JP5678739B2 - Tool changer - Google Patents

Description

  The present invention relates to a tool changer for exchanging tools between a spindle and a tool magazine in a machine tool such as a machining center.

  The machining center performs various types of processing such as milling, drilling and tapping while automatically changing the tool mounted on the spindle. The spindle is supported by a spindle head that can be raised and lowered, and rotates by driving the spindle motor. The tool is mounted on the lower end portion of the main shaft protruding from the main shaft head via a tool holder, and rotates the workpiece while moving up and down together with the main shaft to process the workpiece.

  Tool exchange is performed by the operation of an ATC (automatic tool changer) (see, for example, Patent Document 1). The ATC includes a tool magazine and an exchange arm. The tool magazine has a number of tool pots. The tool pot circulates along a predetermined path. The tool is held in each tool pot via a tool holder and accommodated in a tool magazine. The tool pot positions each tool held by the circular movement at an indexing position in the tool magazine and sends it to an exchange position outside the tool magazine.

  The exchange arm is provided on the spindle head side by side with the spindle. The exchange arm pivots around the vertical axis and rises and falls with respect to the spindle head. The exchange arm includes two gripping portions that extend in opposite directions with respect to the axis of the exchange arm and open and close (see, for example, Patent Document 1).

  The exchange arm rises together with the spindle head when changing the tool after completion of machining, and moves to a height position (gripping position) corresponding to the exchange position. The gripping portion of the exchange arm is closed after moving to the gripping position. One gripping part grips a tool (previous tool) mounted on the spindle, and the other gripping part grips a tool (next tool) in the replacement position.

  The exchange arm grips and lowers the tool with the gripping portions on both sides, pulls out the front tool from the spindle, and pulls out the next tool from the tool pot. After lowering, the exchange arm turns 180 °, moves the previous tool to the tool magazine side, and moves the next tool to the spindle side. The exchange arm rises after turning, and the next tool is fitted into the main shaft, and the previous tool is fitted into the tool pot. The exchange arm opens the grip portion and releases the grip of the previous tool and the next tool. The tool pot holds the previous tool, returns to the index position, and circulates in the tool magazine. The spindle holds the next tool and moves down with the spindle head and moves to the machining area. Tool change in the machining center is performed by a series of operations of the tool magazine and the change arm as described above.

JP-A-10-151542

  In the tool changer operating as described above, the changer arm rises with the spindle head and moves to the gripping position when changing tools. The next tool in the tool magazine is moved from the index position to the replacement position after completion of the movement of the replacement arm in order to avoid interference with the replacement arm (the gripping portion thereof) that rises together with the spindle head. The next tool moving in this way vibrates when stopping at the replacement position. After the next tool has moved to the replacement position, the replacement arm waits for the elapse of a standby time necessary for the convergence of the vibration, so that the next tool moved to the replacement position can be reliably gripped.

  The tool magazine accommodates not only small diameter tools such as drills and taps but also large diameter tools such as end mills. The next tool that moves to the replacement position vibrates greatly when the next tool is a large-diameter tool and takes time to converge. The waiting time before the start of the operation of the exchange arm is set based on the time required for the vibration of the large-diameter tool to converge.

  Tool change is usually performed a plurality of times in one machining step. Therefore, the machining time of the machining center can be shortened by shortening the time required for each tool change, but the waiting time is one factor hindering the shortening of the tool change time.

  An object of the present invention is to optimize the waiting time before the operation of the exchange arm and to shorten the time required for processing including the tool exchange time.

  A tool changer according to the present invention comprises a tool magazine having a plurality of tool pots that circulate while holding a tool, and a changer arm that is provided on a spindle head that supports the spindle and moves together with the spindle head, A previous tool that is positioned at the indexing position by the circular movement of the tool pot and moves to the replacement position together with the tool pot is attached to the spindle by the operation of the replacement arm that occurs after the movement of the next tool. In each of the tool changers to be replaced, a standby time is set for each of the tools, the next tool is moved from the indexing position to the replacement position, and the waiting time corresponding to the next tool elapses. And a control device for controlling the tool magazine and the exchange arm so as to start the operation of the exchange arm.

  In the present invention, a standby time is set for each of the tools in the tool magazine. When changing the tool, the control device moves the next tool in the tool magazine to the replacement position, and operates the replacement arm after the standby time set for the next tool has elapsed. The standby time is set based on the time for the vibration of the tool moved to the replacement position to converge. The exchange arm starts operation immediately after the vibration of the next tool has converged. The exchange arm grips the next tool after a lapse of time without excess or deficiency, and reliably exchanges the next tool with the previous tool.

  Further, the tool changer according to the present invention divides the tools in the tool magazine according to size, and the waiting time is such that the large group is long and the small size group is short. It is characterized by being set for each.

  In the present invention, the tools in the tool magazine are grouped according to size, and a waiting time is set for each group. The standby time is set to be long for a large group with large vibration when moving to the replacement position and short for a small group with small vibration when moving to the replacement position. The exchange arm operates after the standby time has elapsed, and reliably grips the next tool whose vibration has converged. The waiting time is set for each group, and there are few types. The load on the control device is small.

  In the tool changer according to the present invention, the waiting time is set for each of the tools in the tool magazine so that the large size tool is long and the small size tool is short. And

  In the present invention, a standby time is set for each of the tools in the tool magazine. The exchange arm starts operation with a waiting time with no excess or deficiency for all subsequent tools. The time required for tool change can be effectively shortened.

  In the tool changer according to the present invention, after the next tool moves to the change position, the change arm starts to operate after the waiting time set for the next tool elapses. By optimizing the standby time, the next tool can be reliably gripped without consuming unnecessary time, and the machining time including the tool change time can be shortened.

It is a perspective view which shows the structure of the principal part of a machining center. It is a longitudinal cross-sectional view which briefly shows the internal structure of a tool magazine. It is the top view which looked at the exchange arm from the lower part. It is a block diagram of the control system of a machining center. It is a graph which shows the example of a setting of standby | waiting time. It is a flowchart which shows the operation content of a control apparatus.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. The directions (front, back, left, and right) used in the following description are indicated by arrows in FIGS.

  FIG. 1 is a perspective view showing a configuration of a main part of the machining center 1. The machining center 1 includes a column 11 erected vertically on the upper surface of the base 10. The column 11 supports the spindle head 2. The spindle head 2 is movable in the vertical direction along a pair of guides 12 provided on the front surface of the column 11. The column 11 includes a feed screw shaft 13 extending in the vertical direction between the guides 12 and 12. The feed screw shaft 13 is connected to a Z-axis motor 14 fixed to the upper part of the column 11, and rotates around the central axis by driving the Z-axis motor 14. The rear portion of the spindle head 2 is screwed to the feed screw shaft 13 between the guides 12 and 12. The spindle head 2 moves up and down according to the rotation of the feed screw shaft 13 driven by the Z-axis motor 14.

  The spindle head 2 supports the spindle 20 inside thereof. The main shaft 20 is connected to a main shaft motor 21 fixed to the upper portion of the main shaft head 2, and rotates around the central axis in the vertical direction by driving the main shaft motor 21. The lower end portion of the spindle 20 protrudes below the spindle head 2 and holds a tool 3 to be mounted as will be described later. The tool 3 ascends and descends with the spindle head 2 and rotates with the spindle 20 by driving the spindle motor 21.

  The machining center 1 includes a processing table 15 on a base 10 in front of the column 11. The processing table 15 fixes a workpiece on a horizontally maintained upper surface, and is driven in the left-right direction by driving the X-axis motor 84 (see FIG. 4), and in the front-back direction by driving the Y-axis motor 85 (see FIG. 4). Move each one. The workpiece on the processing table 15 moves together with the processing table 15. The tool 3 ascends and descends with the spindle head 2 and rotates with the spindle 20 by driving the spindle motor 21 to process the workpiece on the processing table 15.

  The machining center 1 includes a tool changer. The tool changer includes a tool magazine 4 and an exchange arm 5. As shown in FIG. 1, the tool magazine 4 is provided on the upper left side of the column 11. FIG. 2 is a longitudinal sectional view schematically showing the internal configuration of the tool magazine 4.

  As shown in FIG. 2, the tool magazine 4 includes a rotating disk 41 supported by a support frame 40. The support frame 40 is fixed to the left side surface of the column 11. In FIG. 2, the spindle head 2 and the spindle 20 that are raised to the uppermost position along the column 11 are shown together. The spindle head 2 is located on the right side of the tool magazine 4 at the uppermost position.

  The rotating disk 41 has a cylindrical base portion 41a provided coaxially on one side. The base 41a is supported in a cylindrical support tube 40a projecting from the support frame 40. The rotating disk 41 is rotatable around the axis of the base 41a extending in the left-right direction.

  A magazine motor 43 is attached to the upper portion of the support frame 40. The magazine motor 43 is connected to the cam shaft 44. The cam shaft 44 is supported by the support frame 40 and extends in the vertical direction between the portions of the rotating disk 41 facing the base 41a. The cam shaft 44 has a cylindrical cam 44a having a spiral cam groove on the outer periphery. The cam groove of the cylindrical cam 44a is engaged with a plurality of cam protrusions 41b arranged in parallel on the end surface of the base portion 41a. The cam shaft 44 is rotated by driving the magazine motor 43. The rotation of the cam shaft 44 is transmitted to the rotating disk 41 via the cam protrusion 41b that engages with the cylindrical cam 44a, and the rotating disk 41 rotates around the central axis in the left-right direction.

  A plurality of tool pots 6, 6... Are attached to the rotating disk 41 via separate supports 60, 60. The support bodies 60, 60... Extend outward from the fixed portion on the outer periphery of the rotating disk 41 and have a shape bent to the right. The tool pot 6 is a bottomed cylinder having a tool mounting hole 61 opened at one end, and is supported on the tip of each support 60 via a support shaft 62 provided at the bottom. Are arranged side by side with a predetermined interval.

  The tool pots 6, 6... Attached as described above circulate and move on the circumferential circumference according to the rotation of the rotating disk 41. The support shaft 62 is an axis extending in the tangential direction of the rotary disc 41, and the tool pot 6 can swing around the respective support shafts 62. On the other hand, the tool pot 6 is in contact with the inner surface of the cylindrical guide cover 45 attached to the support frame 40 on the outside of the parallel circumference, and is in a state where the swinging around the support shaft 62 is restricted. As shown in FIG. 2, the tool pots 6, 6,... Circulate in a posture in which the opening of the tool mounting hole 61 faces left. The guide cover 45 has a notch with a predetermined width at the bottom. When the tool pot 6 is at the lowest position (index position) corresponding to the notch on the circulation path, the tool pot 6 can swing around the support shaft 62.

  In FIG. 2, the tool pot 6 at the index position is shown with the tool 3 attached, and the uppermost tool pot 6 is shown with no tool 3 attached. The tool mounting hole 61 of the tool pot 6 has a conical positioning hole that decreases in diameter from the left-facing opening toward the inner back side, and a small-diameter cylindrical stop hole that continues to the positioning hole. The tool 3 is fitted and held in the tool mounting hole 61 via the tool holder 30.

  As is well known, the tool holder 30 includes a conical pull stud portion and a shank portion continuous with the tip portion of the pull stud portion. The tool holder 30 is fitted into the tool mounting hole 61 with the shank portion first. The positioning hole of the tool mounting hole 61 is in close contact with the pull stud portion of the tool holder 30 to position the tool holder 30 and the tool 3 coaxially with the tool pot 6. The shank portion of the tool holder 30 enters the retaining hole of the tool mounting hole 61 and engages with a locking ball 64 protruding into the retaining hole to prevent the tool holder 30 from coming off from the tool pot 6. The tool pots 6, 6... Circulate in units of parallel pitches by driving the magazine motor 43, and position the tools 3 held by each in the index position.

  Each tool pot 6 has a protrusion protruding rightward on the outside of the bottom portion, and a lifting pin 63 that is parallel to the support shaft 62 is provided at the tip of each protrusion. A lifting cylinder 46 is attached to the support frame 40. The pulling cylinder 46 includes a slider 47 at the tip of an output rod 46a that extends downward. The slider 47 is formed with a U-shaped engagement groove 47a that opens toward the left. The pulling cylinder 46 is an air cylinder that moves the output rod 46a forward and backward according to supply and discharge of working air. The slider 47 rises and falls according to the operation of the pulling cylinder 46. As shown in FIG. 2, the lowered slider 47 is positioned on the right side of the tool pot 6 in the index position, and receives the lifting pin 63 of the tool pot 6 in the engagement groove 47a. In FIG. 2, a part of the pulling cylinder 46 (a portion overlapping the cylindrical cam 44a) is cut away.

  The slider 47 is raised by the operation of the lifting cylinder 46 and pulls the lifting pin 63. The tool pot 6 in the indexing position swings about 90 ° about the support shaft 62 when the lifting pin 63 is pulled up, and the tool 3 and the tool holder 30 held by the tool pot 6 move to the replacement position. In FIG. 2, the tool pot 6, the tool 3, and the tool holder 30 in the replacement position are shown by a two-dot chain line together with the lifting pin 63 and the slider 47.

  As shown in FIG. 2, the tool 3 moved to the replacement position protrudes from the lower part of the tool magazine 4, is located on the left side of the spindle head 2 raised to the uppermost position, and is the same as the tool 3 attached to the tip of the spindle 20. It becomes height. The exchange arm 5 operates in the lower part of the spindle head 2 as described later, and exchanges the tool (previous tool) 3 attached to the spindle 20 and the tool (next tool) 3 held by the tool pot 6 at the exchange position. To do.

  The exchange arm 5 is attached to the lower end of the arm shaft 50 that projects downward from the spindle head 2. The arm shaft 50 extends in the vertical direction inside the spindle head 2. The arm shaft 50 can rotate around the central axis and move in the axial direction. The exchange arm 5 rotates in a horizontal plane as the arm shaft 50 rotates. The exchange arm 5 moves up and down as the arm shaft 50 moves in the axial direction.

  FIG. 3 is a plan view of the exchange arm 5 as viewed from below. As shown in FIG. 3, the exchange arm 5 is a flat plate member having a mounting portion for the arm shaft 50 in the center, and gripping portions 51, 51 are respectively provided to two arm portions extending in opposite directions from the position of the arm shaft 50. It has.

  The grip 51 includes a pair of fingers 51a and 51b. Both fingers 51a, 51b are attached to the lower surface of the exchange arm 5 by separate support shafts 52a, 52b. The support shafts 52a and 52b are axes parallel to the arm shaft 50, and are disposed close to each other. The fingers 51a and 51b can swing around the respective support shafts 52a and 52b.

  The fingers 51a and 51b extend on both sides of the respective support shafts 52a and 52b. The tips of both fingers 51a, 51b extend outside the exchange arm 5. The base ends of the fingers 51a and 51b extending inward of the exchange arm 5 are urged away from each other by a closing spring 54 interposed therebetween. Further, the fingers 51a and 51b are provided with protrusions 53a and 53b projecting toward the respective support portions. The protrusions 53a and 53b abut between the fingers 51a and 51b as shown in the figure.

  The exchange arm 5 includes an opening cam 55 at the center of the lower surface. The opening cam 55 is attached to the cam shaft 56. The cam shaft 56 is coaxially supported inside the arm shaft 50, moves in the axial direction together with the arm shaft 50, and rotates independently of the arm shaft 50.

  As shown in FIG. 3, the opening cam 55 is a disc-shaped cam having notches at two opposite locations on the outer periphery. Normally, the opening cam 55 is in the rotational position shown in FIG. The two notches are in contact with the base ends of the fingers 51a and 51b of the grips 51 and 51, respectively, and press them against the biasing force of the closing spring 54. The finger 51a swings around the support shaft 52a. This swing is transmitted to the other finger 51b via the protrusions 53a and 53b, and the finger 51b also swings. The proximal ends of both fingers 51a and 51b approach against the biasing force of the closing spring 54. The tips of the fingers 51a and 51b are in an open state separated by a predetermined interval.

  The opening cam 55 rotates clockwise (in the direction indicated by an arrow in FIG. 3) by driving the cam shaft 56 to release the pressing of the finger 51a. The finger 51a swings clockwise by the biasing force of the closing spring 54. By this swing, the protrusions 53a and 53b are separated from each other, and the other finger 51b swings counterclockwise. The tips of the fingers 51a and 51b approach each other, and the grip 51 is in a closed state. The gripping part 51 in the closed state returns to the open state when the opening cam 55 rotates in the opposite direction by driving of the cam shaft 56 and returns to the rotating position shown in FIG.

  The exchange arm 5 turns according to the rotation of the arm shaft 50. The grips 51 and 51 open and close according to the rotation of the cam shaft 56. An arm motor 57 is attached to the upper part of the spindle head 2. The arm motor 57 drives an arm drive shaft (not shown) inside the spindle head 2. The arm drive shaft is supported in parallel with the arm shaft 50 and the cam shaft 56 inside the spindle head 2, and is connected to the arm shaft 50 and the cam shaft 56 via separate cam mechanisms (not shown).

  In a normal state (including during a machining operation), the replacement arm 5 rises together with the arm shaft 50 and is in a position close to the lower surface of the spindle head 2, and the gripping portions 51 and 51 of the replacement arm 5 are in an open state. As shown in FIG. 2, one grip 51 extends toward the main shaft 20 and is positioned so as to sandwich the tool holder 30 of the tool 3 attached to the main shaft 20.

  When the tool is changed, the spindle head 2 is raised to the uppermost position, and the change arm 5 is moved to the gripping position. As shown in FIG. 2, the other gripping portion 51 of the exchange arm 5 moved to the gripping position extends toward the lower part of the tool magazine 4 and is positioned so as to sandwich the tool holder 30 in the replacement position.

  When changing the tool, the exchange arm 5 closes both the gripping portions 51 and 51 and grips the tool holder 30 at each position. The exchange arm 5 descends together with the arm shaft 50 and pulls the tool holder 30 gripped by the gripping portions 51, 51 downward to remove the tool 3 from the main shaft 20 and the tool pot 6. The exchange arm 5 is rotated 180 ° by the rotation of the arm shaft 50 to change the position of the tool (previous tool) 3 on the spindle 20 side and the tool (next tool) 3 on the tool pot 6 side. The exchange arm 5 ascends together with the arm shaft 50, attaches the repositioned tools 3 and 3 to the tool pot 6 and the main shaft 20, and ends the tool exchange.

  In the tool changer, as described above, the change arm 5 is operated with a set of lowering, rotating and raising, and the gripping portions 51 and 51 of the change arm 5 are opened and closed, so that the tool magazine 4 and the spindle 20 The tool 3 is changed between. Tool exchange operation of the exchange arm 5 including opening and closing of the gripping portions 51 and 51 is performed by driving the arm motor 57 and transmitting the rotation of the arm drive shaft to the arm shaft 50 and the cam shaft 56 through the cam mechanism. Complete in a short operating time.

  As described above, the tool 3 is mounted in the tool pot 6 by fitting the tool holder 30 into the tool mounting hole 61 and preventing the shank portion of the tool holder 30 from coming off by the engagement of the locking balls 64. The main shaft 20 has a tool mounting hole (not shown) similar to that of the tool pot 6, and has a draw bar (not shown) inside the tool mounting hole. The tool 3 is mounted on the spindle 20 by inserting the tool holder 30 into the tool mounting hole and pulling up the shank portion of the tool holder 30 with a draw bar. The tool 3 can be mounted so as to be correctly coaxial with the main shaft 20 by the action of the pull stud portion of the tool holder 30.

  The tool 3 mounted on the spindle 20 descends together with the spindle head 2 and processes the workpiece on the processing table 15 as described above. The tool 3 attached to the tool pot 6 is returned to the index position by the swing of the tool pot 6 according to the operation of the pulling cylinder 46. The tool magazine 4 circulates and moves the tool pots 6, 6... By driving the magazine motor 43, and positions the tool 3 to be used next at the index position.

  FIG. 4 is a block diagram of a control system of the machining center 1. The machining center 1 includes a control device 7 that controls the entire machining operation. The control device 7 is a computer including a CPU 71, a ROM 72, a RAM 73, a nonvolatile memory 76, an input interface 74, and an output interface 75.

  The machining center 1 includes an operation panel 8. The operation panel 8 includes an operation unit 81 and a display unit 82. The operation unit 81 has a numeric keypad for setting various numerical values, an operation key for instructing various operations, and the like. The display unit 82 displays the operation content of the operation unit 81, the operation state of the machining center 1, and the like. The operator operates the operation unit 81 in accordance with the display on the display unit 82 to specify the machining conditions such as the machining program and the tool 3 to be used.

  The operation unit 81 is connected to the input interface 74. The CPU 71 reads the operation content of the operation unit 81 via the input interface 74 and controls the machining center 1 by operating according to the control program stored in the ROM 72. The display unit 82 is connected to the output interface 75 via the drive circuit 82a. The CPU 71 gives an operation command to the drive circuit 82a via the output interface 75, and causes the display unit 82 to perform necessary display.

  The output interface 75 of the control device 7 is connected to the drive circuit 84a of the X-axis motor 84, the drive circuit 85a of the Y-axis motor 85, the drive circuit 14a of the Z-axis motor 14 and the drive circuit 21a of the spindle motor 21. The CPU 71 gives an operation command to the drive circuit 84a, the drive circuit 85a, the drive circuit 14a, and the drive circuit 21a via the output interface 75, and the X-axis motor 84, the Y-axis motor 85, the Z-axis motor 14, and the main shaft motor 21 are supplied to each of them. Drive separately.

  As described above, the X-axis motor 84 moves the machining table 15 in the left-right direction, and the Y-axis motor 85 moves the machining table 15 in the front-rear direction. The Z-axis motor 14 raises and lowers the spindle head 2 and moves the tool 3 mounted on the spindle 20 in the vertical direction. The main shaft motor 21 rotates the main shaft 20 to rotate the tool 3. The CPU 71 drives and controls the X-axis motor 84, the Y-axis motor 85, the Z-axis motor 14, and the main shaft motor 21 according to the machining program, and performs desired machining on the workpiece on the machining table 15.

  The output interface 75 of the control device 7 is also connected to the drive circuit 43a of the magazine motor 43 and the drive circuit 57a of the arm motor 57. The CPU 71 gives an operation command to the drive circuit 43a and the drive circuit 57a via the output interface 75, and drives the magazine motor 43 and the arm motor 57 separately.

  The output interface 75 of the control device 7 is also connected to the lifting cylinder 46. The CPU 71 gives an operation command to the lifting cylinder 46 via the output interface 75 to operate the lifting cylinder 46. As described above, when the lifting cylinder 46 is an air cylinder, the CPU 71 controls a valve that supplies and discharges working air to and from the lifting cylinder 46.

  As described above, the magazine motor 43 circulates and moves the tool pots 6, 6... Of the tool magazine 4. The types of tools 3 in the tool magazine 4 are stored in the RAM 73 in association with the tool pots 6 that hold them. The CPU 71 drives and controls the magazine motor 43 according to the machining program, and positions the tool pot 6 holding the tool 3 used in the next process at the index position. The CPU 71 drives and controls the magazine motor 43 and the arm motor 57 according to the machining program, and causes the exchange arm 5 to perform a series of exchange operations. The exchange arm 5 exchanges the tool 3 between the tool magazine 4 and the main shaft 20.

  The lifting cylinder 46 raises and lowers the slider 47. The tool pot 6 positioned at the indexing position in the tool magazine 4 moves to the replacement position by moving the lifting cylinder 46 upward.

  FIG. 6 is a flowchart showing the operation content of the control device 7, and the control operation executed by the control device 7 at the time of tool replacement will be described based on this drawing. Si (i = 1, 2,...) In the figure is a step number indicating an operation step of the CPU 71.

  The CPU 71 executes the machining program in units of blocks. The CPU 71 sets 1 to the block number n (S1) and reads the nth program block (S2). The CPU 71 determines whether or not the read program block is an end command (S3). When it is a program end command (S3; YES), the CPU 71 ends the control operation.

  If it is not a program end command (S3; NO), the CPU 71 determines whether or not the read program block is a tool change command (S4). If it is not a tool change command (S4; NO), the CPU 71 performs a machining operation according to the read program block (S5). The machining operation is an operation of machining the workpiece on the machining table 15 by driving the X-axis motor 84, the Y-axis motor 85, the Z-axis motor 14 and the spindle motor 21 in combination.

  During execution of the machining operation, the CPU 71 drives the magazine motor 43, circulates the tool pot 6 in the tool magazine 4, and positions the tool 3 (next tool) used in the next process at the index position (S6). . The CPU 71 determines whether or not the positioning to the index position has been completed (S7). The determination of S7 is performed based on the detection result of the rotation detector provided in the magazine motor 43, for example. Information about the next tool is contained in the program block being executed.

  When the positioning is not completed (S7; NO), the CPU 71 shifts the process to S5 and continues the machining operation. When the positioning is completed (S7; YES), the CPU 71 reads a waiting time corresponding to the next tool positioned at the index position (S8).

  The waiting time is determined in advance for each of a large number of tools 3 that can be stored in the tool magazine 4 and stored in the nonvolatile memory 76. The standby time is a time required for the vibration of the tool 3 (including the tool pot 6 and the tool holder 30) moved from the indexing position to the replacement position to converge. The magnitude of the vibration of the tool 3 depends on the size (weight, length, moment of inertia, etc.) of the tool 3, and the length of the convergence time of the vibration depends on the magnitude of the vibration. The waiting time is set for each group so that, for example, the tools 3 are grouped by size and are short for small tools such as drills and taps and long for large tools such as end mills. To do. The set waiting time is stored in the nonvolatile memory 76 in association with each tool.

FIG. 5 is a chart showing an example of setting the standby time. FIG. 5 shows standby times of four types of tools 3 having different sizes (moments of inertia). The tool 3 is divided into two groups, for example, a large size tool having a moment of inertia of a predetermined value (0.04 kg · m ² ) or more and a small size tool having a moment of inertia less than a predetermined value, The standby time of the small size group (tool numbers 1 and 2) is 0.1 sec, and the standby time of the large size group (tool numbers 3 and 4) is 0.2 sec. The moment of inertia is a moment generated when the tool 3 rotates around the support shaft 62 together with the tool pot 6.

  Moreover, you may set the waiting time of the tool of the tool numbers 1-4 individually. In FIG. 5, the waiting time for a tool with a large moment of inertia (tool number 2) in a small group is set to 0.1 sec, and the waiting time for a tool with a small moment of inertia (tool number 1) is set to 0.05 sec. In the large size group, the standby time of a tool (tool number 4) with a large moment of inertia is set to 0.2 sec, and the standby time of a tool (tool number 3) with a small moment of inertia is set to 0.15 sec. .

  The CPU 71 recognizes the types of the plurality of tools 3 in the tool magazine 4 in the initial setting at the start of the operation, reads the standby time corresponding to each tool 3 from the nonvolatile memory 76, and stores it in the RAM 73. The RAM 73 stores the standby time corresponding to the plurality of tools 3 as standby time data corresponding to the tool pot 6 that holds each tool 3. In S8, the CPU 71 reads from the RAM 73 the waiting time corresponding to the next tool (tool pot 6) at the index position.

  The CPU 71 determines whether or not the machining operation has been completed (S9). When the machining operation has not ended (S9; NO), the CPU 71 shifts the process to S5 and continues the machining operation. When the machining operation is finished (S9; YES), the CPU 71 adds 1 to the block number n (S10), shifts the processing to step S2, and repeats the above-described operation.

  If it is determined in S4 that it is a tool change command (S4; YES), the CPU 71 starts a tool change operation. The CPU 71 drives the Z-axis motor 14 to raise the spindle head 2 (S11). The CPU 71 stands by until the spindle head 2 moves up to the uppermost position and the exchange arm 5 moves to the gripping position (S12). The tool 3 (next tool) on the tool magazine 4 side is in the index position by the operation of S6 executed by the CPU 71 during machining. The tool 3 at the index position is in a state of extending in the horizontal direction at the lower part of the tool magazine 4. Even if the tool 3 is a large-sized tool such as an end mill, it does not interfere with the grip portion 51 of the exchange arm 5 that moves to the grip position.

  When the spindle head 2 is raised to the uppermost position (S12; YES), the CPU 71 operates the pulling cylinder 46 to raise the slider 47 (S13). The tool pot 6 swings as the slider 47 rises, and the tool 3 (next tool) held by the tool pot 6 moves to the replacement position. The movement from the indexing position to the replacement position is completed in a short time. The determination at S12 is performed based on the detection result of the rotation detector provided in the Z-axis motor 14, for example.

  The CPU 71 waits until the standby time read in S8 has elapsed (S14). When the standby time has elapsed (S14; YES), the CPU 71 drives the arm motor 57 to operate the exchange arm 5 (S15). As described above, the exchange arm 5 performs a series of operations such as closing both the gripping portions 51 and 51, descending together with the arm shaft 50, turning 180 ° and ascending, and opening the gripping portions 51 and 51 on both sides. The tool 3 on the spindle 20 side and the tool 3 on the tool pot 6 side are exchanged.

  As described above, the standby time is determined as the time required for the vibration of the next tool moved to the replacement position to converge. The exchange arm 5 starts to operate after the standby time corresponding to the type of the next tool has elapsed. The exchange arm 5 starts to operate after a shorter waiting time for a small next tool than for a large next tool. The operation of the exchange arm 5 is usually required every time the tool is changed a plurality of times. The tool changer can reduce the waiting time before the start of the operation of the change arm 5 as a whole, reduce the tool change time, and reduce the machining time of the machining center 1.

  The CPU 71 reads the waiting time corresponding to the previous tool attached to the tool pot 6 (S16). The CPU 71 operates the pulling cylinder 46 to lower the slider 47 (S17), and drives the Z-axis motor 14 to lower the spindle head 2 (S18). The tool 3 attached to the tool pot 6 is swung by the lowering of the slider 47 and returns to the indexing position, so that the circulating movement in the tool magazine 4 is possible. The tool 3 attached to the spindle 20 moves down together with the spindle head 2 and moves to the machining start position of the next process. Next, the CPU 71 waits until the standby time read in S16 elapses (S19). When the standby time elapses (S19; YES), 1 is added to the block number n (S10), and the process proceeds to step S2. The operation described above is repeated.

  As described above, the control device 7 reads the machining program in units of blocks, and executes the machining operation (S5 to S9) or the tool change operation (S11 to S19) according to the read program block. During the machining operation, the control device 7 controls the tool magazine 4, positions the next tool at the index position, and recognizes a standby time corresponding to the next tool. During the tool changing operation, the control device 7 moves the changing arm 5 together with the spindle head 2 to the gripping position. After the movement of the exchange arm 5 is completed, the control device 7 moves the next tool at the exchange position to the exchange position. After the movement of the next tool is completed, the control device 7 waits for the elapse of the standby time corresponding to the next tool to operate the exchange arm 5 to implement the tool exchange.

  A plurality of waiting times are set for each of the tools 3 in the tool magazine 4. The exchange arm 5 starts operation after a minimum time necessary for the vibration of the tool 3 moved to the exchange position to converge. The tool changer shortens the time required for tool change performed a plurality of times, and the machining center 1 can reduce the machining time including the tool change time.

A modification in which the embodiment described above is partially modified will be described.
1) The waiting time may be set to a different time for each of the tools 3, 3... In the tool magazine 4.

2) The movement of the tool 3 between the indexing position and the replacement position is not limited to the swinging of the tool pot 6 around the support shaft 62, but can be realized by other operations such as parallel movement of the tool pot 6. Also good. When the parallel movement of the tool pot is employed, the waiting time mainly depends on the weight of the tool 3. FIG. 5 also shows the weights of the four types of tools. The weight in FIG. 5 is the weight of the entire moving object including the tool 3 and the tool pot 6. In FIG. 5, the magnitude of the weight corresponds to the magnitude of the moment of inertia, and the same standby time is set. For example, the magnitude of the weight corresponds to the magnitude of the moment of inertia depending on the difference in length and shape. Sometimes not.

3) Standby time after the tool pot 6 has moved from the index position to the replacement position (S14 standby time), and standby time after the tool pot 6 has moved from the replacement position to the index position (S19 standby time) May be different times for the same tool 3. When the tool pot 6 is moved to the index position, the lowering of the spindle head 2 as the next operation can be started even when the tool pot 6 is not completely stopped. Accordingly, the standby time after moving to the index position (the standby time in S19) can be set shorter than the standby time after moving to the replacement position (the standby time in S14).

DESCRIPTION OF SYMBOLS 1 Machining center 2 Spindle head 3 Tool 4 Tool magazine 5 Exchange arm 6 Tool pot 7 Controller
20 Spindle

Claims (3)

A tool magazine having a plurality of tool pots that circulate while holding a tool, and a spindle arm that is provided on a spindle head that supports the spindle and moves together with the spindle head, and is indexed by circulating movement of the tool pot. In a tool changer for exchanging the next tool, which is positioned at a position and moved to the change position together with the tool pot, with the previous tool attached to the spindle by the operation of the change arm generated after the move of the next tool,
A standby time is set for each of the tools, and after the next tool is moved from the indexing position to the replacement position, the operation of the replacement arm is started after the standby time corresponding to the next tool has elapsed. A tool changer comprising: a control device that controls the tool magazine and the changer arm so as to cause the change.   The tools in the tool magazine are grouped according to size, and the waiting time is set for each group so that the large size group is long and the small size group is short. The tool changer according to claim 1.   2. The tool change according to claim 1, wherein the waiting time is set for each of the tools in the tool magazine such that a large-sized tool is long and a small-sized tool is short. apparatus.

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