Estimation device, estimation method and machine tool

Abstract

To provide an estimation device and an estimation method of a machine tool which precisely estimate the mass and the center-of-gravity position of a pallet on which a workpiece is mounted for improving the processing precision and the operation efficiency of the workpiece with no increase in the number of components.SOLUTION: A control device 100 comprises: an arm 64 mounted on a drive part 62 which can turn a pallet 76 around a rotation center axis to hold the pallet 76, and to change an attitude within an arm rotation range including a portion between a horizontal state and an upright state; first and second standard loads when turning to first and second arm positions within an arm rotation range alone by the arm 64; a storage part 104 for storing a pallet central part in the horizontal state and a reference distance L being a horizontal distance between the pallet central part in the horizontal state and the rotation center axis; and an estimation part 106 for acquiring first and second loads when changing the pallet 76 to the first and second arm positions and estimating the mass and the center-of-gravity position of the pallet 76 on the basis of at least these loads and the reference distance.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an estimation device, an estimation method, and a machine tool. [Background technology]

[0002] Patent Document 1 discloses a method for detecting the weight of a workpiece using an automatic pallet changer (APC) in a machine tool (machining center). This method calculates the weight of the workpiece based on the load on the pallet lifting servo motor, and optimizes the acceleration and servo loop gain of the pallet lifting servo motor according to the calculated weight. However, in order to improve the machining accuracy of the workpiece and the operating efficiency of the machine tool, it is desirable to be able to detect not only the weight of the workpiece but also the position of the center of gravity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-196105 Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above circumstances, the present invention aims to provide an estimation device and estimation method for a machine tool that accurately estimates the mass and center of gravity position of a pallet on which a workpiece is attached without increasing the number of parts, in order to improve the machining accuracy of the workpiece and the operating efficiency of the machine tool. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided an apparatus for estimating the mass and center of gravity position of a pallet to which a workpiece is attached, comprising: a base; a drive unit attached to the base and configured to be able to rotate the pallet around a rotation center axis extending horizontally and to be able to acquire a load; an arm rotatably attached to the drive unit, holding the pallet having an upper surface on which a workpiece is to be assembled, and configured to change its position within an arm rotation range including a horizontal state in which the upper surface of the pallet is moved toward a horizontal plane and an upright state in which the upper surface of the pallet is moved toward a vertical plane; a first reference load acting on the drive unit when the arm is rotated independently to a first arm position within the arm rotation range; An estimation device is provided, comprising: a memory unit that stores a second reference load that acts on the drive unit when the arm is rotated to a second arm position within the rotation range, and a reference distance that is the horizontal distance between the center of the pallet of the pallet in a horizontal state and the rotation center axis of the drive unit; and an estimation unit that acquires a first load that acts on the drive unit when the position of a pallet held by the arm is changed to a first arm position within the arm rotation range, and a second load that acts on the drive unit when the position of the pallet is changed to a second arm position within the arm rotation range, and estimates the mass and center of gravity position of the pallet based on at least the reference distance, the first reference load, the second reference load, the first load, and the second load.

[0006] According to one aspect of the present invention, a method for estimating the mass and center of gravity position of a pallet on which a workpiece is attached includes holding a pallet having an upper surface on which a workpiece is to be assembled by an arm rotatably attached to a drive unit configured to be able to acquire a load, changing the position of the pallet within an arm rotation range including a horizontal state in which the upper surface of the pallet is moved toward a horizontal plane and an upright state in which the upper surface of the pallet is moved toward a vertical plane, acquiring a first reference load acting on the drive unit when the arm is rotated independently to a first arm position within the arm rotation range, and acquiring a second reference load acting on the drive unit when the arm is rotated independently to a second arm position within the arm rotation range. A method for estimating the mass and center of gravity position of a pallet is provided, comprising: acquiring a reference load; acquiring a first load acting on the drive unit when the pallet held by the arm is changed in position to a first arm position within the arm rotation range; acquiring a second load acting on the drive unit when the pallet held by the arm is changed in position to a second arm position within the arm rotation range; estimating the mass and center of gravity position of the pallet based on a reference distance which is the horizontal distance between the central portion of the pallet of the pallet in a horizontal state and the rotation center axis of the drive unit, and at least the first reference load, the second reference load, the first load, and the second load.

[0007] According to one aspect of the present invention, there is provided a machine tool comprising: a spindle on which a tool is mounted; a table that can receive a pallet with a workpiece attached from an arm and be attached in an upright position; a housing that integrally comprises a table support portion that supports the table, a first actuator mounting portion, and a second actuator mounting portion; actuators that are attached to the first actuator mounting portion and the second actuator mounting portion and that apply forces to the first actuator mounting portion and the second actuator mounting portion in directions that move the first actuator mounting portion and the second actuator mounting portion away from or toward the housing, thereby elastically deforming the housing; an estimation device according to one aspect of the present invention; a calculation unit that calculates adjustment forces that the actuator applies to the first actuator mounting portion and the second actuator mounting portion based on the mass and center of gravity position of the pallet estimated by the estimation device; and a table position control device that operates the actuator so that the calculated adjustment forces act on the first actuator mounting portion and the second actuator mounting portion, thereby elastically deforming the housing and changing the position or attitude of the table support portion, thereby controlling the position of the table. [Effects of the Invention]

[0008] According to one aspect of the present invention, an estimation device includes a memory unit that stores a first reference load acting on a drive unit when the arm is rotated to a first arm position alone, a second reference load acting on the drive unit when the arm is rotated to a second arm position alone, and a reference distance that is the horizontal distance between the center of the pallet and the rotation axis of the drive unit when the arm is rotated to a horizontal position. The estimation device also includes an estimation unit that acquires the first load acting on the drive unit when the arm changes its position to the first arm position within the arm rotation range and the second load acting on the drive unit when the arm changes its position to the second arm position, and estimates the mass and center of gravity of the pallet based on at least the reference distance, the first reference load, the second reference load, the first load, and the second load. This allows the mass and center of gravity of the pallet to be estimated using the drive unit and the arm, and accurately estimates the mass and center of gravity of a pallet with a workpiece attached without increasing the number of parts. This makes it easy to check and adjust the mounting position of the workpiece, and also controls the operation of the machine tool, thereby improving the machining accuracy of the workpiece and the operating efficiency of the machine tool.

[0009] According to one aspect of the present invention, an estimation method can obtain a first reference load acting on the drive unit when the arm is rotated independently to a first arm position within the arm rotation range, and a second reference load acting on the drive unit when the arm is rotated to a second arm position. Furthermore, the method can obtain a first load acting on the drive unit when a pallet held by the arm is changed in position to the first arm position within the arm rotation range, and a second load acting on the drive unit when the arm is changed in position to the second arm position. Furthermore, the mass and center of gravity of the pallet can be estimated based on a reference distance, which is the horizontal distance between the center of the pallet and the rotation axis of the drive unit when the pallet is in a horizontal position, and at least the first reference load, the second reference load, the first load, and the second load. This allows the mass and center of gravity of the pallet to be estimated using the drive unit and the arm, and can accurately estimate the mass and center of gravity of a pallet with a workpiece attached without increasing the number of parts. This facilitates confirmation and adjustment of the workpiece attachment position and also controls the operation of the machine tool, improving the workpiece machining accuracy and the operating efficiency of the machine tool.

[0010] According to one aspect of the present invention, a machine tool includes an estimation device according to one aspect of the present invention, which allows the mass and center of gravity of a pallet to be estimated using a drive unit and an arm, thereby enabling the mass and center of gravity of a pallet with a workpiece attached to be accurately estimated without increasing the number of parts. The machine tool also includes an actuator and a calculation unit that calculates an adjustment force that the actuator applies to the first actuator mounting portion and the second actuator mounting portion based on the mass and center of gravity of the pallet estimated by the estimation device. The machine tool also includes a table position control device that controls the position of the table by operating the actuator so that the calculated adjustment force acts on the first actuator mounting portion and the second actuator mounting portion, thereby elastically deforming the housing and changing the position or attitude of the table support. This makes it easier to check and adjust the workpiece attachment position and controls the operation of the machine tool, thereby improving the workpiece machining accuracy and the operating efficiency of the machine tool. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows a plan view of a machine tool equipped with an estimation device according to this embodiment. [Figure 2] FIG. 2 is a perspective view of the estimation device according to this embodiment. [Figure 3] FIG. 3 shows a view of the finger engaged with the pin in the pallet engaging position as viewed from the longitudinal direction of the arm. [Figure 4] FIG. 4 shows a block diagram of the machine tool according to this embodiment. [Figure 5] FIG. 5(a) shows a side view of the arm when acquiring the first load, and FIG. 5(b) shows a side view of the arm when acquiring the first reference load. [Figure 6] FIG. 6(a) shows a side view of the arm when the second load is acquired, and FIG. 6(b) shows a side view of the arm when the second reference load is acquired. [Figure 7A] FIG. 7A shows a side view of the arm when it picks up a load in a position inclined by θ1 degrees relative to the horizontal plane. [Figure 7B] FIG. 7B shows a side view of the arm when it picks up a load in a position inclined by θ2 degrees relative to the horizontal plane. [Figure 8a-8b] FIG. 8a shows a side view of the arm when picking up a first load when the center of gravity does not coincide with the center of the pallet, and FIG. 8b shows a side view of the arm when picking up a second load. [Figure 8c-8d] FIG. 8c shows a front view of the table when obtaining a first table load, and FIG. 8b shows a front view of the table when obtaining a second table load. [Figure 9] FIG. 9 shows a flowchart of the table position control. [Figure 10] FIG. 10 shows a side view of the pallet being brought in from outside the machine tool. [Figure 11] FIG. 11 shows a side view of the arm rotated to the engaged position and positioned relative to the pallet. [Figure 12] FIG. 12 shows a side view of the pallet with the fingers engaged on the pins actuated into the pallet engaging position. [Figure 13] FIG. 13 shows a side view of the pallet in an upright position. [Figure 14] FIG. 14 shows a side view of a pallet held by an APC arm. [Figure 15] FIG. 15 shows a side view of the pallet in an upright position with the fingers actuated to the pallet disengagement position. [Figure 16] FIG. 16 shows a side view of the arm rotated to the standby position. [Figure 17] FIG. 17 shows a side view of the second pallet being replaced by the APC arm. [Figure 18] FIG. 18 shows a side view of the C-axis rotary table to which the replaced pallet is attached. [Figure 19] FIG. 19 shows a side view of the APC arm that transfers the pallet to the C-axis rotary table. [Figure 20] FIG. 20 shows a side view of a pallet and a workpiece tilting due to its own weight. [Figure 21] FIG. 21 shows a side view of the C-axis rotary table in which the actuator operates to perform tilt compensation. [Figure 22] FIG. 22 shows a side view of the C-axis rotary table rotated toward the spindle for machining. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a machine tool equipped with an estimation device according to an embodiment will be described with reference to the accompanying drawings. Similar or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted. For ease of understanding, the scale of the drawings may be changed.

[0013] 1 shows a schematic plan view of a machine tool 10 equipped with a pallet orientation changing device 42 as an estimation device according to this embodiment. The machine tool 10 is covered by a splash guard 16 to prevent chips generated during machining from scattering, etc. The interior of the splash guard 16 is divided into a machining chamber 12 and a setup chamber 14 by a pivot door 46 that is arranged to be rotatable (pivotable) about a pivot axis R2 (see FIG. 2) that is parallel to the vertical direction. An operator door 12a and a setup chamber door 14a are also attached to the splash guard 16 so that an operator WK (see FIG. 4) can access the interior of the machining chamber 12 and the setup chamber 14 from the outside.

[0014] Inside the machining chamber 12, there are arranged devices such as a spindle 26 for machining workpieces W1 and W2 (see FIGS. 10 and 17) as workpieces, and a C-axis rotary table 36 as a table. A pair of X-axis linear guides 30 extending in the left-right direction, i.e., along the X-axis direction, are arranged on the upper surface of a bed 18 placed on the floor of a factory or the like where the machine tool 10 is installed. A column 22 is arranged upright on the X-axis linear guides 30, allowing it to reciprocate along the X-axis linear guides. The machine tool 10 also has a pair of Y-axis linear guides (not shown) extending vertically (in the Y-axis direction, perpendicular to the plane of the paper in FIG. 1) in front of the column 22, and a saddle 24 is arranged on the Y-axis linear guides, allowing it to reciprocate along the Y-axis linear guides. A spindle 26 rotatable about a horizontal central axis is arranged in front of the saddle 24. Furthermore, a tool 28 for machining the workpieces W1 and W2 is detachably attached to the front side (the setup room 14 side) of the spindle 26. The machine tool 10 is electrically connected to the spindle 26 and includes an NC device (not shown) for controlling machining, and is configured to be able to control machining of the workpieces W1 and W2 using the tool 28.

[0015] A pair of Z-axis linear guides 38 extend along the front-to-rear direction, i.e., the Z-axis direction, on the upper surface of the bed 18 in front of the spindle 26 of the machine tool 10. A Z-axis table 32 is disposed on the Z-axis linear guides 38, allowing it to reciprocate along the Z-axis linear guides 38. A B-axis rotary table 34 is disposed on the Z-axis table 32, allowing it to rotate about a rotation axis (about the B-axis) parallel to the vertical direction. A C-axis rotary table 36 is disposed on the B-axis rotary table 34, and serves as a table configured to be upright so that the top surface 76a (see FIG. 2) of a mounted pallet 76 (first pallet) faces the vertical plane. The C-axis rotary table 36 is also configured to rotate the mounted workpieces W1 and W2 and the pallet 76 about a central axis (about the C-axis) that is horizontal. In this way, the Z-axis table 32, the B-axis rotary table 34, and the C-axis rotary table 36 allow the workpieces W1 and W2 and the tool 28 to be aligned. Furthermore, the machine tool 10 is equipped with an X-axis feed device for driving the column 22 along the X-axis linear guide 30, a Y-axis feed device for driving the saddle 24 along the Y-axis linear guide, and a Z-axis feed device for driving the Z-axis table 32 along the Z-axis linear guide 38 (all not shown).

[0016] 4 and 18, the C-axis rotary table 36 includes a table 36d, a table support portion 36c that supports the rotation axis of the table 36d, and a housing 36e that is integrally formed with a first actuator mounting portion 36a and a second actuator mounting portion 36b that are disposed on the back side of the C-axis rotary table 36. The rotation center axis CC (see FIG. 8c) of the table 36d of the C-axis rotary table 36 extends horizontally, the first actuator mounting portion 36a extends horizontally below the C-axis rotary table 36, and the second actuator mounting portion 36b extends horizontally above the C-axis rotary table 36. The vertical distance between the first actuator mounting portion 36a and the rotation center axis CC and the vertical distance between the second actuator mounting portion 36b and the rotation center axis CC are configured to be the same. An actuator 35 extending vertically and perpendicular to the central axis of rotation CC is attached to the rear side of the C-axis rotary table 36 via a first actuator mounting portion 36a and a second actuator mounting portion 36b. The actuator 35 is a retractable hydraulic cylinder configured to apply a force to the first actuator mounting portion 36a and the second actuator mounting portion 36b in a direction away from or toward the housing 36e, thereby elastically deforming the housing 36e. The table 36d is rotatable by a built-in servo motor 36f. The servo motor 36f has an encoder 36g configured to detect the rotational position and is electrically connected to a servo amplifier 36h configured to supply power to the servo motor 36f and detect the rotational position from the encoder 36g. While the actuator 35 is described as being formed as a single unit, this is not limiting. For example, the actuator may be formed as multiple units, separated into a first actuator mounting portion side and a second actuator mounting portion side. The table support portion 36c may be formed with bearings or the like.

[0017] As shown in Fig. 1, a setup station 40 is disposed within the setup chamber 14 for performing setup such as attaching (assembling) the unmachined workpiece W1 to the pallet 76 and removing the machined workpiece W2. The setup station 40 is equipped with a pallet position change device 42 for changing the position of the workpieces W1 and W2 attached to the pallet 76. The setup station 40 also includes a medium supply unit 80 for supplying a medium, including oil, air, and cutting fluid, to the pallet 76 and any of the workpieces W1 and W2 and / or jigs attached to the pallet 76. The medium supply unit 80 is configured to supply the medium via a coupler (not shown) attached to the underside 76b of the pallet 76 (see Fig. 2).

[0018] The swing door 46, which separates the machining chamber 12 and the setup chamber 14, extends vertically between the side walls of the splash guard 16 and is placed on a swing door holder 48 located below the side walls of the splash guard 16. Specifically, the swing door 46 and the swing door holder 48 are placed in a state where mating portions (not shown) formed on both are fitted together. The swing door 46 has a width direction that is the left-right direction when viewed from the front of the machine, i.e., the X-axis direction. A pallet exchange device 44 is located below the swing door 46, either separately from the swing door 46 or in conjunction with the swing door 46, and is configured to be swingable about a swing axis R1 that is parallel to the vertical direction (Y-axis direction). The pallet exchange device 44 includes an APC arm 50 as a rotating arm that is rotatable (swivelable) about a rotation axis R1 parallel to the vertical direction (Y-axis direction) to transfer an unmachined workpiece W1 and a machined workpiece W2 between the setup chamber 14 and the machining chamber 12, and an APC arm drive mechanism 56 as a rotation drive unit for rotating the APC arm 50. The APC arm 50 is configured to be movable up and down in the vertical direction (Y1 direction in FIG. 2) by the APC arm drive mechanism 56. The APC arm drive mechanism 56 has an actuator (not shown) such as a hydraulic cylinder, a pneumatic cylinder, or a servo motor that enables fine operation setting and adjustment, and the actuator rotates and moves the APC arm 50 up and down. The actuator is configured to be controllable by a control device 100 (see FIG. 4) arranged in the machine tool 10. While the pivoting door holding portion 48 has been described as being located below the side wall of the splash guard 16, the present invention is not limited to this and the pivoting door holding portion may be installed directly on the bed or floor. Furthermore, the pivoting door holding portion may hold the pivoting door in a manner other than by a fitting portion, as long as it can regulate the movement of the pivoting door in the rotational direction and the direction of gravity in place of the APC arm when the APC arm is lowered and not engaged with the pivoting door.

[0019] When the APC arm 50 is not transferring workpieces W1, W2, it is stored in a storage position with its longitudinal direction aligned with the width direction of the swing door 46, i.e., the X-axis direction. A chip cover 52 is formed on the lower side of the swing door 46, and has an inclined surface that extends toward the setup station 40 and the machining chamber 12 (front and rear sides in the Z-axis direction) as it moves downward (vertically downward). The chip cover 52 is formed to cover the APC arm 50 engaged with the swing door 46 from above, and can prevent or suppress chips and the like generated during machining in the machining chamber 12 from adhering to the APC arm 50.

[0020] As shown in FIG. 2, the APC arm 50 is provided with a first pallet holder 82 and a second pallet holder 84 at both ends in the longitudinal direction thereof for holding a pallet 76. The first pallet holder 82 and the second pallet holder 84 have pillar-shaped members at both ends in the width direction of the APC arm 50 and are concave-shaped when viewed in the longitudinal direction of the APC arm 50. A holding member 76f is attached to the abutment side surface 76d of the pallet 76, which is the side surface facing the APC arm 50. The holding member 76f is formed in a plate shape with dimensions that allow it to fit into the concave portions of the first pallet holder 82 and the second pallet holder 84. Therefore, when the pallet 76 is in an upright position, the holding member 76f fits into the concave portions of the first pallet holder 82 and the second pallet holder 84, and the upper surfaces of the pillar-shaped members at both ends of the first pallet holder 82 and the second pallet holder 84 abut against the abutment side surface 76d of the pallet 76. This allows the APC arm 50 to support the pallet 76 and hold the upright pallet 76, the jig 96 attached thereto, and the workpieces W1 and W2 (see FIGS. 10 and 17).

[0021] Note that, here, the first pallet holding unit 82 and the second pallet holding unit 84 of the APC arm 50 are described as supporting the pallet 76 by fitting the holding members 76f into the recessed portions and abutting the upper surfaces of the columnar members at both ends against the abutment side surfaces 76d of the pallet 76, but this is not limitative. For example, the holding units of the APC arm may be configured with a mechanism that clamps the upper and lower surfaces of the pallet.

[0022] As shown in FIG. 1 , the APC arm 50 and the swing door 46 can be engaged with each other by an engagement mechanism 54. The engagement mechanism 54 includes an engagement pin 54a serving as an engaging portion on the APC arm 50 side and a guide hole 46a serving as an engaged portion on the swing door 46 side. The engagement pin 54a is formed on the upper surface of the APC arm 50 and extends upward. Therefore, the engagement pin 54a moves up and down in accordance with the up and down movement of the APC arm 50. The guide hole 46a is formed in the bottom of the swing door 46 so as to be able to engage with the inserted engagement pin 54a. Here, two engagement pins 54a are arranged at equal intervals of 180° around the rotation axis RA2 of the APC arm 50, and four guide holes 46a are formed at equal intervals of 90° around the rotation axis RA2 of the APC arm 50 to correspond to the engagement pins 54a. Note that at least one pair of engagement pins 54a and guide holes 46a is required. The engagement mechanism 54 is configured so that the engagement pin 54a and the guide hole 46a can be engaged or disengaged, thereby engaging the APC arm 50 and the pivoting door 46. Therefore, when the APC arm 50 and the pivoting door 46 are engaged, the APC arm 50 and the pivoting door 46 can be pivoted together. Furthermore, when the APC arm 50 and the pivoting door 46 are disengaged, the APC arm 50 can be pivoted independently to transfer a pallet 76, 94 to the APC arm 50 or to store the APC arm 50 in a storage position when not transferring a pallet. Note that, in this description, the APC arm 50 has the engagement pin 54a and the pivoting door 46 has a guide hole 46a formed in its bottom. However, this is not limiting. For example, the pivoting door may have an engagement pin extending from its bottom, or a guide hole may be formed in the APC arm. In addition to the combination of the engagement pin 54a and the guide hole 46a, the engagement pin may be configured to engage / disengage with claws or the like disposed on both the APC arm and the swing door. Furthermore, the engagement pin is not limited to being rod-shaped or column-shaped, and may be configured to be movable up and down using, for example, a drive mechanism disposed in the engagement mechanism.

[0023] Specifically, the pallet exchange device 44 operates as follows. When the transfer of the pallet 76 begins in the machine tool 10, the engagement mechanism 54 disengages the swing door 46 from the APC arm 50, and the APC arm drive mechanism 56 lowers the APC arm 50. At this time, the engagement pin 54a of the engagement mechanism 54 disengages from the guide hole 46a, disengaging the swing door 46 from the APC arm 50, and the swing door 46 is fitted into and placed on the swing door holder 48. When the APC arm 50 lowers, the APC arm drive mechanism 56 rotates the APC arm 50 by 90 degrees (or 270 degrees). As a result, the first pallet holder 82 and the second pallet holder 84 of the APC arm 50 move along the rotation trajectory TR1 (see FIG. 1) toward the C-axis rotary table 36 and the pallet position changing device 42, and the longitudinal direction of the APC arm 50 becomes aligned with the Z-axis direction.

[0024] When the first pallet holder 82 and the second pallet holder 84 move toward the C-axis rotary table 36 and the pallet attitude changing device 42, the APC arm drive mechanism 56 raises the APC arm 50. As the APC arm 50 rises, the engagement pin 54a of the engagement mechanism 54 is inserted into and engaged with the guide hole 46a. This engages the revolving door 46 with the APC arm 50, and the revolving door 46 is loaded onto the APC arm 50 instead of the revolving door holder 48.

[0025] Once the APC arm 50 has loaded the swing door 46, the APC arm drive mechanism 56 raises the swing door 46 and the APC arm 50. This allows the holding members 76f of the pallet 76 to fit into the recessed portions of the first pallet holder 82 and the second pallet holder 84, and the columnar members at both ends to abut against the abutment side surfaces 76d of the pallet 76, thereby holding the pallet 76. The pallet 76 is then transferred from the C-axis rotary table 36 and the pallet position change device 42 to the APC arm 50. After transferring the pallet 76 to the APC arm 50, the C-axis rotary table 36 and the pallet position change device 42 retract to a standby position where they will not interfere with the swinging APC arm 50 or swing door 46. The APC arm 50 then swings them together 180 degrees. This allows the pallet 76 held by the APC arm 50 to be swapped between the machining chamber 12 side and the setup room 14 side. Once the pallet 76 has been replaced, the C-axis rotary table 36 and / or the arm 64 of the pallet position changing device 42 move from the standby position to the pallet transfer position, where they hold the replaced pallet 76, 94. Furthermore, the APC arm drive mechanism 56 lowers the revolving door 46 and the APC arm 50 holding the pallet 76, and the revolving door 46, which was previously only loaded on the APC arm 50, is placed in a state where it is fitted into the revolving door holder 48. Furthermore, the engagement pin 54a of the engagement mechanism 54 is pulled out of the guide hole 46a, and the engagement is released. After lowering the APC arm 50, the APC arm drive mechanism 56 rotates 90 degrees and moves the first pallet holder 82 and the second pallet holder 84 below the revolving door 46.

[0026] When the first pallet holder 82 and the second pallet holder 84 move below the swing door 46, the APC arm drive mechanism 56 raises the APC arm 50, and the swing door 46 is loaded onto the APC arm 50 instead of the swing door holder 48. Furthermore, the engagement pin 54a of the engagement mechanism 54 is inserted into the guide hole 46a, and they engage with each other. This causes the APC arm 50 to be stored in the storage position below the swing door 46.

[0027] As shown in FIG. 2, the setup station 40 is provided with a pallet position changing device 42 for transferring a pallet 76, on which the pre-machined workpiece W1 and the machined workpiece W2 (see FIGS. 10 and 17) have been mounted, to and from the APC arm 50. The pallet 76 is formed in a plate shape having an upper surface 76a on which the workpieces W1 and W2 and the jig 96 (see FIG. 10) are mounted, and a lower surface 76b. The pallet 76 also has two engaging side surfaces 76e that are in contact with the upper surface 76a and the lower surface 76b and are located on the outer side of the pallet 76 in the X-axis direction, an abutting side surface 76d that is located between the two engaging side surfaces 76e, is located on the rear side of the pallet 76 in the Z-axis direction, and faces the APC arm 50, and a front side surface 76c that is located on the front side of the pallet 76 in the Z-axis direction and faces the setup chamber door 14a. The two engaging side surfaces 76e are formed integrally with the pallet 76 and have pins 78 that extend outward, i.e., outward in the X-axis direction. Here, two cylindrical pins 78 extending along the surface direction of the engagement side surface 76e are formed on each engagement side surface 76e. The two pins 78 are formed at an interval, one on each end side of the engagement side surface 76e in the longitudinal direction (Z-axis direction). Note that one pin may be formed on each engagement side surface, and the pins may be formed in a shape other than a cylindrical shape, such as a rectangular prism or a triangular prism.

[0028] A worker WK places a pallet 76 in the setup station 40 of the setup room 14 and assembles a workpiece W1 and a jig 96 on the pallet 76. The worker WK places the pallet 76 on the medium supply unit 80 in a horizontal position with the upper surface 76a of the pallet 76 facing the horizontal plane. To transfer the pallet 76 between the setup station 40 and the C-axis rotary table 36, to which the pallet 76 is attached in an upright position, a pallet position changer 42 is configured to hold the pallet 76 and change its position, including between a horizontal position and an upright position. Specifically, the pallet position changer 42 includes a base 60 disposed along the X-axis direction and forward of the pivoting door 46 and the APC arm 50 in the Z-axis direction; a drive unit 62 attached to the base 60 and configured so that its rotation axis extending along the X-axis (horizontal direction) can rotate around a rotation center axis RA1 (in the R1 direction); and a pair of arms 64 rotatably attached to the drive unit 62 and extending parallel to the two engagement side surfaces 76e when facing the two engagement side surfaces 76e, thereby being able to hold the pallet 76. 10, the base 60 extends from the outer periphery of the APC arm drive mechanism 56, which is disposed at the rotation center position of the APC arm 50, toward the front side in the Z axis direction (toward the setup chamber door 14a). Therefore, the base 60 can be disposed inside the rotation trajectory TR1 of the APC arm 50 in a plan view, and when the APC arm 50 rotates while holding the pallet 76 on which the workpieces W1 and W2 are mounted at its end, chips can be prevented from falling directly onto the base 60.

[0029] The drive unit 62 is equipped with a hydraulic cylinder, a pneumatic cylinder, or a servo motor 62a (see FIG. 4) that allows for fine operation setting and adjustment, and rotates the rotary shaft using these. The servo motor 62a has an encoder 62b configured to detect the rotational position and is electrically connected to a servo amplifier 62c configured to supply power to the servo motor 62a and acquire the rotational position from the encoder 62b. The servo motor 62a is also configured to be controllable by a control device 100 (see FIG. 4) disposed in the machine tool 10. As will be described later, the pallet position changing device 42 is configured to be able to position (stop) the arm 64 not only between the upright position and the horizontal position, but also by rotating and positioning the arm 64 from the upright position in the upright position to a retracted position beyond the engagement position in the horizontal position. The pallet position changing device 42 is also configured to be able to position (stop) the arm 64 at an intermediate position, such as a standby position between the upright position and the engagement position.

[0030] In the following description, the pallet 76 is assumed to be square in plan view, with two parallel engagement sides 76e held by a pair of parallel arms 64; however, this is not limiting. For example, the pallet may have chamfered corners or may have a shape other than a square, such as an octagonal or round shape in plan view. Furthermore, even if the pallet has a shape other than a square and the two engagement sides are not parallel, the pair of arms may not be parallel to each other, for example, extending in a V-shape in plan view so as to be parallel to the two engagement sides. Furthermore, if the pallet is round, the arms may be curved to fit the outer shape of the pallet.

[0031] 2, the arm 64 has an arm base end 66 that is connected to the rotation shaft of the drive unit 62, and an arm engagement unit 68 that extends linearly from an outer portion of the arm base end 66 in the X-axis direction so as to face the engagement side surface 76e. A receiving portion 74 is formed on the inner side in the X-axis direction of the arm base end 66, which is on the base 60 side of the arm 64, at a position that faces the abutment side surface 76d when the arm 64 holds a pallet 76. When viewed from the side of the machine tool 10 (outside in the X-axis direction) in a horizontal state, the receiving portion 74 is formed in an L-shape or an inverted L-shape, and has a planar first pallet receiving surface 74a that extends perpendicular to the arm 64 and a planar second pallet receiving surface 74b that extends along the longitudinal direction of the arm 64, and is sized so that the abutment side surface 76d can abut against the first pallet receiving surface 74a and the underside 76b can abut against the second pallet receiving surface 74b. The first and second pallet receiving surfaces do not need to be precisely sized, but only need to be formed to a degree that allows them to abut against the pallet and reliably support the weight of the pallet. For this reason, the first and second pallet receiving surfaces are not limited to flat surfaces, and may be formed, for example, in a curved or polygonal pyramidal shape, which may support the pallet in point or line contact.

[0032] Each arm 64 is provided with two slides 70, which are located at both longitudinal ends of the arm engagement portion 68, i.e., both ends in the Z-axis direction, and are configured to slide along the longitudinal direction of the arm engagement portion 68. Furthermore, a finger 72 for engaging with a pallet 76 is attached to each of the two slides 70. The spacing between the two fingers 72 is configured to correspond to the spacing between the two pins 78. A rod disposed within the arm engagement portion 68 is integrally connected to the two slides 70, and the rod is connected to an actuator such as a hydraulic cylinder, a pneumatic cylinder, or a servo motor that allows for fine operation setting and adjustment (all not shown). Therefore, in response to the operation of the rod by the actuator, the slides 70 and the fingers 72 can be moved in the same direction between a pallet engagement position and a pallet disengagement position. Here, the pallet engagement position is configured to be closer to the arm base end 66 than the pallet disengagement position. Furthermore, the actuators that operate the slides 70 and the fingers 72 are configured to be controllable by a control device 100 (see FIG. 4) disposed in the machine tool 10. 3, the finger 72 has a central portion 72c that faces the engagement side surface 76e when the arm engagement portion 68 is moved laterally toward the pallet 76 to hold the pallet 76, an upper surface-side restricting portion 72a formed on the upper side (upper surface 76a side) of the central portion 72c, and a lower surface-side restricting portion 72b formed on the lower side (lower surface 76b side) of the central portion 72c. Therefore, a groove 72d is formed by the central portion 72c, the upper surface-side restricting portion 72a, and the lower surface-side restricting portion 72b. When the finger 72 is viewed from the longitudinal direction of the arm 64, the groove 72d is formed in a concave shape facing the pallet 76 side. The groove 72d is formed so that its depth direction coincides with the extension direction of the pin 78. Therefore, by moving the arm engagement portion 68 laterally of the engagement side surface 76e of the pallet 76 and moving it from a position where the finger 72 and the pin 78 do not face each other along the X-axis direction (pallet disengagement position) to a position where the finger 72 and the pin 78 face each other along the X-axis direction (pallet engagement position) (sliding along the XF1 direction), the finger 72 can be engaged with the pallet 76. This allows the arm 64 to stably hold the pallet 76.Furthermore, since the concave groove portion 72d is shaped to be open to the outside of the finger 72, it is possible to prevent or suppress chips generated by machining from being caught between the finger 72 and the pin 78.

[0033] Here, the finger 72 is described as being formed in a concave shape facing the pallet 76 when viewed from the longitudinal direction of the arm 64, but this is not limited to this and any shape that can engage with the pin will suffice. For example, the finger may be formed in another shape, such as an open V-shape facing the pin when viewed from the longitudinal direction of the arm.

[0034] Furthermore, an arm protrusion 86 (see FIG. 10) extending toward the engagement side surface 76e is formed on the inside in the width direction facing the engagement side surface 76e of the arm engagement portion 68, i.e., on the inside in the X-axis direction. Also, a pallet groove 88 is formed in the engagement side surface 76e so as to be recessed inward of the pallet 76, and is configured so that the arm protrusion 86 can be inserted into it. This allows the arm 64 to hold the pallet 76 using both the fingers 72 and the arm protrusion 86, and therefore the pallet 76 can be held stably.

[0035] Note that, here, the finger 72 of the arm engaging portion 68 is described as being configured to be slidable between a pallet disengagement position and a pallet engagement position along the longitudinal direction of the arm engaging portion 68, i.e., the Z-axis direction (XF1 direction in FIG. 3), but this is not limiting, and the finger may be configured to hold the pallet by sliding in the X-axis direction, i.e., the direction facing the pallet (XF2 direction in FIG. 3). In such a configuration, the finger does not displace in the longitudinal direction of the arm, so the arm can be made space-saving in the longitudinal direction and can be configured compactly.

[0036] FIG. 4 shows a block diagram of machine tool 10. Machine tool 10 is equipped with a control device 100 having an NC device 102 for controlling machining. NC device 102 is electrically connected to a servo amplifier 62c for drive unit 62. It transmits a command for the rotation position of arm 64 to servo amplifier 62c and acquires, via servo amplifier 62c, the current value or torque generated in servo motor 62a and the rotation position of arm 64 detected by encoder 62b. Therefore, machine tool 10 can acquire (calculate) the load acting on arm 64 holding pallet 76 as the torque generated in servo motor 62a from the current value generated in servo motor 62a. Note that, while drive unit 62 is described here as being configured to acquire loads from two arms 64 in a unified manner, this is not limiting. For example, first and second drive units corresponding to the two arms may be provided, and the loads (torques) acquired by these drive units may be summed to acquire the load.

[0037] The NC device 102 is also electrically connected to the servo amplifier 36h for the C-axis rotary table 36, and is configured to transmit a command for the rotation position of the table 36d to the servo amplifier 36h, and to acquire the current value or torque generated in the servo motor 36f and the rotation position of the table 36d detected by the encoder 36g via the servo amplifier 36h. Therefore, the machine tool 10 can acquire (calculate) the load acting on the table 36d that holds the pallet 76 as the torque generated in the servo motor 36f from the current value generated in the servo motor 36f.

[0038] The control device 100 further includes a memory unit 104, an estimation unit 106, and a calculation unit 108. The memory unit 104 is configured to store the load of the drive unit 62 and the load of the C-axis rotary table 36 acquired by the NC device 102. The memory unit 104 is also configured to store in advance a first reference load TB1 (see FIG. 5b) that acts on the drive unit 62 when the arm 64 alone, i.e., in a state where there is no load other than the load on the arm 64 itself, is rotated to a first arm position within an arm rotation range that includes a horizontal position and an upright position, and a second reference load TB2 (see FIG. 6b) that acts on the drive unit 62 when the arm 64 is rotated to a second arm position within an arm rotation range that is different from the first arm position, as will be described later. The memory unit 104 is also configured to store in advance a reference distance L, which is the horizontal distance between the center of the pallet 76 in the horizontal position and the rotation center axis RA1 of the drive unit 62.

[0039] The estimation unit 106 is configured to acquire a first load T1 (see FIG. 5a) that acts on the drive unit 62 when the pallet 76 held by the arm 64 is changed in position to a first arm position within the arm rotation range, and a second load T2 (see FIG. 6a) that acts on the drive unit 62 when the pallet 76 is changed in position to a second arm position within the arm rotation range, and to estimate the mass M of the pallet 76 on which the workpiece W1 is attached from the reference distance L, the first reference load TB1, and the first load T1. The estimation unit 106 is also configured to estimate the position H of the center of gravity GW1 of the pallet 76 on which the workpiece W1 is attached from the estimated mass of the pallet 76, the second reference load TB2, and the second load T2.

[0040] A method for estimating the mass M of the pallet 76 will be described with reference to FIGS. 5a and 5b. First, as shown in FIG. 5a, a reference distance L, which is the horizontal distance between the center of the pallet (here, also the position of the center of gravity GW1) and the central axis of rotation RA1 of the drive unit 62 when the pallet 76 is in a horizontal state, i.e., when the arm 64 is in the engaged position, is obtained in advance from measurement or design information and stored in the storage unit 104. Furthermore, as shown in FIG. 5b, a first reference load TB1 when the arm 64 is in the engaged position as a first arm position, alone, i.e., in a state where there is no load other than the load on the arm 64 itself, is obtained and stored in the storage unit 104. Specifically, the first reference load TB1, which is the torque acting on the drive unit 62, is obtained from the current value generated in the servo motor 62a using a predetermined conversion formula between current and torque. Next, as shown in Figure 5a, the current value of the servo motor 62a when the arm 64 holding the pallet 76 is in the engaged position is obtained, and the first load T1, which is the torque acting on the drive unit 62, is obtained in the same manner as the first reference load TB1. The relational expression among the reference distance L, the first reference load TB1, the first load T1, and the mass M can be expressed as follows: T1-TB1=MgL (1) Here, g represents the acceleration due to gravity. Therefore, equation (1) can be written as M = (T1 - TB1) / gL (2) By transforming it into this, the mass M can be estimated (calculated).

[0041] Next, a method for estimating the position of the center of gravity GW1 of the pallet 76, in this case, the center-of-gravity distance H, will be described with reference to Figures 6a and 6b. The center-of-gravity distance H is defined as the horizontal distance between the center of gravity GW1 and the central axis of rotation RA1 of the drive unit 62 when the arm 64 holding the pallet 76 is in an upright position. First, as shown in Figure 6b, when the arm 64 is in an upright position (a second arm position) without holding the pallet 76, a second reference load TB2, which is the torque acting on the drive unit 62, is obtained from the current value generated in the servo motor 62a and stored in the memory unit 104. Specifically, the second reference load TB2, which is the torque acting on the drive unit 62, is obtained from the current value generated in the servo motor 62a using a predetermined conversion formula between current and torque. Next, as shown in Figure 6a, the current value of the servo motor 62a when the arm 64 holding the pallet 76 is in the upright position is obtained, and the second load T2, which is the torque acting on the drive unit 62, is obtained in the same manner as the second reference load TB2. The relationship between the center of gravity position distance H, which is the horizontal distance between the center of gravity GW1 and the central axis of rotation RA1 of the drive unit 62 when the pallet 76 is in the upright state, the second reference load TB2 obtained as above, the second load T2, and the mass M can be expressed as follows: T2-TB2=MgH (3) Here, g represents the acceleration due to gravity. Therefore, equation (3) can be written as H = (T2 - TB2) / Mg (4) By transforming it as follows, the center of gravity position distance H can be estimated (calculated).

[0042] The mass M and center-of-gravity distance H of the pallet 76 can be estimated even when the arm 64 is in a position other than the engaged position or the upright position. For example, as shown in Fig. 7A, if the torque acting on the drive unit 62 when the arm 64 is tilted by θ1 degrees with respect to the horizontal plane is defined as a first reference load TB1 and a first load T1, and as shown in Fig. 7B, the torque acting on the drive unit 62 when the arm 64 is tilted by θ2 degrees with respect to the horizontal plane is defined as a second reference load TB2 and a second load T2, the relationship between these loads, reference loads, mass M, and center-of-gravity distance H can be expressed by the following equation: T1-TB1=(L×cosθ1-H×sinθ1)Mg (5) Or, T2-TB2=(L×cosθ2-H×sinθ2)Mg (6) Here, g represents the acceleration due to gravity. Therefore, by simultaneously solving equations (1) and (6), equations (3) and (5), or equations (5) and (6), it is possible to estimate (calculate) the mass M and the distance H from the center of gravity. Furthermore, it is also possible to obtain the load and reference load at each of three or more arm positions and perform simple regression analysis to estimate the mass M and the distance H from the center of gravity with even greater accuracy.

[0043] The control device 100 is configured to be able to estimate the mass M and the distance H to the center of gravity at any timing after the load is acquired. For example, the mass M and the distance H to the center of gravity can be estimated in parallel with the operation of exchanging the pallet 76 by the APC arm 50, and the actuator 35 can be operated after the pallet 76 is exchanged. This makes it possible to shorten the work cycle time by the amount of the estimated time.

[0044] The above estimation of mass M and center-of-gravity distance H is based on the assumption that the center of gravity GW1 is located at the center of the pallet. Because various designs are implemented so that the center of gravity GW1 of the pallet 76, including the workpiece and jig, is located near the center of the pallet, it can be said that mass M and center-of-gravity distance H can be estimated with a certain degree of accuracy. However, in other words, each workpiece W1 and jig 96 is uniquely designed, and the center of gravity GW1 is not located precisely in the center of the pallet. Therefore, the above assumption may not allow accurate estimation of mass M and center-of-gravity distance H. In such cases, the accuracy of estimating mass M and center-of-gravity distance H decreases as the center of gravity GW1 moves farther from the center of the pallet in the direction of reference distance L. Therefore, when the position of the center of gravity GW1 of the pallet 76 attached to the table 36d is misaligned in the X-axis and / or Y-axis directions (u and / or v in the figures) from the central axis of rotation CC of the C-axis rotary table 36 that rotates around the horizontal axis (C-axis), as shown in Figures 8c and 8d, the estimation unit 106 of the control device 100 is configured to estimate these misalignments (u and v).

[0045] A specific estimation method will be described with reference to FIGS. 8a to 8d. First, as shown in FIGS. 8a and 8b, the estimation unit 106 of the control device 100 acquires a first load T1 when the arm 64 holding the pallet 76 is in the engaged position and a second load T2 when the arm 64 holding the pallet 76 is in the upright position. Also, as shown in FIGS. 5(b) and 6(b), a first reference load TB1 when the arm 64 is in the engaged position alone, i.e., without holding the pallet 76, and a second reference load TB2 when the arm 64 is in the engaged position without holding the pallet 76 are acquired and stored in advance in the memory unit 104. Next, as shown in FIG. 8c, the estimation unit 106 of the control device 100 acquires a first table load T3 (torque) acting on the table 36d at the first table rotation position from the current value generated in the servo motor 36f of the C-axis rotary table 36 when the C-axis rotary table 36 to which the pallet 76 has been transferred is in the first table rotation position. Specifically, using a predetermined conversion formula between current and torque, the first table load T3 acting on the table 36d is obtained from the current value generated in the servo motor 36f. Furthermore, as shown in FIG. 8d, the estimation unit 106 of the control device 100 rotates the table 36d to a second table rotation position, which is rotated 90 degrees from the first table rotation position, and obtains a second table load T4 (torque) acting on the table 36d at the second table rotation position from the current value generated in the servo motor 36f of the C-axis rotary table 36. Specifically, using a predetermined conversion formula between current and torque, the second table load T4, which is the torque acting on the table 36d, is obtained from the current value generated in the servo motor 36f. The various information obtained in this manner is expressed by the following relational expressions. T1-TB1=Mg(L+v) (7) T2-TB2=MgH (8) T3=Mgu (9) T4=Mgv (10) Here, g represents the acceleration due to gravity. By simultaneously solving equations (7) to (10), the mass M, the distance H between the center of gravity and the deviation (u and v) of the center of gravity GW1 from the rotation center axis CC of the C-axis rotary table 36 are given by M = (T1-TB1-T4) / gL (11) H = (T2 - TB2) / Mg (12) u=T3 / Mg (13) v=T4 / Mg (14) The estimation unit 106 can estimate (calculate) the deviation (u and v) of the center of gravity GW1 from the rotation center axis CC of the C-axis rotary table 36 as described above. Because the estimation unit 106 can estimate the deviation (u and v) of the center of gravity GW1 from the rotation center axis CC of the C-axis rotary table 36, the maximum rotation speed and acceleration for rotating the table 36d can be set taking the deviation (u and v) into account. Since the C-axis rotary table 36 is unloaded when not holding the pallet 76, it is not necessary to acquire the reference loads corresponding to the first table load T3 and the second table load T4. However, these reference loads may be acquired as needed. While torque is described as being acquired here, this is not a limitation. Current values ​​may be acquired from the servo amplifiers 62c and 36h and converted to torque by the control device 100. Alternatively, the mass and center of gravity position may be estimated directly from the current values.

[0046] 4, the control device 100 includes a calculation unit 108 that calculates an adjustment force acting from the actuator 35 on the first actuator mounting portion 36a and the second actuator mounting portion 36b based on the mass M and center-of-gravity distance H of the pallet 76 estimated by the estimation unit 106. The adjustment force here refers to a force that operates the actuator 35 to lift the table 36d that has tilted downward (fallen) due to the weight of the attached pallet 76 and to correct (correct the table 36d from falling) so that the rotation center axis CC of the table 36d that has tilted downward is aligned with the horizontal axis. In this embodiment, the adjustment force is hydraulic pressure for operating the actuator 35. The relationship between the mass M and center-of-gravity distance H and hydraulic pressure, or the relationship between the amount of fall estimated from the mass M and center-of-gravity distance H and hydraulic pressure, is measured and organized through experiments or the like, and is stored in the memory unit 104 in the form of a relational expression or a numerical table. The control device 100 includes a table position control device 110 that controls the position of the table 36d by operating the actuator 35 so that the calculated adjustment force acts, and by elastically deforming the housing 36e via the first actuator mounting portion 36a and the second actuator mounting portion 36b to change the position or attitude of the table support portion 36c. The table position control device 110 operates a hydraulic source (fluid pressure source) 112 included in the machine tool 10 to supply hydraulic pressure to the actuator 35. This allows the actuator 35 to generate an adjustment force. The table position control device 110 is configured to correct the adjustment force of the actuator 35, taking into account the effects of displacement and tilt of the table 36d of the C-axis rotary table 36. Specifically, it controls the hydraulic pressure supplied to the actuator 35 in accordance with the position of the table 36d, which has changed due to the displacement or tilt. Therefore, in response to the change in the position of the center of gravity GW1 due to the change in the position (inclination) of the rotation center axis CC of the table 36d, a precise adjustment force can be applied so that the rotation center axis CC of the table 36d always coincides with the horizontal axis, i.e., so that the workpiece W1 is positioned at the position where it should be processed.

[0047] The table position control device 110 is also configured to change the adjustment force of the actuator 35 in accordance with the progress of the machining process of the workpiece W1 acquired from the NC program and model information of the workpiece W1 in the NC device 102. Furthermore, the table position control device 110 is configured to be able to change the adjustment force generated by the actuator 35 in accordance with position information (displacement information and tilt information) of the table 36d measured using a position sensor or the like arranged on the C-axis rotary table 36.

[0048] The control device 100 has a notification unit 100 (not shown) that notifies the operator WK of the estimated mass M of the pallet 76 exceeding the upper limit of the mass that can be attached to the table 36d (table-attachable upper limit mass), the upper limit of the mass that can be held by the arm 64 (arm-holdable upper limit mass), or the upper limit of the mass that can be held by the APC arm 50 as a rotating arm (APC arm-holdable upper limit mass), which are stored in advance in the memory unit 104. For this reason, for example, after changing the posture of the pallet 76, and before replacing the pallet 76 held by the arm 64 with a pallet 94 attached to the C-axis rotary table 36, the control device 100 can estimate the mass M of the pallet 76, and if the mass M exceeds the table-attachable upper limit mass or the APC arm-holdable upper limit mass, the pallet replacement can be stopped and an alarm (a perceptible display such as sound or light, a notification on a personal computer, mobile terminal, etc.) can be issued to the operator WK. The mass is estimated immediately after acquiring the first load T1, and if it exceeds the upper limit mass that the arm can hold, an alarm can be issued without changing the pallet attitude. This makes it possible to prevent breakdowns in the C-axis rotary table 36, arm 64, and APC arm 50, and improve the operating efficiency of the machine tool 10.

[0049] FIG. 9 shows a flowchart of tipping correction. Additionally, FIGS. 10 to 22 show the setup of the pallet 76 corresponding to the tipping correction flow. The effects of the control device 100 and estimation method for the machine tool 10 according to this embodiment will be explained below through these explanations. The side views of the pallet attitude changing device 42 and the C-axis rotary table 36 shown in FIGS. 10 to 22 are schematic diagrams for explaining the effects of these devices. Therefore, in order to make the drawings easier to read, please note that parts that are not directly visible in actual side views because they are hidden by the arm 64 (fingers 72, receiving portions 74, arm protrusions 86, etc.) and the internal configuration of the C-axis rotary table 36 (table support portion 36c, table 36d, etc.) are drawn in solid lines.

[0050] The control device 100 proceeds to step S10 (see FIG. 9) and starts tipping correction. After tipping correction is started, the process proceeds to step S20 (see FIG. 9) and loads the pallet into the pallet position changing device 42. FIG. 10 shows a state in which a pallet 76, to which a jig 96 and an unmachined workpiece W1 have been attached, has been loaded from outside the machine tool 10. Here, the pallet 76 (shown by the dotted line in FIG. 10) has its underside 76b placed on rails 90 arranged on the top surface of the bed 18 directly below the pallet position changing device 42. The pallet 76 is loaded in a horizontal state from outside the machine tool 10 through the setup room door 14a to the setup station 40 side, i.e., the pallet position changing device 42 side. Note that the method of loading the pallet 76 is not limited to the rails 90. The pallet may be loaded in a horizontal state vertically using a transport device installed above the machine tool, or may be loaded using the forks of a transport vehicle with forks. The loaded pallet 76 stops sliding when it hits a stopper 92 formed at the end of the rail 90, and is positioned in a horizontal setup position. At this time, the arm 64 is positioned (pivoted) in a retracted position that is lower than the engaged position in the horizontal state, and the finger 72 is positioned in a pallet disengagement position. The pallet position changing device 42 is configured so that, in the retracted position, the arm 64 and its components, the finger 72, the receiving portion 74, and the arm protrusion 86, do not interfere with the loading of the pallet 76. Meanwhile, a second pallet 94, on which a machined (post-machined) workpiece W2 and a jig 96 are assembled, is held on the C-axis rotary table 36 (see FIG. 2) on the machining chamber 12 side (not shown).

[0051] When a pallet is carried into the pallet position changing device 42, the process proceeds to step S30 (see FIG. 9 ), in which the arm 64 of the pallet position changing device 42 is actuated to hold the pallet 76 in a horizontal position. FIG. 11 shows the state in which the drive unit 62 rotates the arm 64 to an engagement position where the arm 64 faces the engagement side surface 76e of the pallet 76, thereby positioning the arm 64 relative to the pallet 76. In this state, the arm protrusion 86 and the second pallet receiving surface 74b of the receiving portion 74 may be configured not to contact the pallet 76, or may be configured to contact the pallet 76. When not contacting the pallet 76, the pallet 76 is held on the rail 90. When contacting the pallet 76, the arm protrusion 86 contacts the upper surface of the inner wall of the pallet groove 88, and the second pallet receiving surface 74b contacts the underside 76b of the pallet 76. As a result, the pallet 76 moves away from the rail 90 and is held by the arm 64. In this case, since the arm protrusion 86 is inserted into the pallet groove 88, even if an unexpected external force acts on the pallet 76, the pallet 76 can be prevented from suddenly moving outside the machine tool 10.

[0052] FIG. 12 shows the state in which the finger 72 is moved from the pallet disengagement position to the pallet engagement position (arrow in the figure), engaging the finger 72 with the pin 78. Here, the finger 72 and the pin 78 are sized so that there is a gap (play) between the finger 72 and the pin 78 to prevent the pin 78 from falling out. When the arm 64 holds the pallet 76, the process proceeds to step S40 (see FIG. 9), in which the encoder 62b of the servo motor 62a detects that the rotational position of the arm 64 is at the engagement position (first arm position in estimating the mass M and the distance H from the center of gravity). Furthermore, a current corresponding to the mass M and the distance H from the center of gravity of the pallet 76 is generated in the servo motor 62a of the drive unit 62. The control device 100 (NC device 102) acquires a torque (first load T1) based on the current value at this time from the servo amplifier 62c and stores it in the memory unit 104.

[0053] When the control device 100 acquires the first load T1, the process proceeds to step S50 (see FIG. 9 ), where it activates the arm 64 of the pallet position changing device 42 to rotate the pallet 76 to an upright position. FIG. 13 shows the state in which the drive unit 62 rotates the arm 64 to the upright position, changing the position of the pallet 76 to an upright position. During the position change, the finger 72 and the pin 78 are engaged, restricting the movement of the pallet 76 alone in the rotational direction (direction R1). Furthermore, the second pallet receiving surface 74b abuts against the underside 76b of the pallet 76, and the first pallet receiving surface 74a abuts against the abutment side surface 76d of the pallet 76, thereby supporting the weight of the pallet 76 and restricting movement in the direction of gravity. This allows the arm 64 to stably hold the pallet 76 while changing its position from a horizontal position to an upright position. When the pallet 76 is rotated to an upright position, the process proceeds to step S60 (see FIG. 9), and the encoder 62b of the servo motor 62a detects that the rotation position of the arm 64 is in the upright position (the second arm position in the estimation of the mass M and the distance H from the center of gravity). Furthermore, a current corresponding to the mass M and the distance H from the center of gravity of the pallet 76 is generated in the servo motor 62a of the drive unit 62. The control device 100 (NC device 102) acquires the torque (second load T2) based on the current value at this time and stores it in the memory unit 104.

[0054] When the controller 100 acquires the second load T2, the process proceeds to step S70 (see FIG. 9 ), where the controller 100 activates the APC arm 50 to exchange the pallet 76, 94. FIG. 14 shows the state in which the APC arm 50 of the pallet exchanger 44 is raised and the first pallet holder 82 holds the pallet 76. Specifically, by raising the APC arm 50, the holding member 76f is fitted into the recessed portion of the first pallet holder 82, and the upper surfaces of the columnar members at both ends of the first pallet holder 82 come into contact with the abutment side surface 76d of the pallet 76. This allows the APC arm 50 to hold the pallet 76. At this time, the fingers 72 merely restrict the movement of the pins 78 of the pallet 76 alone in the rotational direction (direction R1). Therefore, the APC arm 50 can lift the pallet 76 without interfering with the arm 64.

[0055] 15 shows a state in which the APC arm 50 holds the pallet 76 and the fingers 72 are moved from the pallet engagement position to the pallet disengagement position. As indicated by the arrow in the figure, by moving the fingers 72 from the pallet engagement position to the pallet disengagement position, only the APC arm 50 holds the pallet 76. At this time, the second pallet 94 on the processing chamber 12 side (not shown) is also removed from the C-axis rotary table 36. As a result, both the pallet 76 on the setup chamber 14 side and the second pallet 94 on the processing chamber 12 side (see FIG. 17) are held by only the APC arm 50.

[0056] 16 shows a state in which the arm 64, with the fingers 72 actuated to the pallet disengagement position, has been rotated to a standby position by the drive unit 62. The pallet position changing device 42 can position (rotate) the arm 64 to a standby position between the upright position (upright state) and the engagement position (horizontal state). This prevents interference between the APC arm 50 and the pivoting door 46 and other components within the pallet position changing device 42 or machine tool 10 when the APC arm 50 and the pivoting door 46 are rotated to exchange the pallet 76 in the setup chamber 14 with the second pallet 94 in the machining chamber 12. Furthermore, because the arm 64 can be positioned to the standby position without returning to the engagement position, the time required to rotate the arm 64 can be minimized, thereby shortening the time required to change the position and replace the pallet 76.

[0057] 17 shows a state in which the pallet 76 (see FIG. 16) on the setup chamber 14 side and the second pallet 94 on the machining chamber 12 side have been swapped (exchanged) by rotating the APC arm 50. By rotating the APC arm 50 holding the pallet 76 and the second pallet 94 180 degrees, the pallet 76 on which the unmachined workpiece W1 has been mounted can be moved to the machining chamber 12 side and handed over to the C-axis rotary table 36, and the second pallet 94 on which the machined workpiece W2 has been mounted can be moved to the setup chamber 14 side.

[0058] In parallel with or after the replacement of the pallets 76, 94, the estimation unit 106 proceeds to step S80 (see FIG. 9 ) and estimates the mass M from the reference distance L, first reference load TB1, and first load T1 stored in the storage unit 104 using the above-described equations (1) and (2). Next, the estimation unit 106 proceeds to step S90 (see FIG. 9 ) and estimates the center-of-gravity position distance H from the second reference load TB2 and second load T2 stored in the storage unit 104 using the above-described equations (3) and (4). At this time, the first reference load TB1 and the second reference load TB2 are obtained in advance by experiment or the like and stored in the storage unit 104. Next, the process proceeds to step S100 (see FIG. 9), where the calculation unit 108 of the control device 100 calculates the adjustment force acting from the actuator 35 to the first actuator mounting portion 36a and the second actuator mounting portion 36b based on the mass M and center of gravity position distance H of the pallet 76 estimated by the estimation unit 106 in order to perform tipping correction.

[0059] Figure 18 shows the C-axis rotary table 36 on which the replaced pallet 76 is attached. The APC arm 50 rotates 180 degrees to replace the pallet 76 toward the processing chamber 12, and the replaced pallet 76 is positioned and attached to the C-axis rotary table 36. While the APC arm 50 is rotating, the C-axis rotary table 36 waits at a standby position (position indicated by a dotted line in Figure 18) where it does not interfere with the APC arm 50 and the pallet 76 it holds, until the rotation is complete. After the rotation is complete, the C-axis rotary table 36 moves along the Z-axis direction toward the APC arm 50 and pallet 76, and holds and attaches the pallet 76 by means of an attachment mechanism (not shown) on the underside 76b of the pallet 76 and the mounting surface of the C-axis rotary table 36.

[0060] FIG. 19 shows a side view of the APC arm 50 transferring the pallet 76 to the C-axis rotary table 36. Once the pallet 76 is attached to the C-axis rotary table 36, the APC arm 50 descends and removes the pallet 76 from the C-axis rotary table 36. Because the APC arm 50 releases the pallet 76, it is now held only by the mounting surface of the table 36d of the C-axis rotary table 36. The pallet 76, jig 96, and workpiece W1 are attached upright to the mounting surface of the table 36d and protrude horizontally. Therefore, a moment generated by the weights of the pallet 76, jig 96, and workpiece W1 acts on the table 36d. As a result, the table 36d tilts downward in the vertical direction, and the rotation axis (C-axis) of the table 36d tilts downward in the vertical direction relative to the horizontal axis. This causes the table 36d to tip over, resulting in reduced machining accuracy. If the workpiece W1 is machined while the workpiece W1 is still tilted, for example, the requirement for parallelism of the upper surface 76a of the workpiece W1 relative to the reference surface of the jig 96 attached to the reference surface of the workpiece W1 cannot be met.

[0061] 20 shows a side view of the pallet 76 and workpiece W1, with the table 36d tilting (falling) due to its own weight. After the pallet 76 is handed over to the C-axis rotary table 36, the process proceeds to step S110 (see FIG. 9), in which the control device 100 operates the table position control device 110 to perform fall correction, and controls the hydraulic source 112 to operate the actuator 35 with the adjustment force (hydraulic pressure) calculated by the calculation unit 108.

[0062] FIG. 21 shows a side view of the C-axis rotary table 36 in which the actuator 35 operates to perform tilt correction. When the table position control device 110 controls the hydraulic source 112 to operate the actuator 35, the process proceeds to step S120 (see FIG. 9 ). The actuator 35 is activated and elastically deforms the housing 36e of the C-axis rotary table 36. Specifically, the actuator 35 is activated by hydraulic pressure and applies an adjustment force to the first actuator mounting portion 36a and the second actuator mounting portion 36b. This applies a force to the housing 36e in a direction away from or toward the housing 36e, elastically deforming the housing 36e so that it tilts (rises) toward the rear side (toward the actuator 35). As a result, the rotation center axis CC of the table 36d, which had been tilted downward together with the jig 96, workpiece W1, and pallet 76, is corrected to align with the horizontal axis, and the table 36d is positioned in its original position. When the table 36d is positioned, the process proceeds to step S130 (see FIG. 9) and the tilt correction is completed.

[0063] 22 shows a side view of the C-axis rotary table 36 rotated by the B-axis rotary table 34 toward the spindle 26 for machining. The workpiece W1 is attached to a pallet 76 that is rotated by the B-axis rotary table 34 and positioned so as to face the spindle 26. The spindle 26, the C-axis rotary table 36, and the B-axis rotary table 34 move relative to each other, and the workpiece W1 is machined by the tool 28 attached to the spindle 26. When machining is complete, the pallet 76 is replaced again.

[0064] According to the control device 100 of the machine tool 10 of this embodiment, the control device 100 is equipped with a memory unit 104 that stores a first reference load TB1 that acts on the drive unit 62 when the arm 64 is rotated alone to the first arm position, a second reference load TB2 that acts on the drive unit 62 when the arm 64 is rotated to the second arm position, and a reference distance L that is the horizontal distance between the central part of the pallet of the pallet 76 in a horizontal state and the rotation center axis RA1 of the drive unit 62. The control device 100 also includes an estimation unit 106 that acquires a first load T1 acting on the drive unit 62 when the position of the pallet 76 held by the arm 64 is changed to a first arm position within the arm rotation range, and a second load T2 acting on the drive unit 62 when the position of the pallet 76 is changed to a second arm position, and estimates the mass M and the position of the center of gravity GW1 (center of gravity distance H) of the pallet 76 based on at least the reference distance L, the first reference load TB1, the second reference load TB2, the first load T1, and the second load T2. Therefore, the mass M and the center of gravity distance H of the pallet 76 can be estimated using the drive unit 62 and the arm 64 without increasing the number of parts.

[0065] Furthermore, according to the machine tool 10 of this embodiment, the machine tool 10 includes an actuator 35 and a calculation unit 108 that calculates an adjustment force that the actuator 35 applies to the first actuator mounting portion 36a and the second actuator mounting portion 36b based on the mass M of the pallet 76 and the center-of-gravity distance H estimated by the control unit 100. The machine tool 10 also includes a table position control device 110 that operates the actuator 35 so that the calculated adjustment force applies to the first actuator mounting portion 36a and the second actuator mounting portion 36b, and controls the position of the table 36d by elastically deforming the housing 36e to change the position or attitude of the table support portion 36c. This makes it possible to correct tilting of the table 36d, thereby improving the machining accuracy of the workpiece W1.

[0066] Furthermore, according to the machine tool 10 of this embodiment, the estimating unit 106 of the control device 100 can acquire the first table load T3 acting on the table 36d when the C-axis rotary table 36 to which the pallet 76 has been transferred is at the first table rotation position. Furthermore, the estimating unit 106 of the control device 100 can rotate the table 36d to a second table rotation position, which is rotated 90 degrees from the first table rotation position, and acquire the second table load T4 acting on the table 36d. Therefore, it is possible to estimate the deviation of the center of gravity GW1 from the rotation central axis CC of the C-axis rotary table 36.

[0067] Furthermore, in the machine tool 10 according to this embodiment, the control device 100 includes an alarm unit 100 that issues an alarm if the estimated mass M of the pallet 76 exceeds the table-mountable upper limit mass, the upper limit mass that can be held, or the upper limit mass that can be held by the APC arm, stored in the memory unit 104. Therefore, after changing the orientation of the pallet 76, the mass M of the pallet 76 can be estimated before replacing the pallet 76 held by the arm 64 with the pallet 94 attached to the C-axis rotary table 36. If the estimated mass M exceeds the table-mountable upper limit mass or the upper limit mass that can be held by the APC arm, the pallet exchange can be stopped and an alarm can be issued to the operator WK. The mass can also be estimated immediately after acquiring the first load T1. If the estimated mass exceeds the upper limit mass that can be held by the arm, an alarm can be issued without changing the orientation of the pallet. This prevents malfunctions in the C-axis rotary table 36, the arm 64, and the APC arm 50, improving the operating efficiency of the machine tool 10.

[0068] Furthermore, in machine tool 10 according to this embodiment, control device 100 is configured to control the speed and / or acceleration of the operation of arm 64, APC arm 50, and the feed axes of machine tool 10 in accordance with the estimated mass M of pallet 76 and center-of-gravity position distance H. Therefore, when mass M is greater than a certain percentage of the upper limit mass that the APC arm can hold, the rotation speed and lifting speed of APC arm 50 of pallet changer 44 can be set low. Furthermore, when center of gravity GW1 is positioned so that the load on the C-axis is relatively small, the acceleration / rotational acceleration of the C-axis, B-axis, and Z-axis can be set high. Conversely, when center of gravity GW1 is positioned so that the load on the C-axis is relatively large, the acceleration / rotational acceleration of the C-axis, B-axis, and Z-axis can be set low, thereby improving the machining accuracy of workpiece W1 and the operating efficiency of the machine tool.

[0069] As explained above, the control device 100 and estimation method for the machine tool 10 according to this embodiment make it possible to accurately estimate the mass M and center-of-gravity distance H of the pallet 76 on which the workpiece W1 is attached without increasing the number of parts, in order to improve the machining accuracy and operating efficiency of the workpiece W1. Furthermore, the estimated mass M and center-of-gravity distance H of the pallet 76 can be used in various situations with the machine tool 10, thereby improving the machining accuracy of the workpiece W1 and the operating efficiency of the machine tool 10.

[0070] Although the embodiments of the control device 100 of the machine tool 10 and the method for estimating the mass M and the distance H from the center of gravity have been described above, the present invention is not limited to the above embodiments. In addition to the above, it is believed that a person skilled in the art would understand that various modifications of the above embodiments are possible. [Explanation of symbols]

[0071] 10 Machine tools 26 Spindle 28 Tools 35 Actuator 36 C-axis rotary table (table) 36a First actuator mounting portion 36b Second actuator mounting portion 36c Table support 36d table 36e Housing 36f servo motor 36g encoder 36h Servo amplifier 38 Z-axis linear guide 40 Setup Station 42 Pallet position change device (estimation device) 44 Pallet exchange device 60 base 62 Drive unit 64 Arm 76 palettes 76a Top side 96 Jig 100 control device 104 Storage section 106 Estimation part 108 Calculation Department 110 Table position control device H Center of gravity distance L Reference distance M mass RA1 Rotational axis of the drive unit TB1 First Reference Load TB2 Second Reference Load T1 First Load T2 Second Load T3 First table load T4 Second table load W1 Work W2 work

Claims

1. An apparatus for estimating the mass and center of gravity position of a pallet on which a workpiece is attached, With the base, a drive unit attached to the base and configured to be capable of rotating the pallet around a rotation center axis extending in a horizontal direction and to be capable of acquiring a load; an arm rotatably attached to the drive unit, holding the pallet having an upper surface on which the workpiece is to be assembled, and configured to change the position of the pallet within an arm rotation range including a horizontal state in which the upper surface of the pallet is moved toward a horizontal plane and an upright state in which the upper surface of the pallet is moved toward a vertical plane; a storage unit that stores a first reference load that acts on the drive unit when the arm is rotated independently to a first arm position within the arm rotation range, a second reference load that acts on the drive unit when the arm is rotated to a second arm position within the arm rotation range that is different from the first arm position, and a reference distance that is the horizontal distance between a pallet center portion of the pallet in the horizontal state and the rotation center axis of the drive unit; an estimation unit that acquires a first load that acts on the drive unit when the pallet held by the arm is changed in position to a first arm position within the arm rotation range, and a second load that acts on the drive unit when the pallet is changed in position to a second arm position within the arm rotation range, and estimates the mass and center of gravity position of the pallet based on at least the reference distance, the first reference load, the second reference load, the first load, and the second load; An estimation device comprising:

2. A method for estimating the mass and center of gravity position of a pallet on which a workpiece is attached, comprising: holding the pallet having an upper surface on which the workpiece is to be assembled by an arm rotatably attached to a drive unit configured to be able to acquire a load, and changing the position of the pallet within an arm rotation range including between a horizontal state in which the upper surface of the pallet is moved toward a horizontal plane and an upright state in which the upper surface of the pallet is moved toward a vertical plane; acquiring a first reference load acting on the drive unit when the arm is rotated alone to a first arm position within the arm rotation range; acquiring a second reference load acting on the drive unit when the arm is rotated independently to a second arm position within the arm rotation range; acquiring a first load acting on the drive unit when the posture of the pallet held by the arm is changed to a first arm position within the arm rotation range; acquiring a second load acting on the drive unit when the posture of the pallet held by the arm is changed to a second arm position within the arm rotation range; estimating a reference distance, which is a horizontal distance between a central portion of the pallet in the horizontal state and the rotation central axis of the drive unit, and estimating a mass and a center of gravity position of the pallet based on at least the first reference load, the second reference load, the first load, and the second load; A method for estimating the mass and center of gravity of a pallet, comprising:

3. A spindle on which tools are attached; a table that can receive the pallet on which the workpiece is mounted from the arm and can be attached in the upright state; a housing in which a table support portion for supporting the table, a first actuator mounting portion, and a second actuator mounting portion are integrally formed; an actuator attached to the first actuator mounting portion and the second actuator mounting portion, the actuator applying a force to the first actuator mounting portion and the second actuator mounting portion in a direction moving away from or approaching the housing, thereby elastically deforming the housing; The estimation device according to claim 1 ; a calculation unit that calculates an adjustment force that the actuator acts on the first actuator mounting portion and the second actuator mounting portion based on the mass and center of gravity position of the pallet estimated by the estimation device; a table position control device that controls the position of the table by operating the actuator so that the calculated adjustment force acts on the first actuator mounting portion and the second actuator mounting portion, and elastically deforming the housing to change the position or attitude of the table support portion; and A machine tool comprising:

4. the table is configured to be rotatable with the pallet attached and to be able to acquire a load; the estimation unit acquires a first table load acting on the table to which the pallet is attached at a first table rotation position, and a second table load acting on the table to which the pallet is attached at a second table rotation position obtained by rotating the table 90 degrees from the first table rotation position, 4. The machine tool according to claim 3, wherein the mass and center of gravity position of the pallet are estimated based on the reference distance, the first reference load, the second reference load, the first load, the second load, the first table load, and the second table load.

5. 5. The machine tool according to claim 3, wherein the estimation device is provided with a notification unit that notifies the user that the estimated mass of the pallet exceeds the upper limit mass that can be attached to the table or the upper limit mass that can be held by the arm, which is stored in the memory unit.

6. The machine tool according to claim 3 or claim 4, wherein the estimation device is configured to control the speed and / or acceleration of the movement of the arm and the feed axis of the machine tool in accordance with the estimated mass of the pallet and the position of the center of gravity of the pallet.

Images