Patent Application
20060243035
The present invention relates to a surface roughness/contour profile measuring instrument and, more particularly, to a surface roughness/contour profile measuring instrument having an improved ability to cause a contact probe to come into contact with a measurement part of a work.
The surface roughness/contour profile measuring instrument measures the surface roughness or the contour profile of a work by moving a pickup having a contact probe along the surface of a work, converting the amount of displacement of the pickup into an electric signal, and reading the displacement using a calculating machine such as a computer. Such a configuration is disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 2002-107144.
A surface roughness/contour profile measuring instrument 1 has a pickup 6 for measuring the surface roughness of a work placed on a table 2 and the pickup 6 is supported by a holder 5 to be fixed on a drive section 4.
The pickup 6 has a contact probe 7 at its front end and the amount of displacement of the contact probe 7 is converted into a voltage by a differential transformer (not shown) built in the pickup 6. The voltage value is converted into a digital signal by an A/D converter and inputted to a data processing device (not shown) such as a computer. Due to this, measurement data indicating the surface roughness of a work is acquired by the data processing device.
By the way, there may be a case where the amount of displacement of the contact probe 7 is detected using a differential inductance or laser interferometer instead of a differential transformer. Further, there may also be a case where the surface position is detected in a no-contact manner by utilizing an optical method etc. without using a contact probe. Here, an explanation is given of a configuration in which the amount of displacement of the contact probe 7 is detected by a differential transformer is taken as an example. However, the present invention is not limited to this and the height of a surface position may be detected by any method as long as the instrument is a surface roughness/contour profile measuring instrument.
As shown in
When performing measurement, an operator places a work on the table 2, operates the operation section to move the pickup 6 with respect to the work, and causes the contact probe 7 to come into contact with a position to be measured (a measurement position) on the work surface.
In order to cause the contact probe 7 to come into contact from the position shown in
As described above, the movement of the contact probe 7 from the position PR to the measurement position PM is stopped after the contact probe 7 comes into contact with the surface of the work 90, as detected by monitoring the detected signal and, therefore, the movement speed at this time cannot be increased too much. Particularly, it is necessary to limit the movement speed of the pickup 6 that detects fine bumps and dips to low speed because the range of displacement (detection possible rage) of the contact probe 7 is narrow.
This operation is the same when the surface position is detected in a non-contact manner such as an optical method, and the pickup is moved toward the surface at low speed and when the pickup is brought into a measuring state, the movement of the pickup is stopped.
Conventionally, such a surface roughness/contour profile measuring instrument is used for evaluation of the brilliance of a painted surface, evaluation of surface properties of a film, measurement of the flatness of a liquid crystal painted film surface, etc., and excellent operability has been an important challenge.
As described above, in the surface roughness/contour profile measuring instrument, the operation for causing the contact probe to come into contact with the contact position of a work, that is, the operation to cause the pickup to move to the measurement directed position is performed by an operator. Because of this, when measuring the surface roughness/contour profile of plural lines of a work, it is necessary for the operator to perform an operation to cause the contact probe to come into contact with the next contact position of the work (an operation to move the pickup to the next measurement directed position) when measurement of each line is completed. Therefore, there is a problem in that it is necessary for the operator to always stay by the surface roughness/contour profile measuring instrument during the period of measurement to monitor the measurement, preventing the operator from doing other work in the meantime. Because of this, automation of the contact operation of a contact probe (moving operation of a pickup) in a surface roughness/contour profile measuring instrument is demanded.
Further, an operator visually judges that the pickup 6 is at the position PR, and there is a trend that the distance from the position PR to the contact position PM is increased because the contact probe 7 is hard to see and it is necessary to prevent the contact probe 7 from coming into contact with the surface of a work. If the distance is increased, as described above, it is necessary to move the contact probe 7 from the position PR to the contact position PM in
In the case of a non-contact type pickup, it is difficult to judge the measurement position and the above-mentioned problem becomes more remarkable in the case of a non-contact type pickup.
As for a three-dimensional coordinate measuring instrument, as described in, for example, Japanese Unexamined Patent Publication (Kokai) No. 10-239042, various control methods for moving and causing a contact probe to come into contact with a work are proposed and a device for automatically setting a movement path of a contact probe is also proposed. However, the contact probe of the coordinate measuring instrument has a larger detection possible range than that of the contact probe of a surface roughness/contour profile measuring instrument and the current state is that the automatic movement contact technique of the contact probe in the coordinate measuring instrument is difficult to apply to a surface roughness/contour profile measuring instrument. Because of this, a surface roughness/contour profile measuring instrument that automatically moves and causes a contact probe to come into contact with a work (movement of a pickup to a measurement directed position) has not been realized so far.
Further, the technique of the movement path automatic setting of a contact probe in a coordinate measuring instrument is premised on the use of the function of the coordinate measuring instrument for measuring the coordinates of a complex three-dimensional form, therefore, an operator is able to set a complex path easily. In contrast to this, a surface roughness/contour profile measuring instrument assumes that the above-mentioned operation is performed by an operator and, therefore, it does not have the function of performing a complex movement in the three-dimensional space or the function of easily setting such a path. Because of this, a technique capable of easily performing the movement path automatic setting of a pickup in a current surface roughness/contour profile measuring instrument is demanded.
The above-mentioned problems being taken into consideration, the present invention has been developed and an object thereof is to realize a surface roughness/contour profile measuring instrument capable of automatically moving a pickup to a measurement directed position.
A surface roughness/contour profile measuring instrument of the present invention comprises a pickup for detecting the height of the surface position of a work and a pickup moving mechanism for relatively moving the pickup with respect to the work, wherein by detecting the change in the height of the surface position of the work when relatively moving the pickup with respect to the surface of the work, the surface roughness or the contour profile of the work is measured and, in order to realize the above-mentioned object, the surface roughness/contour profile measuring instrument further comprises a movement information generation section for generating movement information necessary to move the pickup from the current position to a measurement directed position for detecting the height of a directed surface position of the work surface and a movement control section for relatively moving the pickup with respect to the work based on the movement information generated by the movement information section.
The movement information generation section comprises a movement path generation section for generating a path along which the pickup moves from the current position to a contact position of the contact probe and a movement speed information generation section for determining the speed at the time of movement along the path generated by the movement path generation section.
The movement path generation section generates a path based on the measurement position, the detection direction of the pickup, the current position of the pickup, information as to whether the pickup is in a measuring state, a safe distance set in advance, and information as to a safe range set in advance. There are various methods for generating a path. Examples are described below.
The movement path generation section generates a path along which a pickup moves to a measurement position after moving from a measurement directed position to a position on a straight line extending in the detection direction of the pickup.
The movement path generation section generates a path such that the pickup passes through a reference position a safe distance away from the measurement directed position in the detection direction of the pickup.
The movement path generation section generates a path such that the pickup moves to the reference position after ascending to the height of the reference position when the current position of the pickup is lower than the reference position in the detection direction of the pickup.
The movement path generation section generates a path such that the pickup moves to the reference position after ascending to a safe distance in the detection direction of the pickup when the pickup is in the measuring state.
The safe range is, for example, a cone with the reference position being the vertex and the detection direction of the pickup being the axis.
In the safe range, the movement path generation section generates a path such that the contact probe moves on a straight line to the reference position.
The movement speed information generation section sets the movement speed of the pickup so as to be slow on the path for the movement from the reference position to the measurement directed position and to be fast on the rest of the path.
In the surface roughness/contour profile measuring instrument of the present invention, if the safe distance and the safe range are set in advance and the measurement position and the detection direction of the pickup are set for each work, the current position of the pickup and information as to whether the pickup is in the measuring state can be obtained from the measuring instrument, therefore, the operation to move the pickup to the measurement directed position can be performed automatically. Plural settings can be done for the measurement position and the detection direction of the pickup and the measuring operation in accordance with each setting value is performed sequentially.
A generated path consists of only the movement of the pickup in the detection direction (Z direction) and the movement in the direction perpendicular to that (movement in the X-Y plane) outside the safe range, and a path can be generated easily. Further, outside the safe range, the pickup does not move in the direction perpendicular to the detection direction of the pickup in a state of being lower in height than the reference position, therefore, collision of the contact probe with a work can be avoided.
According to the surface roughness/contour profile measuring instrument of the present invention, by only doing a predetermined simple setting, it is possible to automatically perform the operation to move the pickup to the measurement directed position.
The features and advantages of the invention will be more clearly understood from the following descriptions taken in conjunction with the accompanying drawings in which:
A surface roughness/contour profile measuring instrument in an embodiment of the present invention is explained below. The surface roughness/contour profile measuring instrument in the embodiment is capable of moving a pickup three-dimensionally as shown in
Further, the present invention can also be applied to a surface roughness/contour profile measuring instrument having a pickup of a type that detects the surface position in a non-contact manner such as an optical method etc.
The movement path automatic generation processing 101 automatically generates a path based on the measurement position on the work, the current position of the pickup, the pickup detected information indicating whether the contact probe is in a contact state, the detection direction of the pickup, the safe distance set in advance, and the safe region information indicating the safe range set in advance. The safe distance and the safe region information are inputted to the movement information generation section 16 by utilizing the key input 11, the mouse input 12, and the external communication section 13. The inputted safe distance and the safe region information are stored in the storage device 14. Further, the measurement position and the detection direction of the pickup are set for each work by utilizing the key input 11, the mouse input 12, the external communication section 13, etc., and stored in the storage device 14. By the way, there may be a case where the pickup itself has the function of judging the detection direction, and in this case, the setting of the detection direction is not necessary if the orientation of the surface is known. It is possible to set plural measurement positions by assigning numbers in order and an operation to perform measurement of one line by causing the contact probe to come into contact with the contact position is performed for the specified contact position in the specified order. It is also possible for an operator to perform an operation to move and cause the contact probe to come into contact with the measurement position to cause the position to be stored as a measurement position, and to perform the measurement operation and the movement to the measurement position sequentially in an automatic manner. Further, the detection direction of the pickup is set in accordance with the orientation of the surface of the measurement position. The positional relationship between the coordinate system for moving the contact probe and the actual work surface is performed by setting in the coordinate system the position of the contact point in a state in which the contact probe is caused to come into contact with the work surface by the operation of an operator as before.
The current position of the pickup and the pickup detected information are generated in the measuring instrument 1 and inputted to the movement information generation section 16 via the pickup information section 15.
The movement speed information generation processing 102 automatically sets the speed on the path based the generated path and the safe region information.
L is a safe distance and a position the safe distance L upwardly away from the measurement position PM is assumed to be a reference position PS. Within the range of a cone with the reference position PS being the vertex and the straight line passing through the reference position PS in the Z-axis direction being the axis is a safe region H. In the safe region H, there exists no work surface and the contact probe is unlikely to collide with the work, therefore, it is a region in which the pickup can freely move. In the present embodiment, an example is shown, in which the angle formed by the Z-axis and the slant line of the safe region H is 45 degrees, however, the angle can be set arbitrarily.
When the contact probe is caused to come into contact with the measurement position PM, the contact probe moves to the reference position PS and, then, it moves along the Z-axis at low speed, and is stopped after the contact probe coming into contact with the work surface is detected. In the present embodiment, the distance between the measurement position PM and the reference position PS is set as the safe distance L, however, this is not limited and it is possible to set the distance between the measurement position PM and the reference position PS to an arbitrary value equal to or less than the safe distance L.
As shown in
In step 112, when it is judged that the current position is not on the Z-axis, processing proceeds to step 118 and whether the pickup is in the on state is judged. If the pickup is in the on state, processing proceeds to step 119 and whether P (Z) is smaller than the Z coordinate of the measurement position PM, that is, whether it is negative, is judged. If P (Z) is negative, the current position of the contact probe is, for example, a position P3 in
In step 119, if P (Z) is judged to be positive, the current position of the contact probe is, for example, a position P4 in
When it is judged that the pickup is not in the on state in step 118, processing proceeds to step 122 and whether P (Z) is negative is judged. When P (Z) is negative, the current position of the contact probe is, for example, a position PS in
When it is judged that P (Z) is positive in step 122, processing further proceeds to step 124 and whether P (Z) is smaller than PS (Z) is judged. When P (Z) is smaller than PS (Z), the current position of the contact probe is, for example, a position P6 in
When it is judged that P (Z) is greater than PS (Z) in step 124, processing further proceeds to step 126 and whether the current position is within the safe region is judged. When within the safe region, the current position of the contact probe is, for example, a position P7, then a path 7 is selected in step 127 and processing proceeds to step 129. The path 7 is a path for further movement to PM at low speed after the movement from the current position to the reference position PS along a straight line at high speed.
When it is judged that the current position is not within the safe region in step 126, the current position of the contact probe is, for example, a position P8 in
As described above, in the present embodiment, when the current position is on the Z-axis, the contact position PM is touched without any other action. When the current position is not on the Z-axis, after the ascent at least to the same height as the reference position PS, movement onto the Z-axis is performed, then the contact position PM is touched without any other action. If the pickup is in the on state and the current position is higher than the contact position PM, that is, the Z coordinate of the current position is positive, the movement at the height of the reference position PS is not sufficient in terms of safety, therefore, ascent to a position the safe distance L upward from the current position is made. Therefore, the Z coordinate at this time is greater than the Z coordinate of the reference position PS. Then, the movement onto the Z-axis is performed. After this, the same operation as that on the Z-axis is performed. On the movement path, the movement from PS to PM is performed at low speed while monitoring the detected signal of the pickup and on the rest of the path, movement is performed at high speed.
In other words, in the present embodiment, the downward movement in the Z-axis direction occurs only from PS to PM and within the safe region. The movement in the safe region has no possibility of collision and, therefore, it is possible to move at high speed. Further, the upward movement in the Z-axis direction has no possibility of collision because the movement is in the departing direction from the work and, therefore, it is possible to move at high speed. Furthermore, the movement in the direction perpendicular to the Z-axis is performed at a position higher than at least the reference position, therefore, it is possible to move at high speed. As described above, in the present embodiment, the movement from PS to PM is performed at low speed and the movement in other cases is performed at high speed.
It may also be possible to reduce the speed of the movement from the reference position PS to the contact position PM to a minimum, increase the speed of the movement on the path outside the safe region and, further, to increase the speed of the movement on the path within the safe region.
There can be various modification examples for the generation of the movement path and some of them are explained with reference to
On the path 6 described above, after the temporarily ascent from the current position to the position P6′ at the same height as that of the reference position PS, the movement to PS is performed, however, this can be modified into one in which the movement from the current position to a position P6″ on the Z-axis is performed while the same height, from the current position, is being maintained. This is a path in the case where P6 is not at a position at which the pickup is not on and it can be assumed that there is no work present in the vicinity thereof and there is no possibility of collision with the work.
Further, the safe region can be set arbitrarily and, as shown in
Due to the present invention, the workability of the surface roughness/contour profile measuring instrument is improved and, therefore, the use of the surface roughness/contour profile measuring instrument is made possible in the field in which the use of the surface roughness/contour profile measuring instrument has not been possible from the standpoint of productivity, and the field of use of the surface roughness/contour profile measuring instrument is enlarged.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-132778 | Apr 2005 | JP | national |
