KR101468473B1 - Contact type probe device for coordinate measuring machine - Google Patents

Abstract

According to the present invention, since the through hole is formed in the stylus of the probe in the three-dimensional measuring device, the force of the tip of the probe tip in contact with the object to be measured contacts the probe When a force of a certain level or more is applied, the stylus is broken and the overload of the sensitive sensor unit can be prevented.

Description

[0001] The present invention relates to a contact type probe for a three-dimensional measuring device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type probe for a three-dimensional measurement device, and more particularly, to a technique for protecting a sensor part when measuring an object to be measured.

The CMM (Coordinate Measuring Machine) is a device that measures the shape of an object quickly and accurately and obtains the shape information of the object in three-dimensional space coordinates. The shape of the processed product or part It is a measuring instrument used for evaluating the machining accuracy by comparing the measured result with the designed dimension, or for the reverse design of the product without design data such as drawings.

The measurement method of the three-dimensional measuring apparatus is classified into a contact type using a contact type probe and a non-contact type using a laser interferometer or a CCD camera.

In the case of measuring three-dimensional shape information, a non-contact probe is mainly used to measure a cross section in a two-dimensional plane region. When a probe tip senses an instant of contact with a measured object and generates a signal, A contact type measurement method in which the position of the probe at the probe is read as a coordinate value is mainly used.

In this contact type measuring method, there are a method using a linear variable automatic transformer, a scanning method, and a switching method in which the moment when the probe tip contacts the object to be measured is detected.

In each case, the method of sensing the force and outputting the signal is different. However, when the probe tip of the probe tip contacts the object to be measured, the force is transmitted to the sensor side through the stylus in the same manner.

In this case, the sensor that outputs the signal for coordinate calculation through the sensed force is very sensitive and the price is also high. However, if the probe tip touches the object under a strong force, it may overload the sensor and cause a malfunction.

That is, although the force of contact of the probe tip with the object to be measured must be transmitted, a technique of blocking the force transmission of a certain level or more is required.

On the other hand, Korean Patent Registration No. 10-0605058 and the like are known as a related art related to a three-dimensional measuring device.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems of the prior art as described above, and it is an object of the present invention to provide a probe having a through hole in a stylus of a probe, Dimensional probe, which can prevent the stylus from being damaged when the force is applied, thereby preventing the sensitive sensor unit from being overloaded.

According to an aspect of the present invention, there is provided a contact probe for a three-dimensional measuring apparatus, comprising: a probe tip contacting a surface of a measured object; A stylus connected to the probe tip for transmitting a force that the probe tip contacts the surface of the object to be measured; And a sensor unit coupled to the stylus to receive a force from the stylus in contact with the surface of the object to be measured, and to output a signal for three-dimensional coordinate calculation, And a through hole is formed perpendicularly to the longitudinal direction.

Here, the first through hole and the second through hole may be formed in the stylus so as to cross each other at right angles.

The stylus may be interchangeably coupled to the sensor unit.

According to the contact probe for a three-dimensional measuring apparatus according to the present invention, the minute force when the probe tip is connected to the object to be measured, which is connected to the tip of the stylus, is directly transmitted to the sensor unit through the stylus, A signal for coordinate calculation can be output. If the force of the probe tip contacting the measured object exceeds a certain level, the point where the through hole is formed in the stylus is broken, and excessive force is blocked from being transmitted to the sensor portion. Therefore, the sensor unit designed to be sensitive can be overloaded to prevent malfunctions.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining a three-dimensional measuring apparatus equipped with a touch probe for a three-dimensional measuring apparatus according to an embodiment of the present invention.
Fig. 2 is a side view of the probe in the three-dimensional measuring apparatus shown in Fig. 1;
3 is a perspective view for explaining a through hole formed in a stylus of a probe in the three-dimensional measurement apparatus shown in FIG. 1;
Fig. 4 is a cross-sectional view of the stylus in the probe shown in Fig. 3 taken along the through-hole forming point; Fig.
5 is a view for explaining a situation where a stylus is broken by a lateral force in a probe according to an embodiment of the present invention;
6 is a view for explaining a difference in rigidity with respect to a lateral load when the cross-sectional area is the same;
7 is a view for explaining a resistance difference when a force perpendicular to the stylus acts.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, some configurations which are not related to the gist of the present invention may be omitted or compressed, but the configurations omitted are not necessarily those not necessary in the present invention, and they may be combined by a person having ordinary skill in the art to which the present invention belongs. .

1 is a view for explaining a three-dimensional measuring apparatus equipped with a touch probe for a three-dimensional measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, a three-dimensional measuring apparatus 1 according to an embodiment of the present invention includes a work table 2, a three-dimensional transfer means 3, and a contact probe 4.

The work table 2 is in the form of a table on which the measured object 100 is lifted and may be further provided with a means for fixing the measured object 100 to prevent it from moving.

A three-dimensional transfer means 3 is provided on the upper part of the work table 2 and a contact probe 4 is mounted on the three-dimensional transfer means 3. Therefore, the three-dimensional transfer means 3 transfers the contact probe 4 along the surface of the measured object 100 in the X axis, the Y axis, and the Z axis to measure the outer shape of the measured object 100.

This three-dimensional transfer means 3 is operated under the control of a control means (not shown) which causes the contact probe 4 to be transferred on the basis of the operation of the operator or as previously programmed.

The probe 4 mounted on the three-dimensional transfer means 3 is composed of the sensor portion 10, the stylus 5 and the probe tip 9 as shown in Figs.

The sensor unit 10 is fixed to the three-dimensional transfer means 3 and detects a force transmitted through the probe tip 9 and the stylus 5 and outputs a signal for three-dimensional coordinate calculation.

That is, a separate calculation means (not shown) calculates coordinates based on the output data of the control means for controlling the three-dimensional transfer means 3 and the signal output from the sensor unit 10, Means (not shown) displays the measurement results in numerical or image form.

The sensor unit 10 that receives the force from the stylus 5 and outputs a signal for coordinate calculation may be implemented by a linear variable automatic transmission system, a switching system, a scanning system, or the like.

A method using a linear variable differential transformer (LVDT) is a method in which a solenoid coil is located around a tube, and a cylindrical magnetic core moves along the center of the tube to indicate the position of the object to be measured. In this method using a linear variable automatic transformer, it is necessary to control the measuring force so that it can be scanned with a constant force, and it is possible to obtain a very large amount of measurement data in a short time, which is suitable for curved surface measurement or gear measurement. Also, since the measurement speed is inversely proportional to the measurement accuracy, the measurement speed must be lowered in order to obtain high accuracy.

In the switching method, three mechanical contacts are formed to have an angle of 120 degrees. When the probe tip 9 contacts the measured object 100, a contact is opened and a signal is generated. to be.

The scanning method is a method of outputting a signal for coordinate calculation by using an inductance signal.

A stylus 5 is connected to the center of the sensor unit 10 and a probe tip 9 is connected to the lower end of the stylus 5 to directly receive an external force.

The probe tip 9 may be of any shape as long as it can contact the measured object 100 and transmit the force to the stylus 5. In the present embodiment, Respectively.

When the probe tip 9 provided at the lower end of the contact probe 4 is brought into contact with the measured object 100 by the three-dimensional transfer means 3, the contact force is transmitted through the stylus 5 to the sensor portion 10, and coordinate calculation is performed. At this time, if the probe tip 9 comes into contact with the measured object 100 with an excessive force, the sensor unit 10 may malfunction.

For this purpose, as shown in FIG. 3 in this embodiment, through holes 6 and 7 are formed at a predetermined height of the stylus 5. At this time, the through holes 6 and 7 are formed so as to penetrate the opposite side surface on one side perpendicular to the longitudinal direction of the stylus 5, so that the first through hole 6 and the second through hole 7 are orthogonal to each other Is designed. 4 showing the cross section of the stylus 5 at the point where the through holes 6 and 7 are formed, the upper and lower sides and the left and right are formed by the through holes 6 and 7 at the points where the through holes 6 and 7 are formed It is empty and only the remaining area remains. Therefore, the connecting area is smaller than other points of the stylus 5 and can be easily broken.

That is, as shown in FIG. 5 (a), when the three-dimensional transfer means 3 transfers the contact probe 4 to bring the probe tip 9 into initial contact with the surface of the object to be measured 100, 5 (b), the stylus 5 is slightly bent while the probe tip 9 keeps contact with the surface of the measured object 100, so that the force of the probe tip 9, which is in contact with the probe tip 9, (5) to the sensor unit (10). Therefore, the sensor unit 10 receives the contact force through the probe tip 9 and the stylus 5, and can output a signal for coordinate calculation.

However, if the three-dimensional transfer means 3 is further moved toward the workpiece 100, a contact force of a certain level or more is transmitted to the stylus 5. At this time, the stylus 5 5, the point of formation of the through-holes 6, 7 can not sustain the force and is broken as shown in FIG. 5 (c). Therefore, a force of a predetermined level or more is transmitted to the sensor unit 10 through the stylus 5, so that the sensor unit 10 can be prevented from malfunctioning.

Of course, since the stylus 5 can be replaceably coupled to the sensor unit 10, only the stylus 5 can be replaced with a new one while the expensive sensor unit 10 is protected, have.

In order to easily break the stylus 5 when the probe tip 9 is brought into contact with the measurement object 100, the cross-sectional area of the stylus 5 itself may be designed to be narrow or the periphery of a specific point of the stylus 5 may be broken, There may be a way to reduce.

However, since the minimum force with which the probe tip 9 is brought into contact with the measured object 100 is transmitted to the sensor unit 10 through the stylus 5, coordinate calculation is possible. Therefore, when the stylus 5 is made thin Can not be done.

6 is a view for explaining the resistance against an external force according to the cross-sectional area of the stylus 5. Fig. 6 (a) is a cross-sectional view of a state in which the cross-sectional area 8 'of the stylus is made thinner. FIG. 6 (b) In accordance with an embodiment of the present invention.

In the present embodiment, the cross-sectional area at the point of the through holes 6 and 7 is empty and the cross-sectional area 8 is filled only at the four peripheral portions. That is, as in the case of the thinly filled area 8 'A in FIG. 6 (a), the area 8 of the peripheral part in FIG. 6 (b) The outermost distance L forming the area 8 in FIG. 6 (b) is longer than the outermost distance 1 forming the area 8 'in FIG. 6 (a) . 6 (a), the 'second moment of inertia' is larger than that of FIG. 6 (a), so that the rigidity with respect to the transverse load is more . This is the same principle as using an H beam that increases the stiffness against the transverse load by increasing the 'second moment of inertia' although the cross section is small in construction.

However, in FIG. 6 (a), since the distance from the center to the outermost side is short even with the same cross-sectional area, the stiffness with respect to the transverse load is very weak because the moment of inertia is small. Therefore, there is a high possibility that measurement can not be performed because the stylus breaks before the force of the probe tip 9 contacting the measured object 100 is transmitted to the sensor unit 10 side. On the other hand, if the through-holes 6, 7 intersecting the stylus 5 are formed as in the present embodiment so that the moment of inertia of the cross section is designed to be large, the rigidity against the transverse load is large, The force that is brought into contact with the measured object 100 can be transmitted to the sensor unit 10 side.

Since the connection area of the through holes 6 and 7 is small, if the excessive force is applied after the force detection, the point where the through holes 6 and 7 are formed is broken and excessive force is transmitted to the sensor unit 10 do.

On the other hand, the probe 4 descends in the Z-axis direction under the control of the control means (not shown) in order to contact the surface of the object to be measured 100. At this time, when the probe tip 9 touches the measured object 100, a vertical force is transmitted to the sensor unit 10 through the stylus 5.

However, when the contact probe 4 descends and only the minimum force that the probe tip 9 contacts the measured object 100 is transmitted to the sensor unit 10, if an excessive force is applied to the Z axis, 10). At this time, it is preferable that the stylus 5 breaks at a certain level of force or more.

7 is a view for explaining the resistance difference when a vertical force acts on the stylus according to the shape of the stylus.

As shown in FIG. 7 (a), in the case where the circumferential portion of the point of the stylus is depressed, the buckling collapse does not occur because the thickness of the depressed portion is thick even if the longitudinal force acts on the stylus. That is, the force against the compression load is directly transmitted to the sensor unit 10, and the sensor unit 10 may be overloaded. However, if the circumferential portion of the stylus is dug more, the buckling collapse due to the compressive load can easily occur, but the resistance against the lateral force becomes very weak, so that when the probe tip 9 makes lateral contact with the measured object 100 I can not deliver the power of

However, if the through holes 6 and 7 are formed so as to penetrate the stylus 5 as shown in FIG. 7 (b), only thin connecting points are left at the points. Therefore, the buckling collapse is likely to occur due to the easy deformation of the compression load. The force when the probe 4 descends and comes into contact with the surface of the measured object 100 is transmitted to the sensor unit 10 through the stylus 5. When a further force is applied to the sensor unit 10, 7 collapse and the stylus 5 is broken, so that excessive force is prevented from being transmitted to the sensor unit 10.

Also, as described above, since the connecting area at the point where the through holes 6 and 7 of the stylus 5 are formed is small, the area is distributed far from the center as described above. Therefore, the stiffness with respect to the lateral load is high Force transmission to side contact is fully possible.

As described above in detail, according to the contact probe 4 for the three-dimensional measuring apparatus 1 according to the present invention, the probe tip 9 connected to the end of the stylus 5 contacts the measured object 100 The probe tip 9 can transmit a signal for coordinate calculation while sensing the touch at the sensor unit 10 by transmitting the fine force at the time of the probe tip 9 to the sensor unit 10 through the stylus 5, When the force of contact with the measurement object 100 exceeds a certain level, the point where the through hole is formed in the stylus 5 is broken, and excessive force is blocked from being transmitted to the sensor unit 10 side. Therefore, it is possible to prevent the sensor unit 10, which is designed to be sensitive, from being overloaded to cause a malfunction.

The foregoing description of the preferred embodiments of the present invention has been presented for the purpose of illustration and it will be apparent to those skilled in the art that various modifications, additions and substitutions are possible within the spirit and scope of the invention, And additions should be considered as falling within the scope of the claims of the present invention.

1: 3D measuring device
2: Workbench
3: Three-dimensional conveying means
4: Probe
5: Stylus
6: First through hole
7: Second through hole
8,8 ': Stylus section
9: Probe tip
10: Sensor unit
100: measured object

Claims (3)

A probe tip contacting the surface of the object to be measured; And
A stylus connected to the probe tip for transmitting a force that the probe tip contacts the surface of the object to be measured; And
And a sensor unit connected to the stylus to receive a force that the probe tip contacts with the surface of the object to be measured from the stylus, and to output a signal for three-dimensional coordinate calculation,
Wherein a first through hole and a second through hole are formed at one point of the stylus perpendicularly to the longitudinal direction of the stylus and perpendicular to each other, When the contact force of a predetermined level or more is transmitted, the excessive force is prevented from being transmitted to the sensor unit due to breakage, and the connection area is formed only in the four peripheral portions far from the center of the stylus, , And the rigidity against the lateral load is improved.
delete The method according to claim 1,
Wherein the stylus is replaceably coupled to the sensor unit.

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