JP7463258B2 - Three-dimensional coordinate measuring device - Google Patents

Description

The present invention relates to a three-dimensional coordinate measuring device, and in particular to a three-dimensional coordinate measuring device that moves a measurement probe in three axial directions, the X-, Y-, and Z-axes, to measure the three-dimensional shape of a measurement object.

In a typical three-dimensional coordinate measuring device, a Y carriage that can move freely in the front-to-back direction (Y-axis direction) is placed on top of a base on which the object to be measured is placed. The Y carriage has a columnar X guide that spans along the left-to-right direction (X-axis direction), and the X carriage is supported on the X guide so that it can move freely in the X-axis direction. A columnar Z carriage that runs along the up-down direction (Z-axis direction) is supported on the X carriage so that it can move freely in the Z-axis direction, and a measurement probe is attached to the bottom end of the Z carriage. This allows the measuring tip (stylus) of the measurement probe to be supported so that it can move freely in three axes: the X, Y, and Z axes.

In such a three-dimensional coordinate measuring device, Patent Document 1 discloses a support structure that supports the Y-carriage via air pads (air bearings) on both the left and right sides of the base plate and on the top surface of the base plate.

JP 2007-33052 A

Increasing the rigidity of the Y-carriage is essential for three-dimensional coordinate measuring devices, which are becoming faster and more precise.

However, in Patent Document 1, there is no air pad to prevent the Y carriage from moving upwards, which can lead to vibration of the Y carriage around the X axis (pitching direction), potentially resulting in reduced measurement accuracy.

The present invention was made in consideration of these circumstances, and aims to provide a three-dimensional coordinate measuring device that can suppress vibration of the Y carriage in the pitching direction and improve measurement accuracy.

In order to achieve the above object, a three-dimensional coordinate measuring device according to one aspect of the present invention includes a base having an upper surface perpendicular to the Z axis, a lower surface opposite to the upper surface, and a first side surface along the Y axis direction, on which a measurement object is placed on the upper surface, a Y carriage supporting a measurement probe on the upper surface side of the base and arranged to be movable in the Y axis direction, and a support means supporting the Y carriage to be movable in the Y axis direction, the three-dimensional coordinate measuring device including a groove formed along the first side surface of the base plate and having a second side surface along the Y axis direction, and the support means including first and second support members provided at two locations along the Y axis direction of the Y carriage, the first and second support members being slidably arranged on the upper surface between the first and second side surfaces, and third and fourth support members provided at two locations along the Y axis direction of the Y carriage, the third and fourth support members being slidably arranged on the lower surface of the base plate.

According to this aspect, the base plate supports the Y carriage at two points on the upper surface where the first and second support members contact, and at two points on the lower surface where the third and fourth support members contact, so that vibration of the Y carriage in the pitching direction (around the X axis) is appropriately suppressed.

In another aspect of the three-dimensional coordinate measuring device of the present invention, it is preferable that the first support member and the third support member, and the second support member and the fourth support member are arranged in positions facing each other.

In yet another aspect of the three-dimensional coordinate measuring device of the present invention, the support means can be configured to include fifth and sixth support members provided at two locations along the Y-axis direction of the Y carriage, the fifth and sixth support members being slidably arranged on the first side, and seventh and eighth support members provided at two locations along the Y-axis direction of the Y carriage, the seventh and eighth support members being slidably arranged on the second side.

According to this aspect, vibration of the Y carriage in the yawing direction (around the Z axis) is also appropriately suppressed.

In yet another aspect of the three-dimensional coordinate measuring device of the present invention, the Y-carriage can be configured to include a first support member that extends along the Z-axis direction and is positioned closer to the first side surface and has first, second, third, and fourth support members, and a second support member that extends along the Z-axis direction and is positioned farther from the first side surface, and the second support member can be configured to have a ninth support member that is slidable on the top surface of the base plate.

In yet another aspect of the present invention, the three-dimensional coordinate measuring device includes a driving means provided on the Y carriage for moving the Y carriage in the Y-axis direction relative to the base plate, and the driving means can include a roller that contacts the first side surface at a position between the first support member and the second support member, and a motor that rotates the roller.

In yet another aspect of the three-dimensional coordinate measuring device of the present invention, the support member can be an air pad.

In yet another aspect of the three-dimensional coordinate measuring device of the present invention, the surface plate can be a stone surface plate.

According to the present invention, it is possible to suppress vibration of the Y carriage in the pitching direction, thereby improving measurement accuracy.

FIG. 1 is a perspective view showing the appearance of a three-dimensional coordinate measuring device to which the present invention is applied; FIG. 1 is a front view showing the appearance of a three-dimensional coordinate measuring device to which the present invention is applied. Enlarged front view of the right side of the surface plate Right side view showing an enlarged view of the right side of the surface plate FIG. 1 is a perspective view showing the Y-carriage with the cover removed. FIG. 13 is a top view showing the upper surface of the base plate, illustrating the arrangement of air pads provided on the Y carriage relative to the base plate; FIG. 13 is a right side view showing the right side of the surface plate, illustrating the arrangement of an air pad provided on the Y carriage relative to the surface plate; Enlarged front view of the groove on the surface plate A perspective view showing the Z column removed from the X guide. A perspective view showing the Z column removed from the X guide. A perspective view showing the Z column removed from the X guide. FIG. 1 is a perspective view showing the support part of the Z column removed from the X guide. FIG. 1 is a perspective view showing the support part of the Z column removed from the X guide. A schematic diagram showing the positional relationship of the support points where the Y guide of the surface plate supports the Y carriage, viewed from the top side of the surface plate. A schematic diagram showing the positional relationship of the support points where the Y guide of the surface plate supports the Y carriage, viewed from the right side of the surface plate. FIG. 1 is a front view (front schematic view) showing the appearance of a three-dimensional coordinate measuring device of Comparative Example 1; 17 is a cross-sectional view (schematic cross-sectional view) taken along line XVII-XVII in FIG. FIG. 11 is a front view (front schematic view) showing the appearance of a three-dimensional coordinate measuring device of Comparative Example 2; FIG. 11 is a front view (front schematic view) showing the appearance of a three-dimensional coordinate measuring device of Comparative Example 3; FIG. 1 is a front view (front schematic view) showing the appearance of a three-dimensional coordinate measuring device 1 according to an embodiment of the present invention; 21 is a cross-sectional view (schematic cross-sectional view) taken along line XXI-XXI in FIG. FIG. 13 is a top view showing the top surface of the base plate, illustrating the arrangement of the air pads and the drive unit provided on the Y carriage. FIG. 13 is a front view (schematic front view) showing the appearance of a three-dimensional coordinate measuring device according to another embodiment;

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings.

Figures 1 and 2 are a perspective view and a front view showing the appearance of a three-dimensional coordinate measuring device 1 to which the present invention is applied.

The three-dimensional coordinate measuring device 1 shown in these figures has a base plate 10 supported on an installation surface (floor surface) via a stand 12. The base plate 10 is integrally formed in a rectangular shape from stone material such as granite or marble, and has a flat top surface 10T on which the measurement object is placed. The top surface 10T is arranged parallel to the X-axis and Y-axis, i.e., perpendicular to the Z-axis.

A gate-shaped Y carriage 14 is installed on the top surface 10T side of the base plate 10. The Y carriage 14 has a right Y carriage 16, which is a first support member, and a left Y carriage 18, which is a second support member, which are erected on the right and left sides of the base plate 10 when viewed from the front side and extend along the Z axis direction, and a columnar X guide 20 that is bridged across the upper ends of the right Y carriage 16 and the left Y carriage 18 and extends along the X axis direction.

The lower end of the right Y carriage 16 is supported so as to be freely movable on a Y guide 42 (described later) that is formed on the base plate 10 and runs along the Y axis direction. A drive unit that abuts against the Y guide 42 is provided on the lower end of the right Y carriage 16, and the right Y carriage 16 moves along the Y guide 42 by the driving force of the drive unit. The lower end of the left Y carriage 18 is supported so as to be freely slidable on the upper surface 10T of the base plate 10.

As a result, the Y carriage 14 is supported so as to be movable in the Y-axis direction relative to the base plate 10, and is moved in the Y-axis direction by a drive unit at the lower end of the right Y carriage 16, with the right Y carriage 16 as the driving side and the left Y carriage 18 as the driven side.

The Z column 22 is supported on the X guide 20 so that it can move freely along the X guide 20. The Z column 22 has a built-in drive unit that contacts the X guide 20, and moves in the X-axis direction along the X guide 20 by the driving force of the drive unit.

In addition, inside the Z column 22, a columnar Z carriage 24 extending along the Z axis is supported so as to be movable in the Z axis direction (see FIG. 2), and the lower end side of the Z carriage 24 protrudes from the lower end side of the Z column 22. The Z column 22 incorporates a drive unit that abuts against the Z carriage 24, and the Z carriage 24 moves in the Z axis direction by the driving force of the drive unit.

A measurement probe 26 such as a touch probe is attached to the lower end of the Z carriage 24. The measurement probe 26 has, for example, a rod-shaped stylus 28 with a ball at the tip, and detects whether the tip (ball at the tip) of the stylus 28 is in contact with the object to be measured and the amount of displacement of the stylus 28 caused by the tip of the stylus 28 coming into contact with the object to be measured.

The three-dimensional coordinate measuring device 1 configured as described above moves the stylus 28 of the measuring probe 26 in the X, Y and Z directions by moving the Y carriage 14 in the Y direction, the Z column 22 in the X direction, and the Z carriage 24 in the Z direction, and moves the tip (tip ball) of the stylus 28 along the surface of the measurement object placed on the upper surface 10T of the base plate 10. The three-dimensional coordinates of each position on the surface of the measurement object are measured by measuring the position (movement amount) of the Y carriage 14 in the Y direction, the position (movement amount) of the Z column 22 in the X direction, the position (movement amount) of the Z carriage 24 in the Z direction, and the position (displacement amount) of the stylus 28. Note that the process of measuring three-dimensional coordinates is well known, so a detailed description will be omitted.

Next, we will explain the Y drive mechanism that supports the Y carriage 14 so that it can move in the Y-axis direction and moves it in the Y-axis direction.

First, we will explain the support means (Y guide mechanism) for the Y carriage 14 in the Y drive mechanism.

Figures 3 and 4 are front and right side views showing an enlarged view of the right side of the base plate 10.

As shown in FIG. 3, the base plate 10 has an upper surface 10T and a lower surface 10B perpendicular to the Z axis, and a right side surface 10R perpendicular to the X axis. In addition, a groove 40 is formed along the Y axis direction on the upper surface 10T side of the base plate 10 near the right side surface 10R of the base plate 10.

Note that Figures 1 and 2 show a state in which a flexible covering member such as a bellows cover is installed at the upper opening of the groove 40, and plate-shaped covering members such as metal covers are attached to the front and rear sides of the base plate 10, but Figures 3 and 4 show the state in which these covering members have been removed.

The groove 40 has a right side 40R and a left side 40L that face each other and are perpendicular to the X-axis, and a bottom surface 40B that is perpendicular to the Z-axis.

As a result, the right side surface 40R of the groove 40, the right side surface 10R of the base plate 10, and the upper surface 10T of the base plate 10 and the lower surface 10B of the base plate 10 between them form a Y guide 42 that extends along the Y axis direction.

The right side surface 10R of the base plate 10 and the right side surface 40R and left side surface 40L of the groove 40 do not necessarily have to be perpendicular to the X-axis as long as they are surfaces formed along the Y-axis direction, and the lower surface 10B of the base plate 10 and the bottom surface 40B of the groove 40 do not necessarily have to be perpendicular to the Z-axis.

In the following, the right side 40R of the groove 40 will be referred to as the left side 42L of the Y guide 42, the right side 10R of the base plate 10 will be referred to as the right side 42R of the Y guide 42, the top surface 10T of the base plate 10 between them will be referred to as the top surface 42T of the Y guide 42, and the bottom surface 10B of the base plate 10 will be referred to as the bottom surface 42B of the Y guide 42.

On the other hand, Figure 5 shows a perspective view of the Y carriage 14 with the covers of each part removed, and as shown in Figures 4 and 5, a wide support part 50 is provided in the Y-axis direction at the lower end of the right Y carriage 16.

The support portion 50 is formed in a bifurcated shape when viewed from the front side as shown in Figure 3.

Note that Figures 3 and 4 show the state in which the covering member covering the support portion 50 has been removed.

As shown primarily in FIG. 3, the support portion 50 has a base end portion 52 that faces the upper surface 42T of the Y guide 42 and is arranged along a direction perpendicular to the Z axis (horizontal direction), a right side portion 54 that extends from the base end portion 52 in the Z axis direction and is arranged opposite the right side surface 42R of the Y guide 42, and a left side portion 56 that extends from the base end portion 52 in the Z axis direction and is arranged opposite the left side surface 42L of the Y guide 42.

In addition, support plates 58A, 58A are provided at the lower end of the right side portion 54 as the tip portion 58 of the support portion 50, extending in the X-axis direction to a position facing the lower surface 42B of the Y guide 42.

Each of the base end 52, right side 54, left side 56, and tip end 58 of the support part 50 is provided with a plurality of disk-shaped air pads that can slide against the Y guide 42 by blowing air therethrough, as shown below. In addition, a disk-shaped air pad is also provided at the bottom end of the left Y carriage 18, which can slide against the top surface 10T of the base plate 10 by blowing air therethrough.

Figures 6 and 7 are top and right side views showing the top surface 10T and right side surface 10R of the base plate 10, and show the arrangement of the air pads provided on the Y carriage 14 relative to the base plate 10.

In these figures, the two air pads 62F, 62E arranged along the top surface 42T of the Y guide 42 are provided at two locations along the Y axis direction (two locations on a straight line parallel to the Y axis) at the base end 52 of the support part 50, and are arranged facing downwards, facing the top surface 42T of the Y guide 42.

The two air pads 64F, 64E arranged along the right side surface 42R of the Y guide 42 are provided at two locations along the Y axis direction (two locations on a straight line parallel to the Y axis) on the right side portion 54 of the support part 50, and are arranged facing leftward opposite the right side surface 42R of the Y guide 42.

The two air pads 66F, 66E arranged along the left side surface 42L of the Y guide 42 (the right side surface 40R of the groove 40) are provided at two positions along the Y axis direction (two positions on a straight line parallel to the Y axis) on the left side portion 56 of the support part 50, and are arranged facing the right and facing the left side surface 42L of the Y guide 42.

Two air pads 68F, 68E (see Figures 3 and 7) arranged along the lower surface 42B of the Y guide 42 are provided at two locations along the Y axis direction (two locations on a straight line parallel to the Y axis) at the tip 58 of the support part 50, and are arranged facing upward and facing the lower surface of the Y guide 42.

The air pad 70, which is located on the upper surface of the base plate 10 near its left side, is provided at the lower end of the left Y carriage 18 and is positioned facing downwards, facing the upper surface 10T of the base plate 10.

Here, at each of the base end 52, right side 54, left side 56, and tip end 58 of the support part 50, the air pads 62F, 64F, 66F, and 68F installed on the front side (front surface side) are arranged in approximately the same position in the Y-axis direction (i.e., arranged in a position along the same XZ plane), and the air pads 62E, 64E, 66E, and 68E installed on the rear side (rear surface side) are arranged in approximately the same position in the Y-axis direction.

Air pads 64F, 64E installed on the right side 54 of the support part 50 and air pads 66F, 66E installed on the left side 56 are positioned opposite each other (i.e., approximately in the same position in the Z-axis direction).

Air pads 62F, 62E installed at the base end 52 of the support part 50 and air pads 68F, 68E installed at the tip end 58 are positioned opposite each other (i.e., approximately in the same position in the X-axis direction).

The air pad 70 installed at the lower end of the left Y carriage 18 is positioned in a position in the Y axis direction that approximately coincides with the Y axis position of the center of gravity of all components (Y carriage 14 and Z column 22) that move in the Y axis direction together with the Y carriage 14.

In addition, while the air pads 62F, 62E, and 70 have a diameter of, for example, 110 mm, the air pads 64F, 64E, 66F, and 66E have a smaller diameter, for example, 80 mm, than the air pads 62F, 62E, and 70. Furthermore, the air pads 68F and 68E have a smaller diameter, for example, 60 mm, than the air pads 64F, 64E, 66F, and 66E.

For reference, the base plate 10 has an X-axis direction width (horizontal width) of approximately 800 mm to approximately 1000 mm and a Y-axis direction width (depth) of approximately 1200 mm to approximately 2700 mm, the Y-carriage 14 has a Z-axis direction width (height) of approximately 600 mm to approximately 800 mm, and the support part 50 has a Y-axis direction width (depth) of approximately 650 mm.

According to the support means for the Y carriage 14 configured as described above, the Y carriage 14 is supported on the Y guide 42 (base plate 10) via the air pads 62F, 62E, 64F, 64E, 66F, 66E, 68F, 68E of the support portion 50 in the right Y carriage 16. That is, the Y carriage 14 is supported on the Y guide 42 by the engagement between the support portion 50 and the Y guide 42. At the same time, the Y carriage 14 is supported on the base plate 10 (upper surface 10T) via the air pad 70 in the left Y carriage 18.

In addition, by ejecting air from each of the air pads 62F, 62E, 64F, 64E, 66F, 66E, 68F, 68E, and 70, each of the air pads 62F, 62E, 64F, 64E, 66F, 66E, 68F, and 68E of the support portion 50 in the right Y carriage 16 becomes slidable in the Y-axis direction relative to the Y guide 42, and the air pad 70 in the left Y carriage 18 becomes slidable relative to the top surface 10T of the base plate 10.

As a result, the Y carriage 14 is able to move in the Y-axis direction relative to the base plate 10.

Next, we will explain the driving means for the Y carriage 14 in the Y drive mechanism.

As shown in FIG. 4, the drive unit 80 is provided on the right side 54 of the support unit 50. As also shown in FIGS. 6 and 7, the drive unit 80 is located approximately midway between the two air pads 64F, 64E provided on the right side 54 of the support unit 50.

The drive unit 80 is constructed integrally with a motor 82, a rotatable roller 84, and a reduction mechanism that connects them so that power can be transmitted, all of which are attached to a support member. When the motor 82 is driven, the roller 84 rotates.

As shown in FIG. 6, the drive unit 80 is installed on the right side 54 of the support unit 50 so that the rotation axis of the roller 84 is parallel to the Z axis and the outer circumferential surface of the roller 84 abuts against the right side 42R of the Y guide 42 (the right side 10R of the base plate 10) at a position approximately halfway between the two air pads 64F, 64E.

Therefore, by driving the motor 82 of the drive unit 80 to rotate the roller 84, the support unit 50 moves along the Y guide 42, and the Y carriage 14 moves in the Y-axis direction.

As a driving means for the Y carriage 14, in addition to the driving unit 80, a driving unit that abuts against the left side surface 42L of the Y guide 42 may be provided, for example, facing the driving unit 80, or instead of the driving unit 80, only a driving unit that abuts against the left side surface 42L of the Y guide 42 may be provided.

Next, we will explain the position detection means for the Y carriage 14 in the Y drive mechanism.

Figure 8 is an enlarged front view of the groove 40 of the base plate 10. As shown in the figure, a long plate-shaped scale 112 with a grid scale that constitutes, for example, an optical linear encoder 110 is installed on the left side surface 40L of the groove 40 along the Y-axis direction.

On the other hand, the optical sensor 114 constituting the linear encoder 110 is mounted on a support member on the left side 56 of the support part 50 and is positioned opposite the scale 112. A detection signal resulting from the lattice markings of the scale 112 formed in a position opposite the optical sensor 114 is output from the optical sensor 114.

According to this linear encoder 110, when the Y carriage 14 moves in the Y-axis direction, the optical sensor 114 moves in the Y-axis direction together with the Y carriage 14, and the position of the optical sensor 114 facing the scale 112 changes. At this time, the position of the Y carriage 14 in the Y-axis direction is detected based on the detection signal output from the optical sensor 114.

Next, we will explain the X drive mechanism that supports the Z column 22 so that it can move in the X-axis direction and moves it in the X-axis direction.

First, we will explain the support means (X guide mechanism) for the Z column 22 in the X drive mechanism.

Figure 5 shows the Y carriage 14 with the cover removed as described above, while Figures 9, 10, and 11 show the Z column 22 removed from the X guide 20. As shown in these figures, the Z column 22 has a support section 200 to which various parts are attached, which corresponds to the X carriage, and the support section 200 has a rectangular X guide insertion hole 202 along the X axis direction through which the square pillar-shaped X guide 20 is inserted.

In the support part 200, the front surface 202F, rear surface 202E, upper surface 202T, and lower surface 202B (referred to as the front surface 202F of the X-guide insertion hole 202, etc.) that define the X-guide insertion hole 202 are each provided with a disk-shaped air pad that is able to slide relative to the X-guide 20 by ejecting air.

On the front surface 202F of the X-guide insertion hole 202, as shown in FIG. 10, four air pads 210, 210, 210 are arranged, one at each of four locations that are symmetrical vertically and horizontally, facing backward and facing the front surface 20F of the X-guide 20 (see FIG. 5).

As shown in FIG. 11, three air pads 212, 212, 212 are arranged on the rear surface 202E of the X-guide insertion hole 202, one at each of two locations on the upper side and one at the lower side, facing forward and facing the rear surface 20E of the X-guide 20 (see FIG. 5).

As shown in FIG. 9, two air pads 214, 214 are arranged on the upper surface 202T of the X-guide insertion hole 202, one on each of the two left and right locations, and are arranged facing downward and opposite the upper surface 20T of the X-guide 20 (see FIG. 5).

As shown in FIG. 10, one air pad 216 is disposed on the underside 202B of the X-guide insertion hole 202, facing upward and facing the underside 20B of the X-guide 20 (see FIG. 5).

With the support means for the Z column 22 configured as described above, when the X guide 20 is inserted into the X guide insertion hole 202 of the support part 200, the support part 200 is supported by the X guide 20 via the air pads 210, 212, 214, and 216, and the Z column 22 is supported by the X guide 20 via the support part 200.

In addition, by ejecting air from each of the air pads 210, 212, 214, and 216, each of the air pads 210, 212, 214, and 216 of the support portion 200 becomes slidable in the X-axis direction relative to the X-guide 20.

As a result, the Z column 22 becomes movable in the X-axis direction.

Next, we will explain the drive means for the Z column 22 in the X drive mechanism.

As shown in Figures 9 to 11, a drive unit 220 having a configuration similar to that of the drive unit 80 in the Y drive mechanism described above and equipped with a motor 222 and a roller 224 (see Figure 11) is provided on the rear surface 202E of the X guide insertion hole 202. The drive unit 220 is installed on the rear surface 202E of the X guide insertion hole 202 so that the rotation axis of the roller 224 is parallel to the Z axis, and the outer circumferential surface of the roller 224 is installed so that it abuts against the rear surface 20E (see Figure 5) of the X guide 20 at a position approximately halfway between the two air pads 212, 212 installed on the upper side of the rear surface 202E of the X guide insertion hole 202.

Therefore, by driving the motor 222 of the drive unit 220 to rotate the roller 224, the support unit 200 moves along the X guide 20, and the Z column 22 moves in the X-axis direction.

The X guide 20 and the support section 200 are provided with an optical linear encoder similar to the linear encoder 110 described above in the Y drive mechanism as a position detection means for the Z column 22 in the X drive mechanism, and a long plate-shaped scale is installed along the X axis direction in the X guide 20, and an optical sensor is disposed in the support section 200 in a position opposite the scale.

Next, we will explain the Z drive mechanism that supports the Z carriage 24 so that it can move in the Z-axis direction and moves it in the Z-axis direction.

First, we will explain the support means (Z guide mechanism) for the Z carriage 24 in the Z drive mechanism.

Figures 12 and 13 show the state in which the Z carriage 24 has been removed from the support part 200 of the Z column 22 shown in Figures 9 to 11. As shown in these figures, the support part 200 has a rectangular Z carriage insertion hole 250 aligned in the Z axis direction, through which the square pillar-shaped Z carriage 24 is inserted, provided in front of the X guide insertion hole 202.

In the support section 200, the front surface 250F, rear surface 250E, right side surface 250R, and left side surface 250L (referred to as the front surface 250F of the Z carriage insertion hole 250) that define the Z carriage insertion hole 250 (see FIG. 13) are provided with air pads that can slide relative to the Z carriage 24 by ejecting air.

As shown in FIG. 12, a total of four air pads 260, 262, 264, 266 are arranged near the lower opening of the Z carriage insertion hole 250, one on each of the front 250F, rear 250E, right side 250R, and left side 250L of the Z carriage insertion hole 250, and each of these air pads 260, 262, 264, 266 is arranged facing backward, forward, left, and right, respectively, facing the front 24F, rear 24E, right side 24R, and left side 24L of the Z carriage 24 (see FIG. 11).

As shown in FIG. 13, a total of three air pads 260, 262, 264 are arranged near the upper opening of the Z carriage insertion hole 250, one on each of the front 250F, rear 250E, and right side 10R of the Z carriage insertion hole 250, and each of these air pads 260, 262, 264 is arranged facing backward, forward, and left, respectively, facing the front 24F, rear 24E, and right side 24R of the Z carriage 24.

On the other hand, two air pads 266, 266 are arranged on the left side surface 250L of the Z carriage insertion hole 250 near the upper opening of the Z carriage insertion hole 250, and these air pads 266, 266 are arranged facing the right and facing the left side surface 24L of the Z carriage 24.

With the support means for the Z carriage 24 configured as described above, when the Z carriage 24 is inserted into the Z carriage insertion hole 250 of the support part 200, the support part 200 supports the Z carriage 24 via the air pads 260, 262, 264, and 266.

In addition, by blowing air from each of the air pads 260, 262, 264, and 266, each of the air pads 260, 262, 264, and 266 of the support unit 200 becomes slidable relative to the Z carriage 24, and the Z carriage 24 becomes movable in the Z-axis direction.

Next, we will explain the driving means of the Z carriage 24 in the Z drive mechanism.

As shown in Figures 12 and 13, a drive unit 270 having a configuration similar to that of the drive unit 80 in the Y drive mechanism described above and equipped with a motor 272 and a roller 274 (see Figure 13) is provided on the front surface 250F of the Z carriage insertion hole 250. The drive unit 270 is installed on the front surface 250F of the Z carriage insertion hole 250 so that the rotation axis of the roller 274 is parallel to the X axis, and the outer circumferential surface of the roller 274 is installed so that it abuts against the front surface 24F of the Z carriage 24 at a position approximately halfway between the two air pads 260, 260 installed on the front surface 250F of the Z carriage insertion hole 250.

Therefore, by driving the motor 272 of the drive unit 270 to rotate the roller 274, the Z carriage 24 moves in the Z axis direction relative to the support unit 200.

The Z carriage 24 and the support unit 200 are provided with an optical linear encoder similar to the linear encoder 110 described above in the Y drive mechanism as a position detection means for the Z carriage 24 in the Z drive mechanism, and a long plate-shaped scale is installed along the Z axis direction on the Z carriage 24, and an optical sensor is disposed on the support unit 200 in a position opposite the scale.

The cable protection tube 278 shown in Figures 9 to 13 is a bendable guide member that guides the cable by inserting it inside. The cable of the measurement probe 26 attached to the lower end of the Z carriage 24 is inserted inside the Z carriage 24 and the cable protection tube 278 inside the Z column 22, preventing interference with other components.

In the three-dimensional coordinate measuring device 1 configured as described above, we will mainly explain the effect of suppressing vibration of the Y carriage 14 around the Z axis (yawing direction) and around the X axis (pitching direction).

Figure 14 is a schematic diagram showing the positional relationship of the support points at which the Y guide 42 of the base plate 10 supports the Y carriage 14, viewed from the top surface 10T side of the base plate 10.

In the figure, the two front and rear support points P1 and P2 on the left side 42L of the Y guide 42 formed on the base plate 10 indicate the positions where the air pads 66F and 66E of the Y carriage 14 (support part 50) contact, the two front and rear support points P3 and P4 on the right side 42R of the Y guide 42 indicate the positions where the air pads 64F and 64E of the Y carriage 14 (support part 50) contact, and the support point P0 on the right side 42R of the Y guide 42 indicates the position where the roller 84 of the drive part 80 of the Y carriage 14 (support part 50) contacts (see Figure 6).

Furthermore, support points P1 and P2 indicate fixed support points, and support points P3 and P4 indicate auxiliary support points. That is, air pads 66F and 66E, which are fixed support points P1 and P2, are supported in the support part 50 of the Y carriage 14 so that they cannot move forward or backward in the normal direction of the left side surface 42L of the Y guide 42, which is the guide surface along which they slide. On the other hand, air pads 64F and 64E, which are auxiliary support points P3 and P4, are supported in the support part 50 of the Y carriage 14 so that they can move forward or backward in the normal direction of the right side surface 42R of the Y guide 42, which is the guide surface along which they slide, and are biased in the direction of contact with the right side surface 42R.

As a result, when the roller 84 of the drive unit 80 is pressed against the right side surface 42R of the Y guide 42, the Y guide 42 is stable in a state where it is supported by one support point P0 on the right side surface 42R and two support points P1 and P2 on the left side surface 42L, with support points P3 and P4 acting as auxiliary support points.

Therefore, the angular position of the Y carriage 14 around the Z axis (yawing direction) is uniquely determined by the positions of support points P1 and P2, and vibration in the yawing direction is suppressed. Furthermore, by suppressing vibration in the yawing direction of the X guide 20 (X axis), the X and Y coordinate values measured for a measurement object placed in a measurement area (area that does not interfere with the Y carriage 14) on the top surface 10T of the base plate 10 can be obtained with high precision using the position of the Y guide 42 (left side surface 42L) as a reference.

Figure 15 is a schematic diagram showing the positional relationship of the support points where the Y guide 42 of the base plate 10 supports the Y carriage 14, viewed from the right side 10R of the base plate 10.

In the figure, the two front and rear support points P5 and P6 on the upper surface 42T of the Y guide 42 formed on the base plate 10 indicate the positions where the air pads 62F and 62E of the Y carriage 14 (support part 50) abut, and the two front and rear support points P7 and P8 on the lower surface 42B of the Y guide 42 indicate the positions where the air pads 68F and 68E of the Y carriage 14 (support part 50) abut (see Figure 7).

As a result, the Y guide 42 supports the Y carriage 14 not only by two support points P5 and P6 on the top surface 42T, but also by two support points P7 and P8 on the bottom surface 42B.

Therefore, the vibration of the Y carriage 14 around the X axis (pitching direction) is suppressed not only by support points P5 and P6, but also by support points P7 and P8, and vibration of the Y carriage 14 in the pitching direction is suppressed even when the Y carriage 14 is moved in the Y axis direction at high speed.

In particular, since the drive unit 80 is disposed between support points P5, P6 and support points P7, P8 in the Z-axis direction (see FIG. 7, etc.), the driving force of the drive unit 80 is less likely to generate a rotational force in the pitching direction on the Y carriage 14, which also prevents the Y carriage 14 from vibrating in the pitching direction.

It is desirable that the position of the drive unit 80 in the Y-axis direction be approximately the same as the Y-axis direction position of the center of gravity of all components (Y carriage 14 and Z column 22) that move in the Y-axis direction together with the Y carriage 14.

By preventing the Z carriage 24 (Z axis) from vibrating in the pitching direction, the Y and Z coordinate values of the object in the measurement area measured by the measurement probe 26 can be obtained with high precision based on the position of the Y guide 42 (top surface 42T).

In addition, by forming grooves 40 in the base plate 10 and using a portion of the area along the right side surface 10R of the base plate 10 as the Y guide 42, the Y guide 42 is less likely to be thermally deformed and the linearity of the Y guide 42 is more easily maintained than when the Y guide 42 is made of a separate member. Also, compared to when both the left and right sides of the base plate 10 are used as Y guides, the respective faces of the Y guide 42 are close to each other, so the relative amount of change of each face is small and the linearity of the Y guide 42 is more easily maintained.

As a result, the yawing and pitching vibrations of the Y carriage 14 caused by changes in the position of the Y carriage 14 in the Y-axis direction are small, and the movement of the Y carriage 14 in the Y-axis direction can be continuously stabilized, allowing measurement accuracy to be maintained continuously. In addition, the Y guide 42 (Y guide mechanism) can be constructed simply and inexpensively compared to when the Y guide 42 is constructed from a separate member.

Therefore, by making part of the base plate 10 the Y guide 42, the shape of the Y guide 42 changes less during measurement compared to when the Y guide 42 is constructed as a separate member from the base plate 10, and measurement errors due to curvature of the Y guide 42, etc., can be easily reduced by correcting them in the calculations. However, the base plate 10 does not necessarily have to be a stone base plate.

As described above, the three-dimensional coordinate measuring device 1 of the above embodiment may be configured with the left and right sides reversed, and the groove 40 and the Y guide 42 may be formed along the left side surface of the base plate 10, rather than along the right side surface 10R of the base plate 10.

In addition, in the above embodiment, an air pad (air bearing) is used as a support member that slidably contacts each surface of the Y guide 42, etc., but a support member of a type other than an air pad may also be used.

The following provides a supplementary explanation of the effects of the three-dimensional coordinate measuring device 1 described above.

In the three-dimensional coordinate measuring device 1 of the above embodiment, the axis of the roller 84 of the driving unit 80 is arranged perpendicular to the top surface 10T of the base plate 10. Therefore, the roller 84 contacts the vertical surface of the base plate 10, so it does not catch dirt, and accurate measurements can be made using the side surface of the base plate 10 as a reference.

The roller 84 also drives along the side surface (right side surface 10R) of the base plate 10. Therefore, even if the base plate 10 deforms slightly, measurements can be made based on the base plate 10. If the roller 84 moves along a rail different from the base plate 10, it will not be synchronized with the deformation of the base plate 10 due to other factors such as thermal expansion of the rail.

Air pads 64F, 64E, 66F, and 66E are also arranged vertically along the side of base plate 10. Therefore, as described above, their positions are set based on base plate 10. In addition, yawing error, which occurs when Y carriage 14 moves left and right relative to the direction of travel, can be reduced.

The roller 84 of the vertically arranged drive unit 80 is also arranged so that it is sandwiched between the air pads 66F and 66E, which are also vertically arranged. Therefore, even in the case of sudden drive, the air pads on the front and back can be used to reduce yawing errors and vibrations without losing posture.

In addition, the distance (spacing) between support points P1 and P2 on the Y carriage 14 is sufficiently large compared to the distance (spacing) between support points P1, P2 and drive point P0. This reduces the vibration of the Y carriage 14, and also reduces yawing errors in which the movement direction swings left and right relative to the movement direction.

In addition, air pads 66F, 66E are arranged perpendicular to the side of groove 40 of base plate 10. Therefore, by forming groove 40 in base plate 10 and making support points P1, P2 by air pads 66F, 66E the side of groove 40 of base plate 10, it is possible to follow deformations such as thermal expansion of base plate 10 and to make measurements based on base plate 10.

Furthermore, air pads 66F, 66E, which face support points P3, P4 provided by air pads 64F, 64E, exist as support points P1, P2 on the side of groove 40 of base plate 10, and are supported by Y guide 42. Therefore, the side of base plate 10 is used as a reference, and Y carriage 14 is supported only on the drive side (right Y carriage 16 side where drive unit 80 is located) with respect to the driven side (left Y carriage 18 side). Therefore, the sliding resistance on the driven side is negligible, and yawing error is significantly reduced.

In addition, only the air pad 70 in the Z-axis direction is arranged on the driven side of the Y carriage 14, and there is no air pad to suppress the Y-axis direction. Therefore, without creating unnecessary resistance on the driven side, movement in the Y-axis direction follows the movement of the driving side. As a result, vibration and yawing can be reduced.

The position in the Y-axis direction of the air pad 70 in the Z-axis direction on the driven side of the X-guide 20 and Y-carriage 18 is between the air pads 66F, 66E (support points P1, P2) or the air pads 64F, 64E (support points P3, P4) on the driving side of the Y-carriage 18. Therefore, even with sudden acceleration and deceleration, the moment of the X-guide 20 and the measuring unit is only received by the width of support points P1, P2 (or support points P3, P4), and there is almost no sliding resistance. As a result, vibration and yawing errors are extremely small.

Next, the three-dimensional coordinate measuring device 1 of this embodiment will be compared with the three-dimensional coordinate measuring devices of Comparative Examples 1 to 3 to explain the effects of the three-dimensional coordinate measuring device 1 of this embodiment in more detail. Note that the present invention is not limited to the following explanation of the effects.

Figure 16 is a front view (schematic front view) showing the appearance of three-dimensional coordinate measuring device 300 of Comparative Example 1 disclosed in JP-A-5-312556. Also, Figure 17 is a cross-sectional view (schematic cross-sectional view) taken along line XVII-XVII in Figure 16. Note that in the three-dimensional coordinate measuring device 300 of Comparative Example 1, components that are the same in function or configuration as the three-dimensional coordinate measuring device 1 of this embodiment are given the same reference numerals and their description will be omitted.

As shown in Figures 16 and 17, in the three-dimensional coordinate measuring device 300 of Comparative Example 1, the support unit 50 supporting the right Y carriage 16 on the side directly driven by the drive unit 301 (hereinafter abbreviated as the drive side) is supported on the base plate 10 via air pads 302R and 302T. Air pad 302R is disposed on the right side of the base plate 10, and air pad 302T is disposed on the right end side of the upper surface 10T of the base plate 10. Air pads 302T are also provided at two positions along the Y direction (see Figure 17).

Meanwhile, in the three-dimensional coordinate measuring device 300 of Comparative Example 1, the left Y carriage 18 on the driven side (hereinafter abbreviated as the driven side), which moves in the Y direction following the right Y carriage 16 on the driving side, is slidably supported on the upper surface 10T of the base plate 10 via air pads 303T and 303L. The air pads 303T are disposed on the upper surface 10T of the base plate 10. In addition, the lower end of the left Y carriage 18 has a support portion 18a that faces the left side surface of the base plate 10, and this support portion 18 positions the air pad 303T on the left side surface of the base plate 10.

The drive unit 301 has basically the same configuration as the drive unit 80 of this embodiment, for example, and is provided near the air pad 302R. Note that the rectangular frame represented by the two-dot chain line in FIG. 17 indicates the position of the drive unit 301.

In the three-dimensional coordinate measuring device 300 of Comparative Example 1, two air pads 302T are arranged along the Y direction on the right end side of the upper surface 10T of the base plate 10, but unlike the three-dimensional coordinate measuring device 1 of this embodiment, no air pads are arranged on the lower surface side of the base plate 10. In other words, the three-dimensional coordinate measuring device 300 of Comparative Example 1 does not have air pads facing the lower surface of the base plate 10 or the Y guide (not shown) provided on this base plate 10, so the part that determines the position of the right Y carriage 16 on the driving side in the vertical direction (Z axis direction) is only the upper surface of the base plate 10. For this reason, pitching error is a problem in the three-dimensional coordinate measuring device 300 of Comparative Example 1.

To reduce pitching errors, the positional relationship between the drive unit 301 that drives the right Y carriage 16 in the Y direction and the air pad that supports the right Y carriage 16 is important. For example, in the three-dimensional coordinate measuring device 300 of Comparative Example 1, the drive unit 301 is provided below the upper surface 10T of the base plate 10, so the right Y carriage 16 momentarily tilts (sways) around the X axis with the upper surface 10T of the base plate 10 as the fulcrum. For this reason, if the right Y carriage 16 on the driving side is supported only on the base plate 10 as in the three-dimensional coordinate measuring device 300 of Comparative Example 1, the support point is only one point in the vertical direction, and when driven by the drive unit 301, a rotational moment acts with the support point on the base plate 10 as the fulcrum. As a result, the right Y carriage 16 swings around the X axis, causing a noticeable pitching error.

Therefore, in order to reduce pitching errors, as in the three-dimensional coordinate measuring device 1 of this embodiment, it is necessary to sandwich the upper and lower surfaces of the base plate 10 with air pads 62E, 62F, 68E, and 68F (see FIG. 7) and provide the drive unit 80 (see FIG. 7) between the upper and lower surfaces. As a result, when the Y carriage 14 (right Y carriage 16) is moved in the Y direction, both the upper and lower surfaces of the base plate 10 become support points for the right Y carriage 16, and the drive unit 80 is located at a position sandwiched between these two support points, so that pitching errors are less likely to occur even when the Y carriage 14 is accelerating and decelerating. In addition, in order to suppress pitching errors during acceleration and deceleration, it is preferable that the drive unit 80 is located at the center of gravity position in the Y direction of the Y carriage 14 (right Y carriage 16), for example, at the center position between the air pads 62E and 62F.

In addition, in the three-dimensional coordinate measuring device 300 of Comparative Example 1, air pads 302R and 303L are arranged on both side surfaces (vertical surfaces on both sides) of the base plate 10 in FIG. 16. In this case, it may seem stable at first glance when moving the Y carriage 14 back and forth in the Y direction, but yawing error becomes large when the Y carriage 14 moves back and forth in the Y direction.

That is, when the air pads 302R and 303L are arranged on both sides of the surface plate 10, the right Y carriage 16 on the driving side and the left Y carriage 18 on the driven side are not clearly divided into the side that controls the main driving operation and the side that follows that operation, and both have similar sliding resistance. As a result, when the Y carriage 14 is moved in the Y direction, the positional relationship in the Y direction between the right Y carriage 16 and the left Y carriage 18 is not constant, and for example, the yawing error increases due to the oscillation around the Z axis. For this reason, as in this embodiment, the right Y carriage 16 on the driving side is moved along the Y guide 42 (see FIG. 3) and the left Y carriage 18 on the driven side has as small a sliding resistance as possible, so that the left Y carriage 18 moves following the right Y carriage 16 on the driving side, and the oscillation around the Z axis described above does not occur.

In the three-dimensional coordinate measuring device 300 of Comparative Example 1, the driving unit 301 is not disposed near the driven-side air pad 303L, and the driven-side air pad 303L is located on the opposite side of the Y-carriage 14 from the driving-side air pad 302R, and presses down on both sides of the base plate 10 together with the air pad 302R. In this case, the driven-side air pad 303L is located on the opposite side of the base plate 10, away from the driving unit 301, so that the sliding between the air pad 303L and the left side of the base plate 10 generates a large rotational moment with the driving unit 301 as the fulcrum.

In addition, when air pads 302R and 303L are pressed from both sides of base plate 10 so as to sandwich both sides of the base plate 10, and air pads 302R and 303L are moved in a direction perpendicular to the pressing direction of base plate 10 (Y direction), the balance of the sliding resistance during this movement is slightly disrupted, and the yawing error significantly worsens.

As a method for reducing such yawing errors, for example, Japanese Patent Application Laid-Open Publication No. 7-218247 discloses the provision of a drive unit with a special structure that can prevent twisting and bending of the Y carriage 14 even when the Y carriage 14 is moved in the Y direction with a large acceleration. However, when a drive unit with this special structure is adopted, there is a problem that the three-dimensional coordinate measuring device 300 becomes larger and the structure of the drive unit becomes complicated. Therefore, the three-dimensional coordinate measuring device 300 of Comparative Example 1 has a problem that a yawing error occurs when the Y carriage 14 moves.

In addition, when the Y carriage 14 (right Y carriage 16) is supported only on the base plate 10, the pitching error when driving the Y carriage 14 also affects the yawing error. In other words, when a pitching error occurs, one of the front and rear air pads 302T in the Y direction moves away from the top surface 10T of the base plate 10, and the other moves closer to the top surface 10T. In this case, it is preferable that the right Y carriage 16 and the left Y carriage 18 have an asymmetric structure in which the sliding resistance of the driving side right Y carriage 16 is greater than that of the driven side left Y carriage 18, but because of this asymmetry, the sliding resistance cannot be balanced between the left and right due to changes caused by the pitching error. For this reason, the Y carriage 14 is further deformed so that it is twisted significantly. As a result, there is a risk of the yawing error worsening.

Furthermore, when the air pad 302T is placed on the upper surface side of the base plate 10 but not on the lower surface side, as in the three-dimensional coordinate measuring device 300 of Comparative Example 1, the load of the Y carriage 14 is divided approximately equally between the right Y carriage 16 on the driving side and the left Y carriage 18 on the driven side. If half the weight of the Y carriage 14 is placed on the driven side, the sliding resistance of the left Y carriage 18 on the driven side increases accordingly. As a result, the yawing error increases.

In the three-dimensional coordinate measuring device 300 of Comparative Example 1, an air pad is not provided on the underside of the base plate 10, and the right Y carriage 16 has only one support point in the vertical direction, so there is a risk of not only a pitching error around the X axis, but also a rocking movement of the right Y carriage 16 around the Y axis, i.e., a rolling error. When such a rolling error occurs, the sliding resistance cannot be balanced between the left and right, just as in the case of a pitching error, which may lead to an increase in the yawing error.

In contrast, the right Y carriage 16 of the three-dimensional coordinate measuring device 1 of this embodiment is supported by air pads 62E, 62F, 68E, 68F (see FIG. 7) that press down on not only the top side of the base plate 10 but also the bottom side, restraining and supporting the right Y carriage 16 from above and below. As a result, the sliding resistance of the right Y carriage 16 on the driving side becomes large, but the sliding resistance of the left Y carriage 18 on the driven side can be kept relatively small accordingly. At this time, by sandwiching the base plate 10 in the vertical direction with the right Y carriage 16 on the driving side, the forward and backward tilt (swing) of the Y carriage 14 in the Y direction, i.e., pitching error, can be corrected, and the weight on the Y carriage 14 can be supported almost entirely by the driving side portion.

In addition, the left Y carriage 18 on the driven side of the three-dimensional coordinate measuring device 1 of this embodiment serves the role of simply supporting the right Y carriage 16 on the driving side using the top surface 10T of the base plate 10 as a reference to eliminate rolling error centered on the right Y carriage 16 on the driving side. For this reason, the right Y carriage 16 on the driving side rolls against the base plate 10 to support the Y carriage 14, but the left Y carriage 18 on the driven side only needs to be lightly supported by the top surface 10T of the base plate 10 to mitigate the rolling error. As a result, no sliding resistance is generated in the left Y carriage 18 on the driven side, and as a result, the sliding resistance of the right Y carriage 16 on the driving side determines the speed, and the yawing error can be kept small.

Figure 18 is a front view (front schematic view) showing the appearance of the three-dimensional coordinate measuring device 400 of Comparative Example 2 disclosed in JP-A-64-035310 or JP-A-62-235502. In the three-dimensional coordinate measuring device 400 of Comparative Example 2, components that are the same in function or configuration as the three-dimensional coordinate measuring device 1 of this embodiment are given the same reference numerals and their description is omitted.

As shown in FIG. 18, in the three-dimensional coordinate measuring device 400 of Comparative Example 2, the support part 50 supporting the right Y carriage 16 on the drive side (drive part not shown) is supported on the Y guide 42 (base plate 10) via air pads 402R, 402T, 402L and 402B. Air pad 402R is disposed on the right side of the Y guide 42 of the base plate 10, air pad 402T is disposed on the upper surface side of the Y guide 42, air pad 402L is disposed on the left side of the Y guide 42 and air pad 402B is disposed on the lower surface side of the Y guide 42.

The three-dimensional coordinate measuring device 400 of Comparative Example 2 also has a driven-side left Y carriage 18L and its support part 50L that move in the Y direction following the driving-side right Y carriage 16. Here, the driven-side left Y carriage 18L and support part 50L and the driving-side right Y carriage 16 and support part 50 have a symmetrical shape.

A groove 40A and a Y guide 42A are formed on the left end side of the upper surface 10T of the base plate 10. The groove 40A and the Y guide 42A have a symmetrical shape to the groove 40 and the Y guide 42. The support portion 50L is supported by the Y guide 42A so as to be freely movable along the Y direction.

The driven side support portion 50L is supported by the Y guide 42A (base plate 10) via air pads 403T and 403B. Air pads 403T are arranged on the upper surface side of the Y guide 42A, and air pads 403B are arranged on the lower surface side of the Y guide 42A. The three-dimensional coordinate measuring device 400 of Comparative Example 2 can also be configured with an air pad arranged further to the left side of the Y guide 42A.

In the driven left Y carriage 18L, similar to the driving right Y carriage 16, if air pads 403T and 403B are placed on the top and bottom surfaces of the Y guide 42A, the sliding resistance increases in both the driving right Y carriage 16 and the driven left Y carriage 18L. As a result, in the three-dimensional coordinate measuring device 400 of Comparative Example 2, similar to the above-mentioned Comparative Example 1, when the Y carriage 14 is moved in the Y direction, the positional relationship in the Y direction between the right Y carriage 16 and the left Y carriage 18L is not constant, and there is a risk of a large yawing error due to, for example, swinging around the Z axis.

Therefore, in order to suppress yawing errors, it is preferable to clearly separate the side that controls the main drive operation from the side that follows that operation, as in the three-dimensional coordinate measuring device 1 of this embodiment. In other words, it is preferable for the right Y carriage 16 on the drive side to have a large sliding resistance so that it moves along the Y guide 42 even if only slightly, while the left Y carriage 18 on the driven side follows the drive side and supports it to the minimum extent that it does not resist its movement.

Figure 19 is a front view (front schematic view) showing the appearance of the three-dimensional coordinate measuring device 500 of Comparative Example 3. Note that in the three-dimensional coordinate measuring device 500 of Comparative Example 3, components that are the same in function and configuration as the three-dimensional coordinate measuring device 1 of this embodiment are given the same reference numerals and their description is omitted.

As shown in FIG. 19, the support unit 50 that supports the right Y carriage 16 on the drive side driven in the Y direction by the drive unit 501 is supported on the Y guide 42 (base plate 10) via air pads 502R, 502T, and 502L. Air pad 502R is disposed on the right side of the Y guide 42 of the base plate 10, air pad 502T is disposed on the upper surface side of the Y guide 42, and air pad 502L is disposed on the left side of the Y guide 42. Air pads 502R, 502T, and 502L are each provided at two positions along the Y direction.

In the three-dimensional coordinate measuring device 500 of Comparative Example 3, the driven left Y carriage 18, which moves in the Y direction following the driving right Y carriage 16, is supported slidably on the upper surface 10T of the base plate 10 via an air pad 503T.

The driving unit 501 is a shaft-type linear motor provided on the right side of the Y guide 42 (base plate 10). The driving unit 501 includes a movable element 501B of the shaft-type linear motor fixed to the support unit 50, a stator (shaft) 501C arranged parallel to the Y direction, and a fixing unit 501A that fixes both ends of the stator 501C to the right side of the Y guide 42.

In the three-dimensional coordinate measuring device 500 of Comparative Example 3, the scale 112 is provided on the right side of the Y guide 42 and the left side of the base plate 10.

In the three-dimensional coordinate measuring device 500 of Comparative Example 3, as in Comparative Example 1 described above, since no air pads are arranged facing the underside of the base plate 10, the right Y carriage 16 may swing around the X axis, causing a noticeable pitching error. In addition, as described in Comparative Example 1 above, due to changes caused by pitching errors, the balance of the sliding resistance of the right Y carriage 16 and the left Y carriage 18 becomes unbalanced on the left and right, and the load of the Y carriage 14 is divided approximately equally between the right Y carriage 16 and the left Y carriage 18. As a result, the yawing error may also worsen. Therefore, in order to reduce pitching errors and yawing errors, it is preferable to sandwich the upper and lower surfaces of the base plate 10 with air pads 62E, 62F, 68E, and 68F, as in the three-dimensional coordinate measuring device 1 of this embodiment, and provide a drive unit 80 between the upper and lower surfaces.

In the three-dimensional coordinate measuring device 500 of the comparative example 3, the fixed part 501A and the stator 501C constituting the drive part 501 of the shaft-type linear motor are provided on the right side of the Y guide 42 (base plate 10). When the fixed part 501A and the stator 501C are provided on the right side of the Y guide 42 (base plate 10) in this way, there is a risk that an installation error of the fixed part 501A and the stator 501C with respect to the base plate 10 occurs, or that the fixed part 501A and the stator 501C are distorted due to the bimetal effect caused by the difference in the thermal expansion coefficient of each. In this case, it is difficult to obtain measurement accuracy based on the base plate 10. For this reason, it is preferable to provide a drive part 80 having a roller 84 that abuts against the right side of the Y guide 42 (base plate 10) as in the three-dimensional coordinate measuring device 1 of this embodiment.

Furthermore, in the three-dimensional coordinate measuring device 500 of Comparative Example 3, the scale 112 is provided on the right side of the Y guide 42 and the left side of the base plate 10, and the distance from the measurement area on the top surface 10T of the base plate 10 where the measurement target is placed to the scale 112 becomes longer. As a result, the difference between the Y coordinate value of the position where the probe of the stylus 28 is actually placed and the Y coordinate value of the probe obtained from the Y coordinate value of the Y carriage 14 actually measured by the scale 112 becomes larger. In addition, the measurement accuracy of the Y coordinate value of the Y carriage 14 is likely to decrease due to the yawing direction vibration of the Y carriage 14, etc. Furthermore, when the scale 112 is installed on the periphery of the base plate 10, the scale 112 is easily affected by the ambient temperature because it is close to the outside air, and errors are also likely to occur due to the expansion and contraction of the scale 112 itself.

For this reason, it is preferable to provide the scale 112 on the left side 40L (see FIG. 3) of the groove 40 as in the three-dimensional coordinate measuring device 1 of this embodiment, and to shorten the distance from the measurement area on the top surface 10T of the base plate 10 where the measurement target is placed to the scale 112. By providing the scale 112 on the drive side (right Y carriage 16 side) and close to the measurement area, even if there is a yawing error, the error can be minimized. Note that if the scale is provided on the left side 40L perpendicular to the top surface 10T, even if dirt or dust falls from above the base plate 10, it will not land on the scale 112, and there will be no malfunction in reading the scale 112 due to dirt or dust.

Figure 20 is a front view (schematic front view) showing the appearance of the three-dimensional coordinate measuring device 1 of this embodiment. Figure 21 is a cross-sectional view (schematic cross-sectional view) along line XXI-XXI in Figure 20. Figure 22 is a top view showing the upper surface 10T of the base plate 10, and shows the arrangement of each air pad and the drive unit 80 provided on the Y carriage 14. The rectangular frame indicated by the two-dot chain line in Figure 21 indicates the position of the drive unit 80.

As shown in Figures 20 to 22, the three-dimensional coordinate measuring device 1 of this embodiment has the following differences 1 to 4 compared to the above comparative examples 1 to 3.

Difference 1: In the three-dimensional coordinate measuring device 1 of this embodiment, because the rotational moment caused by the drive unit 80 is applied to the Y-carriage 14, air pads are placed above, below, left, right, front and back of the part driven by the drive unit 80 so as to sandwich the drive unit 80. This makes it possible to reduce pitching and rolling errors.

Difference 2 is that in the three-dimensional coordinate measuring device 1 of this embodiment, the right Y carriage 16 on the driving side and the left Y carriage 18 on the driven side that follows (moves in a following manner) the movement of the right Y carriage 16 are clearly separated (asymmetrical structure), and the sliding resistance of the left Y carriage 18 on the driven side is made as small as possible. This suppresses oscillation around the Z axis when the Y carriage 14 is moved along the Y direction, thereby suppressing yawing errors.

In other words, in the three-dimensional coordinate measuring device 1 of this embodiment, in order to reduce yawing errors, the right Y carriage 16 on the driving side is configured to sandwich the base plate 10 (Y guide 42) from above, below, left and right. Furthermore, with the driving unit 80 at the center, air pads 62E, 64E, 66E, 68E and air pads 62F, 64F, 66F, 68F are arranged in front of and behind the driving unit 80 in the Y direction. Furthermore, the air pads 70 on the driven side are arranged only on the upper surface side of the base plate 10, and are arranged between the front and rear spaces of each air pad on the driving side in the Y direction. As a result, sliding resistance is concentrated on the driving side, and the driven side simply provides support.

22, the driven-side air pad 70 is positioned on the approximate opposite side of the base plate 10 with respect to the drive unit 80, and the line LX connecting the driven-side air pad 70 and the drive unit 80 is perpendicular to the line LY connecting the two pairs of air pads located before and after the drive unit 80. From another perspective, it is preferable to provide the drive unit 80 at the midpoint between the two pairs of air pads on the drive side, and also provide the driven-side air pad 70 at the midpoint between the two pairs of air pads on the drive side.

As a third difference, the three-dimensional coordinate measuring device 1 of this embodiment is provided with a drive unit 80 having a roller 84 that contacts the right side surface of the Y guide 42 (base plate 10). This prevents installation errors in the drive unit 80 and distortion due to the bimetal effect from occurring in the drive unit 80, unlike comparative example 3, and therefore provides measurement accuracy based on the base plate 10.

Difference 4: In the three-dimensional coordinate measuring device 1 of this embodiment, a scale 112 is provided on the left side surface 40L of the groove 40, and the distance from the measurement area on the top surface 10T of the base plate 10, where the measurement object is placed, to the scale 112 is shortened. This improves the measurement accuracy.

In the above embodiment, the Y guide 42 is formed by a groove 40 formed on the top surface 10T of the base plate 10, but the Y guide may be formed by other methods.

Figure 23 is a schematic front view of another embodiment of a three-dimensional coordinate measuring device 1A that includes a Y guide 42Z different from the embodiment described above. As shown in Figure 23, a convex portion that is convex in the Z direction and extends in the Y-axis direction is formed on the right end of the upper surface 10T of the base plate 10 in the figure (the end facing the right Y carriage 16). This convex portion forms a Y guide 42Z that supports the right Y carriage 16 so that it can move freely in the Y-axis direction. The three-dimensional coordinate measuring device 1A has basically the same configuration as the three-dimensional coordinate measuring device 1 of the embodiment described above, except for the fact that it includes a Y guide 42Z.

In this way, it is also possible to form the Y guide 42Z using a convex portion. Here, if the Y guide 42Z is formed from a material different from that of the base plate 10, for example, the thermal conductivity of the base plate 10 and the Y guide 42Z will differ, and the Y guide 42Z may be deformed. Also, if the base plate 10 is slightly warped, it may not be possible to perform measurements based on the base plate. For this reason, it is preferable to form the Y guide 42 using a groove 40, as described in the above embodiment.

1...three-dimensional coordinate measuring device, 10...base plate, 10B, 20B, 42B, 202B...lower surface, 10R, 24R, 40R, 42R, 250R...right side surface, 10T, 20T, 42T, 202T...upper surface, 12...frame, 14...Y carriage, 16...right Y carriage, 18...left Y carriage, 20...X guide, 20E, 24E, 202E, 250E...rear surface, 20F, 24F, 202F, 250F...front surface, 22...Z column, 24...Z carriage, 24L, 40L, 42L, 250L...left side surface, 26...measuring probe, 28...stylus, 40...groove, 4 0B... bottom surface, 42... Y guide, 50, 200... support part, 52... base end, 54... right side, 56... left side, 58... tip, 58A... support plate, 62E, 62F, 64E, 64F, 66E, 66F, 68E, 68F, 70, 210, 212, 214, 216, 260, 262, 264, 266... air pad, 80, 220, 270... drive part, 82, 222, 272... motor, 84, 224, 274... roller, 110... linear encoder, 112... scale, 114... optical sensor, 202... X guide insertion hole, 250... Z carriage insertion hole

Claims (1)

A surface plate on which an object to be measured is placed;
a Y carriage that straddles the base plate and moves in a Y-axis direction of the base plate, the Y carriage having a first support member with a drive mechanism that drives the Y carriage in the Y-axis direction, and a second support member that moves following the first support member;
a Y guide that is provided on the first support member side of the base plate and is formed integrally with the base plate and is parallel to the Y axis direction;
a first side surface support portion provided on the first support member and sandwiching both side surfaces of the Y guide to guide the movement of the first support member in the Y axis direction;
an X guide provided on the Y carriage, the X guide spanning upper ends of the first support column member and the second support column member and extending in the X-axis direction;
an X-axis direction moving mechanism that supports the measurement probe and moves the measurement probe in the X-axis direction along the X guide;
a scale provided on the first support member and configured to measure a position of the Y carriage moving in the Y-axis direction;
Equipped with
the X-axis direction movement mechanism has second both-side support parts that sandwich both side surfaces of the X guide and guide the movement of the X-axis direction movement mechanism in the X-axis direction,
the Y guide is formed on the base plate at a groove formed on an upper surface of the base plate,
A three-dimensional coordinate measuring device in which, when the area on the top surface of the base plate on which the object to be measured is placed is defined as the measurement area, the scale is provided on the side of the groove on the measurement area side within the inner surface of the groove.

Images