JP2007075902A - Axis feed device of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axis feed device which holds down deterioration of working accuracy due to vibration and displacement of the tool body, has excellent workability, and is suitable for precise working. <P>SOLUTION: In this axis feed device, two cancel moving bodies 20 reciprocating in two axial directions parallel to the X-axis at an equal distance L in the horizontal direction with a slider 10 interposed between them, are provided symmetrical about a moving axis. The slider 10 is driven by a linear motor 30 including a stator 30A provided on a top lid 3 on a beam 2 and a needle 30B. The cancel moving body 20 is driven by a linear motor 40 including a stator 40A and a needle 40B. The cancel moving body 20 is independently controlled to move by a control device to move in the opposite direction to the slider 10 so that the position of the center of gravity is not moved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a canceling moving body that moves in a direction opposite to the movement of the main moving body so that the center of gravity of the machine is at the same position in a shaft feed device of a machine tool that drives the main moving body with a linear motor. The present invention relates to a shaft feed device of a machine tool.

  A linear motor drive type machine tool that drives a moving body with a linear motor is known. Linear motors have less friction that affects the movement of moving objects, and have a simpler structure and higher rigidity than rotary servo motors. As motor control devices and positioning control technologies are developed, many linear motors are used in machine tools. It is becoming applicable.

  Since the linear motor has few spring elements and excellent response performance, the linear motor drive system aims to reciprocate the moving body at high speed. As a result, in the linear motor drive system, high acceleration, sudden deceleration, and reversal of the moving body are complicatedly repeated, and therefore, vibration and displacement are likely to occur in the airframe due to the reaction force of the inertia of the moving body and the thrust of the linear motor. In order to suppress the vibration and displacement of the airframe, it is conceivable to slow down the acceleration / deceleration or to give a pause at the time of reversal, but the advantages of the linear motor are not fully demonstrated. Thus, as a method for preventing vibration and displacement of the airframe, a method of providing a counter balance weight corresponding to the mass of the moving body and a method of applying a force that counteracts the reaction force of the thrust of the linear motor are considered.

  As a method of giving a counter balance weight, there are a method of connecting a counter mass widely used in a counterbalancer of a vertical axis, and a method of connecting an air cylinder or a hydraulic cylinder to a moving shaft of a moving body. The method of providing balance by means of a counter mass or cylinder is passive, so it is difficult to follow with a high-speed response. In addition, the above-described method causes the positioning performance of the linear motor to deteriorate in order to directly apply resistance to the moving body, and causes more loss of thrust. Therefore, the above method is disadvantageous in a linear motor drive type machine tool that is expected to obtain high positioning accuracy by utilizing high speed and high response. In addition, in a machine tool in which the mass of the moving body may vary greatly, it is necessary to replace the counter mass or change the pressure of the air cylinder.

  On the other hand, in the method of canceling the reaction force due to the thrust of the linear motor, specifically, as disclosed in Patent Document 1, the counter mass can be moved by a linear motor drive system, and the linear motor of the counter mass is There is a method of generating a reaction force due to this thrust force to cancel the reaction force due to the thrust force of the linear motor of the moving body. The shaft feeding device configured to cancel the reaction force in this way is called a cancel type. Since the cancel-type shaft feeding device is active, the high-speed performance and response performance of the linear motor drive system can be exhibited more. In addition, the reaction force due to the movement of the counter mass that cancels the reaction force generated by the movement of the moving body can be adjusted to some extent by driving and controlling the linear motor of the counter mass. The

  The basic structure of a cancel type shaft feeding device having a configuration for connecting a moving counter mass as shown in Patent Document 1 (hereinafter referred to as a connection method) is a moving shaft of a moving body as shown in Patent Document 1. There are a serial arrangement structure in which counter masses are connected coaxially, and a parallel arrangement structure in which a movable body and a counter mass are arranged side by side and connected by a connecting member, as shown in Patent Document 2 and Patent Document 3.

  In the case of a connection type cancellation type axial feed device, a counter mass and a linear motor of the same size as a moving body are required, so simply speaking, the axial feed device has a double axial distance, area, or height. Therefore, the size tends to increase with respect to the size of the workpiece that can be processed by the machine. In addition, in the configuration of the connection type canceling shaft feeder, the countermass linear motor must be controlled by a certain amount of calculation to suppress the reaction force, so there is a limit to the accuracy with which vibration and displacement can be prevented. Yes, if the requirements for errors due to allowable machine vibrations and displacements become severe, performance cannot be fully achieved. In addition, since the counter mass is connected directly or via a pulley or the like with a joint, cable-like body, belt, etc., the configuration becomes relatively complicated, and the counter mass moves as the moving body moves faster. There is a risk that it will not be able to sufficiently follow the movement of the.

  On the other hand, as in Patent Document 4, the primary side and the secondary side of the linear motor are moved in opposite directions so that the center of the moving shaft is always the same as the center of gravity of the moving body. There is a method of suppressing vibration and displacement of the machine by canceling the reaction force (hereinafter referred to as a non-connection method). Such a non-connection type cancellation type axial feeding device is more compact than a connection type cancellation type axial feeding device, and has an excellent performance of suppressing vibration. However, the cancel type axial feed device configured to simply move the primary side and the secondary side in opposite directions is limited to a linear motor such as a voice coil motor because of its structure. Therefore, it is difficult to directly adopt a non-connection type canceling type shaft feeding device for a shaft feeding device that requires a large thrust, such as a shaft feeding device of a machine tool.

  By the way, a machine tool is required to move at least a tool and a workpiece in three axis directions. Regardless of the cancel type axial feeding device, if the moving bodies in the horizontal one-axis direction (X-axis) and the horizontal one-axis direction (Y-axis) orthogonal to the horizontal one-axis direction are arranged in an overlapping manner, the height becomes too high and workability deteriorates. As a structure that can avoid the overlapping arrangement, a structure that separates moving bodies in the X-axis direction and the Y-axis direction, such as column feed type, gate type, gantry type, and monocoque type, is known. Each structure has advantages and disadvantages, but detailed description is omitted here. For example, Patent Document 5 and Patent Document 6 disclose a monocoque structure as an advantageous structure for a precision processing machine.

JP-A-11-189332 JP-A-5-258749 JP 2004-40939 A JP 2002-283174 A JP 2001-96434 A Japanese Patent Laid-Open No. 4-226846

  In order to make it possible to apply a non-coupled system to a shaft feed device that uses a linear motor that can obtain a larger thrust as a drive source, such as a machine tool shaft feed device, a main moving body and a cancel moving body are respectively It is conceivable to use a structure that is driven by a separate linear motor. However, in the case where a linear motor is provided for each of the main moving body and the canceling moving body, a canceling movement with a large mass commensurate with the canceling moving body in order to cancel the reaction force caused by the movement of the moving body. Body or large thrust linear motors are required. Accordingly, it is possible to simplify the configuration as compared to the connection type cancellation type shaft feeding device, and it is considered that the cancellation moving body is excellent in followability to the main moving body, but it is difficult to reduce the size.

  Therefore, when such a cancel type shaft feeding device is provided in a machine tool, workability is considerably deteriorated. Further, when the main moving body in the X-axis direction and the Y-axis direction is completely separated in order to ensure workability, one of the moving bodies must be disposed in the upper part of the machine body as in the monocoque type. Disappear. However, if the main moving body and the cancel moving body are placed on the upper part of the aircraft, the weight on the upper side becomes relatively large, the center of gravity of the machine becomes higher, and the vibration and displacement of the aircraft are more likely to occur. Become. On the other hand, if the main moving body and the cancel moving body are arranged side by side, the balance between the moving body and the cancel moving body is lost, and vibration and displacement of the airframe also occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a non-connection type cancellation type shaft feeding device suitable for practical use as a shaft feeding device for a machine tool that requires high machining accuracy. Specifically, the present invention provides an axial feeding device having two cancel moving bodies that can move back and forth in parallel with the moving body at an equal distance in the horizontal direction. Some specific advantages of the present invention will be described in detail later.

  The present invention is a non-connection type cancellation type shaft feeding device that can be realized by a machine tool. A main moving body that can be reciprocated in a horizontal axis direction, a stator and a main moving body that are provided in a machine structure. A linear motor that drives the main moving body, and is provided so as to be able to reciprocate in two axial directions that are equidistant in the horizontal direction across the main moving body, opposite to the direction in which the main moving body moves It comprises two canceling moving bodies that move in the direction, and two linear motors each composed of a stator provided on the main moving body and a mover provided on the canceling moving body, each driving the two canceling moving bodies.

  Preferably, the linear motor that drives the main moving body is a coreless linear motor. The linear motors that drive the main moving body are two coreless linear motors of the same type that are provided symmetrically about the moving axis of the main moving body. Further, the two linear motors that drive the cancel moving body are coreless linear motors. Further, the two cancel moving bodies are of the same type, and the two linear motors that move the cancel moving body are of the same type.

  Moreover, the control apparatus which controls two cancellation moving bodies so that the gravity center of a machine exists in the same position is included. Preferably, the control device controls the two cancel moving bodies independently. Further, a linear scale for detecting the position of the main moving body and a linear scale for detecting each position of the cancel moving body are provided. The main moving body is arranged independently of the moving body provided so as to be able to reciprocate in the horizontal one-axis direction orthogonal to the horizontal one-axis direction. Further, the main moving body is provided with a spindle on the lower side for rotating the tool around the vertical axis, and is installed on the upper side of the table on which the workpiece is placed.

  The machine tool axial feed device of the present invention is a non-coupled cancellation type axial feed device, so the cancel moving body is excellent in controllability and followability, and the center of gravity of the machine can be stably held at the same position. Vibration and displacement can be more reliably suppressed, the configuration of the shaft feeder can be simplified, and the size can be made relatively small. And since it is the structure which provided the two cancellation moving bodies which move equidistantly in the horizontal direction across the moving axis of the main moving body and move in parallel to the main moving body, the position of the center of gravity of the machine does not increase, Vibration and displacement can be suppressed more stably. Further, the moving bodies in the horizontal one axis direction and the horizontal one axis direction orthogonal thereto can be easily separated and arranged. In addition, the symmetrical structure is excellent in balance, and vibration and displacement of the airframe are less likely to occur. Therefore, it is suitable for a machine tool in which a decrease in machining accuracy due to vibration and displacement of the machine body is small, workability is excellent, and precise machining is required.

  When the linear motor that drives the main moving body and the cancel moving body is a coreless linear motor, adverse effects such as displacement of the machine body due to the suction force of the linear motor are suppressed. And a non-coupled cancellation type axial feed device provided with two cancel moving bodies that move parallel to the main moving body in the axial direction equidistant in the horizontal direction across the moving axis of the main moving body and the main moving body This structure can be realized more easily. In particular, since the shaft feeding device can be made compact and lightweight, it is easy to install the shaft feeding device in the upper part of the machine body.

  Also, the linear motor for moving the main moving body is made of two coreless linear motors of the same type provided symmetrically about the moving axis of the main moving body, so that the thrust distribution on the moving axis and the two cancel shafts is evenly distributed. It is excellent in balance and can stably suppress vibration and displacement of the fuselage. In particular, the two cancel moving bodies are of the same type, and the two linear motors that move the cancel moving body are of the same type, so that it is easy to keep the center of gravity at the same position.

  In the axial feed device, since the two cancel moving bodies are controlled by the control device so that the center of gravity of the machine is always at the same position, vibration and displacement of the machine body are more accurately suppressed. In addition, since the control device controls the two cancel moving bodies independently, the center of gravity always seems to be at the same position even in a configuration in which the two cancel moving bodies are arranged separately and driven by different linear motors. The movement can be controlled. Further, since the respective positions of the main moving body and the canceling moving body are detected and controlled by the linear scale, vibration and displacement of the airframe are more accurately suppressed.

  Since the main moving body is arranged independently of the other moving bodies, the height of the machine can be made lower and more stable. In particular, by adopting a so-called monocoque structure in which the main moving body is equipped with a main spindle on the lower side and installed on the upper side of the table, the airframe is compact and the center of gravity of the machine is lowered, making it more stable. High machine accuracy can be maintained, and a structure suitable for a precise processing machine can be obtained.

  FIG. 1 shows an overall configuration of a machine tool showing a preferred embodiment of the present invention. FIG. 1 shows a section of the fuselage cut away so that the inside can be seen, with the cut site indicated by hatching. The machine tool shown in FIG. 1 specifically shows a so-called monocoque type cutting machine in which a moving body in the X-axis direction is arranged above a box-shaped beam composed of a plurality of aggregates (frames). . Below, the outline of the whole machine tool carrying the shaft feeding device of the present invention is explained.

  The horizontal axis 1 (X-axis direction) axial feeding device 1 is provided on a canopy 3 that can be removed on the upper side of the body structure (beam) 2. An axial feed device 4 in the horizontal uniaxial direction (Y-axis direction) orthogonal to the horizontal uniaxial direction is provided inside the beam 2. Therefore, the main moving body (slider) 10 of the shaft feeding device 1 provided so as to be capable of reciprocating in the X-axis direction is a moving body (slider 10) of the shaft feeding device 4 provided so as to be capable of reciprocating in the Y-axis direction orthogonal to the X-axis direction. Saddle) 42 is arranged independently. More specifically, the slider 10 includes a spindle 5 that rotates a tool around the vertical axis (around the Z axis) on the lower side thereof, and is moved in the Y-axis direction along with the movement of the saddle 42 to place a workpiece. It is installed above the table 74 to be placed. In this configuration, the displacement of the movable body is small, the workability is excellent, and high machining accuracy is required as compared with the configuration in which the X-axis direction axis feeding device 1 and the Y-axis direction axis feeding device 4 are arranged in an overlapping manner. Suitable for equipment.

  The shaft feed device 4 in the Y-axis direction has a cancel-type structure in which a cancel moving body 44 is arranged coaxially with the saddle 42 at a rear portion of the airframe. Therefore, the reaction force accompanying the movement of the moving body generated in the Y-axis direction is canceled out by the cancel moving body 44, and vibration and displacement are suppressed. The shaft feeder 4 is installed on the bed 6. Therefore, this configuration is advantageous in that the center of gravity of the machine can be positioned on the lower side in the configuration in which the movable body in the X-axis direction is disposed on the upper side of the machine body, and the machine body is more stable.

  The shaft feeding device 7 in the vertical one-axis direction (Z-axis direction) is provided on the saddle 42 so as to be capable of reciprocating in the Z-axis direction, and moves integrally with the saddle 42. A moving body (slider) 72 of the shaft feeder 7 reciprocates in the Z-axis direction by a rotary servo motor, a shaft linear motor, a coreless linear motor, or the like. The slider 72 is provided with a table 74 for placing the workpiece on the upper portion thereof, and a chuck 76 for mounting and fixing the workpiece on the table 74 with a holder.

  FIG. 2 shows the details of the axial feed device in the horizontal one-axis direction of the embodiment shown in FIG. FIG. 3 shows a cross-sectional side view of the shaft feeder shown in FIG. FIG. 4 shows an upper surface of the shaft feeding device shown in FIG. As shown in each drawing, the shaft feeding device of the present invention has two cancel moving bodies arranged in parallel at equal distances in the horizontal direction across the main moving body.

  The shaft feeder 1 is provided so as to be reciprocally movable in two axial directions parallel to the X axis and a slider 10 provided so as to be reciprocally movable in the X axis direction, and equidistant (L) in the horizontal direction across the X axis. And two cancel moving bodies 20 that move in the direction opposite to the direction in which the slider 10 moves. The shaft feeder 1 also includes a linear motor 30 that drives the slider 10 and a linear motor 40 that drives each of the two cancel moving bodies 20. The linear motor 30 includes a stator 30A provided on the canopy 3 attached and fixed to the beam 2 shown in FIG. 1 and a mover 30B provided on the slider 10. The linear motor 40 includes a stator 40A provided on the canopy 3 attached and fixed to the beam 2 and a mover 40B provided on the cancel moving body 20.

  The shaft feeder 1 not only cancels the reaction force and suppresses the vibration, but also moves the cancel moving body provided away from the main moving body in the opposite direction to the main moving body so that the center of gravity is always placed at the same position. Therefore, vibration and displacement are suppressed, so that the configuration is simple and the cancel moving body can be controlled more easily and accurately, and the anti-vibration effect is high. In addition, the axial feed device 1 is configured to provide two cancel moving bodies symmetrically across the moving body, thereby avoiding overlapping arrangements and reducing the height to keep the center of gravity of the machine low and ensure balance. Thus, the shaft feeding device 1 can be disposed in the upper part of the machine body so that vibration and displacement do not increase.

  The linear motor 30 is a coreless linear motor in which the stator 30A is a secondary magnet plate and the mover 30B is a primary coreless coil. As shown in FIG. 3, the linear motor 30 is composed of two coreless linear motors of the same type provided symmetrically about the moving axis of the slider. Specifically, secondary stator 30A is a magnet unit that is arranged so that two magnet plates in which a plurality of permanent magnets are arranged in a frame having a concave cross section are opposed to each other. The primary side mover 30B is a coil unit in which a coreless coil is integrated with a base portion by a mold so as to have a convex cross section. Then, the coil unit is interposed in the magnet unit so that the coreless coil is movably disposed on the magnet plates on both sides of the secondary side stator 30A with a predetermined gap.

  On the other hand, the linear motor 40 is a coreless linear motor in which the stator 40A is a primary coreless coil and the mover 40B is a secondary magnet plate. The two linear motors 40 are the same type as the linear motor 30. Each linear motor 40 is provided symmetrically about the moving axis of the slider. The cancel moving body 20 is basically designed to be half the mass of the moving part on the main moving body side including the slider 10 and the spindle 5.

  Therefore, in order to keep the center of gravity of the machine at the same position, a control device (not shown) controls the positioning of the slider 10 and the direction opposite to the direction in which the slider 10 moves relative to the movement of the slider 10. The movement of the canceling moving body 20 is controlled. By controlling the movement of the cancel moving body 20 in this way, the reaction force is canceled and the center of gravity of the machine is not shaken to reliably prevent vibration and displacement. Therefore, while the movement control of the cancel moving body 20 is relatively simple, the vibration can be suppressed more reliably.

  At this time, the control device simultaneously controls the two linear motors 30 that drive the slider 10 with one control signal. On the other hand, the control device controls the two cancel moving bodies 20 independently with different control signals. Therefore, even if the two cancel moving bodies 20 are provided separately from each other, the movement of the cancel moving body 20 can be controlled, and the center of gravity can be prevented from moving more reliably. The control device always moves the slider 10 and the two cancel moving bodies 20 in opposite directions. Therefore, when the moving direction of the slider 10 is reversed, the moving direction of the cancel moving body 20 is also reversed. When stopping, the linear motor 30 and the linear motor 40 are controlled synchronously so that the cancel moving body 20 also stops.

  Since the slider 10 driven by the two linear motors 30 is controlled to move simultaneously based on a command signal based on the machining program, a position detection device (linear scale) 50 for performing positioning control of the slider 10 is possible. As long as the displacement of the slider 10 is small, one is provided near the moving axis. On the other hand, in order to make it possible to control the movement of the cancel mobile body 20 independently, the position detectors (linear scales) 60 of the two cancel mobile bodies 20 are provided in the respective cancel mobile bodies 20 and each cancel mobile body 20 is controlled. Each position of the moving body 20 can be detected. However, while the positioning accuracy required in the positioning control of the slider 10 directly affects the processing accuracy required in processing, the cancel moving body 20 cancels the reaction force generated as the slider 10 moves. Therefore, the linear scale provided in the cancel moving body 20 needs to be a high-precision linear scale compared to the linear scale provided in the slider 10, as long as it is within a range that can accurately follow the movement of the slider 10. There is no.

  The slider 10 includes a spindle 5 that rotates a tool 8 such as a ball end mill around the Z axis. The slider 10 includes a table 74 on which a workpiece is placed, a slider 72 that reciprocates (lifts) the workpiece in the Z-axis direction, and a saddle 42 that moves the table 74 to move the workpiece in the Y-axis direction. It is installed on the upper side. Such an arrangement of the moving body is suitable for a precision machining apparatus that requires higher-precision machining, as already described. In the case of providing the cancel type axial feed device with such a structure, the center of gravity of the machine may be changed to the upper side and vibration may increase. However, the axial feed device 1 according to the embodiment includes the slider 10 and the slider 10. Since it is configured to include two cancel moving bodies that move in two axial directions that are equidistantly spaced apart and parallel to the X axis, the center of gravity can be kept low, and machining with higher accuracy can be performed. I am doing so.

  The guide device 70 for guiding the movement of the slider 10 is a cross roller guide in which a ball is interposed between a guide rail 70A laid on the canopy 3 and a guide rail 70B laid on the slider side. The guide device 80 that guides the movement of the two cancel moving bodies 20 is a linear guide including a guide rail 80 </ b> A laid on the canopy 3 and a bearing body 80 </ b> B provided on the cancel moving body 20.

  The present invention is applied to a machine tool. In particular, it is suitable for a precision machining apparatus that requires higher precision machining. The present invention greatly improves the performance of a machine tool such as a cutting machine, and greatly contributes to progress in processing technology.

1 is a perspective view showing an overall configuration of a machine tool according to a preferred embodiment of the present invention. It is a perspective view which shows the example of the axial feeder of this invention. It is sectional drawing which shows the side surface of the axial feed apparatus of this invention. It is a top view which shows the upper surface of the axial feeder of this invention.

Explanation of symbols

1 Axis feeder (X axis)
2 Airframe structure (beam)
3 Canopy 4 Axis feeder (Y axis)
5 Spindle 6 Bed 7 Axis feeder (Z axis)
8 Tool 10 Main moving body (slider)
20 cancel moving body 30 linear motor 30A mover 30B stator 40 linear motor 40A mover 40B stator 42 moving body (saddle)
44 Canceled moving body 50 Position detection device (linear scale)
60 Position detector (linear scale)
70 Guide device (cross roller guide)
80 Guide device (Linear guide)

Claims (10)

A linear motor for driving the main moving body, comprising a main moving body provided so as to be capable of reciprocating in one horizontal axis direction, a stator provided in the airframe structure, and a mover provided in the main moving body; Two cancel moving bodies provided so as to be reciprocally movable in two axial directions that are equidistant in the horizontal direction across the moving body and move in the opposite direction to the direction in which the main moving body moves; An axis feeding device for a machine tool comprising a stator provided on the machine structure and a mover provided on the cancel moving body, and two linear motors respectively driving the two cancel moving bodies. The shaft feeding device according to claim 1, wherein the linear motor that drives the main moving body is a coreless linear motor. 2. The shaft feeding device according to claim 1, wherein the linear motor that drives the main moving body includes two coreless linear motors of the same type that are provided symmetrically about the moving axis of the main moving body. The shaft feeding device according to claim 1, wherein the two linear motors that drive the cancel moving body are coreless linear motors. 2. The shaft feeding device according to claim 1, wherein the two cancel moving bodies are of the same type, and the two linear motors that move the cancel moving body are of the same type. The shaft feeding device according to claim 1, further comprising a control device that controls the two cancel moving bodies so that the center of gravity of the machine is at the same position. The shaft feeding device according to claim 1, wherein the control device controls the two cancel moving bodies independently. The shaft feeding device according to claim 1, comprising: a linear scale that detects a position of the main moving body; and a linear scale that detects each position of the cancel moving body. 2. The shaft feeding device according to claim 1, wherein the main moving body is arranged independently of a moving body provided so as to be reciprocally movable in a horizontal one-axis direction orthogonal to the horizontal one-axis direction. 2. The shaft feeding device according to claim 1, wherein the main moving body includes a spindle for rotating a tool around a vertical axis on the lower side, and is installed on the upper side of a table on which a workpiece is placed.

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