JP2015182170A - Machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool in which a turning shaft can be accurately controlled by properly reducing backlash.SOLUTION: A machine tool 1 works a workpiece using a turning shaft A as a control shaft and comprises: a fan-shaped gear 20 in which teeth are formed in an arc-like end part with the turning shaft A as the center; first and second pinion gears 21 and 22 meshing with the fan-shaped gear 20; a motor M1 for imparting driving force to the first pinion gear 21; a saddle 9 to which the fan-shaped gear 20 is fixed and the driving force imparted to the first pinion gear 21 by the motor M1 is transmitted via the fan-shaped gear 20, and which turns around the turning shaft A by the transmitted driving force; and a motor M2 for imparting to the second pinion gear 22, preload for reducing a backlash between: the fan-shaped gear 20 ; and the first and second pinion gears 21 and 22.

Description

  The present invention relates to a machine tool, and more particularly, to a machine tool that processes an object to be processed using a pivot axis as a control axis.

  2. Description of the Related Art Conventionally, machine tools that process a workpiece by multi-axis control are known. For example, Patent Document 1 discloses an X-axis that moves the table in the front-rear direction, a Z-axis that moves the cross rail up and down, a Y-axis that moves the saddle in the left-right direction, and a pivot axis parallel to the X-axis. A technique is disclosed that uses a 5-axis control axis consisting of an A-axis that pivots the spindle head around the axis and a C-axis that is indexed by rotating the table around a pivot axis that is parallel to the Z-axis. In the technique disclosed in this Patent Document 1, turning of the spindle head with the A axis as the control axis is realized by converting the linear motion by the ball screw into the turning motion. Patent Document 2 also discloses a technique for turning a member using a mechanism that converts a linear motion into a turning motion.

Japanese Patent No. 3939604 JP 2001-162467 A

However, in the technique for controlling the turning axis by converting the linear motion by the ball screw to the turning motion as described above, the relationship between the linear movement amount and the turning angle change amount is not a proportional relationship. It was necessary to use a relatively complicated conversion formula. For this reason, in this technique, if multiple axes (for example, five axes) including a rotation axis that is controlled by converting a linear motion into a rotation movement are controlled simultaneously, the control becomes complicated. It was difficult to achieve simultaneous control.
On the other hand, there is also known a technique for controlling the turning axis by using a gear mechanism. However, in this technique, there is a case where the turning control cannot be performed with high accuracy due to a backlash generated in the gear mechanism. .

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a machine tool that can appropriately reduce backlash and accurately control a pivot axis. To do.

In order to achieve the above object, the present invention provides a machine tool for processing a workpiece by using a pivot axis as a control axis, wherein a tooth is formed at an arcuate end portion around the pivot axis. A first gear, a second gear and a third gear meshing with the first gear, a motor for applying a driving force to at least one of the second gear and the third gear, and the first gear, respectively. A driving portion applied to at least one of the second gear and the third gear is transmitted through the first gear, so that a turning portion that turns about the turning shaft, a first gear, a second gear, and a third gear; A preload imparting mechanism for imparting a preload for reducing backlash between the second gear and the third gear to one of the second gear and the third gear.
In the present invention configured as described above, since the driving force from the motor is transmitted using the gear mechanism including the first gear, the second gear, and the third gear, the swivel portion is swung. As described above, since it is not necessary to convert the linear motion by the ball screw into a turning motion (for example, there is no need to use a conversion formula for converting a linear motion into a turning motion, etc.), the swing axis can be easily controlled. Can do. Therefore, it becomes possible to appropriately perform simultaneous control with respect to multiple axes including the turning axis.
In the present invention, in order to reduce backlash between the first gear and the second and third gears by the preload applying mechanism, there is no backlash between the first gear and the second and third gears. A turning part can be turned. Therefore, the control for turning the turning portion around the turning axis can be performed with high accuracy.

In the present invention, preferably, the preload applying mechanism is a motor that applies a preload to one of the second and third gears.
In the present invention configured as described above, the backlash between the first gear and the second and third gears can be appropriately reduced by applying a preload to one of the second and third gears by the motor. Can do.

In the present invention, preferably, the preload applying mechanism applies a preload to one of the second and third gears using a spring or hydraulic pressure.
In the present invention configured as described above, by applying a preload to one of the second and third gears using a spring or hydraulic pressure, an appropriate backlash between the first gear and the second and third gears is achieved. Can be reduced.

In the present invention, preferably, the X-axis extending in the front-rear direction, the Y-axis extending in the left-right direction, the Z-axis extending in the up-down direction, and any two of these X-axis, Y-axis, and Z-axis are parallel to each other. The five axes including the two pivot axes including the pivot axis described above are used as control axes, and these five axes can be driven simultaneously.
In the present invention configured as described above, the X axis, the Y axis, the Z axis, and five axes including two swivel axes are used as control axes. As described above, in the present invention, since the swivel portion is swung using the gear mechanism, the swiveling axis can be easily controlled, so that simultaneous control with respect to the five control axes can be appropriately realized. it can.

  According to the machine tool of the present invention, it is possible to appropriately reduce backlash and accurately control the pivot axis.

1 is a perspective view showing a schematic configuration of a machine tool according to an embodiment of the present invention. It is a top view which shows roughly the internal structure of the saddle by the embodiment of this invention observed along the X-axis. It is the top view which expanded the sector gear by the embodiment of the present invention, the 1st and 2nd pinion gear. FIG. 4A is a diagram for explaining a preload imparting mechanism according to a modification of the embodiment of the present invention, and FIG. 4A is a plan view of only the sector gear, the first and second pinion gears, and FIG. Fig. 4 is a side view of a gear applied to the sector gear, the first and second pinion gears, and the first and second pinion gears, and Fig. 4 (C) is a partial view of Fig. 4 (B). It is a top view of only a gear. It is a perspective view which shows schematic structure of the machine tool by the modification of embodiment of this invention.

  Hereinafter, a machine tool according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the machine tool according to the present embodiment will be described with reference to FIG. FIG. 1 is a perspective view showing a schematic configuration of the machine tool according to the present embodiment.

  As shown in FIG. 1, the machine tool 1 according to the present embodiment is a so-called portal machine tool, and is mainly installed on a bed 2 and a bed 2 on which a workpiece (not shown) is placed. A table 3, a column 5 erected on both sides of the bed 2 and the table 3, a cross rail 6 laid horizontally near the upper end of the column 5, a feed base 8 installed on the cross rail 6, A spindle on which a saddle 9 installed on the feed base 8, a head holder 11 attached to the lower part of the saddle 9, and a tool (not shown) held by the head holder 11 for processing a workpiece are attached. A head 12 and a control device 14 that controls each component of the machine tool 1 are provided.

  The table 3 is installed on the bed 2 so as to be movable in the X-axis direction (front-rear direction), and the feed base 8 is installed on the cross rail 6 so as to be movable in the Y-axis direction (left-right direction). The saddle 9 is installed on the feed base 8 so as to be movable in the Z-axis direction (vertical direction), and is configured to be turnable as indicated by an arrow A1 with an A axis parallel to the X axis as a turning axis. The head holder 11 rotatably holds the spindle head 12 as indicated by an arrow B1 with a B axis parallel to the Y axis as a turning axis.

  The machine tool 1 according to the present embodiment has such an X-axis, Y-axis, Z-axis, A-axis, and B-axis (the X-axis, Y-axis, and Z-axis are linear axes, and the A-axis and B-axis are swing axes. The workpiece to be processed placed on the table 3 is processed using the five axes as a control axis. In other words, the machine tool 1 moves and turns each component according to the five control axes, thereby moving the workpiece while moving and turning the tool to process the workpiece. Such control regarding movement and turning of each component of the machine tool 1 is executed by the control device 14 via a drive motor (not shown) or the like.

  The saddle 9 is not configured to be movable in the Z-axis direction, but another member is disposed between the saddle 9 and the feed base 8 and this member is installed on the feed base 8 so as to be movable in the Z-axis direction. May be. In this case, the saddle 9 may be installed on the member so as to be pivotable about the A axis.

  Next, a mechanism for turning the saddle 9 as a turning portion will be described with reference to FIG. FIG. 2 is a plan view schematically showing the internal structure of the saddle 9 when observed along the X-axis (that is, when observed from the front).

  As shown in FIG. 2, a sector gear 20 as a first gear is attached to the saddle 9. The end portion of the sector gear 20 is formed in an arc shape with a center angle corresponding to the turning angle range of the saddle 9 with the turning axis A as a center, and teeth are formed at this end portion. The sector gear 20 is fixed to the saddle 9 so as to rotate integrally with the saddle 9. The sector gear 20 is engaged with first and second pinion gears 21 and 22 (that is, double pinions) as second and third gears. A motor M1 is connected to the first pinion gear 21, and a motor M2 as a preload imparting mechanism is connected to the second pinion gear 22.

  The motor M1 applies a driving force to the first pinion gear 21. The driving force applied from the motor M 1 to the first pinion gear 21 is transmitted to the sector gear 20 via the first pinion gear 21. That is, the first pinion gear 21 is rotated by the driving force from the motor M1, and the sector gear 20 is also rotated by this rotation. As a result, the saddle 9 to which the sector gear 20 is fixed turns (see arrow A1).

  On the other hand, the motor M2 applies a preload (preload) to the second pinion gear 22. Basically, the motor M2 applies a preload having a force opposite to the direction of the driving force applied from the motor M1 to the first pinion gear 21 to the second pinion gear 22. By doing so, the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 is set to zero.

  As described above, the motors M1 and M2 are controlled by the control device 14. Specifically, the control device 14 drives the driving force to be applied from the motor M1 to the first pinion gear 21 based on the turning angle and the turning speed of the saddle 9 according to the processing to be performed on the workpiece. And the motor M1 is controlled so that this driving force is output. Further, the control device 14 obtains a preload required to make the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 zero according to the driving force thus obtained. The motor M2 is controlled so that the preload is output.

  Note that a gear mechanism (including motors M1 and M2) including the sector gear 20 and the first and second pinion gears 21 and 22 as shown in FIG. Instead, or in addition to this, the present invention may be applied to a mechanism (mechanism mounted on the head holder 11) for turning the spindle head 12 with the B axis as a turning axis.

  Next, a state in which the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 is zero will be described with reference to FIG. FIG. 3 is an enlarged plan view of the sector gear 20 and the first and second pinion gears 21 and 22.

  As shown in FIG. 3, when the backlash between the sector gear 20 and the first and second pinion gears 21, 22 is zero, the teeth of the first pinion gear 21 that abuts the teeth of the sector gear 20. The surface 21a and the tooth surface 22a of the second pinion gear 22 in contact with the teeth of the sector gear 20 are in a state of being opposed to each other.

  In a state where the first pinion gear 21 is applied with a driving force from the motor M1 to rotate the sector gear 20 (assuming that the sector gear 20 is rotated counterclockwise in FIG. 3), the first pinion gear 21 is rotated. As for the 21 teeth, the surface 21 a on the rotation direction side comes into contact with the teeth of the sector gear 20. In this case, if the preload is not applied to the second pinion gear 22 from the motor M <b> 2, the surface of the second pinion gear 22 is also in contact with the teeth of the sector gear 20 on the rotation direction side. However, when a preload opposite to the driving force applied from the motor M1 to the first pinion gear 21 is applied from the motor M2 to the second pinion gear 22, the teeth of the second pinion gear 22 are applied as shown in FIG. The surface 22a on the opposite side to the rotation direction comes into contact with the teeth of the sector gear 20. Such a state is a state in which the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 is zero.

  Next, the function and effect of the machine tool 1 according to the present embodiment will be described.

  In the machine tool 1 according to the present embodiment, the saddle 9 is turned using a gear mechanism including the sector gear 20, the first and second pinion gears 21 and 22, and therefore, linear motion by a ball screw is performed as in the above-described prior art. Is not required to be converted into a turning motion (for example, it is not necessary to use a conversion equation for converting a linear motion into a turning motion), and thus the swing axis can be easily controlled. Therefore, according to this embodiment, simultaneous control with respect to five control axes can be appropriately performed. Specifically, the control of turning the saddle 9 around the A axis while moving the table 3, the feed base 8, and the saddle 9 along the X axis, the Y axis, and the Z axis is easy and accurate. It can be carried out. Therefore, according to the machine tool 1 according to the present embodiment, a complicated free-form surface can be continuously and appropriately formed.

  In addition, when a gear mechanism including the sector gear 20, the first and second pinion gears 21 and 22 is applied to the saddle 9, and a similar gear mechanism is also applied to the head holder 11, the X axis, the Y axis, While moving the table 3, the feed base 8 and the saddle 9 along each of the Z axes, the saddle 9 can be swung around the A axis and the spindle head 12 can be swung around the B axis. And it can be performed with high accuracy.

  Further, according to the present embodiment, the motor M2 applies a preload to the second pinion gear 22, and the backlash between the sector gear 20 and the first and second pinion gears 21, 22 is reduced to 0. The saddle 9 can be turned in a state where there is no backlash between the gear 20 and the first and second pinion gears 21 and 22. Therefore, the control of turning the saddle 9 around the A axis can be performed with higher accuracy, that is, the control of the swing axis A can be performed with higher accuracy.

  Next, a modification of the above-described embodiment will be described.

  In the embodiment described above, the preload applying mechanism for applying the preload from the motor M2 to the second pinion gear 22 has been shown. A mechanism may be used.

  With reference to FIG. 4, a modified example of such a preload imparting mechanism will be described. 4A is a plan view of only the sector gear 20, the first and second pinion gears 21 and 22, and FIG. 4B is a plan view of the sector gear 20, the first and second pinion gears 21, 22, FIG. 4C is a side view of the gears 26, 27, 28, and 29 applied to the first and second pinion gears 21 and 22. FIG. 4C is a side view of the gears 26, 27, and 29 shown in FIG. FIG.

  As shown in FIG. 4B, the sector gear 20, the first and second pinion gears 21, 22 are helical gears. The other gears 26, 27, 28, and 29 are also helical gears. The first pinion gear 21 is connected to the gear 26 via the shaft 24. The second pinion gear 22 has a shaft 25 passing therethrough, and the through hole of the second pinion gear 22 and the shaft 25 are coupled by a spline (see arrow X1). The shaft 25 has a gear 27 connected to one end and a spring 23 inserted into the other end. The spring 23 applies a force in the arrow X2 direction to the second pinion gear 22.

  When the force in the direction of the arrow X2 is applied from the spring 23 to the second pinion gear 22 in this way, the second pinion gear 22 moves along the shaft 25 by the above-described spline. When the second pinion gear 22 moves to some extent along the shaft 25, the teeth of the sector gear 20 and the teeth of the second pinion gear 22 come into contact with each other because the sector gear 20 and the second pinion gear 22 are helical gears. As a result, the movement of the second pinion gear 22 along the shaft 25 stops. The state in which the movement of the second pinion gear 22 stops corresponds to a state in which the backlash between the sector gear 20 and the second pinion gear 22 is zero. At this time, the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 becomes zero. Therefore, the control for turning the saddle 9 about the A-axis can be performed with high accuracy also by the modification.

The force in the direction of the arrow X2 applied from the spring 23 to the second pinion gear 22 is a force corresponding to preload. Therefore, in the configuration shown in FIG. 4B, the spring 23 and the like form a preload imparting mechanism. Thus, the spring 23 is not limited to applying the force in the arrow X2 direction to the second pinion gear 22, and the force in the arrow X2 direction may be applied to the second pinion gear 22 by hydraulic pressure. In that case, a mechanism for applying hydraulic pressure forms a preload applying mechanism.
The force in the direction of the arrow X2 is not limited to the second pinion gear 22 applied by the spring 23 or the hydraulic pressure, and a force in the direction opposite to the direction of the arrow X2 may be applied to the second pinion gear 22.

  4B and 4C, a gear 26 connected to the first pinion gear 21 via the shaft 24 and a gear 27 connected to the second pinion gear 22 via the shaft 25 are illustrated. In between, two gears 28 and 29 that mesh with both the gear 26 and the gear 27 are provided. The gear 29 is connected to a motor M <b> 3 that applies a driving force for turning the saddle 9 via the sector gear 20. In the modified example, the driving force from the motor M3 is applied to both the first pinion gear 21 and the second pinion gear 22 via the gear 29, the gears 26 and 27, and the shafts 24 and 25. That is, the driving force from the motor M3 is distributed to the first pinion gear 21 and the second pinion gear 22.

  Further, a distance adjustment mechanism capable of adjusting the distance between the gear 28 and the gear 29 is provided between the gear 28 and the gear 29 (see arrow X3). In FIG. 4B, the details of the distance adjustment mechanism are not shown for convenience of explanation, but the distance adjustment mechanism adjusts the distance between the gear 28 and the gear 29 by, for example, a spring, hydraulic pressure, liner adjustment, or the like. . With such a distance adjustment mechanism, each of the gear 28 and the gear 29 moves in a direction in which the distance between the gear 28 and the gear 29 increases. When the gears 28 and 29 move to some extent, the gears 26, 27, 28, and 29 are helical gears, so that the teeth of the gear 28 and the teeth of the gears 26 and 27 come into contact with each other, and the teeth of the gear 29 and the gear 26 , 27 contact with the teeth, the movement of the gears 28, 29 is stopped.

  The state in which the movement of the gears 28 and 29 stops corresponds to a state in which the backlash between the gears 28 and 29 and the gears 26 and 27 is zero (strictly speaking, when liner adjustment is used as the distance adjustment mechanism). May not have a zero backlash). Thus, when the backlash between the gears 28 and 29 and the gears 26 and 27 becomes zero, the backlash between all the gears on the path for transmitting the driving force from the motor M3 to the sector gear 20 becomes zero. As a result, the control of turning the saddle 9 about the A axis can be performed with high accuracy.

  The adjustment for increasing the distance between the gear 28 and the gear 29 by the distance adjustment mechanism is not limited, and an adjustment for decreasing the distance between the gear 28 and the gear 29 may be performed by the distance adjustment mechanism.

  Next, a machine tool according to a modification of the above-described embodiment will be described with reference to FIG. FIG. 5 is a perspective view showing a schematic configuration of a machine tool according to a modification. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown in FIG. 5, the machine tool 1a according to the modification differs from the machine tool 1 according to the above-described embodiment (see FIG. 1) in that it does not have the head holder 11 but has a circular table 16. Specifically, in the machine tool 1a according to the modification, instead of the spindle head 12 turning with the B axis parallel to the Y axis as the turning axis, the circular table 16 has the arrow C1 with the C axis parallel to the Z axis as the rotation axis. It differs from the machine tool 1 by embodiment mentioned above by the point which rotates as shown by.

  The machine tool 1a according to the modified example has an X axis, a Y axis, a Z axis, an A axis, and a C axis (the X axis, the Y axis, and the Z axis are linear axes, and the A axis and the C axis are swivel axes and rotations. The workpiece to be processed placed on the circular table 16 is processed using five axes consisting of the control axes as control axes. Further, the gear mechanism (see FIG. 2 or FIG. 4) including the sector gear 20 and the first and second pinion gears 21 and 22 is similarly applied to the saddle 9 of the machine tool 1a according to the modified example. This is applied to a mechanism for turning the saddle 9 around the A axis.

  In the embodiment and the modification described above, the example in which the gear mechanism including the sector gear 20 and the first and second pinion gears 21 and 22 is applied to a mechanism that turns around the A axis as a turning axis is mainly shown. When the machine tool is configured to turn the member about the B axis as a turning axis, or to turn the member about the C axis as a turning axis, the gear mechanism turns around the B axis. The present invention may be applied to a mechanism for turning as an axis, and a mechanism for turning around a C axis as a turning axis.

  In the above-described embodiment, the preload is applied so that the backlash between the sector gear 20 and the first and second pinion gears 21 and 22 is zero. However, the backlash is completely zero. It is not limited to giving a preload. Even if the backlash does not become zero, preload may be applied so that the backlash is reduced as much as possible.

DESCRIPTION OF SYMBOLS 1, 1a Machine tool 2 Bed 3 Table 9 Saddle 11 Head holder 12 Spindle head 14 Control apparatus 20 Fan-shaped gear (1st gear)
21 First pinion gear (second gear)
22 Second pinion gear (third gear)
M1, M2, M3 motor

Claims (4)

A machine tool that processes a workpiece using a pivot axis as a control axis,
A first gear having teeth formed on an arcuate end centered on the pivot axis;
Second and third gears respectively meshing with the first gear;
A motor for applying a driving force to at least one of the second and third gears;
The first gear is fixed, and the driving force applied to at least one of the second and third gears by the motor is transmitted through the first gear, so that the rotation axis is the center. A revolving part that revolves;
A preload imparting mechanism for imparting a preload for reducing backlash between the first gear and the second and third gears to one of the second and third gears;
A machine tool characterized by comprising:   The machine tool according to claim 1, wherein the preload applying mechanism is a motor that applies the preload to one of the second and third gears.   The machine tool according to claim 1, wherein the preload applying mechanism applies the preload to one of the second and third gears using a spring or hydraulic pressure.   2 including the X-axis extending in the front-rear direction, the Y-axis extending in the left-right direction, the Z-axis extending in the up-down direction, and the turning axis parallel to any two of these X-axis, Y-axis, and Z-axis. The machine tool according to any one of claims 1 to 3, wherein five axes including two pivot axes are used as control axes, and the five axes can be driven simultaneously.

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