JPS63109977A - Automatic grinding wheel dimension measuring device for numerically controlled grinder - Google Patents

Abstract

PURPOSE:To rapidly measure the dimension of a grinding wheel even when the range of measuring object dimensions are large by providing a position detecting means which detects the arrival of said grinding wheel at a position at a certain distance apart from a contact member and which switches over the feed speed of said grinding wheel from a high speed to a low speed. CONSTITUTION:When it is necessary to measure the dimension of the grinding wheel 1a of a tool 1 to be measured, a reference tool 12 having a grinding wheel 12a the dimension of which is previously known is installed on the main spindle 2 of a numerically controlled grinder A and the main spindle 2 is rotated, moving the reference tool 12 from a starting point toward a contact member 10 at a rapid feed speed. Then, when the grinding wheel 12a arrives at a position a certain distance apart from the contact member 10, a position detecting means 20 detects this and switches over the feed speed of the reference tool 12 by means of a driving motor 5 to a low speed, and the position of the main spindle 2 when the grinding wheel 12a is brought into contact with the contact member 10, is detected by a detecting means 22. And, by installing the tool 1 to be measured on the spindle 2, the position of the main spindle 2 at the time of the contact of the grinding wheel 1a of the tool 1 to be measured with the contact member 10 is equally detected by the detecting means 22. And, the dimension of the grinding wheel 1a is calculated from those positions of the main spindle 2 by an operating means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dimension measuring device that automatically measures the diameter, length, etc. of a grinding wheel in a numerically controlled grinding machine.

[Conventional technology]

In a numerically controlled grinding machine, when it is necessary to remeasure the diameter or length of a grinding wheel that has become smaller due to workpiece grinding, automatic truing, or automatic dressing, conventionally, the grinding wheel (tool) is numerically controlled grinding. It was removed from the main shaft of the board. However, with this method, the tool to be measured must be removed from the main shaft of the numerically controlled grinding machine, transported outside the grinding machine, and then measured, which is time-consuming and requires interruption of automatic operation. Therefore, there is a problem in that the efficiency of the grinding work is reduced and the grinding accuracy is reduced because the dimensions of the grindstone cannot be measured frequently.

For this reason, the inventors of the present invention moved the grinding wheel from the starting point toward the reference plate while rotating the main shaft equipped with the tool for ￥f, detected the contact of the grinding wheel with the reference plate, and calculated the distance traveled. We have developed a method for calculating the dimensions of a tool to be measured from the difference in the amount of movement between a basic tool whose dimensions are known in advance and a fixed tool (patent application filed on October 7, 1988).

[Problem that the invention seeks to solve]

However, although this is fine when the dimensions to be measured are concentrated in a narrow range, there is a problem in that it takes a long time to measure a small grindstone when the tools are of various sizes and have a wide range of dimensions. That is, the grindstone is eccentric to some extent, and therefore, the grindstone's outer periphery that is farthest from the rotation axis is adopted as the size of the grindstone. Therefore, in order to measure this, it is necessary to rotate the grindstone and measure it, and in order to measure with high precision, the amount of feed per revolution must be less than or equal to the required resolution.

For this reason, the measurement speed is very slow. On the other hand, when moving from the starting point to the measurement reference position for measurement, it is necessary to maintain the measurement speed at least within the range of the target dimension so that the reference position can be reached at any point. . The smaller the target size, the longer the distance the tool must be moved at a slower speed, and if there are a large number of tools to be measured, the overall measurement time will be very long.

[Means for solving problems]

The present invention includes a main shaft on which a tool having a grindstone is attached,
In a numerically controlled grinding machine, the main shaft is configured to be moved by a drive motor in at least one direction of the X-axis, Y-axis, and Z-axis. contact detection means for detecting contact; position detection means for detecting when the grindstone has arrived at a position a certain distance away from the contact member and slowing down the feed speed of the spindle by the drive motor; The above-mentioned conventional problems are solved by providing calculation means for calculating the dimensions of the grindstone from the position of the main spindle when the wheels come into contact with each other.

[Effect]

When it becomes necessary to measure the dimensions of a tool to be measured, a reference tool with a grindstone whose dimensions are known in advance is attached to the main shaft of a numerically controlled grinder, the main shaft is rotated, and the reference tool is used as a starting point. From there, the spindle moves at a high feed rate toward a contact member attached to a numerically controlled grinder. When the grindstone of the reference tool reaches a position a certain distance away from the contact member, the position detection means detects this and reduces the feed speed of the reference tool by the drive motor. When the reference tool whose feed speed has been reduced in this manner comes into contact with the contact member, a contact signal is generated, and by detecting the contact signal, the contact position of the reference tool with respect to the contact member is known.

In addition, the tool to be measured is attached to the main shaft, the main shaft is rotated, and the tool to be measured is moved from the starting point toward the contact member at a high feed rate in the same manner as described above, so that the grindstone of the reference tool is moved a certain distance from the contact member. The position detection means detects that the tool has reached the desired position, reduces the feed speed, and brings the grindstone of the tool to be measured into contact with the contact member to determine the position of the main shaft at that time. The dimensions of the tool to be measured are measured by calculating the contact positions of the reference tool and the tool to be measured with respect to the contact member.

The dimension is measured several times by bringing the tool to be measured into contact with a new portion of the contact member for each measurement, and when there is no uncontacted portion of the tool to be measured on the contact member, the contact member is replaced with a new contact member.

〔Example〕

The present invention will be explained below based on the drawings.

Figures 1 to 3 show an example of an automatic grindstone size measuring device of the present invention for measuring the diameter of a grindstone.
is a numerically controlled grinding machine (hereinafter referred to as NG grinding machine) having an automatic tool changer (not shown). This NC grinding machine A has the same basic structure as a so-called grinding center, and has a grinding wheel 1a [
is taken out from a tool magazine (not shown) and mounted on the main shaft 2, and the NO control device 3 controls the drive motors 4, 5.6 for the X, Y, and Z axes, respectively. .

The automatic grindstone dimension measuring device of the present invention is attached to this NC@grinding machine A, in which the grindstone 1a of the tool I, which is moved in the Y-axis direction by the main shaft 2, is spaced a certain distance tlli from a fixed point for measurement. a position detection means 20 for detecting that the grinding wheel 1a has reached a fixed position, and a reference plate (
a contact detection means 22 for detecting contact with the contact member) 10; and a calculation means 8 for calculating the diameter of the grindstone 1a of the tool l by performing a predetermined calculation described later based on the detection signal obtained by the contact detection means 22. It is composed of.

In this embodiment, as the position detecting means 20, a non-contact type sensor is used since the contact portion of a contact type sensor is damaged by the rotating grindstone. Specifically, it is a photoelectric switch, and in FIG. 2, a light emitter 20a and a light receiver 20b are disposed facing each other with a reference plate IO in between. Moreover, the detection area of this photoelectric switch 20 is elongated as seen in the shape of the slit 20c. As a result, detection is possible no matter where the outer circumference of the grindstone 1a in the Z-axis direction blocks this detection area. Further, the signal output from the photoelectric switch 20 is input to the signal processing section 21, and when the amount of received light becomes equal to or less than a set value, the signal processing section 21 outputs a contact signal.

Further, as the contact detection means 22, the grindstone 1 of the tool l
A detection signal (acoustic emission signal, hereinafter referred to as AE multiplied signal) generated when a contacts the reference plate IO is used.

That is, the AE multiplied signal generated by this contact passes through the jig 11 that fixes the reference plate lO, and is transmitted to this jig 1.
It is detected by a contact detection means (AE sensor) 22 fixed at 1. The detection signal detected by the contact detection means 22 is converted into a contact signal by the signal processing section 23 and guided to the NC control device 3. The signal processing section 23 is the fourth
As shown in the figure, only specific frequency components are extracted and simultaneously amplified using the AE multiplied signal, a low-pass filter, and a bypass filter. After processing in the detection processing section, the detected signal level is compared with the threshold set by the comparator. If it is above the threshold,
This turns on the contact.

Note that the above AE multiplied signal is generated from cracks, etc. that gradually progress before the material is completely destroyed, and is an elastic wave of −i.

The calculation means 8 is provided inside the NC control device 3, and includes an AND gate 81 that transmits a feed pulse f, and a servo control of the YIlilffi motor 5 by the feed pulse f from the AND gate 8a. Interpolator 8 that generates output turns for controlling the device
b and the AE multiplied signal from the position detection means 20 or the contact detection means 22, when the grindstone 1a of the tool 1 reaches a position a certain distance away from the reference plate 10 from the counter inside the spacer 8b, Alternatively, the position Y (coordinate value on the Y axis) of the tool 1 when the grinding wheel 1a contacts the reference plate IO is taken in, and the AND gate 8a is
A CPU (central processing unit) 8c that stops the movement of the main spindle 2, that is, the tool l, in the Y-axis direction in the FF state, and calculates the grinding wheel diameter of the tool l based on the principle described later;
and a storage device 8d connected to the storage device 8c. A control program for controlling the NC control device 3 and the device that measures the dimensions of the grindstone is registered in the storage device 8d. In addition, in FIG. 1, 9 is an NC tape.

Next, the operation of the automatic grindstone dimension measuring device for the NC grinding machine of the present invention will be explained.

5 and 6 are detailed explanations of the present invention when measuring the diameter of the grinding wheel 1a.
is at the starting point, and the distance between the spindle 2 and the reference plate 10 (hereinafter referred to as reference distance) is Lo, then the diameter d of the grinding wheel 1a of the tool 1 is calculated by the following formula % formula % Here, a is the tool to be measured The moving distance of the grinding wheel 1a of 1 is shown. In other words, the position when it is at the starting point is Yo, and the position of whetstone 1 is
If the position of the main shaft 2 when a contacts the reference plate 10 is Y, then Y = ly - Yol (2)
It is determined by This operation will be explained with reference to FIGS. 1 to 3.

First, the position Yo at the starting point of the tool to be measured 1 is stored in the storage device 8d. Next, when the tool to be measured I is moved along the Y axis, the grinding wheel 1a of the tool to be measured I is moved to the reference plate 10. The position Y at that time is taken into the CPU 8c, and at the same time, the axis movement is stopped. This CPU8
c is the measured tool 1 from these detection positions Yo, Y.
Calculate the moving distance a.

Further, the reference pressure ILo in equation (1) is determined by the following equation.

Lo=do/2+ao ＋＋＋・−・＋＋＋＋＋＋(
:3) Here, do is the known diameter of the grinding wheel 12a of the reference tool 12, and aO is the diameter when the reference tool 12 is mounted on the spindle 2 instead of the tool to be measured l, and in the same way as the tool to be measured l. This is the moving distance of the reference tool I2 obtained by moving it, and is obtained in the same manner as the moving distance a.

In this way, the reference distance Lo is measured in advance using the reference tool 12 having the grindstone 12a with a known diameter, and then the tool to be measured l is mounted on the spindle 2 and the tool movement distance a is determined. , calculate the grindstone diameter d according to equation (1).

The operation of the apparatus when measuring the grinding wheel diameter d using the control program in the storage device 3 based on the above principle will be explained with reference to the flowchart shown in FIG.

First, with the main spindle 2 returned to the starting position Yo, the automatic tool changer is operated to obtain a known diameter d from a tool magazine (not shown). The reference tool 12 having the grindstone 122L is taken out and mounted on the spindle 2, and the position Y0 at the starting point of the reference tool 12 is stored in the storage device 8d of the calculation means 8 (step St).

Next, the main shaft 2 is rotated (step S2). Then, the main spindle 2 is moved in the Y-axis direction, and the reference tool 12 is moved downward in FIG. 1 at a fast feed rate (step S3
). Then, the gate signal of the AND gate 8a of the calculation means 8 becomes ON, and the feed pulse f passes through the AND gate 8a and enters the interpolator 8b. The interpolator 8b outputs a control signal for the Y-axis drive motor 5 based on this feed pulse f, and the Y-axis drive motor 5 continues to operate. and,
When the grindstone 12a of the reference tool 12 enters the detection area of the photoelectric switch 20, the photoelectric switch 20 detects a decrease in the amount of received light, and the signal is converted into a contact signal by the signal processing unit 21 and output (step S4), and the calculation means 8's CPU'8c.

When this detection signal is input, the CPU 8c turns off the gate signal of the AND gate 8a, stops inputting the feed pulse f to the interpolator 8b, and turns off the Y-axis drive motor 5.
to stop. Thereafter, the Y-axis drive motor 5 operates again to move the main shaft 2 in the Y-axis direction at a slow feed rate (step S5). When the grindstone 12a of the reference tool 12 comes into contact with the reference plate IO, the contact detection means 22 outputs an AE multiplied signal, which is detected by the signal processing section 23 (step S6) and input to the CPU 8c of the calculation means 8.

When this contact signal is input, the CPU 8c takes in the number of pulses of the feed pulse f from the counter inside the interpolator 8b as the position Y of the reference tool 12, and stores it in the storage device 8d.
(step S7), and turns off the gate signal of the AND gate 8a to input the feed pulse f.
The input to the spacer 8b is stopped, the Y-axis drive motor 5 is stopped, and the reference tool 12 is returned to the starting point (step S8).

Furthermore, the CPU 8c calculates the moving distance based on the control program registered in the storage device 8d.
9), confirm that the tool inserted in the spindle 2 is the reference tool (step 5IO), and
Calculate the standard pressure MLo using the grindstone diameter do of the standard tool 12 registered in d and the control program.Step 5
ll), and register this in the storage device 8d (step 51
2). Then, the automatic tool changer is operated to exchange the reference tool 12 of the spindle 2 with the tool to be measured 1, and the grindstone diameter of the tool to be measured 1 is measured by almost the same procedure as in the case of the reference tool 12 described above. . That is, the position Yo at the starting point of the tool to be measured 1 is stored in the storage device 8d (step Sl). Next, the main shaft 2 is rotated (step S
2). Then, the main shaft 2 is operated to rotate the tool 1 to be measured and move it downward at a high feed rate in FIG. 1 (step S3). At this time, the feed pulse f passes through the AND gate 8a and enters the interpolator 8b, and a control signal for the Y-axis drive motor 5 is output from the interpolator 8b. When the grindstone 1a of the tool to be measured 1 enters the detection area of the photoelectric switch 20, the signal processing section 21 detects a decrease in the amount of light caused by the photoelectric switch 20 and sends a contact signal to the CP1J8c (step S4).

When this detection signal is input, the CPU 8c turns the gate signal of the AND gate 81 into an OFF state, stops inputting the feed pulse f to the interpolator 8b, and stops the Y-axis drive motor 5. Thereafter, the Y-axis drive motor 5 operates again to move the main shaft 2 in the Y-axis direction at a slow feed rate (step S5). The grindstone of the reference tool 12 is the reference plate IO.
When contacted, the contact detection means 22 outputs an AE multiplied signal,
The signal is detected by the signal processing unit 23 (step SS)
, enters the CPL 78c of the calculation means 8. CPU8c is
When this contact signal is input, the number of pulses of the feed pulse f is counted from the counter inside the storage device 8d to the tool to be measured.
is captured as position Y and registered in the storage device 8d (step S7), and the AND gate 8a is turned OFF to stop inputting the feed pulse f to the interpolator 8b.
The shaft drive motor 5 is stopped and the tool to be measured 1 is returned to the starting point (step S8). Further, the CPU 8c calculates the movement distance using the control program in the storage device 8d and confirms that the tool inserted in the spindle 2 is the tool to be measured (steps S9, 5IO). Storage device 8
The grindstone diameter d of the tool to be measured l is calculated using the reference distance 1flLo stored in d and the control program (step 513), and the calculated value is registered in the storage device 8d as the measured grindstone diameter d, and the process ends (step 513). Step S14).

In the above, the feed rate of the main shaft 2 from when the movement of the grinding wheel is detected by the position detection means 20 until the grinding wheel contacts the reference plate IO is 4 [IRIIl/min].
], the rotation speed is set to 4000 [rpm], and the feed amount per rotation of the spindle 2 is 1 μm,
In this way, by rotating the main shaft 2, the grindstone is placed on the reference plate 1.
Since the grinding wheel is brought into contact with zero, even if the grinding wheel is eccentric, its influence is completely removed. Note that the amount of feed per revolution of the main shaft 2 during measurement is determined to be less than or equal to the resolution derived from the required accuracy. Further, the feed speed of the main spindle 2 from the starting point until the movement of the grindstone is detected by the position detection means 20 is set to 15 [m/min].

When the target tool has a radius of 30 [mm] and is moved toward the reference plate IO at a feed rate of 4 [++v/min], the smallest grinding wheel will move toward the reference plate IO. The contact time T is: T I = 3 0 [mm] ÷ 4 [mm
/min×60=450 [sec].

On the other hand, in the case of the present invention in which the position detection means 20 is provided at a position 1 mm in front of the reference plate IO, the time ta required for the grindstone to be detected by the reference plate IO from the starting point is ta = 2 9 [m
m] + (15 [m/min XIO3)X60
= Q , l l 6 [sec] Also, the time tb from when the movement of the grinding wheel is detected by the position detection means 20 until the grinding wheel contacts the reference plate IO is: b = I [mmi+4 [mm/mi
n]X 6 0 = 1 5 [sec]. After all, their total time T, is Tz=1 5+0
．． 1 16 = 1 5.1 1 6 [sec], and the measurement time is significantly reduced.

For the second measurement, the reference plate IO is moved in the X-axis direction or the I11 direction so that the grindstone of the tool to be measured comes into contact with the uncontacted portion of the reference plate 10. Further measurements are repeated, and when the measurement surface of the reference plate IO is polished with each of the above grindstones and there are no uncontacted areas, the measurement surface is automatically polished with another grindstone, and the reference plate IO is used again. Try to get it.

In addition, although the case where the diameter of the grindstone is measured by moving the tool in the Y-axis direction is explained above, the tool is moved in the X-axis direction (
The diameter of the whetstone can be measured by moving the tool in the direction perpendicular to the paper in Figure 1), and the length of the whetstone can be measured by moving the tool in the ZI direction (direction perpendicular to the paper in Figure 1). You can also do it. In this case, the reference plate 10 and the position detection means 2o
Needless to say, the positions are rearranged in the direction of movement of the tool.

Furthermore, according to experiments, even when the grinding wheel contacts the reference plate 10 by a very small amount of 1 at the resolution level (1 μm), the detected AE multiplied signal level is high and a fast response speed is obtained. In this case, the contact signal is not limited to the AE multiplied signal.

〔Effect of the invention〕

As explained above, the present invention includes a main shaft to which a tool having a grindstone is mounted, and the main shaft is configured to be moved by a drive motor in at least one direction of the X-axis, Y-axis, and Z-axis. In a numerically controlled grinding machine, a contact member that contacts a grindstone of a tool, a contact detection means that detects contact of the grindstone with this contact member, and a contact detection means that detects that the grindstone has arrived at a position a certain distance away from the contact member, and It is equipped with a position detection means that slows down the feed speed of the spindle by the drive motor, and a calculation means that calculates the dimensions of the grindstone from the position of the spindle when the grindstone comes into contact with the contact member, and the position detection means moves the grindstone. The grindstone is configured to detect this, switch the feed speed of the grindstone from high speed to low speed, and bring it into contact with the contact member, so even when the range of dimensions to be measured is wide, it is possible to quickly measure the dimensions of the grindstone. can. Also, N
Since the grindstone dimensions can be measured by effectively utilizing the functions of the NC grinder in the C grinder, measurements can be made quickly without interrupting the automatic operation of the NC grinder. Therefore,
High precision grinding work can be done efficiently. Furthermore, if a reference plate with a large surface area and a new contact area can be freely taken as many times as desired, measurements can be made accurately and many times with the tool rotated to eliminate its eccentricity. It has its advantages.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a device for implementing the device of the present invention, FIG. 2 is a view taken along arrow W in FIG. 1, FIG. 3 is a block diagram of the device, and FIG. 4 is a signal A block diagram showing an example of a processing section, FIGS. 5 and 6 are diagrams for explaining the principle of measuring dimensions, and FIG. 7 is a flowchart of the present invention. l...Tool to be measured, 1a...Wheelstone, 2...Spindle,
8... Calculating means, IO... Contact member (reference plate), 12... Bracket semi-tool, 12a... Grindstone, 20...
- Position detection means (photoelectric switch), 22... Contact detection means (AE sensor).

Claims (1)

[Claims] In a numerically controlled grinding machine comprising a main shaft on which a tool having a grinding wheel is attached, and the main shaft is configured to be moved by a drive motor in at least one direction of the X-axis, Y-axis, and Z-axis, the grinding wheel of the tool is A contact member to be brought into contact, a contact detection means for detecting contact of a grindstone with the contact member, and a detection means for detecting that the grindstone has reached a position a certain distance away from the contact member and slowing down the feed speed of the main shaft by the drive motor. An automatic grindstone dimension measuring device for a numerically controlled grinding machine, comprising: a position detection means; and a calculation means for calculating the dimensions of the grindstone from the position of the spindle when the grindstone contacts the contact member.