with the master workpiece 9.

If it is determined that the tool 30a is not in contact with the master workpiece 9 (S5: NO), the CPU 41 returns the process to step S5. If it is determined that the tool 30a is in contact with the master workpiece 9 (S5: YES), the CPU 41 acquires the coordinates of the spindle 30, i.e., the center coordinates of the spindle 30 (S6). The CPU 41 that executes step S5 corresponds to the approach contact determination unit, and the CPU 41 that executes step S6 corresponds to the acquisition unit.

The CPU 41 determines whether or not the distance D between the center of the spindle 30 at the time of contact and the search teaching point is less than the search pitch (S7). If the distance D is not less than the search pitch (S7: NO), the CPU 41 calculates the search path, i.e., the target center position of the spindle 30 at the time of separation (S9). If the distance D is less than the search pitch (S7: YES), the CPU 41 updates the search teaching point (S8) and proceeds to step S9. In step S8, for example, the CPU 41 updates the search teaching point from teaching point _P2 to _P3 .

After processing step S9, the CPU 41 determines whether or not the modified teaching point has been passed (S10). The CPU 41 compares the coordinates of the modified teaching point with the coordinates acquired in step S6, and determines whether or not the acquired coordinates are located forward of the coordinates of the modified teaching point in the traveling direction of the spindle 30.

If the changed teaching point has not been passed (S10: NO), the CPU 41 executes a separation operation of the spindle 30 in the direction indicated by the flag (S11). In the initial state, for example, the flag indicating the separation direction is "1", and the spindle 30 separates toward the first area A1 and does not contact the master workpiece 9 when separating. The CPU 41 determines whether or not the search for all center coordinates of the spindle 30 has been completed (S12). If it is determined that the search for all center coordinates of the spindle 30 has not been completed (S12: NO), the CPU 41 returns the process to step S4.

If the modified teaching point has been passed (S10: YES), the CPU 41 updates the modified teaching point (S14). For example, the CPU 41 updates the modified teaching point from teaching point _P2 to _P3 . Even if the searched teaching point has not been passed, the CPU 41 updates the searched teaching point if the distance D is less than the search pitch, but updates the modified teaching point only when the modified teaching point has been passed.

The CPU 41 executes a separation operation at a low speed (S15). The CPU 41 rotates the spindle 30 at a low speed while moving it in the opposite direction to the movement direction of the approach operation, i.e., toward the first area A1 at a low speed. The CPU 41 determines whether the torque of the spindle motor 12 is equal to or greater than a threshold value (S16).

If the torque is equal to or greater than the threshold (S16: YES), i.e., if the spindle 30 cannot be separated, the movement of the spindle 30 is stopped (S17) and the separation direction is changed (S18). That is, the CPU 41 changes the flag indicating the separation direction to "2". The CPU 41 returns the spindle 30 to its original position, i.e., the position indicated by the coordinates acquired in step S6 (S19). In step S16, if the torque is not equal to or greater than the threshold (S16: NO), i.e., if the spindle 30 can be separated, the process proceeds to step S12. The CPU 41 that executes step S16 corresponds to the separation contact determination unit, and the CPU 41 that executes step S18 corresponds to the change unit.

After executing step S19, the CPU 41 advances the process to step S9. If it is determined in step S12 that the search for all center coordinates of the spindle 30 has been completed (S12: YES), the CPU 41 generates a machining path based on the stored multiple center coordinates, stores the generated machining path in the storage unit 42 (S13), and ends the process. The CPU 41 that executes step S13 corresponds to the generation unit.

In addition, a force sensor may be provided on the spindle 30, and if the load detected by the force angle sensor is equal to or greater than a predetermined value, or if the torque acting on the moving axis motor 13 is equal to or greater than a predetermined value, it may be determined that the tool 30a and the master workpiece 9 have come into contact.

In the machine tool 1 according to the embodiment, the spindle 30 alternately repeats an approach operation to the peripheral portion of the master workpiece 9 and an action of moving away from the peripheral portion along the reference path. If the tool 30a comes into contact with the peripheral portion during the approach operation, the CPU 41 acquires the coordinates of the spindle 30, and generates a machining path with high accuracy based on the coordinates, thereby reducing the operator's correction work. In addition, the direction in which the spindle can move away without interfering with the master workpiece 9 differs depending on whether the spindle is located on the outer or inner side of the master workpiece 9. When passing through a teaching point, it is determined whether the tool 30a will come into contact with the master workpiece 9 during the moving away operation, and if it is determined that the tool 30a will come into contact with the master workpiece 9, the moving away direction is changed, so that the spindle 30 is automatically prevented from interfering with the master workpiece 9 during the moving away operation, and the operator's correction work can be reduced.

During the separation operation, it is possible to determine whether the torque acting on the spindle 30 is equal to or greater than a predetermined threshold value, and to check whether the tool 30a interferes with the master workpiece 9. When a separation operation is performed to one of the first area A1 and the second area A2, and it is determined that the tool 30a will come into contact with the master workpiece 9, the separation direction is changed so that the separation operation is performed to the other area of the first area A1 and the second area A2, thereby preventing interference with the master workpiece 9 during the separation operation.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents to the scope of the claims.

1 Machine tool 30 Spindle 30a Tool 40 Control device 41 CPU
42 Storage section 43 RAM

Claims (5)

A spindle on which tools are attached;
a moving unit capable of executing an approaching operation of the spindle to a peripheral portion of a master workpiece and an action of the spindle moving away from the peripheral portion along a reference path on an outer peripheral side and an inner peripheral side of the master workpiece, the reference path being determined based on a plurality of reference points;
a separation contact determination unit that determines whether or not the tool contacts the master workpiece during the separation operation;
a change unit that changes a direction in which the spindle moves during the separation operation relative to a traveling direction of the reference path when the separation contact determination unit determines that the tool will come into contact with the master workpiece;
an approach contact determination unit that determines whether or not the tool has come into contact with the peripheral portion during an approaching operation by the moving unit;
an acquisition unit that acquires coordinates of the main axis each time the approach contact determination unit determines that contact has occurred;
a generation unit that generates a machining path for the spindle based on the multiple coordinates acquired by the acquisition unit. The machine tool according to claim 1 , wherein the separation contact determination unit determines that the tool will come into contact with the master workpiece when a torque acting on the spindle is equal to or greater than a predetermined threshold value. the moving unit performs the separating operation to one of a first region and a second region defined by a line connecting a center of the spindle and the reference point located closest to the spindle in a direction of travel of the spindle,
3. The machine tool according to claim 1, wherein when the separation contact determination unit determines that the tool has come into contact with the master workpiece, the change unit changes a direction in which the spindle moves during the separation operation so as to perform the separation operation to the other of the first area and the second area. A machining path generating method for generating a machining path for a spindle on which a tool is mounted, comprising the steps of:
When a spindle on which a tool is mounted is moved toward and away from a peripheral portion of a master workpiece along a reference path on an outer periphery side and an inner periphery side of the master workpiece, the reference path being determined based on a plurality of reference points,
determining whether or not the tool comes into contact with the master workpiece during the separating operation;
When it is determined that the tool comes into contact with the master workpiece during the separating operation, a direction in which the spindle moves during the separating operation is changed relative to a traveling direction of the reference path ;
determining whether the tool contacts the peripheral edge portion during the approaching operation;
acquiring coordinates of the spindle each time it is determined that the tool comes into contact with the peripheral edge portion during the approaching operation;
The machining path generating method further comprises generating the machining path based on the acquired plurality of coordinates. A computer program executable by a machine tool for generating a machining path for a spindle on which a tool is mounted, comprising:
The machine tool,
When a spindle on which a tool is mounted is moved toward and away from a peripheral portion of a master workpiece along a reference path on an outer periphery side and an inner periphery side of the master workpiece, the reference path being determined based on a plurality of reference points,
determining whether or not the tool comes into contact with the master workpiece during the separating operation;
When it is determined that the tool comes into contact with the master workpiece during the separating operation, a direction in which the spindle moves during the separating operation is changed relative to a traveling direction of the reference path ;
determining whether the tool contacts the peripheral edge portion during the approaching operation;
acquiring coordinates of the spindle each time it is determined that the tool comes into contact with the peripheral edge portion during the approaching operation;
A computer program that executes a process of generating the machining path based on the acquired multiple coordinates.

Images