JPH08110220A - Measuring element replaceable measuring head and automatic size measuring device equipped with the same - Google Patents

Abstract

PURPOSE: To measure numerous kinds of sizes with a measuring head with a measuring unit replaced by removably fixing the measuring unit to a measuring head body. CONSTITUTION: A measuring unit 40 including a measuring element 48 is removably fixed to a measuring head body 20 incorporating a detection sensor 36. That is, three pairs of chuck balls 29 on a side of the body 20 and three cylinders 42 on a side of the unit 40 are engaged with one another to have the unit 40 positioned on the body 20. At the same time, a removable piston 20 and a removable cylinder 25 of the body 20 and a chuck ring 43 of the unit 40 operate to fix or release the unit 40. Therefore, according to a change in measurement, only the unit 40 can be replaced. A measuring unit including four elements 48 is mainly used for measuring a hole diameter while a unit including an element 48 is used for measuring a point (end face, hole depth, etc.), wherein when the signal element 48 is used, only one of the four sensors 36 is used. Therefore numerous kinds of sizes can be measured by a single measuring head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring head for measuring the size of an object to be measured (hereinafter referred to as "workpiece") and a measuring apparatus equipped with the measuring head, and particularly to various types of dimensions by exchanging a probe. The present invention relates to a stylus-interchangeable measuring head that can measure a workpiece with a single measuring head, and further relates to an automatic dimension measuring device that includes the measuring element and that automatically measures the dimension of a workpiece.

[0002]

2. Description of the Related Art As a measuring device for automatically measuring dimensions such as hole diameter, shaft diameter, hole center distance, hole depth, etc. of a work, a dedicated measuring machine specially designed for the relevant work and various A measuring head interchangeable measuring machine that can measure some kinds of workpieces by automatically replacing the measuring heads, and a coordinate measuring machine that can measure many kinds of workpieces with one measuring head are known. There is.

In this case, an analog sensor such as a differential transformer is generally used as a measuring head of a dedicated measuring machine or a measuring head exchange type measuring machine, and a comparative measuring system based on a master gauge is adopted. Since the measurement accuracy of an analog sensor such as a differential transformer is generally inversely proportional to the measurement range, the measurement range cannot be set so wide in order to increase the measurement accuracy.

Further, as shown in FIGS. 19 and 20, a posture error occurs when the contacting posture of the measuring element with respect to the work changes with respect to the time of measuring the master gauge. 19 and 20.
In each case, the hole diameter is measured. FIG. 19 shows a case where the probe 101 is displaced in the radial direction, and FIG. 20 shows a probe 101.
Is when it is tilted in the axial direction. Assuming that the measurement diameter is U and the deviation amount is ε in FIG. 19, the measurement value Ua is as follows. Ua ² = U ² -4ε measured at ² 20 diameter V, when the inclination theta, measured value Va is as follows. Va = V / cos θ For this reason, for example, when measuring the hole diameter, a guide shaft having an outer diameter slightly smaller than the lower limit of the tolerance of the hole diameter is used as the probe 1.
It is provided in the vicinity of 01 and is inserted into the work together with the probe 101.

Therefore, since the measurement range cannot be wide and the guide shaft is required,
The measuring head is specially designed according to the measurement content. It should be noted that these measuring heads generally include two measuring heads 101.
Is in contact with the workpiece at the same time, and the measurement can be performed with one operation (insertion into the hole if the diameter is the hole diameter). Hereinafter, the measuring head described here will be referred to as a dedicated measuring head.

In the dedicated measuring machine, the above-mentioned dedicated measuring heads are attached to all the measuring positions, so that the measuring time can be the shortest among the above-mentioned three types of measuring machines.

Examples of the measuring head exchange type measuring machine are disclosed in Japanese Patent Application Laid-Open No. 4-005510 (measuring machine) disclosed by the present applicant, and in Japanese Patent Application Laid-Open No. 4-005510 disclosed by other applicants. 74902 (automatic inner diameter measuring device and zero setting method therefor) "and" JP-A-4-74903 (automatic measuring device) ".

In the one disclosed in Japanese Patent Laid-Open No. 4-005510, a detector mounting portion is horizontally provided on a horizontal arm type three-dimensional moving mechanism to support it in a three-axis direction so that it can move in a plurality of axial directions. A detector changer for accommodating the above detector is provided, and the detector corresponding to the measurement content of the target work is taken out from the detector changer and attached to the detector mounting portion for measurement. In this case, the detector used,
That is, the measuring head is the above-described dedicated measuring head, and the dedicated measuring head that can measure not only the hole diameter but also the distance between the centers of the holes is used.

Further, those disclosed in "JP-A-4-74902" and "JP-A-4-74903" are as follows.
The attachment / detachment device is provided downwardly on a three-dimensional moving means (having a built-in three-axis length measuring means) such as a fixed bridge type (table moving type) to support it so as to be movable in three axis directions, and at the same time, a measuring head (inner diameter). A stocker for accommodating a measurement gauge head or a contact probe is provided, and the measurement head (inner diameter measurement gauge head or contact probe) corresponding to the measurement content of the target work is taken out from the stocker and attached to a detachable device for measurement. In this case, of the measuring heads, the inner diameter measuring gauge head is the dedicated measuring head described above, which measures the inner diameter of the workpiece, and the contact probe is the touch probe described below. Measure distance etc.

In the coordinate measuring machine, a touch probe (an electronic probe that outputs a signal at the moment of contact with a work) as a measuring head is orthogonal to two axes, or is orthogonal to each other.
Each axis is supported so as to be movable in the axial direction, and each axis is provided with length measuring means for detecting the coordinate position of the touch probe, and the data of the coordinate position of the touch probe when the touch probe is brought into contact with the measurement position of the workpiece is calculated. To measure the dimensions of the work piece. In this case, it is not a comparative measurement method based on the master gauge but an absolute measurement method based on the length measuring means itself. It is versatile and generally cheaper than dedicated measuring machines and measuring head exchange type measuring machines.

[0011]

However, since the dedicated measuring machine must be newly designed and manufactured when the measurement content (type of measurement item or type of measurement size) changes, it is difficult to cope with the change of measurement content. However, there is a problem that the cost is high because the driving means for the measuring head is required for the number of measuring positions.

[0012] In addition, "Japanese Patent Laid-Open No. 4-005510" introduced as an example of the measuring head exchange type measuring machine and "Japanese Patent Laid-Open No. 4-5104".
-74902 "and" JP-A-4-74903 ",
The number of measurement heads required for the number of measurement contents is higher than that of a coordinate measuring machine, and the measurement heads need to be replaced frequently, which requires a longer measuring time for a dedicated measuring machine. There is.

Furthermore, since the coordinate measuring machine can measure the measuring position of the work piece by point, it takes a longer measuring time than a dedicated measuring machine using a dedicated measuring head or a measuring head exchange type measuring machine (for example, hole diameter). Since three or more points are required to determine the value, the touch probe must be contacted three or more times).

The present invention has been made in view of the above circumstances, and provides a measuring head capable of handling a large number of measurement contents at a low price, and using the measuring head, a short measuring time and a low-priced automatic dimension. An object is to provide a measuring device.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention collects a measuring element into a measuring element unit for hole diameter measurement, point measuring, etc. Is replaced, and the measurement range of one type of probe is widened by using a detection sensor with a wide measurement range.

That is, the measurement head includes: (a) a measurement head main body having a built-in detection sensor; and (b) a probe having one end abutting against the workpiece and the other end abutting the detection sensor. A sub-unit, (c) positioning means for deciding the mounting position of the stylus unit with respect to the measuring head main body, and (d) an attaching / detaching means for fixing the stylus head unit to the measuring head main body and releasing the measuring head unit from the measuring head main body. , Composed of.

In this case, the positioning means is a set of two conductive spheres, one set for each of the two engaging surfaces on which one of the measurement head main body and the tracing stylus unit engages, and the insulating portion on the other side. They are fixed at intervals of about 120 degrees on the circumference of the circle, and three conductive cylinders are fixed to the insulating part of the other surface at positions corresponding to three sets of spheres, and three sets of spheres and three If all three contact points consisting of the cylinder contact each other, 3
A contact circuit for outputting a signal when the pair of spheres are electrically connected is provided.

Further, the detection sensors were digital length measuring sensors, and four sensors were provided on the same circumference at central angle intervals of about 90 degrees.

Further, escape means for moving the tracing stylus in the direction opposite to the measuring direction are provided at four locations near the detection sensor of the measuring head body.

Further, one kind of the tracing stylus unit (stylus tracing unit 40) is positioned on the measuring head main body by the positioning means and the mounting / dismounting means, and the tracing stylus can be swung freely on the unit base. 4 support mechanisms are provided on the same circumference at a center angle of about 90 degrees, and one end of the probe contacts the work and the other end contacts the detection sensor. The measurement direction is set so as to be away from each other, and a biasing unit that biases the tracing stylus in the measurement direction is provided.

The other type of the tracing stylus unit (stylus tracing unit 60) is positioned on the measuring head main body by the positioning means and the mounting / dismounting means, and the tracing stylus can be swung freely on the detachable unit base. One leaf spring support mechanism is provided to support one end, and one probe is configured so that one end contacts the work and the other end contacts the detection sensor.

Further, in order to achieve the above-mentioned object, the present invention supports (a) an automatic dimension measuring device by movably supporting the measuring element exchangeable measuring heads in three axial directions orthogonal to each other and automatically driving them. In addition, a three-dimensional coordinate measuring machine equipped with a length measuring means for detecting the three-dimensional coordinate position of the probe-interchangeable measuring head, and (b) a probe-interchangeable measuring head supported by the three-dimensional coordinate measuring machine. A measuring head main body, (c) at least one tracing stylus unit 40, (d) at least one tracing stylus unit 60, and (e) a plurality of tracing stylus provided on a fixed part of the three-dimensional coordinate measuring machine. The measuring element storage rack for storing the unit and (f) a master gauge provided on a fixed portion of the three-dimensional coordinate measuring machine and serving as a standard for calibrating the measuring element exchange type measuring head.

[0023]

According to the measuring element exchangeable measuring head of the present invention, the measuring element unit having the measuring element is detachably attached to the measuring head body having the built-in detection sensor, and the measuring element changes when the measurement content changes. Only the unit is replaced. In this case, the tracing stylus unit and the measuring head main body are positioned by the three spherical bodies, one set of two fixed to one surface, and the three cylindrical bodies fixed to the other surface, which are fixed to each other. At the same time, it is fixed or released by the attaching / detaching means, and when all three contact points come into contact, a positioning confirmation signal is output.

In addition, the measuring head unit 40 having four measuring heads
Is mainly used for hole diameter measurement, and a single probe head unit is used for one-point measurement (end face, hole depth, etc.). Although four detection sensors are provided, in the case of the one tracing stylus unit 60, only one detection sensor is used. Since a digital length measuring sensor is used as the detection sensor, it is possible to measure a wide range with one type of probe unit.

Further, according to the automatic dimension measuring apparatus according to the present invention, a plurality of tracing stylus units are stored in advance in the storage rack. However, even if the dimension to be measured or the measuring position is changed, the measurement item of the workpiece and the measurement are performed. As long as the dimension is within the measurement target range of the tracing head unit, measurement is continued with the tracing head unit as it is. When the measurement item changes or the measurement size is out of the measurement target range of the probe unit, the probe unit is replaced. The measuring head is calibrated by the master gauge for each tracing head unit. Each measured value of the work is calculated from the value detected by the detection sensor of the measuring head and the value detected by the length measuring means of the three-dimensional coordinate measuring machine.

[0026]

EXAMPLES Preferred examples of the measuring head according to the present invention will be described below. Example 1 of Measuring Head FIGS. 1 to 5 show Example 1 of the measuring head according to the present invention. In the first embodiment, the measuring head has a measuring head unit 20 in which a tracing stylus unit 40 mainly for measuring a hole diameter is mounted. In FIG. 1, the tracing stylus unit 40 is a measuring head main body 2
FIG. 2 shows a state in which the cover 55 is removed, FIG. 2 is a state in which the cover 55 is removed in the A arrow view (front view) of FIG. 1, and FIG. 3 is a portion corresponding to the BB cross section of FIG. FIG. 4 is a diagram schematically showing a contact circuit by unfolding a portion, FIG. 4 is a diagram showing a state in which the tracing stylus unit 40 is removed from the measuring head main body 20, and FIG. 5 is a measurement in a state where the tracing stylus unit 40 is not attached. It is a figure which shows the head main body 20.

First, the measuring head body 20 will be described. 1, 3 and 5, the leg 21a has a circular outer shape.
The base 21 having a circular outer shape is attached to the mounting base 21 on which the
Are fixed by screws or the like, and four detection sensors 36 are attached at four locations in the vicinity of the outer periphery of the main body base 22 at central angle intervals of about 90 degrees on the same circumference. The detection sensor 36 is a digital length measuring sensor. The digital length-measuring sensor referred to in this specification is a sensor in which a scale is provided with an optical or magnetic scale and the measured length is obtained by counting the scale. Since the accuracy is almost the same, it is also used as the length measuring means of a three-dimensional coordinate measuring machine.

On the side of the tracing stylus unit 40 of the main body base 22 (hereinafter, referred to as “F direction” or “F side”), two pieces are provided at intervals of about 120 degrees on the same circle inside the detection sensor 36. Three sets of conductive spheres 23 sandwiching a cylindrical body 42, which will be described later in a set, are fixed. The portion to which the spheres 23 are fixed is electrically insulated from the others, and as shown in FIG. 3, the six spheres 23 are separated from each other by the space between the spheres 23 adjacent to each other except two which sandwich the cylinder 42. The electric wire 24a is connected to the power supply 24b, and the power supply 24b and the signal output unit 24c are connected to form a contact circuit 24.

A removable cylinder 25 is fixed to the center of the main body base 22, one end of the removable cylinder 25 is covered with a cap 26, and compressed air is supplied from the cap 26 side. Detachable piston 27 in detachable cylinder 25
Is provided slidably, and the attachment / detachment piston 27 is attached by a compression spring 28 to the Y spindle 15 side (hereinafter, “G direction” or “G side”) of the three-dimensional coordinate measuring machine 10 described later.
Is called). In addition, at least two holes formed on the same circumference of the tip of the detachable piston 27 are provided with chuck spheres 29 that are movable in the radial direction of the detachable piston 27 and do not come out inside.

Further, four escape cylinders 31 are fixed to the main body base 22 at four locations inside the same central angle direction as the detection sensor 36, one end of the escape cylinder 31 is covered with a cap 32, and compressed from the cap 32 side. Air is supplied. A piston 33 is placed in the escape cylinder 31.
Is slidably provided, and the piston 33 is biased in the G direction by a compression spring 34. Mounting base 21
A cover 37 is provided on the outer periphery of the main body base 22.

Next, the tracing stylus unit 40 will be described. 1, FIG. 2, FIG. 3, and FIG. 4, the unit base 41 has a circular outer shape, and on the G side, three conductive balls are provided at positions corresponding to three sets of spheres 23 fixed to the main body base 22. The cylindrical body 42 is fixed so that its axial direction faces the center of the unit base 41. Like the sphere 23, the portion to which the cylindrical body 42 is fixed is also electrically insulated from the others. However, in this example, the cylindrical body 42 has a semi-cylindrical shape.

At one location on the outer periphery of the unit base 41,
In order to prevent the posture from changing when the tracing stylus unit 40 is stored in the tracing stylus storage rack 70 described later,
The notch 41a is formed. Further, a shaft portion 41a is formed at the center on the G side, and a chuck ring 43 is attached to the shaft portion 41a so as to be movable in the radial direction of the shaft portion 41a but supported so as not to come off in the axial direction. There is.

A bearing base 44 is fixed to the F side of the unit base 41, and the bearing base 44 has four bearing portions 44 in the vicinity of the center at the center angle of about 90 degrees on the same circumference.
a is formed. A spindle 46 is swingably supported by a deep groove ball bearing 45 on the bearing portion 44a, and a substantially L-shaped probe 48 is fixed to the spindle 46. Deep groove ball bearing 4
5 is a disc spring 47 and a nut 46a provided on the support shaft 46.
Pre-load is applied in the axial direction to suppress the clearance between the inner and outer rings and the steel balls.

A pulley 50 is rotatably supported by a shaft 49 fixed to one end of the side surface of the bearing base 44 at four positions, and a wire 52 attached to a hook portion 48a of a tracing stylus 48 is attached to the pulley 50. It is attached to the tension spring 53 via. The other end of the tension spring 53 is hooked on a spring hook 51 provided on the other end of the side surface of the bearing base 44. Further, a tip sphere 48b is fixed to the tip of one of the tracing stylus 48 (on the side of the detection sensor 36), and the tip sphere 4b is attached to the tip of the other (the side in contact with the work).
8c is fixed, and a stopper 54 is attached near the hook portion 48a. Reference numeral 55 is a cover of the tracing stylus unit 40.

Next, the mounting relationship and action of the measuring head main body 20 and the tracing stylus unit 40 of the measuring head thus constructed will be described. When the tracing stylus unit 40 is released from the measuring head main body 20, the tracing stylus 48 opens until the tracing stylus 48 is constrained by the stopper 54, as shown in FIG. 4. In this state, the tracing stylus storage rack 70 is stored. When the measuring head body 20 moves in the F direction in the state shown in FIG. 5 (compressed air is supplied to the detachable cylinder 25 and compressed air is not supplied to the escape cylinder 31), the chuck ring 43 of the tracing stylus unit 40 is moved. The chuck sphere 29 of the measuring head body 20 is pushed outward and enters the hole 27a at the tip of the detachable piston 27.

When the compressed air in the detachable cylinder 25 is released from this state, the detachable piston 27 is released by the compression spring 28.
Moves in the G direction, the chuck sphere 29 moves from the large diameter portion 25a of the attachment / detachment cylinder 25 to the small diameter portion 25b, contacts the taper portion 43a of the chuck ring 43, and pulls the chuck ring 43 in the G direction. As a result, the three sets of spherical bodies 23 fixed to the main body base 22 and the three cylindrical bodies 42 fixed to the unit base 41 come into contact with each other, and the tracing stylus unit 40 is fixed to the measurement head main body 20. As a result, as shown in FIG. 3, since the contact circuit 24 is a closed circuit, a signal is output from the signal output unit 24c.

A measuring head unit 40 is attached to the measuring head main body 20.
Is fixed, the spindle 36a of the detection sensor 36
Is brought into contact with the tip sphere 48b of the probe 48, so that the probe is in a measurable state. However, since the probe 48 is open to the outside (phantom line in FIG. 1), compressed air is released to the relief cylinder 31. After supplying and making the contact point 48 closed by the piston 33 (solid line in FIG. 1), it is inserted into the hole to be measured. Next, when the compressed air in the escape cylinder 31 is released, the piston 33 moves in the G direction, the probe 48 opens, and the tip ball 48c comes into contact with the measurement position.

In this case, the distance from the swinging fulcrum of the probe 48 to the detection sensor 36 is C, and the tip sphere 48 of the probe 48 is
When the distance to c is D, the displacement amount of the spindle 36a of the detection sensor 36 is approximately "C / D" times the measured dimension, but strictly speaking, an arc error occurs. Calibrate. In this example C /
Since D = 1/3, since the digital measuring sensor is used as the detecting sensor 36 and the measurable range is wide as described above, the measuring element unit 40
The hole diameter dimension from Ea to Eb (for example, about 10 mm to 50 mm) can be measured.

When the hole diameter and the hole position depth of the object to be measured are wide, the shape (D dimension or the range from Ea to Eb) of the probe 48 of the probe unit 40 is divided into several ranges. To prepare the tracing stylus unit 40.

Although the tracing stylus unit 40 is mainly used for measuring the hole diameter, the tracing stylus 48 can be used one by one. For example, when measuring a hole diameter larger than the maximum measurable diameter Eb, the measuring head is moved in four directions until the tip sphere 48c of the probe 48 contacts the measurement surface of the hole and a predetermined value is detected by the detection sensor 36. The hole diameter is calculated by moving the moving amount of the measuring head detected by the three-dimensional coordinate measuring machine and the detection value from the detection sensor 36. Similarly, the shaft diameter and the like can be measured by a measuring head equipped with the tracing stylus unit 40.

Embodiment 2 of Measuring Head FIG. 6 and FIG. 7 show a measuring head according to the present invention, in which the probe is 1
The individual tracing stylus units 60 are shown. FIG. 6 is a side view showing a state where the measuring head body 20 is mounted, and FIG. 7 is a front view showing a state where the cover 69 is removed.

6 and 7, the unit base 6
1 has the same shape and dimension as the unit base 41, and three cylindrical bodies 42 are fixed to the G side at positions corresponding to the three sets of spheres 23 fixed to the main body base 22, and the outer periphery of the unit base 61. A notch 61a is formed at one location. Although not shown in the figure, a shaft portion 61a is formed at the center of the unit base 61 on the G side, and a chuck ring 43 is attached to the shaft portion 61a.

A fulcrum block 62 is fixed to the F side of the unit base 61, and L-shaped leaf springs 63 are fixed to the fulcrum block 62 at both ends by spring retainers 64. At the corner of the leaf spring 63, a probe 65 is provided with a spring retainer 6
6 is attached with the leaf spring 63 sandwiched therebetween, and a bar 65a is fixed to the tracing stylus 65 to form a substantially L shape, and a tip sphere 65b is formed at the tip on the detection sensor 36 side.
Is fixed, and the tip of the bar 65a (the side that contacts the work)
A tip ball 65c is fixed to the. In addition, the probe 65
A spring guide 67 is attached to the spring guide 67, and a compression spring 68 is supported by the spring guide 67. 69 is a cover of the tracing stylus unit 60.

Next, the operation of the tracing stylus unit 60 thus configured will be described. However, the method of positioning and fixing the tracing stylus unit 60 with respect to the measuring head body 20 is the same as that of the tracing stylus unit 40, and therefore the description thereof is omitted.

When the hole diameter is measured by the above-mentioned tracing stylus unit 40, the values detected by the four detection sensors 36 are calculated to calculate the hole diameter, and the measuring head detected by the three-dimensional coordinate measuring machine. The coordinate value of is used for correction of the value detected by the detection sensor 36, measurement of the center distance between measured holes, and the like. In the case of the tracing stylus unit 60, the basic measurement value is a cubic value. The coordinate value of the measuring head detected by the original coordinate measuring machine, which is the same as the displacement probe (an electronic probe that can measure a certain range, also called a tracing probe) that has been used in three-dimensional coordinate measuring machines. Used as.

Therefore, the amount of displacement of the tracing stylus 65 may be much smaller than that of the tracing stylus 48 of the tracing stylus unit 40, so that the tracing stylus 6 may be fixed to the measuring head body 20.
5 so that the tip ball 65c of 5 is at a predetermined position.
The pressure of 8 is adjusted. Naturally, the escape by the escape cylinder 31 is not necessary, and the piston 33 is left in the retracted state.

In this case, the distance from the swinging fulcrum (corner portion) of the tracing stylus 65 to the detection sensor 36 is H, and the tip sphere 65 is
When the distance to c is I and J, the displacement amount of the spindle 36a of the detection sensor 36 is approximately "H / J" times the measured dimension in the K and L directions and approximately "H" in the G direction.
/ I ”times. The measuring direction of the tracing stylus unit 60 is the direction of G, K, and L. It becomes a tracing stylus unit that can measure in the direction perpendicular to and in the G direction.

FIG. 8 and FIG. 9 show the essential parts of the tracing stylus storage rack 70 for storing the tracing stylus unit 40 and the tracing stylus unit 60 of the measuring head according to the present invention. FIG. 8 is a front view, and FIG.
Is a side view showing a state in which the tracing stylus unit 40 is stored. 8 and 9, the storage base 71 is provided with substantially semicircular cutout portions 71a at predetermined intervals so that the measurement head can be inserted and removed. Further, a groove 71b which is slightly larger than the outer diameter and width of the unit base 41 of the tracing stylus unit 40 is formed in the cutout portion 71a, and a compression spring 73 is urged in the vicinity of the cutout portion 71a. A plurality of pins 72 are provided to connect the unit base 41 to the groove 7
It is pressed against the end face of 1b. Further, a positioning pin 75 is fixed to one direction of the groove 71b in the N direction, and is engaged with a notch 41a formed in the unit base 41.

Stylus storage rack 7 configured in this way
When storing the tracing stylus unit 40 in 0, the tracing stylus unit 40 is fixed to the measuring head main body 20 and the unit base 41 is inserted into the groove 71b from the direction M in FIG. The notch 41 a engages with the positioning pin 75. Next, the detachable cylinder 2
5, compressed air is supplied, the detachable piston 27 moves in the F direction, and the chuck ball 29 moves from the small diameter portion 25b to the large diameter portion 25.
a to the chuck ring 4 of the unit base 41.
3 is released from the chuck sphere 29. After that, the measuring head body 20 moves in the G direction, and the tracing stylus unit 40
The stylus unit 40 is stored away.

When taking out the tracing stylus unit 40 from the tracing stylus storage rack 70, at the position where the center of the measuring head main body 20 and the center of the tracing stylus unit 40 substantially coincide with each other,
The measurement head body 20 moves in the F direction, the chuck ring 43 of the tracing stylus unit 40 pushes the chuck sphere 29 of the measurement head body 20 outward, and enters the hole 27a at the tip of the attachment / detachment piston 27. Next, compressed air is released from the detachable cylinder 25, the detachable piston 27 moves in the G direction,
The chuck ring 43 of the unit base 41 is pulled in the G direction by the chuck sphere 29, and the measurement head main body 2
The tracing stylus unit 40 is fixed to 0. After that, the measuring head main body 20 is moved in the N direction in FIG. 8 to take out the tracing stylus unit 40 from the tracing stylus storage rack 70. The same applies when the tracing stylus unit 60 is stored or taken out.

Although the tracing stylus units 40 and 60 are pressed by the pin 72 and abut against the G side of the groove 71b in the stored state, the target position of the measuring head main body 20 is set at the time of storing or taking out. About half of the width gap between the groove 71b and the unit bases 41, 61 is set in the F direction. As a result, the positioning error of the measuring head body 20 in the F and G directions with respect to the tracing stylus storage rack 70 is absorbed.
Further, the measuring head main body 2 for the tracing stylus storage rack 70
The direction perpendicular to the M and N directions of 0 is absorbed by the radial gap between the groove 71b and the unit bases 41 and 61.

Next, an example of an automatic dimension measuring device in which the measuring head according to the present invention is incorporated in an automatic three-dimensional coordinate measuring machine will be described. A three-dimensional coordinate measuring machine 10 shown in FIG. 10 (front view) and FIG. 11 (side view) is a horizontal arm type three-dimensional coordinate measuring machine, and an X carriage 13 is mounted on an X-axis guide portion 12 mounted on a base 11. Are movably supported in the X-axis direction. The X carriage 13 is provided with a Z-axis guide portion, the Z carriage 14 is supported along the Z-axis guide portion so as to be movable in the Z-axis direction, and the Y carriage is provided along the Y-axis guide portion built in the Z carriage 14. The spindle 15 is supported so as to be movable in the Y-axis direction. Further, each guide portion has an automatic driving mechanism and a length measuring means built therein, whereby the tip of the Y spindle 15 is movable in three XYZ directions orthogonal to each other and is automatically driven, and at the same time, coordinates are coordinated. The position is detected.

A measuring head body 20 of the measuring head according to the present invention is attached to the tip of the Y spindle 15, and a tracing stylus unit 60 is attached to the measuring head body 20. Further, the base 11 has a tracing stylus unit 40.
Probe storage rack 70 for storing the probe contact unit 60
And a master gauge 80 is provided. Although not shown, the work is placed on the base 11 or on the table of the transfer line provided in front of the base 11.

In the case of measuring a work with the automatic dimension measuring apparatus configured as described above, first, the tracing stylus units 40 and 6 are used.
Measure the master gauge 80 with 0 attached,
Calibration of the measuring head (positional relationship of the tracing stylus unit with respect to the master gauge 80, relationship between the positions of the tracing stylus 48 and 65 and the detection value of the detection sensor 36, etc.) is performed. As shown in FIG. 12, the master gauge 80 has a rectangular ring shape, and has a diameter P of a central hole 81a and four faces (81c) from the center 81b.
・ 81d ・ 81e ・ 81f) up to Qa ・ Qb ・ Q
c · Qd is known, and the base 11 is attached via the support base 82.
It is fixed to.

First, the calibration when the tracing stylus unit 40 is mounted is performed as follows. When the tracing stylus 48 was inserted into the hole 81a of the master gauge 80, as shown in FIG. 12, the center 48d of the tracing stylus unit 40 (two lines connecting the centers of the tip spheres 48c of the tracing stylus 48 of the same axial direction) It is assumed that the intersection point is eccentric by α in the X-axis direction and β in the Z-axis direction. In this state, since the tip sphere 48c is not in contact with the diameter portion of the hole 81a, the measuring head is moved in the direction in which the detection value of the detection sensor 36 increases, and The center 48d of the tracing stylus unit 40 is the center 81 of the master gauge 80.
It is considered that the position coincides with b, and X of the measuring head at this time
The X-axis and Z-axis coordinate values are used as the X-axis and Z-axis coordinate value references of the measuring head.

After that, the relationship between the position of each tracing stylus 48 and the detection value of the detection sensor 36 is calibrated. The Z-axis direction will be described in detail including the center position setting of the tracing stylus unit 40 described above. . 13 to 15 are schematic diagrams for explaining the method of calibrating the measuring head equipped with the tracing stylus unit 40.

FIG. 13 is a view showing setting of the center position of the tracing stylus unit 40, and shows a state in which the hole 81a of the master gauge 80 is measured and the detection value of the detection sensor 36 becomes maximum. The detection value of the detection sensor 36 at this time is Ro,
The coordinate value of the measuring head is Zo.

Next, the measuring head is brought out to the outside lower side of the master gauge 80, and the upper stylus 48 is placed on the surface 81 of the master gauge 80 until the detection value of the detection sensor 36 becomes Ro.
While being brought into contact with f, the coordinate value Za of the measuring head at this time is stored (left side in FIG. 14). From this state, the measuring head is moved further upward to the coordinate value Zb, and the detection value Ra of the detection sensor 36 at that time is read (FIG. 14).
On the right). As a result, the ratio ka of the change amount of the detection value of the detection sensor 36 to the displacement amount of the upper stylus 48 is obtained as follows. ka = (Ra-Ro) / (Zb-Za) This operation is performed at predetermined intervals and also in the downward direction.

As is apparent from the left side of FIG. 14, since Zo-Za = Qd + P / 2, the coordinate value (Zo-Za) detected by the three-dimensional coordinate measuring machine 10 is the value of the master gauge 80 ( Qd + P /
It can also be calibrated in 2).

An example of measuring the hole diameter of the work after the measurement head is calibrated in this way is shown in FIG.
Assuming that the detection value of the detection sensor 36 by Rb is Rb and the coordinate value of the measuring head is Zc, the distance Sa from Zc to the measurement surface of the hole of the work is obtained as follows. Sa = (Rb-Ro) / ka Similarly, if the lower probe 48 is also calibrated, the detection value Rc of the detection sensor 36 determines the distance Sb from Zc to the measurement surface of the hole of the work. From this, the hole diameter of the work is obtained as “Sa + Sb”.

At this time, the coordinate values of the center of the hole of the work are as follows. Zc + (Sa-Sb) / 2

The calibration when the tracing stylus unit 60 is attached is performed as follows. In the tracing stylus unit 60 of this example, Y
Since it is possible to measure in one direction of Z and two directions of Z, the two surfaces (81d and 81f) of the master gauge 80 in the Z direction and the end surface 81g are measured, and the measuring element unit 40 is mounted in the same manner as when the measuring element unit 40 is mounted. The relationship between the position of the tip sphere 65c of 65 and the detection value of the detection sensor 36 is calculated.

In this case, since the tracing stylus unit 40 does not measure in the Y-axis direction, the correlation between the mounting of the tracing stylus unit 60 and the mounting of the tracing stylus unit 40 is unnecessary in the Y-axis direction. With respect to the Z-axis direction, the probe head unit 40 is attached and the coordinate values of the two surfaces (81d and 81f) of the master gauge 80 in the Z direction are obtained in advance, and the coordinate values are used to determine the coordinate values of the measuring head on which the probe head unit 60 is attached. Calibrate.

That is, as shown on the left side of FIG. 16, the coordinate value when the surface 81f of the master gauge 80 is measured by the measuring head with the tracing stylus unit 40 is set to Zc, and the measuring head with the tracing stylus unit 60 is mounted. Rd is the detection value of the detection sensor 36 when the tip ball 65c of the probe 65 is brought into contact with the surface 81f of the master gauge 80 (the probe 65 is slightly displaced from the neutral state), and the coordinates of the measurement head When the value is Zd, the coordinate value of the surface with which the upper side of the tip sphere 65c is in contact when the detection value of the detection sensor 36 is detected as Rd is set to Zc.

From this state, as shown on the right side of FIG. 16, when the measuring head is moved upward by "Ze-Zd" and the detection value of the detection sensor 36 at that time is Re, the tip sphere 65c is moved. The ratio kb of the amount of change in the detection value of the detection sensor 36 to the amount of displacement is as follows. kb = (Re-Rd) / (Ze-Zd)

In this way, the relationship between Zd and Rd with respect to the coordinate value Zc of the surface 81f of the master gauge 80 and kb
Then, when the lower surface of the work is measured as shown in FIG. 17, the Z-axis coordinate value Zg of the lower surface of the work can be calculated as follows. When the Z-axis coordinate value of the measuring head at this time is Zf and the detection value of the detection sensor 36 is Rf, the displacement amount of the tracing stylus 65 is (Rf-Rd) / kb, so Zg = Zf-Zd + Zc- ( Rf-Rd) / kb.

The calibration of the positional relationship of the measuring head with respect to the position of the master gauge 80 must be performed after the three-dimensional coordinate measuring machine 10 is powered on. However, the displacement of the tracing stylus and the change in the detection value of the detection sensor 36 are changed. Calibration of the ratios ka and kb of the quantities can be performed collectively before the measurement, or by using the tracing stylus units 40, 6
It may be performed every time 0 is exchanged.

When the calibration of the measuring head is completed, the reference surface of the work is measured by the measuring head equipped with the tracing stylus unit 60, and the positional relationship between the XYZ coordinate reference position of the three-dimensional coordinate measuring machine 10 and the work. And the amount of inclination of the workpiece with respect to the XYZ coordinate axes. After that, when measuring the end surface of the work, the depth of the hole, etc., the tracing stylus unit 60 may be used as it is,
When measuring the hole diameter, the tracing stylus unit 60 is replaced with the tracing stylus unit 40 for measurement.

When the hole diameter is measured, as described in the prior art, if the contacting attitude of the contact point with the workpiece changes with respect to the master gauge measurement, an attitude error occurs. However, the measuring head according to the present invention measures the hole in four directions and calculates the hole diameter from the four measured values (the hole diameter can be specified if there are three measured values). Even if the tracing stylus is displaced in the radial direction (Fig. 19), accurate measurement can be performed. The correction necessary for the measuring head equipped with the tracing stylus unit 40 according to the present invention is when the measuring surface of the hole is inclined with respect to the coordinate axes of the three-dimensional coordinate measuring machine (the same as the example shown in FIG. 20). Is shown in FIG.

In this case, the tracing stylus unit 6 is prepared in advance.
The reference plane Wa of the workpiece is measured at 0 to obtain the tilt amount with respect to the coordinate axes of the three-dimensional coordinate measuring machine, and the tilt amount is used for correction. However, for a hole in which it is known in advance that the measurement surface of the hole is not at right angles to the reference surface Wa of the workpiece, the tilt amount is also corrected. If the inclination of the workpiece reference plane Wa with respect to the coordinate axes of the three-dimensional coordinate measuring machine is γ °, the inclination of the hole with respect to the workpiece reference plane Wa is δ °, and the calculated values of the two detection sensors 36 are Ta, The diameter T is as follows. T = Ta × cos (γ + δ−90)

The present invention is not limited to the contents described above, but can be applied to the following cases.

Two positioning means are provided on the measuring head body 20.
3 sets of spheres 23 are fixed by one set, and the tracing stylus unit 40
Although the three cylindrical bodies 42 are fixedly provided on the or 60, they may be provided in the opposite manner, or instead of the three spherical bodies 23 of two pairs, three cylindrical bodies of two pairs are formed. May be provided in a V shape.

Although four detection sensors 36 are provided on the measuring head main body 20 and four measuring sensors are provided on the measuring head unit 40, three measuring sensors may be provided.

The detection sensor 36 is a digital length measuring sensor whose accuracy does not change so much even if the measuring range is long. However, if high measuring accuracy is not required, the lever ratio (C / D) of the probe 48 is reduced. You may use the sensor (differential transformer etc.) which cannot take a wide measurement range.

Although the support mechanism for the tracing stylus 48 of the tracing stylus unit 40 is the bearing portion 44a of the deep groove ball bearing 45,
When the swing angle of the tracing stylus 48 is small, a leaf spring support mechanism may be used like the tracing stylus unit 60.

Although the measuring element escape cylinder 31 is provided in the measuring head body 20, it is provided in the measuring element unit 40 and fixed to the measuring head body 20 and then the measuring head body 20.
A method in which compressed air is supplied from the side may be used.

Although the probe escape cylinder 31 is not supplied with compressed air when the probe unit 40 is attached or detached, it may be supplied with compressed air.

The means for attaching and detaching the tracing stylus units 40 and 60 and the measuring head main body 20 is a conventionally used method, and it goes without saying that another method may be used.

The measuring element storage rack 70 is also an example, and other methods may be used. The present invention can be applied if the shapes of the unit bases 41 and 61 are changed depending on the structure of the tracing stylus storage rack 70.

The three-dimensional coordinate measuring machine is not limited to the horizontal arm type shown in the embodiment, but a bridge gate moving type three-dimensional coordinate measuring machine and other structural types can be used by using the measuring head according to the present invention. Work can be measured.
However, when the axis on which the measuring head is mounted is downward, the tracing stylus storage rack 70 is arranged in the horizontal direction (the G direction is upward), and the attitude of the master gauge 80 is such that the end surface 80g is upward.

[0081]

As described above, according to the contact point exchange type measuring head according to the present invention, the contact point is assembled into the contact point unit for hole diameter measurement or point measurement, and the detection sensor is not replaced. Since the probe head unit is replaced and a detection sensor having a wide measurement range is used, it is possible to provide a measurement head that can handle a large number of measurement contents at a low cost.

The measuring head was mounted on an automatic three-dimensional coordinate measuring machine to construct an automatic dimension measuring device. Therefore, it is possible to provide an automatic dimension measuring device that is inexpensive even for a large number of measurement contents and does not require frequent replacement of the measuring element, so that the measuring time is short.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which a tracing stylus unit 40 of a measurement head embodiment 1 according to the present invention is fixed to a measurement head main body.

FIG. 2 is a view as seen from the arrow A in FIG. 1 (front view).

FIG. 3 is a diagram schematically showing a contact circuit by expanding a positioning portion in a portion corresponding to the BB cross section of FIG.

FIG. 4 is a diagram showing a state in which the tracing stylus unit 40 of the measurement head Example 1 according to the present invention is removed from the measurement head body.

FIG. 5 is a view showing a measuring head main body in a state in which a tracing stylus unit according to the present invention is not attached.

FIG. 6 is a view (side view) showing a state in which a tracing stylus unit 60 according to a second embodiment of the measuring head according to the present invention is fixed to a measuring head main body.

FIG. 7 is a front view of FIG.

FIG. 8 is a view (front view) showing a main part of a tracing stylus storage rack for storing a tracing stylus unit of a measuring head according to the present invention.

9 is a side view of FIG.

FIG. 10 is a front view of an automatic dimension measuring device according to the present invention.

FIG. 11 is a side view of the automatic dimension measuring device according to the present invention.

[Figure 12] Schematic diagram of the master gauge

FIG. 13 is a diagram illustrating a method of setting the center position of the tracing stylus unit 40.

FIG. 14 is a diagram illustrating a method of obtaining a variation amount of a detection sensor detection value with respect to a displacement amount of a tracing stylus of a tracing stylus unit 40.

FIG. 15 is a diagram showing an example of measuring a hole diameter of a work with a measuring head equipped with a tracing stylus unit 40.

FIG. 16 is a diagram illustrating a method of obtaining a variation amount of a detection sensor detection value with respect to a displacement amount of a tracing stylus of a tracing stylus unit 60.

FIG. 17 is a diagram showing an example of measuring an end surface of a work with a measuring head equipped with a tracing stylus unit 60.

FIG. 18 is a diagram illustrating correction when a hole tilted with respect to the coordinate axes of the three-dimensional coordinate measuring machine is measured by the measuring head according to the present invention.

FIG. 19 is a diagram for explaining an error when the tracing stylus is displaced in the radial direction in the conventional measuring head.

FIG. 20 is a diagram for explaining an error when the tracing stylus is tilted in the axial direction in the conventional measuring head.

[Explanation of symbols]

 20 …… Measuring head main body 22 …… Main body base 23 …… A set of two spheres 24 …… Contact circuit 25 …… Removable cylinder 27 …… Removable piston 29 …… Chuck sphere 31 …… Escape cylinder 33 …… Piston 36 ...... Detection sensor 36a ... Spindle 40 ... Measuring element unit 41 ... Unit base 42 ... Cylinder 43 ... Chuck ring 46 ... Spindle 48 ... Measuring element 48b ... Tip sphere 48c ... Tip sphere 53 ... Pulling Spring 54 ... Stopper

Claims (7)

[Claims] 1. A measuring head main body having a built-in detection sensor, a tracing stylus unit having a tracing stylus whose one end contacts an object to be measured and the other end abuts on the detection sensor, and the measuring head. Positioning means for deciding the mounting position of the tracing stylus unit with respect to the main body, and attachment / detachment means for fixing the tracing stylus unit to the measuring head body and releasing the tracing stylus unit from the measuring head body. Measuring head exchange type measuring head. 2. The positioning means engages the measuring head body and the tracing stylus unit with each other.
Of the two engaging surfaces, three pairs of electrically conductive spheres are fixed to the insulating portion of one surface at a central angle of about 120 degrees on the same circumference, and the other surface of the engaging surface. When the three electrically conductive cylinders fixed to the insulating part of the above are fixed at positions corresponding to the spheres, and all three contact points formed by the three sets of spheres and the three cylinders are in contact with each other. The contact point type measurement head according to claim 1, further comprising: a contact circuit that outputs a signal when the three sets of spheres are electrically connected. 3. The probe tip exchange according to claim 1, wherein the detection sensor is a digital length measuring sensor, and four sensors are provided on the same circumference at central angle intervals of about 90 degrees. Measuring head. 4. An escape means for moving the tracing stylus in a direction opposite to the measuring direction is provided at four locations near the detection sensor of the measuring head main body, claim 2, or claim 3. An interchangeable probe head according to item 3. 5. A unit base configured such that the tracing stylus unit is positioned on the measuring head main body by the positioning means and the attaching / detaching means and is attachable / detachable, and a center angle on the same circumference of the unit base is about the same. Four support mechanisms that are provided at 90-degree intervals and that swingably support the tracing stylus, and that are supported by the support mechanism, one end of which is in contact with the object to be measured, and the other end of which is in contact with the detection sensor. As you touch
4. The four measuring elements having measuring directions in directions orthogonal to each other and separated from each other, and an urging means for urging the four measuring elements in the measuring direction. , Claim 2,
The stylus-interchangeable measuring head according to claim 3 or 4. 6. A unit base, wherein the measuring head unit is positioned on the measuring head main body by the positioning means and the attaching / detaching means and is configured to be attachable / detachable. One leaf spring support mechanism that is movably supported, and one probe that is supported by the leaf spring support mechanism and has one end abutting the object to be measured and the other end abutting the detection sensor. And claim 1, characterized in that
The stylus-interchangeable measuring head according to claim 3 or 4. 7. A measuring head for movably supporting and automatically driving said measuring head exchangeable measuring head in directions of three axes orthogonal to each other, and further for detecting a three-dimensional coordinate position of said measuring head exchangeable measuring head. A three-dimensional coordinate measuring machine provided with a long means, a measuring head main body of the measuring-point interchangeable measuring head supported by the three-dimensional coordinate measuring machine, and at least one tracing stylus unit according to claim 5. At least one tracing stylus unit according to claim 6, a tracing stylus storage rack that is provided on a fixed portion of the three-dimensional coordinate measuring machine, and stores a plurality of the tracing stylus units; An automatic dimension measuring device comprising: a master gauge provided on a fixed portion and serving as a reference for calibrating the measuring element exchange type measuring head.