JP3674338B2 - Linear actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear motion actuator such as a three-axis combination robot module in an orthogonal coordinate system in which one X axis is arranged between two Z axes.
[0002]
[Prior art]
A conventional biaxial synchronous linear actuator has a configuration as shown in FIG.
[0003]
That is, a pair of Z-axis guides 50 are arranged side by side at a predetermined interval, and the pair of Z-axis carriers 51 are movable along the Z-axis guides 50 in synchronization. An X-axis guide 52 is installed horizontally between the pair of Z-axis carriers 51, and the X-axis carrier 53 is linearly driven along the X-axis guide 52.
[0004]
Each Z-axis carrier 51 is driven using a pair of servo motors or the like as a drive source, and the two Z-axis carriers 51 are controlled to move in parallel in synchronization with each other, whereby an X-axis guide 52 (X The shaft carrier 53) moves in the Z-axis direction while maintaining the horizontal state.
[0005]
Here, the mounting structure of the Z-axis carrier 51 and the X-axis guide 52 in the linear motion actuator shown in FIG. 2 is used to absorb the mounting error of the two Z-axis guides 50. Are rigidly coupled to one Z-axis guide 50 (right side in FIG. 2) and connected to one Z-axis guide 50 by pin support (left side in FIG. 2).
[0006]
[Problems to be solved by the invention]
Here, if the brake timing of the above two motors shifts due to a power failure or a failure of the motor and the control unit or only the brake of one of the motors becomes ineffective, only the Z-axis carrier 51 on the side where the brake has not been effective will The X-axis guide 52 tilts while falling and receiving its own weight.
[0007]
Then, in the conventional linear actuator as described above, a large moment may be input to the attachment portion between the rigidly coupled X-axis guide 52 and the Z-axis carrier 51, and the attachment portion may be damaged or broken. If the mounting portion is damaged or broken, the positioning accuracy of the actuator deteriorates or becomes inoperable. Furthermore, there is a problem that the X-axis guide 52 and the X-axis carrier 53 are dropped depending on circumstances.
[0008]
Even during normal operation, moments are repeatedly input to the Z-axis guide 50 on the rigid coupling side due to a slight synchronization mismatch due to a difference in torque generated between the motors driving the two Z-axis carriers 51. This may contribute to a reduction in the life of the device, or increase the size of the device by setting the rigidity of the Z-axis guide 50 and the like accordingly.
[0009]
The present invention has been made paying attention to the above-described problems, and can absorb mounting errors and motion errors of a pair of Z-axis guides, and even if the Z-axis carrier is out of synchronization, the X-axis It is an object of the present invention to provide a linear motion actuator that can prevent damage or breakage of a guide mounting portion.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a pair of Z-axis carriers that are guided by a pair of parallel Z-axis guides and move linearly in synchronization, and a pair of Z-axis carriers supported by the pair of Z-axis carriers. A linear motion actuator including a first beam material extending in the X-axis direction orthogonal to
The first beam member is attached to the Z-axis carrier via a bracket, and a second beam member is horizontally mounted between the pair of Z-axis carriers, and the second beam member is extended. A linear motion actuator characterized in that it is divided at a position in the middle of the present direction, and a pair of opposed sectional surfaces thereof are in a non-contact state with a predetermined gap and have surfaces opposed to each other when viewed from the Z-axis direction. Is to provide.
[0011]
According to the present invention, when the synchronization of the pair of Z-axis carriers is largely lost, the first beam material tends to tilt in the Z-axis direction.
[0012]
At this time, there is a possibility that a large load is applied to the attachment portion between the Z-axis carrier such as the bearing support portion and the first beam member, resulting in breakage or damage. When the height is shifted, the opposing surfaces of the split surface of the second beam member as viewed from the Z-axis direction come into contact with each other, and the second beam member further shifts the mutual height position between the Z-axis carriers. Is prevented, and damage or breakage of the attachment portion of the first beam material to each Z-axis carrier or each bracket is prevented.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0014]
In the present embodiment, the vertical direction is described as the Z-axis direction.
[0015]
First, the configuration will be described. As shown in FIG. 1, two Z-axis guides 1a and 1b each having an axis directed in the Z-axis direction are arranged at a predetermined distance from each other. , Z-axis carriers 2a and 2b that are guided by the Z-axis guides 1a and 1b and move linearly are disposed. The Z-axis carriers 2a and 2b are moved linearly along the Z-axis guides 1a and 1b by a known linear drive mechanism (not shown) such as a linear guide or a ball screw.
[0016]
Here, in the following description, the left Z-axis guide 1a and the Z-axis carrier 2a in FIG. 1 are referred to as the first Z-axis guide and the first Z-axis carrier, and the right Z-axis guide 1b and Z in FIG. The shaft carrier 2b is referred to as a second Z-axis guide 1b and a second Z-axis carrier 2b to distinguish between the two 1a, 1b, 2a, 2b.
[0017]
An X-axis guide 3 that is the first beam material is disposed horizontally (extending in the X direction) between the two Z-axis guides 1a and 1b, and each end of the X-axis guide 3 is The first and second brackets 4 and 5 are attached to the Z-axis carriers 2a and 2b, respectively.
[0018]
The first bracket 4 attached to the first Z-axis carrier 2a extends downward from the position of the Z-axis carrier 2a, and the main body has a T-shaped cross section. That is, the first bracket 4 is integrally fixed to the first Z-axis carrier 2a and extended downward, and integrally joined to the side end surface of the first plate member 4a by butt welding or the like. A second plate member 4b that is fixed and extends downward along a surface facing the second Z-axis guide 1b of the first Z-axis guide 1a, and is further reinforced by a reinforcing plate 4d to set high rigidity. Has been.
[0019]
The second plate member 4b has an L-shaped vertical cross section, and a horizontal portion at the bottom protrudes toward the second Z-axis guide 1b to form a mounting portion 4c. One end of the shaft guide 3 is supported by a bearing 8 whose shaft is directed up and down. The thickness of the vertical portion of the second plate member 4b is set to 19 mm so as to prevent the occurrence of bending.
[0020]
The second bracket 5 is a plate member having an L-shaped vertical cross section, and the upper portion of the vertical portion 5a is fixed to the second Z-axis carrier 2b and extends downward, and is formed at the lower end portion of the vertical portion 5a. A continuous horizontal portion 5b protrudes toward the first Z-axis guide 1a. By being attached to the second Z-axis carrier 2b in this way, the second bracket 5 is in a cantilever support state, and the vertical portion 5a is bent in a direction orthogonal to the Z-axis, whereby the X-axis guide 3 The horizontal portion 5b to which the horizontal portion 5 is attached is allowed to move in a direction orthogonal to the Z axis, and the vertical portion 5a is bent around the attachment point to the second Z axis carrier 2b, so that the horizontal portion 5b is A slight tilt in the vertical direction is allowed.
[0021]
And the other end part of the X-axis guide 3 is attached to the horizontal part 5b.
[0022]
In FIG. 1, reference numeral 6 represents an X-axis carrier that moves along the X-axis guide 3.
[0023]
In addition, the second beam member 7 is horizontally mounted between the left and right brackets 4 and 5 at substantially the same height as the left and right Z-axis carriers 2a and 2b. The second beam material 7 is divided at the central portion in the extending direction (the portion indicated by symbol A in FIG. 1). A pair of divided sections resulting from the division are in a non-contact state with a predetermined gap therebetween, and a recess 7a is formed at the center of one of the divided sections, and the recess 7a is formed at the center of the other divided section. A convex portion 7b that can be loosely fitted is formed, and the convex portion 7b is fitted into the concave portion 7a with a predetermined gap.
[0024]
Here, the upper and lower surfaces of the concave portion 7a and the upper and lower surfaces of the convex portion 7b form surfaces facing each other when viewed from the Z-axis direction. In addition, this opposing surface does not need to be a horizontal surface orthogonal to the Z-axis, and may be inclined. In short, it suffices if they face each other when viewed from the Z-axis direction. Further, the dividing position is not limited to the central portion, and may be close to one of the Z-axis guides 1a and 1b. However, it is desirable that the dividing position is a central portion from the viewpoint of reducing the moment received by each of the Z-axis guides 1a and 1b when the concave portion 7a and the convex portion 7b come into contact with each other.
[0025]
Next, the operation and effect of the linear motion actuator having the above configuration will be described.
[0026]
In the above configuration, one end of the X-axis guide 3 is attached to the first Z-axis carrier 2a via the rigid first bracket 4 and the bearing 8 that allows rotation around the vertical axis. The other end portion of the X-axis guide 3 is attached to the second Z-axis carrier 2b via a second bracket 5 that is allowed to move the horizontal portion 5b in a direction orthogonal to the Z-axis.
[0027]
As a result, even if there is a slight attachment error between the two Z-axis guides 1a and 1b, the error can be absorbed by the attachment structure of the X-axis guide 3 to the brackets 4 and 5.
[0028]
For example, even if the span between the Z-axis guides 1a and 1b is slightly longer or shorter than the desired dimension, the vertical portion 5a of the second bracket 5 is absorbed by bending in the X direction. However, if a long hole having a long diameter in the X direction is provided in the horizontal portion 5b of the second bracket 5 so that the attachment position in the X axis direction can be adjusted, the vertical portion of the second bracket 5 can be adjusted. 5a is not attached in a bent state.
[0029]
Even if the two Z-axis guides 1a and 1b are slightly offset in the Y-axis direction, one end portion of the X-axis guide 3 is supported by the first bracket 4 so that the X-axis guide The end portion of the guide 3 can be rotated in the XY plane, and the horizontal portion 5b of the second bracket can be bent slightly around the Z axis, so that the mounting error in the Y axis direction can be absorbed. However, if the attachment of the X-axis guide 3 to the second bracket 5 is a pin joint or a bolt joint with the shaft up and down, even if there is an attachment error in the Y-axis direction on the two Z-axis guides 1a and 1b, The second bracket 5 is prevented from being bent.
[0030]
In the linear motion actuator having the above-described configuration, the pair of Z-axis carriers 2a and 2b are moved up and down synchronously by a drive source such as a pair of servo motors, so that the X-axis guide 3 is also moved up and down while maintaining the horizontal state. .
[0031]
Even during this normal operation, a slight offset occurs in the relative height position of the two Z-axis carriers 2a and 2b due to a difference in torque generated by the motor, or vibration input from other devices The two Z-axis guides 1a and 1b may vibrate so as to be offset (drooped) in the XY direction.
[0032]
At this time, conventionally, a moment according to the offset amount and the generated torque difference is applied to the Z-axis guide.
[0033]
On the other hand, in the present embodiment, slight vertical and horizontal offsets between the two Z-axis carriers 2a and 2b are caused by the rotation of the bearing 8 on the first bracket 4 side in the horizontal direction (X -Y plane) offset is absorbed by the vertical alignment of the bearing, and the second bracket 5 is absorbed by bending, and a moment is applied to the Z-axis guides 1a and 1b. It is not loaded or very small. As a result, the load applied to the attachment portion between the Z-axis guides 1a and 1b and the Z-axis carriers 2a and 2b and the X-axis guide 3 is reduced compared with the conventional case, and the life of the apparatus is improved.
[0034]
In addition, only one Z-axis carrier 2a or 2b falls by its own weight due to a failure or a power failure of the servo motor or the like, and the other Z-axis carrier is not related to the one Z-axis carrier 2a or 2b being stopped. If the synchronization between the two Z-axis carriers 2a and 2b is broken so that the 2b or 2a continues to operate, the X-axis guide 3 may be greatly tilted up and down to damage the mounting part such as the bearing support part. However, in this embodiment, when the X-axis guide 3 is tilted up and down more than allowed in normal operation, the concave portion 7a and the convex portion 7b in the divided section of the second beam material 7 are in the Z-axis direction. A further difference in height between the Z-axis carriers 2a and 2b is restricted, that is, the X-axis guide 3 can be tilted only slightly, and the bearing support portion is broken or damaged. To be avoided
[0035]
Here, when the specification values are set as shown in FIG. 1 and FIG. 2, assuming that only the first Z-axis carrier 2a is servo-off and the brakes are not effective and falls by its own weight as described above, In the conventional linear actuator (see FIG. 2), a moment of 30 kg × 1.8 m × 60 kg × 1.0 m = 114 kg · m is applied to the second Z-axis guide 50.
[0036]
In contrast, in the linear actuator of the present embodiment, the moment applied to the second Z-axis guide 1b at the same position of the X-axis is (30 kg + 60 kg / 2 + 5 kg) × 1 m + 5 kg × 0.5 m = 67.5 kg · m. It turns out that it becomes small and advantageous.
[0037]
Further, when the motor for the Z-axis carrier on one side is locked and the Z-axis is squeezed by the motor thrust for the other Z-axis carrier, a moment of 2 × m is generated in the conventional example, whereas in the present invention, the thrust × It is reduced to 1m and half.
[0038]
As described above, when the configuration of the linear actuator of the present embodiment is adopted, not only the tolerance of the mounting error of the Z-axis guides 1a and 1b is widened, but also the allowable value for the moment of the Z-axis guides 1a and 1b is compared with the conventional structure. The size can be greatly reduced, and the price and size can be reduced.
[0039]
Here, in the above description, the X-axis guide 3 is disposed below the height position of the Z-axis carriers 2a and 2b, and the second beam material 7 is disposed above the X-axis guide 3. However, the present invention is not limited to this. For example, the brackets 4 and 5 may be extended upward from the height positions of the Z-axis carriers 2a and 2b, and the X-axis guide 3 may be disposed above the height positions of the Z-axis carriers 2a and 2b. Good. Alternatively, the brackets 4 and 5 may be extended horizontally from the Z-axis carriers 2a and 2b in the Y-axis direction, and the X-axis guide 3 may be disposed on the side of the Z-axis carriers 2a and 2b.
[0040]
In addition, a switch or a sensor for detecting the presence or absence of contact of the divided section is provided at the divided section position A of the second beam material 7 so that the X-axis guide 3 is tilted more than allowable and the second beam material 7 is provided. When the cross section is in contact, the motor power may be shut off and the brake may be operated so that no further load is applied.
[0041]
Alternatively, a switch or sensor for detecting the contact pressure or gap (approach distance) between the divided sections of the second beam member 7 including the direction at two or more levels is provided. When the switch is turned ON, the faster Z-axis current limit value is decreased and the operation is delayed to synchronize. (2) When the second switch is turned ON, the motor power is cut off and the brake is applied. You may comprise so that control, such as operating may be performed.
[0042]
The linear actuator according to the present invention has a particularly effective structure when the Z-axis guides 1a and 1b are set in the vertical direction as described above, but the Z-axis guides 1a and 1b are set in the horizontal direction. Even if it is, it has the above-mentioned actions and effects.
[0043]
【The invention's effect】
As described above, when the linear actuator of the present invention is employed, even if the synchronization of the two Z-axis carriers is lost due to a failure or the like, the tilt of the X-axis guide in the Z-axis direction is restricted by the second beam material. Therefore, it is possible to prevent breakage / damage of the mounting portion between the X-axis guide and the Z-axis carrier.
[Brief description of the drawings]
FIG. 1 is a front view showing a linear actuator according to an embodiment of the present invention.
FIG. 2 is a front view showing a conventional linear actuator.
[Explanation of symbols]
A Beam parts 1a, 1b Z-axis guides 2a, 2b Z-axis carrier 3 X-axis guide (first beam material)
4 First bracket 4a First plate member 4b Second plate member 4c Attachment portion 4d Reinforcement plate 5 Second bracket 5a Vertical portion 5b Horizontal portion 6 X-axis carrier 7 Second beam material 7a Recess 7b Protrusion 8 bearing

Claims (1)

A pair of Z-axis carriers that are guided by a pair of parallel Z-axis guides and move linearly in synchronization, and a first that is supported by the pair of Z-axis carriers and extends in the X-axis direction perpendicular to the Z-axis. In a linear actuator with a beam material of
The first beam member is attached to the Z-axis carrier via a bracket, and a second beam member is horizontally mounted between the pair of Z-axis carriers, and the second beam member is extended. A linear motion actuator characterized in that it is divided at a position in the middle of the present direction, and a pair of opposing sectional surfaces thereof are in a non-contact state with a predetermined gap and have opposing surfaces when viewed from the Z-axis direction. .

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