JP2006055934A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a machine width to the minimum in relation to moving stroke of an X-axis by replacing a moving in an X-axis direction showing the machine width with a turning moving in a conventional machine tool constituted of three orthogonal axes. <P>SOLUTION: As for an X-axis (an axis for showing the machine width) of the conventional machine tool of orthogonal three axes, a straight line axis is replaced with an axis in which a rotation driving part 15 of a link mechanism 11 and a spindle 12 are joined by the link mechanism 11 and an angle control is performed at a rotation center of the link mechanism 11. This machine tool is freely positioned by a cooperative control of the positioning by the turning and the positioning of a Y-axis. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a configuration of a moving shaft for reducing the machine width of a machine tool.

When configuring a production line consisting of a plurality of machine tools, the machine tools that are the constituent elements are arranged neatly along the production line, but from the viewpoint of logistics and workability for work pieces, installation space, The line is required to be shorter.
Since the length of the line is roughly determined by the sum of the widths of each machine tool, a machine tool with a small lateral width is desired. However, machine tool manufacturers respond to such customer demands. I have tried to make a machine tool with a small width.
For example, the size of the moving body has been reduced, and the cover and the drive motors and support parts at both ends of the ball screw have been devised. However, the moving axes of conventional general machine tools consist of three orthogonal axes. Therefore, further miniaturization has not been easy under this basic shaft configuration.

FIG. 1 shows a shaft configuration of a machine tool that is generally considered.
Since the processing table 5 is mounted on the slidable guide rail 10 and the processing table 5 and the nut 3 are integrated, the rotational force of the X-axis driving motor 1 is transmitted to the nut 3 via the ball screw 6. A linear movement can be performed along the ball screw 6.
However, in this conventional configuration, as is apparent from the drawing, gaps that increase the machine width as shown by D1 and D2 are formed on both sides of the moving stroke of the table. Inevitable.
The gap portion indicated by D1 includes the folded slide cover 4 (or bellows), the pointing portion 7 of the ball screw 6 and the like, and the side on which the X-axis driving motor 1 is installed is the same as the X-axis driving motor 1 A gap as shown by D2 by the coupling 8 is added.
That is, the machine tool designer must consider the machine width in consideration of the gaps D1, D2 and the like with respect to the original X-axis movement stroke.

FIG. 2 shows an example in which the X-axis driving motor 1 is housed inside the bed 2 among conventional examples.
In this case, the rotational force of the X-axis driving motor 1 is transmitted to the ball screw 6 via the belt 9, but the X-axis driving motor 1 is housed inside, so that the X-axis driving motor 1 shown in FIG. The machine width can be suppressed by the length D2.
However, since the ball screw 6 is rotationally driven indirectly by the belt 9, mechanical backlash occurs around the belt portion, and spatial interference caused by housing the drive motor 1 inside the bed 2 can be avoided. Therefore, large restrictions on the component layout are inevitable.
And even with such a structure, it is impossible to eliminate the gap shown by D1.

  1 and 2 shown above, it is difficult to solve the problems in the mechanical structure derived from the structure and the drive motor derived from both ends of the slide cover 4 and the support portion 7 of the ball screw 6. In particular, the improvement in machine width does not progress easily.

  As described above, in a generally used three-axis orthogonal coordinate system machine tool, the machine width is the size of the moving body, the stroke of the X axis, the telescopic cover (or bellows) at both ends of the moving body, and both ends of the ball screw. The dimensions of the installed drive motor and support must be taken into consideration, and in general machine configurations, even if an attempt is made to reduce the machine width, the inevitable limit on the machine configuration is faced. Will be.

When the X-axis is not the table movement but the main-axis movement, the machine configuration is as shown in FIG. 3, but the mechanical elements such as the slide cover 4, the ball screw 6 and the nut 3 are the same. A distance D3 between the main shaft and the cover becomes a gap with respect to the movement stroke, and the machine width increases by this amount.
As described above, in either the table side movement or the spindle side movement, the gap that is inevitably generated by the conventional movement axis configuration and driving method is unavoidable. The situation was that it became quite large.

Although some attempts have been made to reduce the machine width by devising a protective cover around the spindle in the conventional example, it is premised on a machine configuration having a conventional three-axis axis configuration consisting of XYZ axes. Then, it is only an individual approach, and since the effect becomes limited, it does not lead to a big improvement.
That is, in the conventional apparatus configuration of the moving shaft, necessary structural members have to be arranged at both ends of the X axis, so that the machine width is surely increased by this amount.
JP 2000-84786 A

  The problem to be solved is to consider the slide cover, bellows, support parts at both ends of the ball screw, X-axis drive motor, etc. in addition to the movement stroke in the X-axis direction in the X-axis direction that determines the machine width of the machine tool. It is necessary to increase the machine width greatly.

The present invention does not use a member for a linear movement axis such as a ball screw, a guide rail, or a slide cover (bellows) in the X axis related to the machine width in order to suppress the machine width of the machine tool.
As an alternative, the most important feature is that the support body has a rotation movable part around the Z axis, and the rotation movable part of the support body and the main shaft are joined by a link mechanism so that the main shaft can freely move in an arc. And

The structure of the moving shaft according to the present invention is to support the ball screw which has been conventionally provided at both ends of the X axis while securing the moving stroke in the X axis direction by replacing the linear movement in the X axis direction indicating the machine width of the machine tool with an arc movement. By eliminating the need for servo motors, etc., for driving parts and ball screws, and slide covers (bellows), it is possible to provide machine tools with reduced machine width, and a production line consisting of multiple machine tools There is an advantage that the line length can be shortened.
According to the first aspect, the width of the machine body in the width direction can be narrowed, and it can be applied to a processing line composed of a large number of units.
Furthermore, the X axis has been linearly moved. “Slide covers, bellows, ball screws, ball screw support portions and other members can be omitted, and the cost of the machine can be reduced and the configuration can be simplified.”
As a result, the machine width can be made as close as possible to the size of the X-axis stroke + the spindle head diameter.
Further, the present invention can be used for both a vertical machining center and a horizontal machining center.
According to claim 2, “when the main shaft is driven in the X-axis direction, the displacement generated in the Y-axis or Z-axis direction of the main shaft is corrected and controlled by dividing the Y-axis motor or Z-axis motor into minute sections. The axis can move linearly. "
According to claim 3, the circular cover not only protects the drive unit of the link mechanism and the like from chips and cutting fluid, but also the circular cover itself rotates with the link mechanism, and is attached to the circular cover by its centrifugal force. Since the chips fall, the circular cover itself is clean, and it is no longer necessary to take the chips to the surrounding components in the moving range. Can be brought to a person.

  Conventional machine tools perform three-dimensional positioning freely by a combination of three orthogonal linear axes of movement with the X, Y, and Z axes, but without sacrificing the degree of freedom of positioning. A component member that increases the size of the machine in the X-axis direction is unnecessary, and the machine width of the machine tool can be suppressed.

As shown in FIG. 4, the configuration of the present invention includes a rotation drive unit 15 of a link mechanism, a link mechanism 11, and a main shaft 12, and the main shaft 12 moves in an arc locus with reference to the rotation center 14 of the link mechanism.
Since this configuration does not have a ball screw, a guide rail or the like for horizontal linear movement, the accessibility of the spindle 12 and the side cover 13 of the machine tool is remarkably improved, and the width of the machine tool with respect to the movement stroke in the X-axis direction is significantly improved. The increase can be minimized.

  The position of the X and Y axes of a general machine tool is controlled in a Cartesian coordinate system by ball screw driving. The position control according to the present invention includes a Y axis driven by a ball screw 6 and the Y axis as shown in FIG. It is constituted by a rotation drive unit 15 of a link mechanism that moves linearly integrally with the shaft nut 3.

An example in which the shaft configuration according to the present invention is mounted on a machine tool is shown in FIGS.
6 shows a case where it is mounted on a vertical machining center, and FIG. 7 shows a case where it is mounted on a vertical machining center.
In either case, since there is no linear movement axis constituted by a ball screw or the like in the X-axis direction indicating the machine width, the ball screw support portion, slide cover, bellows, or the like, which is an additional material, is unnecessary.
Accordingly, there is no interference at both ends in the X-axis direction, and the side cover of the machine can be brought close to the movement stroke in the X-axis direction, and the machine width can be suppressed.
FIG. 7 is an example of mounting the circular cover 17 and is provided integrally with the link mechanism 11 as shown in the figure.
It is desirable to increase the rigidity of the outer periphery of the circular cover 17 by bending so that no bending occurs during movement or rotation.
With respect to securing the rigidity of the circular cover, it is possible to increase the rigidity by thickening the steel sheet, bonding a plurality of steel sheets as a composite steel sheet, or increasing the rigidity three-dimensionally by inserting ribs.

FIG. 14 shows the circular cover as viewed from the direction of the extension line of the rotating shaft.
The center of the circular cover 17 is aligned with the link mechanism rotation center 14 and rotates together with the link mechanism.
This circular cover functions as a shield, and can protect various drive units and the like on the back side from chips and cutting fluid.

  FIG. 8 is viewed from the direction of the extension line of the rotation shaft of the link mechanism, and the main shaft 12 freely positions an arc locus having the radius of the link mechanism 11 as a radius.

FIG. 9 shows the positioning control.
Since the main shaft turns and positions, if the X-axis coordinate moves, the Y-axis coordinate changes accordingly.
Therefore, in positioning, the turning angle is obtained, and correction of the Y axis that moves due to this turning is performed together.
First, considering the X axis, the turning angle with respect to the X coordinate to be positioned is uniquely obtained as shown in Formula C1.
Next, a movement amount Y1 in the Y-axis direction that is moved together by positioning the X coordinate is obtained by Expression C2.
Next, a numerical value obtained by subtracting Y1 that has been swung from the Y coordinate Y to be positioned is a coordinate command for the Y axis, which is shown in Expression C3.
With regard to the above movement route, if the movement route is divided into minute sections and coordinated control of the turning angle and linear movement is performed for each minute section, linear movement can be performed with accuracy according to the width of the minute section. Is possible.
As described above, the movement command is unique and can be processed, and real-time processing can be performed while maintaining sufficiently high accuracy if the processing capability of a recent computer or control device is used.

Next, the possible range of the XY plane according to the present invention is shown in FIG.
Unlike the conventional combination of linear axes, a turning element is added, so the area that can be moved as a rectangular area is area A2.
A region obtained by combining the areas A1 and A3 having strong meanings of the turning elements is the movable range.
In actual operation, a rectangular area is easy to handle in the movable range, so the area shown in area A2 in FIG. 11 is considered to be used for general purposes during processing.

Next, the setting of the link length will be described.
As for the link length, as shown in FIG. 12, a half length of the required movement stroke of the X axis is required at a minimum, but the shorter one is advantageous in terms of rigidity. It seems that it is better to set the length to exactly half of the moving stroke.
However, in the case of such a link length setting, since the X-axis coordinate = link length × COS (angle), even at the same rotational speed, the actual feed speed in the X-axis direction of the main shaft is low at both ends, and the center The change in the moving speed peculiar to the cosine function appears remarkably as the part is high speed.

On the other hand, FIG. 13 shows a setting where the length of the link length is set somewhat longer.
When the link length is increased, the angle control with respect to the stroke width becomes less than 180 degrees, and accordingly, the change in the feed speed for each angle is also reduced.
Further, even if the rotational speed is the same, if the link length is increased, the spindle can be positioned at a higher speed.
In addition, since the support and the main shaft are further separated from each other, they are less likely to interfere with a workpiece or a jig.
If the link length is increased, the amount of displacement in the Y-axis direction that occurs when moving in the X-axis direction is reduced, so that it is possible to cope with a smaller correction amount.

According to the machine configuration of the embodiment of the present invention, the following effects can be obtained.
The main shaft can move at both ends of the X axis by rotation of 180 degrees or less, which is clearly faster than the linear movement speed of the X axis by the conventional ball screw.
This high speed becomes more prominent as the link length becomes longer, and is particularly advantageous in shortening the positioning time for drilling, tapping and other hole processing.
In addition, the mechanical configuration according to the present invention is not suitable for heavy cutting with a high load because the structure tends to have low rigidity, but conversely, if it is used only for drilling with a small cutting load, the cycle time is excellent with high speed. Can contribute to reduction.
Conventionally, a large slide cover or bellows has been used in accordance with the X-axis stroke as a measure against chips during cutting. However, the shaft configuration according to the present invention eliminates the need for a large slide cover as described above, and is round, semi-circular. Since it can be handled with a simple cover in the shape of a circle or a fan, the production cost can be reduced, and troubles such as chips clogging in the slide cover can be avoided.

  Although the present invention has been described as an example of a vertical and horizontal three-axis machining center as a general machine tool, it can also be applied to a processing machine having a linear movement axis.

It is a block diagram of the X-axis of the conventional general machine tool. It is a block diagram of the X-axis of the conventional general machine tool. It is a block diagram of the X-axis of the conventional general machine tool. It is a block diagram of the X-axis by this invention. It is a block diagram of the X-axis and a Y-axis by this invention. It is a block diagram of a vertical machining center according to the present invention. 1 is a configuration diagram of a horizontal machining center according to the present invention. FIG. It is an operation | movement figure which shows the turning motion of the main axis | shaft by this invention. 3 is a coordinate calculation formula for positioning the X axis and the Y axis according to the present invention. 3 shows the movable range of the X and Y axes according to the present invention. It is a rectangular area in the movable range of the X axis and the Y axis according to the present invention. It is an operation | movement figure at the time of operating by the turning angle 180 degree | times by this invention. It is an operation | movement figure at the time of operating with the turning angle less than 180 degree | times by this invention. It is an external view of the circular cover by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X axis drive motor 2 Bed 3 Nut 4 Slide cover 5 Table 6 Ball screw 7 Support part 8 Coupling 9 Belt 10 Guide rail 11 Link mechanism 12 Main shaft 13 Cover 14 Link mechanism rotation center 15 Link mechanism rotation drive part 16 Y Axis drive motor 17 Cover 18 Z-axis drive motors D1, D2 Gap D3, D4 Distance between the center of the spindle and the cover

Claims (3)

The axis of movement of the main shaft in the horizontal direction of the machine body is the X axis, the movement axis of the main shaft in the direction of the rotation axis is the Z axis, and the movement axis of the main shaft in the front-rear direction or the vertical direction is the Y axis. In machine tools with linear movement axes,
In order to make the movement path in the X-axis direction into an arc, the main shaft is supported by the machine body and pivoted to a movable body that moves in the Z-axis direction and a link mechanism that swings in the X-axis direction. A shaft motor is arranged, and the main shaft is supported by a support provided at the free end of the link mechanism,
Further, a machine tool characterized in that the main shaft includes a Y-axis motor and a Z-axis motor that linearly drive in the Y-axis direction and the Z-axis direction, respectively.   In order to correct the movement trajectory of the main shaft in the X-axis direction from arc movement to linear movement, a link mechanism that supports the main shaft is generated in the Y-axis or Z-axis direction of the main shaft when driven in the X-axis direction by the X-axis motor. The machine tool according to claim 1, wherein the Y-axis motor or the Z-axis motor is divided into minute sections and corrected and controlled in a direction to cancel the displacement.   2. The machine tool according to claim 1, wherein a circular cover having the same center as the rotation center of the link mechanism is provided integrally with the link mechanism, and is rotated together with the link mechanism.

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