JPH0339607B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is applicable to a three-dimensional device that measures the shape, dimensions, etc. of an object to be measured using signal data from a measuring device through relative movement between a probe and an object to be measured. The present invention can be used to improve measurement accuracy, especially for measuring machines that employ a two-stage measurement method.

[Background Art and Problems Therein] Measuring machines are known that measure the shape, dimensions, etc. of a workpiece by moving a measuring head and a workpiece relative to each other and processing output signal data from a measuring device in a prescribed manner. Compared to conventional micrometers, calipers, etc., they have features such as higher accuracy, faster measurement speed, and the ability to measure complex shapes, so they are becoming widespread in the measurement fields of various industries.

FIG. 4 shows a conventional three-dimensional measuring machine that is such a measuring machine. A mounting board 32 is placed on the base 31, and a gate-shaped probe support 33 is mounted on this mounting board 32 for placing the object to be measured. A slider 35 is provided on the cross beam member 34 which is a component of the measuring element support 33, and a measuring element 37 is provided at the lower end of a spindle 36 which is attached to the slider 35 so as to be movable in the vertical direction. The probe 37 is displaced in the Y-axis direction as the probe support 33 moves along the guide rail 38, and is displaced in the X-axis direction as the slider 35 moves along the crossbeam member 34. Spindle 36 is slider 3
By moving up and down with respect to 5, it is displaced in the Z-axis direction. The above mounting plate 32, measuring element support 33,
The measuring head 3 is controlled by the slider 35, spindle 36, etc.
A moving mechanism is configured to move 7 relative to the object to be measured, and the amount of movement in three orthogonal axes directions of the Y-axis, X-axis, and Z-axis is measured by measuring devices 39, 40, and 41, respectively.

The moving mechanism moves the measuring stylus 37 relative to the object to be measured. The amount of movement displacement of the measuring stylus 37 with respect to the measuring point or the coordinates of this measuring point from the origin are determined by the measuring devices 39, 40,
41, and these measuring devices 39, 40,
The output signal data from 41 is subjected to predetermined processing in an arithmetic processing unit, for example, arithmetic processing for determining the average coordinates of a plurality of points to be measured from the origin, and the shape, dimensions, etc. of the object to be measured are measured.

There are two types of operating methods for the moving mechanism: a manual type in which the operator manually pushes the measuring element support 33, etc., and an automatic type in which the measuring element support 33 and the like are provided with a drive means such as a motor and are automatically moved. It becomes possible to automatically measure a plurality of measurement points of an object under program-based computer control.
Furthermore, the three-dimensional measuring machine shown in FIG. 4 was of the type in which the probe 37 moved relative to the mounting plate 32 on which the object to be measured was placed, but the probe was stationary and the mounting plate was moved. There are several types, and there is also a type that moves both the probe and the mounting plate.

The measurement accuracy of the above measuring device is determined by the accuracy of the measuring device. This measuring device is constructed by extending in the measuring direction a long scale in which minute light-transmitting parts and non-light-transmitting parts are alternately formed in a checkered pattern, thereby achieving a high level of measurement accuracy. In order to achieve this, it is necessary to form this scale finely and accurately over the entire measurement stroke. However, in reality, it is technically difficult to make a long scale without errors such as accumulation, and even if such a scale is made, the measurement stroke may be affected during use due to external factors such as assembly and adjustment work. It is difficult to achieve uniform accuracy over the entire length. These problems become more common as the measuring device becomes larger.
That is, the problem becomes more noticeable as the measurement stroke becomes larger, and there is a certain limit to the measurement accuracy that can be improved.

Furthermore, when the moving mechanism is operated by computer control as described above, and this moving mechanism is controlled by a feedback signal from a measuring device, the moving mechanism may adjust the permissible displacement stroke of the probe due to an error in the scale. Problems may arise, such as the probe operating beyond the limit or stopping the probe before it reaches a predetermined position.

Furthermore, as mentioned above, if the scale is minutely formed over the entire measurement stroke, the relative movement speed between the measuring point and the object to be measured by the moving mechanism must be kept below a certain value in order to prevent scale reading errors. Therefore, it is not possible to improve the measurement work.

[Object of the Invention] The present invention has been made by focusing on the fact that the above-mentioned conventional problems occur because both the coarse range and the narrow range in one direction are measured by the same measuring device. be.

An object of the present invention is to eliminate the need for finely and precisely forming the scale of a measuring device that detects the amount of relative movement displacement between the measuring tip and the measured point of the object to be measured, and to improve the accuracy of the measuring device. To provide a measuring machine that is easy to manufacture and can obtain a high degree of measurement accuracy even if the measuring stroke is large.

[Means and effects for solving the problem] Therefore, the configuration of the present invention includes a moving mechanism for relatively moving the measuring point and the object to be measured, and a relative movement displacement between the measuring point and the measuring point of the object to be measured. A measuring device that detects the quantity or the coordinates of the measured point, and arithmetic processing that calculates the shape, dimensions, etc. of the measured object by predetermined processing of the output signal data of this measuring device when the measuring head and the measured object come into contact. A measuring device comprising: a scale that is attached to either the movable side or the stationary side of the moving mechanism and has contact surfaces arranged at a constant pitch in the measurement direction; a first detector that detects an integral multiple of the pitch of these contact surfaces; and a contact that is attached to the other of the movable side and the stationary side of the moving mechanism and contacts the contact surfaces. It has the resolution to measure the length of the pitch in minute units of subdivision using this contact surface as a reference point, and the contact within the pitch when movement by the moving mechanism starts and ends. The second step detects the movement start point and movement end point from the plane.
and a detector, and the arithmetic processing unit adds and subtracts the output signal data of the first and second detectors to calculate the amount of relative movement displacement or the amount of displacement between the measuring tip and the part to be measured of the object to be measured. The method is characterized in that the predetermined process is performed after determining the coordinates of the measurement point, and the measuring device is configured to perform two-stage measurement using a first detector for coarse range detection and a second detector for narrow range detection. method.

[Example] FIG. 1 shows a measuring machine according to this embodiment, and this measuring machine is a three-dimensional measuring machine of a type in which a measuring point moves.

Rail members 2 are horizontally attached to the left and right side surfaces 1B and 1C of the mounting board 1, on which the object to be measured is placed on the upper surface 1A, with mounting members 3, and these rail members 2 extend in the longitudinal direction of the mounting board 1. It extends in the Y-axis direction. The gauge head support 5 that supports the gauge head 4 is gate-shaped and consists of left and right columns 6, 7, and a crossbeam member 8 installed across the top of these columns 6, 7. A rolling member such as a roller is disposed inside the legs 6A, 7A, and this rolling member engages with the rail member 2 in a rolling manner, so that the weight of the probe support 5 is supported by the rail member 2. It is designed to be able to move in the Y-axis direction while being moved.

A slider 9 is slidably attached to the cross beam member 8, and a spindle 11 is provided in a spindle case 10 that is integrated with the slider 9 so as to be movable in the vertical direction. Child 4 is provided.

The gauge head support 5 moves along the rail member 2 to move the gauge head 4 in the Y-axis direction, and the slider 9 slides along the crossbeam member 8 to move the gauge head 4 in the X-axis direction. Accordingly, movement of the measuring head 4 in the Z-axis direction is performed by moving the spindle 11 up and down with respect to the spindle case 10, respectively.

A screw shaft 12 formed by a ball screw is provided on the side surface 1B of the mounting board 1 in parallel with the rail member 2. Both ends of the screw shaft 12 are rotatably supported by bearing members 13 and 14, and one end of the screw shaft 12 is supported by bearing members 13 and 14. There is a mounting board 1
A drive shaft 16A of a motor 16 mounted on a bracket 15 is connected to the side surface 1B of the motor. Screw shaft 12
inserts the leg 7A of the support column 7, and
Since a nut member that is screwed onto the screw shaft 12 is disposed, when the screw shaft 12 is rotated by the motor 16, the probe support 5 moves in the Y-axis direction by the screw feeding action of the screw shaft 12. Slider 9
The movement in the X-axis direction with respect to the cross beam member 8 and the movement in the Z-axis direction of the spindle 11 with respect to the spindle case 10 may also be automatically fed by a driving means such as a motor, similarly to the movement in the Y-axis direction.

The above mounting plate 1, probe support 5, slider 9, spindle 11, screw shaft 12, motor 16
A moving mechanism 17 is configured to move the measuring stylus 4 in three orthogonal directions of the X-axis, Y-axis, and Z-axis with respect to the object to be measured placed on the upper surface 1A of the mounting plate 1.
etc. constitute the stationary side of the moving mechanism 17, and the probe support 5 etc. constitute the movable side.

In this embodiment, the probe 4 is a touch signal type probe, and outputs a touch signal by coming into contact with a predetermined location of the object to be measured.

As shown in FIG. 2, a pulse generator 18 is connected to the motor 16, and this pulse generator 18 generates pulses corresponding to the number of rotations of the motor 16. As shown in FIG. 3, the pulse generator 18 is connected to a first detector 19, and the first detector 19 counts the number of pulses generated by the pulse generator 18 to move the probe support 5 over a large stroke. It has a function to detect with coarse resolution. As shown in FIG.
A scale 20 parallel to is provided, and this scale 20 is held by holders 21 and 22 at both ends. This scale 20 is constructed by, for example, connecting two types of block gauges, long and short, in the thickness direction, and as shown in FIG.
mm) vertical contact surfaces 20A are provided in parallel in the Y-axis direction.

As shown in FIG. 1, a communication groove 21 for inserting the scale 20 is formed in the leg portion 7A of the column 7 of the gauge head support 5, and movement of the gauge head support 5 in the Y-axis direction is ensured. In addition, as shown in FIG. 2, a second detector 22 is disposed inside the leg portion 7A. This second detector 22 has a lever-type contactor 22A that contacts the contact surface 20A of the scale 20. As shown in FIG. 3, the second detector 22 is connected to the arithmetic processing unit 23 together with the first detector 19,
A measuring device 24 includes the first detector 19, the second detector 22, the scale 20, and the like.

The first detector 19 is the pulse generator 18
By counting the number of pulses generated at
It is detected how many integral multiples of the pitch t is. On the other hand, the second detector 22 has a measurement range that is the same as or larger than the pitch t of the contact surface 20A, and uses the contact surface 20A as a reference point to measure the length of the pitch t in minute units of subdivision. It has a resolution for measurement and detects the movement start point and movement end point from the contact surface 20A within the pitch t when the movement of the probe support 5 starts and ends. For this reason, the first detector 19 is used for coarse range detection to measure on a large scale how many integer multiples of the pitch t the amount of movement corresponds to, and the second detector 22 is used for coarse range detection to measure how many integral multiples of the pitch t the amount of movement corresponds to. The measurement device 24 is used for narrow range detection to measure quantities in small scales, and the measurement device 24 has a two-stage measurement configuration using first and second detectors 19 and 22.

From the above, it is sufficient for the scale 20 to form the contact surface 20A with a certain pitch t through precision machining.
It is not necessary to finely and accurately form scales in minute units below the pitch t, and fine precision over the entire measurement stroke is not required, and the amount of movement below the pitch t can be accurately measured by the second detector 22 with high resolution. can be measured. Therefore, even if the measurement stroke becomes large, it is only necessary to divide the scale 20 into sections at a constant pitch, which simplifies production, prevents errors such as accumulation, and improves measurement accuracy. be able to.

Note that the distance between the contact surfaces 20A of the scale 20 may have a relatively small error with respect to the accurate pitch t, so in consideration of such cases, the distance between each contact surface 20A from the reference point is adjusted. Surface 20A
The distance is precisely measured in advance, and the error due to this measurement result is stored in the storage device 25 shown in FIG.

In this example, the measurement station for Y-axis direction measurement is the first one.
Although a two-stage measurement method using a second detector and a second detector is adopted, this may be performed for measuring devices for measuring in the X-axis direction and for measuring in the Z-axis direction. i.e. X axis, Y axis
All of the three measuring devices provided corresponding to the axis and the Z-axis may be a two-stage measuring device including a first detector and a second detector.

The motor 1 is driven by the drive circuit 26 shown in FIG.
6 is driven, the probe support 5 moves due to the screw feeding action of the screw shaft 12, and this movement continues until the probe 4 comes into contact with the measuring point of the object to be measured and outputs a touch signal. , this signal is input to the drive circuit 26 to stop the motor 16. In addition,
During this movement, the scale 20 is lowered and the second
The contacts 22A of the detector 22 may be prevented from hitting the scale 20. In other words, the holders 21 and 22 that hold the scale 20 are provided with the function of raising and lowering the scale 20, and the scale 20 is raised only during measurement work, and the second detector 2
The second contactor 22A may be brought into contact with the contact surface 20A.

The number of pulses generated by the pulse generator 18 due to the drive of the motor 16 is detected by the first detector 19, and as a result, the amount of movement of the probe support 5 can be determined by one pitch t.
is detected as the smallest unit. This detected amount is n×
Let it be t. Also, let the indicated value of the second detector 22 before movement be m ₀ and the indicated value after movement be m ₁ . m ₁ −
m ₀ represents a fraction of the amount of movement of the measuring element support 5 less than or equal to the pitch t, that is, an accurate amount of movement of the measuring element support 5 less than or equal to the pitch t. Here, the second
Scale 2 that contacts 22A of the detector 22
Let Δln be the error with respect to the exact distance n×t between the two contact surfaces 20A.

Note that, for example, two second detectors 22 are provided, shifted by half of one pitch t, and the scale 20 is placed on the convex portion 20.
B. By forming two recessed portions 20C shifted by half of one pitch, measurement by the second detector 22 is possible at any stop position of the probe support 5. In addition, when the probe support 5 is configured to be manually movable, the contact 22A of the second detector 22 is moved to the scale 20 using the overstroke of the probe 4, which is a touch signal type probe.
The movement of the probe support 5 may be stopped at a position that coincides with the recess 20C.

As mentioned above, the contact point 4
When a touch signal is output from the touch signal, this output signal is also input to the arithmetic processing unit 23 as shown in FIG. This input signal becomes a command signal for inputting the measurement data of the first detector 19 and the second detector 22 to the arithmetic processing unit 23, and based on the input of these data and the data stored in the storage device 25. The data of Δln is also input. As a result, in the arithmetic processing unit 23, the first detector 1
9, the output signal data from the second detector 22 and the storage device 25 are added and subtracted. The result of this addition and subtraction indicates the amount of movement of the probe support 5, that is, the displacement L of the probe 4, and L=(n×1)+(m ₁ −m ₀ )+△ln. In the original measuring machine, the amount of movement displacement of the measuring stylus 4 or the coordinate position of the measuring point from the origin to the measuring point of the measuring object is determined, and then the arithmetic processing unit 23 calculates, for example, the average coordinate position of the plurality of measuring points. Predetermined processing is performed on the measured values to determine the center position of the hole, and the results of this processing are displayed on the display 27 to measure the shape, dimensions, etc. of the object to be measured.

In the above, the drive circuit 26 for driving the motor 16 can be configured to be activated by a switch operation by an operator, but it can also be configured to be activated by computer control based on a program. When computer control is adopted in this way, when there are many points to be measured on the object to be measured, there are advantages such as being able to quickly measure the points to be measured in the order according to the program. The moving mechanism 17 can be controlled by feeding back the output signal data of the first detector 19 and the like.

Note that when the error of any contact surface 20A of the scale 20 from the reference point is a negligible amount, the data in the storage device 25 may become zero.

In this embodiment, the scale 20 is attached to the mounting plate 1 constituting the stationary side member of the moving mechanism 17, and
Although the detector 22 was attached to the measuring element support 5 constituting the movable side member, these may be reversed. Further, the first detector may not be a pulse counter as in this embodiment, but may be one that optically or magnetically reads a scale with a constant pitch, and this also allows the scale to be read over the entire measurement stroke. This eliminates the need for detailed and precise manufacturing, and since this scale does not have minute graduations, there is no need to solve the problem of reading errors, and the relative movement speed between the probe and the object to be measured can be adjusted. can be increased.

The present invention is applicable not only to a three-dimensional measuring machine in which the measuring point moves and the object to be measured is stationary as in this embodiment, but also to a type of measuring device in which the measuring point is stationary and the object to be measured moves, or to a type of measuring device in which the measuring point is stationary and the object to be measured is moving. It can also be applied to measuring machines in which both objects move, and if necessary, it can be applied to measuring machines in which the measuring head and the object to be measured move relative to each other, and the moving mechanism causes relative movement between the measuring head and the object to be measured. Any configuration may be used as long as it allows for this. Furthermore, the present invention can be applied not only to a three-dimensional measuring machine but also to a two-dimensional measuring machine or a measuring machine in which the probe and the object to be measured move relative to each other only in one axis direction.

[Effects of the Invention] According to the present invention, it is no longer necessary to finely and precisely form the scale of the measuring device that detects the amount of relative displacement between the contact point and the measured point of the object to be measured over the entire measurement stroke. Therefore, the measurement station is easy to manufacture and the measurement accuracy can be improved even if the measurement stroke becomes large.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the coordinate measuring machine according to this embodiment, Fig. 2 is a diagram showing the configuration of the measuring device and movement by the moving mechanism, and Fig. 3 is a diagram showing the connection state of the measuring device, arithmetic processing device, etc. The block diagram and FIG. 4 are perspective views showing a conventional example. DESCRIPTION OF SYMBOLS 1... Mounting board, 4... Measuring element, 5... Measuring element support, 17... Moving mechanism, 19... First detector,
20...Scale, 20A...Contact surface, 22...
Second detector, 23... arithmetic processing device, 24... measurement device.

Claims (1)

[Scope of Claims] 1. A moving mechanism for relatively moving a measuring point and an object to be measured, and a measuring device for detecting the amount of relative movement displacement between the measuring point and a point to be measured of the object to be measured or the coordinates of the point to be measured. , a measuring device equipped with an arithmetic processing device for calculating the shape, dimensions, etc. of the object to be measured by processing the output signal data of the measuring device in a predetermined manner when the measuring head and the object to be measured come into contact; , a scale that is attached to either the movable side or the stationary side of the moving mechanism and has contact surfaces arranged at a constant pitch in the measurement direction, and the amount of movement by the moving mechanism is an integer of the pitch of these contact surfaces. a first detector for detecting whether the pitch is doubled, and a contact element attached to the other of the movable side and the stationary side of the moving mechanism and in contact with the contact surface, and the pitch is adjusted using the contact surface as a reference point. It has the resolution to measure the length in minute units of subdivision, and detects the start point and end point of movement from the contact surface within the pitch when movement by the movement mechanism starts and ends. a second detector;
After the arithmetic processing unit adds and subtracts the output signal data of the first and second detectors to obtain the amount of relative movement displacement between the probe and the measuring point of the object to be measured or the coordinates of the measuring point, A measuring device characterized in that it is configured to perform predetermined processing. 2. In claim 1, the movement mechanism has a movement function in three orthogonal axes directions: the X-axis, the Y-axis, and the Z-axis, and the measuring device
A measuring device characterized in that there are three measuring devices corresponding to the Y-axis and the Z-axis, and all of these measuring devices include the first and second detectors.