JPH11166816A - Method for determining shape and dimension of subject for measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for rationally determining the shape and the dimensions of a subject for measurement by use of a measuring device having a positioning means using numerical control and a sensor detection means using a laser beam. SOLUTION: A scanning point is provided in the measuring range of a subject T for measurement, and measurements taken at adjacent measuring points are compared. Only the greater of the measurements is sequentially left behind in a memory and used as the measurement to determine the maximum measurement as the measurement in the measuring range. For not one but plural scanning measurements, the subject T for measurement is automatically moved into a range in which a measurement start point is preset for measuring procedures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the shape and size of the surface of an object to be measured, and more particularly to processing a measured value obtained by scanning within a predetermined range to be measured to obtain a maximum value. Is determined as a measurement value representative of the range.

[0002]

2. Description of the Related Art Non-contact laser length measuring machines (for example, BLU)
There is a method of measuring the tool size using a tool manufactured by M. Co., Ltd., but at present, the beam diameter is reduced to 0.1 mm or less so that the size of the laser beam can be measured even with a small-diameter tool. For this reason, unless the measurement position is accurately positioned so that the beam is irradiated, a position deviating from the original position will be measured. This is an important point to be aware of when measuring (FIG. 8). In particular, when measuring a cutting edge with a nose R, it was necessary to measure a position excluding the position of R (FIG. 9).

Normally, when measuring the diameter and length of a tool using a touch sensor, the measurement position is moved to the tip of the cutting edge of the tool and brought into contact with the tip of a flat touch sensor to detect the measurement position [FIG. 10]. In this case, since there is a flat contact surface, the highest position of the cutting edge of the tool can be measured even if the blade is positioned at approximately that position. However, since this measurement method is a measurement in a state where the blade is stationary without rotating the blade, in the case of a multi-blade tool, only one blade can be measured. Alternatively, the position of each blade and the attached angle are checked in advance, and the main axis is determined at that angle, and measurement is performed for each blade. This method requires a long measurement time when the number of blades is large, and it is difficult to match the rotationally indexed position with the highest position of the blade when measuring in the tool length direction [FIG.
1], especially when measuring in the radial direction of the tool, is a very difficult operation.

[0004]

In the method of measuring a tool dimension using a non-contact laser length measuring machine described in the prior art, it may be difficult to position the tool at a position to be measured. In the touch sensor type measuring method, a multi-blade tool needs to index and measure one blade at a time, which requires a long measuring time.

[0005]

In order to achieve the above object, a method of determining the shape and size of an object to be measured according to the present invention comprises moving the object to be measured by numerical control means and detecting the contour of the object by a laser beam. A method of determining the shape and dimensions from the position data, wherein the measurement axis direction in the direction perpendicular to the measurement axis and the optical axis of the laser beam within the range to be measured on the surface of the object to be measured in the measurement axis direction Move the DUT sequentially
The position data in the measurement axis direction of each point on the object to be measured is read based on a sensor signal output when the laser beam is blocked by the object to be measured or when the laser beam that has been blocked is transmitted, and the read is performed. The position data of each point on the measurement object is compared, the position data of a point on the measurement object located outside the measurement object is obtained, and the shape and size of the surface of the measurement object are determined from the outermost position data. Is what you want. According to the present invention, a predetermined scanning area is set in advance in a range to be measured of an object to be measured, and the scanning position is sequentially moved in order to determine a measurement value representative of the area and automatically measured to be the largest. It is intended to provide a method for efficiently determining and determining a value.

In addition, the position data in the measurement axis direction is read and stored, and the position data in the measurement axis direction of two adjacent measurement points of the measurement object are compared with each other to compare the position data on the measurement object outside the measurement object. The points to be measured are compared with the position data in the measurement axis direction of the adjacent measurement points sequentially in the range to be measured, and the position data in the measurement axis direction stored in advance are stored. The shape and dimensions of the surface of the object to be measured are obtained from the position data. According to the present invention, the largest data stored by comparing the previously stored data with the data of the adjacent measurement sequentially in the range to be measured is displayed as the shape and size of the surface of the measured object, It is possible to quickly measure a measured value representing a predetermined range of the measured object.

The object to be measured is a tool attached to a main shaft of a machine tool, and the measurement is performed while rotating the tool to obtain a tool length and a tool diameter as shape dimensions. According to this method, it is easy to determine the shape and size of the tool, particularly the size in the tool radial direction, in the machine.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a laser measuring instrument attached to a cross rail of a portal machining center, which is a processing machine, and a spindle head. In FIG. 1, a cross rail 1 is installed on a column erected on the side of a bed (not shown) so as to be movable and positioned in a Z-axis direction. The cross rail 1 has a Y-axis direction guide surface on a front surface thereof. A spindle head 2 is mounted so as to be movable and positioned along the Y-axis guide. A spindle ram 3 is provided on the spindle head 2 so as to be movable and positioned in the Z-axis direction. An attachment 4 is mounted on the spindle ram 3, and a spindle (not shown) is rotatably supported by a plurality of bearings inside the attachment. I have. A ball end mill T, which is a tool to be measured, held by a milling chuck 5 is detachably mounted in a tapered end of the attachment 4.

A laser measuring instrument 6 is fixed to the lower surface of the cross rail 1 near the Y-axis moving end via a mount 7 so that the laser optical axis is directed in the X-axis direction. The laser measuring device 6 monitors the laser light a emitted from the laser light emitting part 6a to reach the diode inside through the small window of the light receiving part 6b, and shuts off when the tool crosses the laser light a at right angles. The sensor 8 outputs a sensor signal when the shadow becomes 90% of the small window. The cable 8 is a wire for supplying the power supply voltage and sending the sensor signal to an NC device (not shown), and 9 is a protective cover.

As the laser measuring device 6, a commercially available laser measuring device such as a "MICRO" Laser for machining centers manufactured by BLUM can be used. When an NC device (not shown) of the machining center receives the sensor signal from the laser measuring device 6, it reads the current position at the time of reception and stops the axis movement on the spot.

FIG. 2A shows a state in which the object does not block the optical axis of the laser beam and no sensor signal is output, and the contour of the object is not detected. FIG. 2B shows a state in which the sensor signal is output with the object blocking the laser beam optical axis, but the contour of the object is not detected. FIG. 2C shows that the sensor signal starts to be output and the contour of the measured object is detected when the optical axis of the laser beam is interrupted by the contour of the measured object.

Next, an embodiment in which the measuring method of the present invention using the measuring system configured as described above is applied to measurement of the contour of a tool will be described with reference to FIG. In FIG. 3, a scanning area (hereinafter abbreviated as PSPN) is set on the contour of the cutting edge of a tool as a measurement object, and + PSPN and -PSPN directions are determined from the vicinity of the center to the left and right, and 1 μm is defined.
The position of the measurement axis for scanning with a predetermined width in a range from m to 5 mm is determined. This fixed width for scanning may be referred to as a scanning pitch (hereinafter abbreviated as PPIC), and the width of the PPIC may be used as a unit of movement in a measurement cycle of the tool in the Z-axis direction. The tolerance of the measured value (hereinafter abbreviated as PTOL) is determined in advance, and the PSPN, PPI
C and PTOL are input as numerical data and commanded.

[0013]

FIG. 4 shows an embodiment in which an object to be measured is a tool. When measuring the upper surface of the cutting edge of the tool, a laser beam having an optical axis orthogonal to the tool axis is cut off by the cutting edge, and a sensor signal is output to detect the position of the cutting edge of the tool [FIG. )]. The device under test is moved from the position provided as the reference position by the scanning pitch (PPIC) to the plus scanning area (+ PSPN), and the measurement result A is stored (FIG. 4B). Here, the measurement means moving the object to be measured by the PPIC, and then approaching the laser beam from the direction perpendicular to the laser beam, blocking the light beam and outputting the sensor signal. This means that the difference between the position data and the reference position data provided on the device under test is determined as the measurement result A.

Next, the object to be measured is sequentially positioned at positions adjacent to each other by 1 PPIC in the + PSPN direction and measured, and a measurement result B at the adjacent position is obtained each time. The measured value of B is compared with A previously stored, and the stored value is replaced with a larger value (FIGS. 4C and 4D). Next, when the measurement B is obtained, the value of AB is obtained and within the allowable measurement error (PTOL) and + PSP
If the measurement is within the range of N, the measurement is further repeated.
-PSP in the minus direction when exceeding the range of + PSPN
The measurement is performed by positioning the device under test at a position adjacent to each other by 1 PPIC within N, and the measurement is terminated when the measured value exceeds -PSPN.

When AB exceeds PTOL,
At the time of + PSPN measurement, after storing the maximum value so far,
Even if an unmeasured scanning area remains in the range of + PSPN, the measurement is interrupted, and the measurement in the range of -PSPN is performed. If AB exceeds PTOL even in the -PSPN range, the measurement is interrupted even if an unmeasured scanning area remains in the -PSPN range, and the maximum value so far is set as the final measured value.

In the measurement, when the above AB is smaller than the allowable measurement error, the previously stored A is left as a measured value. Next, the same measurement value comparison process is performed in the range of -PSPN, and the maximum value finally stored in the memory is used as the measurement value (FIGS. 4E, 4F, and 4G). To measure the height of the blade, it takes too much time to return to the first measurement position on the Z axis. For this reason, the second measurement can be started from a position shifted by a predetermined distance from the first measurement point. For example, the predetermined range can be selected from a width of 1 μm to 5 mm, and this distance can be selected as 1 PPIC [FIG.
(A)].

The advantage of this selection is that the scanning pitch of the PSPN when instructing the measurement and the measurement start point of the adjacent point are automatically brought closer to the laser beam from a position 1 PPIC away from the previous measurement point. This makes it possible to reduce the number of command values. [FIG. 5 (b)].

Assume now that the object to be measured is returned by 1 PPIC from the previous measurement point and measurement is started. When there is a sensor signal output at this position, the measurement is repeated by 1 PPIC until the disappearance of the sensor signal can be confirmed, and the measurement is repeated, so that even if the shape of the adjacent measurement point is greatly shifted, the measurement start point is quickly reached. [Figure 5
(C)].

By returning the position of the object to be measured to the position where no sensor signal is output by the above-described procedure, the object is brought closer to the laser beam, and the sensor signal is output at the time when the optical axis is cut off. The laser beam is approached from a direction away from the beam, and the measurement is performed so as to eliminate the measurement error caused by the means for moving the object to be measured.

Next, the concrete operation of comparing the adjacent measured values and storing the larger measured value, which is the method of determining the measured value of the present invention, will be described with reference to the flowchart of FIG. The X-axis direction is a scanning axis for measuring the measurement surface of the object at a fixed interval, and the minus direction of the Z-axis is a measurement axis for measuring the distance from the reference position of the measurement surface of the object.

The abbreviations used in the flowchart are as follows. PSPN; scanning area one side width, PPIC; adjacent scanning distance, PTOL allowable; measurement error (| AB | ≦)
A measurement cycle is continued at the time of PTOL), A: previous measurement value, B: subsequent measurement value, do: scanning position command value indicates a reference position (X axis), fo: measurement reference value (Z
axis).

Prior to measurement, data of an X-axis command value and a Z-axis reference value are set in advance (step S1). Subsequently, a scanning area is determined and data is set (step S).
2). The object to be measured is moved to the position to be scanned and positioned (step S3-1), measured, and processing data A is obtained and stored (step S3). The processing data A represents a difference between a measured value of a measurement point adjacent to the reference position do.

The measurement is continued within the area of + PSPN when the scanning position is over the area of + PSPN.
The process proceeds to the measurement of the SPN area (step S4). If the processing data of the adjacent measurement point has not been input yet (step S5), the processing data B is obtained at the measurement point adjacent to the measurement point of step S3, and the processing data A and the processing data B previously stored are compared. When A> B, the processing data A previously stored is left (step S6). Subsequently, when AB ≦ PTOL is satisfied for the stored processing data A and B, that is, when AB is within the allowable measurement error, the process proceeds to the measurement of the next adjacent measurement point and the measurement is continued. (Steps S7, S
8, S9, S10, S11).

When the value of AB exceeds the allowable measurement error PTOL and exceeds the scanning area, the measured object is set to -PS.
Move to the PN scanning area and start measurement in this area (Step S7, Step S9). -PS
The measurement operation in the PN region is performed in basically the same procedure as the operation in the + PSPN region (step S12).
To S19). -Measurement in the PSPN range is completed and AB ≤ P
If it is TOL (step S17), the measurement cycle is completed with A as the last measured value (step S20).

According to the method of determining measured values of the present invention, when measuring a plurality of positions, the processing data measured after an adjacent position is compared with the processing data measured in the previous measurement. This is a method in which the largest processing data in the entire PSPN of the larger processing data is automatically measured and obtained by comparing with the larger processing data. Therefore, processing data representing a scanning area can be efficiently determined by appropriately selecting adjacent scanning distances according to the purpose.

The process of the measuring cycle of the device under test according to the present invention will be described with reference to the flowchart of FIG. The measurement cycle after the object to be measured is moved to the measurement position where scanning is performed in the operation sequence described in FIG. 6 and positioned is as follows. An embodiment in which the scanning pitch (XPIC) of the X axis and the return amount of the Z axis, which is the measurement axis of the device under test, are set to the same distance will be described. Here, the return amount of the Z-axis refers to the direction in which the laser beam can be received without the laser beam being interrupted by the object when the laser beam is interrupted by the object and no sensor signal is output. It means the unit movement amount when moving in the (positive direction of the axis).

In this embodiment, 1 PPIC is used as a unit movement amount. First, the Z-axis return amount C is input and stored (Step S101). An initial position is determined for the Z-axis reference value Z1 (step S102). Positioning at the scanning position to be measured on the X axis (Step S1
03). When the measurement is started and there is no output of the sensor signal (step S104), the laser beam is not interrupted by the object to be measured, so that the object to be measured is moved and the process moves to the Z-axis measurement cycle (step S107). At this time, in consideration of the amount of backlash inherent in the moving means of the object to be measured, the object is moved by adding the amount, and the measurement is completed. If the sensor signal remains output (step S104), the device under test is moved in the + Z-axis direction by 1 PPIC and moved back until the sensor signal output cannot be detected (step S105), and the measurement cycle is completed (step S105). Step S107). According to this measurement cycle, the unit movement amount PPC at the time of measurement can be set in advance according to the purpose and automatic measurement can be performed, and the time required for measurement can be reduced.

[0028]

The method for measuring the shape and dimension of an object to be measured according to the present invention has the following effects. Measure one point of a predetermined measurement area on the surface of the object to be measured and determine the measurement value by efficiently taking out the maximum value from the measurement values measured at a constant scanning pitch within the measurement area without using that measurement value. Therefore, an objective measurement value can be obtained as shape data. In addition, since the operation procedure for moving and measuring the object to be measured is simplified, the measurement time can be determined in a short time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a measuring device used when the method for determining a measurement according to the present invention is performed.

FIG. 2A shows a positional relationship between a laser beam and a device under test when there is no sensor signal output, FIG. 2B shows a positional relationship between the laser beam and a device under test when there is a sensor signal, (C) is a diagram showing a positional relationship at the time when the object to be measured comes into contact with the laser beam and a sensor signal is output.

FIG. 3 is an explanatory diagram showing a positional relationship between a scanning area and an adjacent measurement point in the measurement of the present invention.

FIG. 4 shows an example in which the object to be measured is moved so that the laser beam moves from the reference position to both the measurement areas from −PSPN to + PSPN by 1 PPIC.
It is explanatory drawing which measures at the pitch of FIG.

5A is a diagram in which 1 PPIC is used as a movement unit of an X axis (scanning pitch) and a Z axis (movement of a measured object before a measurement cycle), and FIG. 5B is a diagram showing a PPI when a tool shape is changed.
It is a figure which shows the position of C, and (c) is a figure which shows the case where it moved by 2PPIC in the Z-axis direction.

FIG. 6 is a flowchart illustrating a procedure for comparing adjacent measured values and storing a large measured value according to the method for determining a measured value of the present invention.

FIG. 7 is a flowchart showing a measurement cycle of the Z-axis (measured object) according to the present invention.

FIG. 8 is an explanatory diagram showing a state of measurement of a drill by a laser beam in the related art.

FIG. 9 is an explanatory diagram showing a measurement state of a multi-blade tool by a laser beam in a conventional technique.

FIG. 10 is an explanatory diagram showing a state of measurement of a blade edge by a touch sensor according to a conventional technique.

FIG. 11 is an explanatory diagram showing a state of measurement of a blade edge by a touch sensor in the related art.

[Explanation of symbols]

 T Object to be measured (tool) a Laser beam 1 Cross rail 2 Spindle head 3 Spindle ram 4 Attachment 5 Milling chuck 6 Laser measuring device 6a Laser light emitting part 6b Laser light receiving part 7 Mounting stand 8 Cable 9 Protective cover

Claims (3)

[Claims] 1. A method of moving an object to be measured by numerical control means, detecting a contour of the object to be measured with a laser beam, and determining a shape and dimensions from position data, wherein an attempt is made to measure the surface of the object to be measured. The object to be measured is sequentially moved in the measurement axis direction at regular intervals in a direction perpendicular to the measurement axis and the optical axis of the laser beam within the range, and when the laser beam is interrupted or interrupted by the object to be measured. Read the position data in the measurement axis direction of each point on the object to be measured based on the sensor signal output when the laser beam is transmitted,
The read position data of each point on the measurement object is compared to obtain position data of a point on the measurement object located outside the measurement object, and the surface data of the measurement object is obtained from the outermost position data. A method for determining the shape and size of an object to be measured, wherein the shape and size of the object are measured. 2. The method according to claim 1, wherein the position data in the measurement axis direction is read and stored, and the position data in the measurement axis direction of two adjacent measurement points of the measurement object are compared to each other on the measurement object outside the measurement object. The points to be measured are compared with the position data in the measurement axis direction of the adjacent measurement points sequentially in the range to be measured, and the position data in the measurement axis direction stored in advance are stored. 2. The method according to claim 1, wherein a shape and a size of a surface of the object to be measured are obtained from position data.
The method for determining the shape and dimension of an object to be measured as described in the above. 3. An object to be measured is a tool attached to a main shaft of a machine tool, and measurement is performed while rotating the tool.
3. A tool length and a tool diameter are obtained as shape dimensions.
The method for determining the shape and dimension of an object to be measured as described in the above.