JPH06235604A - Attenuating device for measuring apparatus - Google Patents

Abstract

PURPOSE:To provide an attenuating device of a measuring apparatus which can achieve measurement at high speeds while maintaining high accuracy. CONSTITUTION:Oil pans 21A, 21B with openings at upper faces thereof are provided for leg blocks 2A, 2B along the moving direction (Y-axis direction) of an X-axis beam 6. Oils 24A, 24B are contained in the oil pans 21A, 21B. Moreover, damper plates 25A, 25B having ends thereof dipped into the oils 24A, 24B are fixed to Y-axis carriages 4A, 4B at both ends of the X-axis beam 6. When the speed of the X-axis beam 6 is changed from low to high or from high to low, a movable part 6 vibrates. However, the vibration is quickly attenuated by the oils 24A, 24B and damper plates 25A, 25B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping device for a measuring machine. For example, the present invention relates to a damping device of a coordinate measuring machine for promptly attenuating vibration generated when a movable part moves, in a coordinate measuring machine.

[0002]

2. Description of the Related Art In a CNC coordinate measuring machine, not only high accuracy but also high measurement efficiency is required. In order to improve the measurement efficiency, it is indispensable to increase the speed of each axis carriage and drive it with high acceleration and deceleration. However, high-speed, high-acceleration / deceleration driving of each axis carriage causes vibration of each axis carriage, resulting in deterioration of measurement accuracy. In other words, high speed and high acceleration / deceleration driving of each axis carriage and high accuracy are contradictory. Up to now, in a coordinate measuring machine, an air bearing is often used as a guide bearing in order to improve the motion accuracy, but since the air bearing is a non-contact bearing, the vibration damping effect is extremely small. Therefore, in such a coordinate measuring machine, when the measurement speed is increased, there is a problem that a relative displacement between the probe and the displacement detector is caused by the vibration generated when each axis carriage is moved, which causes a measurement error. .

Conventionally, the following method has been adopted as a method for solving these problems. For example, the method of keeping the driving speed high while suppressing the acceleration / deceleration to reduce the occurrence of vibration, the approach distance from the high speed driving to the low speed driving at the time of measurement, until the probe actually touches the object to be measured. Is used to increase the time required for the vibration generated during speed transition to be dampened, and to add friction separately from the bearing in order to positively dampen it.

[0004]

However, any of the above-mentioned methods has the following problems. First,
In the methods (1) and (2), the acceleration / deceleration is reduced to attenuate the vibration, and the approach distance is lengthened to lengthen the measurement time, so that the purpose of speeding up the measurement cannot be achieved. In the method, the direction of the frictional force also changes depending on the driving direction, and a moment is generated between the point of action of driving and the place where the sliding resistance of friction acts, which deforms the structure and improves the geometrical accuracy. There was a problem that madness was likely to occur.

It is an object of the present invention to provide a damping device for a measuring machine, which can solve the problems of the prior art and can achieve high speed measurement while maintaining high accuracy. is there. It is another object of the present invention to provide a damping device for a measuring machine, which can prevent a decrease in energy efficiency in a high speed region and can obtain a sufficient damping characteristic in a low speed region.

[0006]

A first aspect of the present invention is a damping device for a measuring machine having a movable portion movably provided with respect to a fixed portion, wherein the fixed portion is arranged in a moving direction of the movable portion. An accommodating portion having an opening is provided along the accommodating portion, and a viscous fluid is accommodated in the accommodating portion, and a damper plate whose tip is immersed in the viscous fluid in the accommodating portion through the opening is provided in the movable portion. is there. A second aspect of the present invention is the displacement of the first aspect, wherein the damper plate is displaced so that the thickness of the viscous fluid layer between the damper plate and the side wall of the accommodating portion or the contact area of the damper plate with the viscous fluid changes. It is a structure provided with means.

[0007]

In the first aspect of the present invention, in the measurement, when the movable portion is moved along the fixed portion, when the movable portion moves, the speed changes from low speed to high speed and from high speed to low speed. Vibration occurs in the movable part. However, since the tip end of the damper plate fixed to the movable portion side is immersed in the viscous fluid in the accommodating portion provided on the fixed portion side, the vibration generated in the movable portion is quickly attenuated. As a result, the vibration can be already dampened at the stage of taking in the coordinate position of the measurement point, etc., so that it is possible to achieve high-speed measurement while maintaining high accuracy.

By the way, as shown in FIG. 1, in the case of a construction in which a damper plate is provided in the movable part and is immersed in the viscous fluid in the accommodating part, the viscous resistance F is F = μ · A · v / ε ... … Given in (1). Here, μ is the viscosity coefficient, A is the contact area of the damper plate with the viscous fluid, ε is the thickness of the viscous fluid layer between the damper plate and the side wall of the accommodating portion (the side wall closer to the damper plate) (FIG. 1). V) is the relative speed between the damper plate and the side wall of the accommodating portion. Therefore, from the equation (1), in the case of the configuration of FIG. 1, when the movable part moves at the highest speed, the driving resistance becomes very large and the energy efficiency is lowered, while in the low speed region, the viscous resistance of the viscous fluid is small and sufficient. It is conceivable that the attenuation characteristic will not be obtained.

According to the second aspect of the present invention, the displacement means for displacing the damper plate is provided so that the thickness of the viscous fluid layer between the damper plate and the side wall of the accommodating portion or the contact area of the damper plate with the viscous fluid changes. Therefore, it is possible to prevent a decrease in energy efficiency in the high speed region and obtain a sufficient damping characteristic in the low speed region.

[0010]

The preferred embodiments of the damping device for a measuring machine according to the present invention will be described below in detail with reference to the accompanying drawings. First Embodiment A first embodiment is shown in FIGS. In FIG. 2, reference numeral 1 is a surface plate on which an object to be measured is placed. Leg blocks 2A and 2B as fixing portions are fixed to both sides of the upper surface of the surface plate 1 along the front-rear direction (direction orthogonal to the paper surface; this is referred to as Y-axis direction). On the upper surface of each leg block 2A, 2B, Y-axis carriages 4A, 4B provided on both ends of the X-axis beam 6 as movable parts via Y-axis rails 3A, 3B are provided so as to be movable in the Y-axis direction. Has been. Y-axis carriage 4A,
The 4B is provided with three air pads 5A and 5B, which are respectively arranged on the upper surface and both side surfaces of the Y-axis rails 3A and 3B so as to face each other, and eject air toward them. It is slid in the Y-axis direction using 3B as a guide.

An X-axis slider 7 is provided on the X-axis beam 6 so as to be movable in the left-right direction (X-axis direction). X
A Z-axis member 8 is supported on the shaft slider 7 so as to be able to move up and down, and a touch signal probe 9 that outputs a contact signal upon contact with the object to be measured is attached to the lower end of the Z-axis member 8. Incidentally, 10 is the Y-axis carriage 4
It is a drive shaft for moving the A, 4B and X-axis beams 6 in the Y-axis direction. In addition, the X-axis slider 7 and the Z-axis member 8
Are moved in respective axial directions by respective axis drive systems (not shown), and the amount of movement in each axial direction is detected by a displacement detector (not shown) for each axis.

Above the leg blocks 2A and 2B,
As shown in detail in FIG. 3 (only the right side of FIG. 3), an oil pan 2 as an accommodating portion having an opening on the upper surface along the moving direction of the Y-axis carriages 4A and 4B (that is, the Y-axis direction).
1A and 21B are provided, respectively. Oil pan 2
As shown in FIG. 4, 1A and 21B have ears 22 at the front and rear ends, and the ears are fixed to the leg blocks 2A and
It is fixed to 2B. In the oil pans 21A and 21B,
A viscous fluid, here oil 24A, 24B, is contained. On the other hand, each Y-axis carriage 4A corresponding to this,
On the 4B side, the oil 24 in the oil pans 21A, 21B
Damper plates 25A and 25B whose lower parts are immersed in A and 24B
The top of is fixed. Note that 26A and 26B are covers that cover the oil pans 21A and 21B and the damper plates 25A and 25B.

Due to such a structure, Y is measured.
The shaft carriages 4A and 4B and the X-axis beam 6 are driven to rotate by the feed screw shaft 10 in the Y-axis direction, and the X-axis slider 7 is moved.
Are moved in the X-axis direction by the X-axis drive system and the Z-axis member 8 is moved in the Z-axis direction by the Z-axis drive system according to a preset order, and when a touch signal is output from the touch signal probe 9, The coordinate position is read, and the size or shape of the measured object is measured based on these coordinate values.

In this measurement, the Y-axis carriage 4A,
4B and the X-axis beam 6 move in the Y-axis direction by the rotational drive of the feed screw shaft 10, each Y-axis carriage 4A,
Since the lower parts of the damper plates 25A, 25B which are projected from the 4B side are immersed in the oils 24A, 24B in the oil pans 21A, 21B, the vibrations accompanying the acceleration / deceleration of the Y-axis carriages 4A, 4B and the Y-axis beam 6 are prompt. Is attenuated to.

Therefore, according to the first embodiment, an oil pan 21A having an opening on the upper surface of each leg block 2A, 2B along the moving direction of the Y-axis carriages 4A, 4B (that is, the Y-axis direction) is provided. 21B respectively, while each Y
On the side of the shaft carriages 4A, 4B, the oil pan 21A,
Since the damper plates 25A and 25B, the lower portions of which are immersed in the oils 24A and 24B in 21B, are fixed.
Vibration accompanying the acceleration / deceleration of the shaft carriages 4A, 4B and the X-axis beam 6 can be quickly damped. as a result,
At the stage where the touch signal probe 9 comes into contact with the object to be measured and captures its coordinate position, the vibration can be already dampened, so that it is possible to achieve high speed measurement while maintaining high accuracy.

Further, Y-axis carriages 4A, 4B and X
When the portal frame is constituted by the axial beam 6, the drive system in the Y-axis direction is arranged at a position away from the center of gravity of the portal frame, that is, the drive shaft 10 is located at one side away from the center of gravity of the portal frame. Will be placed. Then, a moment is generated during the acceleration / deceleration of the drive, and the movement of the portal frame becomes oscillating, but a high damping effect can be exerted against this vibration as well, so measurement can be performed while maintaining high accuracy. It is possible to achieve high speed. .

Structurally, the leg blocks 2A and 2B are also provided.
Since the oil pans 21A and 21B are attached to the upper part of the above and the damper plates 25A and 25B are fixed to the Y-axis carriages 4A and 4B side, respectively, the structure is extremely simple.
Moreover, since the covers 26A and 26B are provided, even if the oils 24A and 24B are scattered to the outside of the oil pans 21A and 21B when the damper plates 25A and 25B are moved, the cover 2
Since it is covered with 6A and 26B, the surface plate 1 and the object to be measured are not contaminated.

Second Embodiment A second embodiment is shown in FIG. 5 (only the right side is shown corresponding to FIG. 3, but the left side is the same) to FIG. In the description of these drawings, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified. In this embodiment, as shown in FIG. 5, the damper plates 25A, 2B are interposed between the Y-axis carriages 4A, 4B and the damper plates 25A, 25B via a bracket 30.
Displacement means 31 for displacing the damper plates 21A, 21B in parallel in the X-axis direction is provided so that the thickness ε of the oil 24A, 24B layers between the 5B and the side walls of the oil pans 21A, 21B changes.

The displacement means 31 has a base end portion fixed to the bracket 30 and a tip end displacement portion at the damper plate 25.
It is composed of a displacement magnifying mechanism 32 in which the upper portions of A and 25B are fixed, and two sets of laminated piezoelectric displacement elements 33 and 34 for displacing the tip displacement portion of this displacement magnifying mechanism 32 in the X-axis direction. The displacement magnifying mechanism 32, as shown in detail in FIG. 6 and FIG.
5 and the damper plate 25A from the central position of the mounting portion 35,
25B integrally formed in a direction orthogonal to 25B.
6, a displacement portion 38 which is integrally formed in the vertical direction parallel to the damper plates 25A and 25B from the tip of the base portion 36 through a constricted portion 37, and an upper and lower end of the displacement portion 38 in the same direction as the base portion 36. And a supporting portion 39 that is formed in a protruding manner. The laminated piezoelectric displacement elements 33 and 34 are arranged between the mounting portion 35 and the displacement portion 38 and on both sides of the base portion 36.

Here, FIG. 6 shows a laminated piezoelectric displacement element 33,
FIG. 7 shows a state before a voltage is applied to 34, and FIG. 7 shows a state after a voltage is applied to the laminated piezoelectric displacement elements 33 and 34. Now, the distance from the center of each constricted portion 37 of the displacement magnifying mechanism 32 to each laminated piezoelectric displacement element 33, 34 is L _1, the distance from each laminated piezoelectric displacement element 33 _, 34 to each support 39 is L ₂ , Δ is the displacement of the laminated piezoelectric displacement elements 33, 34 when a voltage is applied, the displacement Δε of the damper plates 25A, 25B
Is represented by Δε = L ₂ / L ₁ δ ... (2). Therefore, by using the displacement magnifying mechanism 32, the displacement of the laminated piezoelectric displacement elements 33, 34 can be magnified.

The voltage applied to the laminated piezoelectric displacement elements 33 and 34 is a pulse signal from a displacement detector for detecting the Y-axis position or an encoder signal used for controlling the speed of the drive motor F / V. The voltage is converted (frequency / voltage conversion) to a required voltage and given. For example, in FIG.
As shown in, the scale 51 (Y on the leg blocks 2A, 2B
The pulse signal obtained from the position detector 52 provided on the Y-axis carriages 4A and 4B facing each other (fixed along the moving direction of the axis carriages 4A and 4B) is frequency / voltage converted by the F / V converter 53, Then, after being amplified by the amplifier 54, it is applied to the laminated piezoelectric displacement elements 33 and 34. By doing so, the voltage applied to the laminated piezoelectric displacement elements 33, 34 changes according to the moving speed of the Y-axis carriages 4A, 4B, so that ε of ε according to the moving speed of the Y-axis carriages 4A, 4B. The value can be changed.

The viscous damping coefficient C is given by the following equation. C = μ · A / ε (3) Further, the damping ratio ζ required as the damping mechanism is given by the following equation.

[0023]

[Equation 1]

Here, m is the mass of the vibrating body (in this case, the mass of the Y-axis carriage), k is the spring constant (in this case, the rigidity of the drive unit). From this, the viscous resistance F and the damping ratio ζ are
Both are given as a function of ε, and it can be seen that the values of the viscous resistance F and the damping ratio ζ can be changed by making the value of ε variable.

Therefore, according to the second embodiment, the value of ε can be changed in accordance with the moving speed of the Y-axis carriages 4A and 4B, so that the damper plate 25A has a large value of ε in the high speed region. , 25B are displaced, and damper plates 25A, 25A, so that the value of ε becomes small in the low speed region.
By displacing 25B, a decrease in energy efficiency can be prevented in the high speed region, and sufficient damping characteristics can be obtained even in the low speed region.

In the second embodiment, the value of ε is changed according to the moving speed of the Y-axis carriages 4A and 4B, but it is necessary regardless of the moving speed of the Y-axis carriages 4A and 4B. The value of ε may be arbitrarily changed depending on the situation. Further, instead of changing the value of ε, as shown in FIG. 9, displacement means 31A for displacing the damper plates 25A, 25B in the vertical direction is provided, and the damper plates 25A, 25B are arranged as necessary or according to the speed. Similar effects can be expected by displacing in the vertical direction. That is, when the damper plates 25A and 25B are displaced in the vertical direction,
Since the value of A in the equation (1) changes, the same effect can be expected.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the configurations of the above embodiments, and various improvements and design changes are made without departing from the gist of the present invention. Of course, you can For example, in the above embodiment, it is provided only for damping the vibration of the member that moves in the Y-axis direction, but the present invention is not limited to this.
It may be applied to damp the vibration of the X-axis slider 7 moving in the X-axis direction. To this end, an oil pan may be provided on the X-axis beam 6 along the X-axis direction, and a damper plate whose lower part is immersed in the oil in the oil pan may be provided on the X-axis slider 7.

The viscous fluid is not limited to the oil described in the above embodiment, but may be any fluid having a constant viscosity. Further, in the above embodiment, the example applied to the coordinate measuring machine has been described, but the present invention is not limited to this, and can be applied to all measuring machines having a structure in which the movable part moves with respect to the fixed part. it can.

[0029]

As described above, according to the damping device for a measuring machine of the present invention, it is possible to achieve high speed measurement while maintaining high accuracy. Further, it is possible to prevent a decrease in energy efficiency in the high speed region and obtain sufficient damping characteristics in the low speed region.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of the present invention.

FIG. 2 is a front view showing the first embodiment of the present invention.

FIG. 3 is a diagram showing a main part in the embodiment.

FIG. 4 is a perspective view showing an oil pan mounting structure in the embodiment.

FIG. 5 is a diagram showing a main part of a second embodiment of the present invention.

FIG. 6 is an enlarged view showing a displacement means in the above embodiment.

FIG. 7 is an enlarged view showing a displacement state of the displacement means in the embodiment.

FIG. 8 is a diagram showing a drive circuit for a laminated piezoelectric displacement element according to the same example.

FIG. 9 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

 2A, 2B Leg block (fixed part) 4A, 4B Y-axis carriage (movable part) 6 X-axis beam (movable part) 21A, 21B Oil pan (accommodation part) 24A, 24B Oil (viscous fluid) 25A, 25B Damper plate 31 , 31A Displacement means

Claims (2)

[Claims] 1. A damping device for a measuring machine, comprising a movable part movably provided with respect to a fixed part, wherein said fixed part is provided with an accommodating part having an opening along a moving direction of said movable part. A damping device for a measuring machine, characterized in that a viscous fluid is accommodated in the accommodating portion, and a damper plate whose tip is immersed in the viscous fluid in the accommodating portion through the opening is provided in the movable portion. 2. A damping device for a measuring machine, comprising a movable part movably provided with respect to a fixed part, wherein said fixed part is provided with an accommodating part having an opening along a moving direction of said movable part, A viscous fluid is accommodated in the accommodating portion, and a damper plate whose tip is immersed in the viscous fluid in the accommodating portion through the opening is provided in the movable portion, and the viscosity between the damper plate and the accommodating portion side wall is increased. A damping device for a measuring machine, comprising a displacement means for displacing a damper plate so that a thickness of a fluid layer or a contact area of the damper plate with respect to a viscous fluid changes.