JP2017032585A - Three-dimensional coordinate measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high accuracy three-dimensional coordinate measuring instrument capable of manufacturing with a simple constitution and at a low manufacturing cost.SOLUTION: A three-dimensional coordinate measuring instrument measures a measured object on a base 11 by using a measurement probe 51 that is moved by movement mechanisms 31, 60, 70, and 80 arranged across the base 11. The movement mechanisms include on one side the linear guide 70 having a driving unit movable with respect to the base, and on the other side the air bearing mechanism 80 that is moved parallel with the linear guide.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a three-dimensional coordinate measuring machine, and more particularly to a moving mechanism of the three-dimensional coordinate measuring machine.

  A three-dimensional coordinate measuring machine is used to measure the coordinates of the outer shape of the object. The three-dimensional coordinate measuring machine sequentially forms on the base a moving mechanism that moves in the three-axis directions orthogonal to the X-axis, Y-axis, and Z-axis, and a member that can move in the final three-axis direction (third movement) Part) is provided with a displacement measuring device, and the surface position coordinates of the object are calculated by combining the displacement amount when the probe of the displacement measuring device is brought into contact with the outer shape of the object and the coordinate values in the three-axis directions at that time. . The movement position coordinates by each movement mechanism are the basis of the coordinates to be measured, and the movement coordinates are required to be highly accurate.

A moving mechanism such as a three-dimensional coordinate measuring machine is generally realized using a linear guide.
FIG. 1 is a view showing a linear guide, (A) is a perspective view showing an appearance, and (B) is a sectional view.

  The linear guide includes a rail 1 and a moving unit 2 that slides and moves on the rail 1. As shown in FIG. 1B, the moving unit 2 is in contact with the rail 1 via the bearing ball 3, and the bearing ball 3 rotates during movement. As shown in FIG. 1A, there are three rotational components P, Y, and R in which the moving unit 2 rotates with respect to the rail 1. P is called pitching, Y is called yawing, and R is called rolling.

  When the moving mechanism is configured, a plurality of linear guides are used in order to eliminate the influence of the rotation. For example, two moving units that move on the same rail are attached to the same moving unit. Thereby, the influence of pitching P and yawing Y can be reduced. In this case, the number of rails is one and the attachment can be performed relatively easily.

  In addition, a plurality of rails and a plurality of moving units are used. For example, two rails are arranged in parallel, and two moving units that move on the respective rails are attached to the same moving unit. In this case, as described above, two moving units are also attached to each rail, and in this case, four moving units are used. Thereby, in addition to pitching P and yawing Y, the influence of rolling R can also be reduced.

FIG. 2 is a diagram illustrating a configuration example of a moving mechanism of the three-dimensional coordinate measuring machine. This configuration is a so-called cantilever method.
The three-dimensional coordinate measuring machine includes a base 11 made of a stone surface plate such as synthetic marble, a Y column 21 provided on one side of the base 11, and two pieces provided in parallel on the Y column 21. Y-axis rails 22A and 22B, Y-moving part 31 that moves on Y-axis rails 22A and 22B, two X-axis rails 32A and 32B provided in parallel on Y-moving part 31, and X-axis rail 32A An X moving part 40 that moves on and 32B, a Z column 41 that is fixed to the X moving part 40 and extends in the vertical direction, and two Z-axis rails 42A and 42B provided in parallel on the Z column 41, And a Z moving part 50 that moves on the Z-axis rails 42A and 42B. A displacement measuring device 51 is attached to the Z moving unit 50, and the measuring probe of the displacement measuring device 51 is brought into contact with the surface of the object to be measured. Since the cantilever type moving mechanism can be accessed on the base 11 from the direction other than the rear surface, there is an advantage that the arrangement of the object to be measured, the contact position of the measurement probe, etc. can be easily confirmed.

  Since two moving units are arranged on each rail, four moving units are attached to the Y moving unit 31, the X moving unit 40, and the Z moving unit 50. In the configuration of FIG. 2, the two rails provided in parallel are arranged close to each other on the same surface of the same member, and therefore can be arranged with high parallelism relatively easily.

  However, in the cantilever type moving mechanism of FIG. 2, the Y moving portion 31 is supported at a portion near the end even though it is supported by two rails 22A and 22B and four moving units. Therefore, the displacement at the other end occurs due to the bending. The amount of bending changes in moment as the X moving unit 40 moves. In other words, the rigidity of the Y moving part 31 is insufficient.

  In order to reduce the influence of bending (rigidity) of the above-mentioned cantilever type moving mechanism, both ends of the Y moving unit 31 are supported.

FIG. 3 is a diagram showing another configuration example of the moving mechanism of the three-dimensional coordinate measuring machine, showing only the configuration for moving the Y moving unit 31, and the other shaft moving mechanisms are not shown. Here, the moving mechanism of the type shown in FIG.
The L-type moving mechanism of the three-dimensional coordinate measuring machine in FIG. 3 supports one end of the Y moving portion 31 with two Y-axis rails 22A and 22B provided in parallel on the Y column 21. 2 is the same as the configuration of FIG. 2, but is provided with a support member 60 that supports the opposite end of the Y moving portion 31, and the lower surface of the support member 60 is supported by a sub-guide 61 disposed on the base 11. This is different from the configuration of FIG. The sub guide 61 is, for example, a linear guide.

  In the configuration of FIG. 3, it is required that the straightness of the sub-guide 61 is maintained with very high accuracy. The straightness error of the sub-guide 61 can be expressed as, for example, the height variation of the surface of the base 11. When the height of the surface of the base 11 in the sub guide 61 changes by Δ1, the height of the end portion on the opposite side of the Y moving portion 31 also changes, but one end of the Y moving portion 31 is caused by the two linear guides of the Y column 21. It is supported and is equivalent to being fixed. Therefore, the Y moving part 31 is bent (warped), and the height of the opposite end changes by Δ2 and balances. When such a deflection occurs in the Y moving unit 31, the Z moving unit 50 is tilted, and the position of the measurement probe of the displacement measuring device 51 is displaced by Δ3, thereby generating a coordinate measurement error.

  The deflection of the Y moving part 31 changes with the movement in the Y-axis direction, and also changes depending on the temperature and the like. The error in the contact position of the measurement probe due to the deflection of the Y moving part 31 can be corrected to some extent by a correction formula calculated based on the measurement result of the reference object. There is a problem that it is difficult.

  FIG. 4 is a diagram illustrating a configuration example of a moving mechanism of the three-dimensional coordinate measuring machine. This configuration is called a so-called bridge system.

  The bridge-type three-dimensional coordinate measuring machine shown in FIG. 4 is provided with two Y columns 21A and 21B on opposite sides of the base 11, one Y-axis rail 22A on the Y column 21A, and the Y column 21B. One Y-axis rail 22B is provided. In the case where two moving units are used for each rail, the Y moving unit 31 is attached with four moving units that move the two rails 22A and 22B. The other parts are the same as in FIG.

  The bridge-type three-dimensional coordinate measuring machine shown in FIG. 4 is obtained by processing the parallelism and straightness of the rail mounting surfaces of the two Y columns 21A and 21B to which one set of rails are mounted with extremely high accuracy. There is a problem that the manufacturing cost becomes very high. Further, the bridge-type three-dimensional coordinate measuring machine shown in FIG. 4 has a problem that it is difficult to confirm the arrangement of the object to be measured and the contact position of the measurement probe because access to the base 11 is restricted.

  A so-called portal type three-dimensional coordinate measuring machine in which the Y moving part 31 is shaped like a gate and the Y-axis rails 22A and 22B are provided on the base is also known. It is necessary to process the parallelism and straightness of the bottom surface with very high accuracy, and there are the same problems as described above.

JP 2012-002715 A JP 2012-042267 A

  As described above, the cantilever type moving mechanism has insufficient rigidity, and the bridge type and the L-type moving mechanism similar thereto require a very high processing accuracy, which increases the manufacturing cost. There was a problem.

  In order to solve the above problems, the three-dimensional coordinate measuring machine of the present invention supports one end of the first moving unit corresponding to the Y moving unit with one linear guide, and the other end of the first moving unit. It supports by the air moving part which moves along the air bearing sliding guide part provided in parallel with this linear guide.

  That is, the three-dimensional coordinate measuring machine according to the present invention includes a base, a first axis moving mechanism provided on the base, and a second moving part provided on the first moving unit moved by the first axis moving mechanism. An axial movement mechanism, and a third axial movement mechanism provided in a second movement unit that is moved by the second axial movement mechanism, wherein the first axial movement mechanism uses a mechanical bearing. A linear guide; an air bearing sliding guide portion provided in parallel with the linear guide; and an air moving portion that moves along the air bearing sliding guide portion, wherein the first moving portion includes: One is attached to a linear moving unit that is moved by the linear guide, and the other is attached to the air moving portion so as to be swingable.

  In the three-dimensional coordinate measuring machine of the present invention, the parallelism / straightness between one linear guide and the air bearing sliding guide part is insufficient, and the linear guide and the air bearing sliding guide part relative to each other depending on the moving position. When the height changes, the difference in height change can be absorbed to some extent by the air bearing. When the height of the other end of the first moving part changes, the inclination of the first moving part changes, in other words, rolling, but this is because the first moving part is supported by one linear guide. It can be absorbed by the rolling R shown in FIG. As a result, the inclination of the first moving part, that is, the rolling changes, but the first moving part does not bend. If there is no deflection, the error change is reproducible. If the current correction technique is applied, high-accuracy correction is possible, and the movement position can be controlled with high accuracy. In other words, the present invention positively allows the rolling R that has been attempted to be suppressed as much as possible so far, supports one of the first moving parts with one linear guide, supports the other with an air bearing, The relative height change of the part supporting one moving part is absorbed by the air bearing, and the inclination change of the first moving part is absorbed by the rolling allowed by one linear guide and the swingable connecting part. To do.

  In addition, by using both linear guides and air bearings, which are mechanical (mechanical) bearings, the friction surface is only on one line of the mechanical bearing sliding surface, and the drive point is installed on the friction surface, reducing reciprocal hysteresis. it can.

The first moving unit may be an L-type configuration having one column shown in FIG. 3, a bridge-type configuration having two columns shown in FIG. 4, or a gate-type configuration without a column. .
In the L-shaped configuration having one column, a column having a mounting surface parallel to the base surface provided on one side of the base is provided, and one linear guide of the first shaft moving mechanism is mounted on the column. An air moving part is attached to a support member provided on the mounting surface and provided at the other end of the first moving part, and is supported by an air bearing sliding guide provided on the base.

  The first moving unit needs to be swingably attached to the air moving unit. The connecting unit includes, for example, a spherical tip and a receiving portion that receives a spherical tip having at least a part of a conical surface. Are configured.

  According to the present invention, a highly accurate three-dimensional coordinate measuring machine can be realized with a simple configuration and low manufacturing cost.

FIG. 1 is a diagram illustrating a linear guide. FIG. 2 is a diagram illustrating a configuration example of a cantilever type moving mechanism of the three-dimensional coordinate measuring machine. FIG. 3 is a diagram illustrating another configuration example of the L-type moving mechanism of the three-dimensional coordinate measuring machine. FIG. 4 is a diagram illustrating a configuration example of a bridge-type moving mechanism of the three-dimensional coordinate measuring machine. FIG. 5 is a diagram showing a basic configuration of the three-dimensional coordinate measuring machine of the present invention, where (A) is applied to an L type having one column, and (B) is applied to a portal type. Show the case. 6A and 6B are diagrams showing a configuration of a three-dimensional coordinate measuring machine according to an embodiment in which the present invention is applied to an L shape, where FIG. 6A is a front view and FIG. 6B is a side view. FIG. 7 is a diagram illustrating a configuration example of the coupling mechanism.

  FIG. 5 is a diagram showing a basic configuration of the three-dimensional coordinate measuring machine of the present invention, where (A) is applied to an L type having one column, and (B) is applied to a portal type. Show the case. In FIG. 5, only the configuration for moving the Y moving unit is shown, and the other axis moving mechanisms are not shown.

  As shown in FIG. 5A, an L-type three-dimensional coordinate measuring machine to which the present invention is applied includes a base 11, a Y column 21, and a Y (first) moving unit that moves on the upper surface of the Y column 21. 31 and a support member 60 that supports the Y moving portion 31. The Y column 21 is provided along one side of the base 11, and the upper surface of the Y column 21 is parallel to the surface of the base 11. The Y moving unit 31 is connected to the rail of one linear guide provided on the upper surface of the Y column 21 via a linear moving unit, and moves by the linear guide. In the figure, the connection part between the Y moving part 31 and one linear guide is indicated by reference numeral 70. The Y moving unit 31 is further provided with an X axis moving mechanism and a Z axis moving mechanism, and the position coordinates of the probe of the displacement measuring instrument 51 attached to the Z moving unit 50 move in the three axis directions.

  The other end of the Y moving portion 31 is supported by the support member 60. The lower part of the support member 60 is supported by the air moving unit so as to be swingable. The air moving portion and the air bearing sliding guide portion provided on the base 11 in parallel with the linear guide on the upper surface of the Y column 21 constitute an air bearing mechanism 80. Even when the relative height of the linear guide and the air bearing sliding guide portion is changed by the air bearing mechanism 80, the difference in height change can be absorbed to some extent by the air bearing mechanism. Further, the lower part of the support member 60 is swingably supported by the air moving part, and even if the inclination of the Y moving part 31 changes, there is only one linear guide, which absorbs a certain amount of rolling. be able to. Thereby, even if the Y moving unit 31 rolls, the Y moving unit 31 does not bend, and the moving position can be controlled with high accuracy by correction. Also, by using both linear guides and air bearings, which are mechanical (mechanical) bearings, the friction surface can be only one line of the mechanical bearing sliding surface, and the drive point is installed on the friction surface, reducing the reciprocal hysteresis. it can.

  In the L-type moving mechanism shown in FIG. 5A, the linear guide is lifted above the surface of the base 11, and the center of gravity of the Y moving portion 31 is compared to the portal-type moving mechanism described below. The distance between the position and the driving point (linear guide) can be shortened, and the weight of the Y moving unit 31 can be reduced. Thereby, the pitching of the Y moving part 31 at the time of acceleration / deceleration can be reduced, and the driving force necessary for improving the movement response or realizing the same movement response can be reduced. Further, since the base 11 can be easily accessed from the direction other than the back surface, the arrangement of the object to be measured, the confirmation of the contact position of the measurement probe, and the like can be easily performed.

  As shown in FIG. 5B, the portal-type three-dimensional coordinate measuring machine to which the present invention is applied does not include the Y column 21, the Y moving portion 31, the parallel portion 61, and the first support member 62. 5 and the second support member 63 is different from the L type in FIG.

  The lower portion of the first support member 62 is supported by a connecting portion 70 with one linear guide provided along one side of the base 11. The lower part of the second support member 63 is supported by the air bearing mechanism 80 in the same manner as the support member 60 of FIG.

  5B is provided with both the linear guide 70 and the air bearing sliding guide portion of the air bearing mechanism 80 on the upper surface of the base 11, and therefore the linear guide 70 and the air bearing slide are provided. It is easy to maintain the parallelism of the moving guide portion with high accuracy. On the other hand, the gate-shaped Y moving unit 31 has a problem that it is heavier than the L type shown in FIG.

  In addition, although the example of L type and a gate type was demonstrated in FIG. 5, it can apply similarly to other formats, such as a bridge type.

  6A and 6B are diagrams showing a configuration of a three-dimensional coordinate measuring machine according to an embodiment in which the present invention is applied to an L shape, where FIG. 6A is a front view and FIG. 6B is a side view. FIG. 6 is the same as the conventional example except for the Y moving unit, and therefore, only the configuration for moving the Y moving unit is shown, and the other shaft moving mechanisms are not shown.

  The three-dimensional coordinate measuring machine of the embodiment includes a base 11 made of a stone surface plate such as synthetic marble, a hollow Y column 21 provided on one side of the base 11, and a parallel arrangement on the Y column 21. One Y-axis rail 22, two Y-moving units 23A and 23B that move on the Y-axis rail 22, a Y-moving unit 31 attached to the Y-moving units 23A and 23B, and a Y-moving unit 31 There are two X-axis rails provided in parallel on the top and a total of four X movement units 33AA, 33AB, 33BA and 33BB which move on the two X-axis rails. An X moving unit and the like are configured on this, but illustration and description thereof are omitted.

  A columnar support member 60 is attached to the end of the Y moving portion 31 opposite to the side supported by the Y column 21. The lower part of the support member 60 is swingably supported by the air moving unit 82 by the coupling mechanism 81. An air bearing sliding guide portion 83 is provided along a side facing the air moving portion 82 on the base 11. The air bearing sliding guide portion 83 is a groove having a width of the air moving portion 82 extending in the Y-axis direction, for example. The air moving part 82 is able to move in the Y-axis direction while air supplied from the outside is jetted onto the surface of the air bearing sliding guide part 83 and floats at a constant interval. In other words, the air moving unit 82 can move in the Y-axis direction, but does not move in the X-axis direction, and can be displaced by a minute amount in the Z-axis direction. Here, the part constituted by the air moving part 82 and the air bearing sliding guide part 83 is referred to as an air bearing mechanism 80.

  FIG. 7 is a diagram illustrating a configuration example of the coupling mechanism 81. As shown in FIG. 7, an air moving portion 82 is disposed opposite to the surface of the air bearing sliding guide portion 83 on the upper surface of the base 11. The air moving part 82 has a receiving part 92 at least partially having a conical hole. A hemispherical tip 91 is provided at the tip of the support member 60 and contacts the conical hole of the receiving portion 92. Here, the distal end portion 91 is pressed against the conical hole of the receiving portion 92 by the weight of the first moving portion 31 and the X and Z-axis mechanisms and the support member 60 that are formed thereon. Thereby, the support member 60 (Y moving part 31) is supported by the air moving part 82 so that rocking | fluctuation is possible.

  It is desirable that the relative height of the upper surface of the Y column 21, that is, the rail 22 of one linear guide and the surface of the air bearing sliding guide portion 83 is constant, but some errors are inevitable in manufacturing. . In the embodiment, even when the relative height of the linear guide rail 22 and the air bearing sliding guide portion 83 is changed by the air bearing mechanism 80, the difference in height change is absorbed to some extent by the air bearing mechanism 80. Can do. Further, the lower part of the support member 60 is swingably supported by the air moving part, and even if the inclination of the Y moving part 31 changes, there is only one linear guide, which can be absorbed by a certain degree of rolling. it can. As a result, even if the Y moving unit 31 rolls, the Y moving unit 31 does not bend, and the Y moving unit 31 only tilts. It can be controlled with high accuracy.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that the modification of each place is possible.

  The present invention is applicable to a three-dimensional coordinate measuring machine.

11 base 21 Y column 31 Y moving part 60 support member 70 one linear guide 80 air bearing mechanism

Claims (3)

In a three-dimensional coordinate measuring machine for measuring an object to be measured on the base using a measurement probe that moves by a moving mechanism disposed on both sides of the base across the base,
The moving mechanism includes, on one side, a linear guide that is a mechanical bearing having a drive unit movable with respect to the base;
A three-dimensional coordinate measuring apparatus comprising an air bearing mechanism that moves in parallel with the linear guide on the other side.   The three-dimensional coordinate measuring apparatus according to claim 1, wherein the air bearing mechanism is provided on a base.   The three-dimensional coordinate measuring apparatus according to claim 1, wherein the linear guide is located higher than the air bearing mechanism.

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