JPH0521708B2 - - Google Patents

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.

[Prior Art] 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, automatic dressing, etc., conventionally, the grinding wheel (tool )
was being removed from the main shaft of a numerically controlled grinding machine. However, this method requires removing the tool to be measured from the main shaft of the numerically controlled grinding machine and carrying it outside the grinding machine for actual measurement, which is time-consuming and requires interrupting automatic operation.
There are problems 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 rotated a main shaft equipped with a tool having a grindstone and moved it from a starting point toward a reference plate, detected contact of the grindstone with the reference plate, and measured 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 reference tool whose dimensions are known in advance and the tool to be measured (patent application filed on October 7, 1985).

[Problem that the invention seeks to solve]

However, while 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 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 provides a numerically controlled grinding machine comprising a main shaft on 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. A contact member that contacts a whetstone of the tool in a rotating state; a contact detection means that detects contact of the whetstone with the contact member; and a contact detection means that detects that the whetstone has arrived at a position a certain distance away from the contact member. position detection means for slowing down the feed speed of the spindle by the drive motor; a calculation means for calculating the dimensions of the grindstone from the position of the spindle when the grindstone contacts the contact member; The present invention is characterized by comprising contact position moving means for moving either the contact member or the grindstone to change the contact position between the grindstone and the contact member during dimension measurement.

[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.

For each dimension measurement, either the contact member or the tool to be measured is moved by the contact position means, and the contact position between the contact member and the tool to be measured at the time of dimension measurement is changed, and the tool to be measured is brought into contact with the tool. Measure the dimensions several times by touching the new part of the part,
When the contact member no longer has any uncontacted parts of the tool to be measured, replace it 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, and A in the figure indicates an automatic tool changer (not shown).
This is a numerically controlled grinding machine (hereinafter referred to as an NC grinding machine). This NC grinding machine A is so-called
It has the same basic structure as a grinding center, in which a tool 1 having a grinding wheel 1a is taken out from a tool magazine (not shown) and mounted on a spindle 2, and an
The drive motors 4, 5, and 6 for the Y-axis, Y-axis, and Z-axis are respectively controlled.

The automatic grindstone dimension measuring device of the present invention is attached to this NC grinding machine A, and the grindstone 1a of the tool 1, which is moved in the Y-axis direction by the main shaft 2, is located at a certain distance away from a fixed point for measurement. a position detecting means 20 for detecting that the grinding wheel 1a has reached the
A contact detection means 22 detects that the reference plate (contact member) 10, which is a fixed point, is in contact with the reference plate (contact member) 10, and the grindstone 1a of the tool 1 is and a calculation means 8 for determining the diameter of.

In this embodiment, as the position detection means 20,
Since the contact part of a contact type sensor is damaged by the rotating grindstone, a non-contact type sensor is used. 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 10 in between. Further, the detection area of this photoelectric switch 20 is elongated as seen in the shape of the slit 20c. With this, the grindstone 1a
Detection is possible no matter where the outer periphery in the Z-axis direction blocks this detection area. Further, the signal output from the photoelectric switch 20 is transmitted to the signal processing section 21.
When the amount of received light falls below the set value,
A contact signal is output from the signal processing section 21.

Further, as the contact detection means 22, the tool 1
A detection signal (acoustic emission signal, hereinafter referred to as AE signal) generated when the grinding wheel 1a contacts the reference plate 10 is used.
In other words, the AE signal generated by this contact is
The contact detection means (AE sensor) 22 fixed to the jig 11 passes through the jig 11 fixing the reference plate 10, and detects the contact detection means (AE sensor) 22 fixed to the jig 11. Contact detection means 2
The detection signal detected in step 2 is converted into a contact signal by a signal processing section 23 and guided to the NC control device 3. As shown in FIG. 4, the signal processing unit 23 extracts only specific frequency components from the AE signal using a low-pass filter and a high-pass filter, amplifies the signal at the same time, processes it in a detection processing unit, and compares it with a threshold value set in a comparator. If the detected signal level is equal to or higher than the threshold value, the contact is turned on.

Note that the above AE signal is generated from cracks that gradually progress before the substance is completely destroyed, and is a kind of elastic liquid.

The calculating means 8 is provided inside the NC control device 3, and includes an AND gate 8a that transmits a feed pulse f, and a servo device of the Y-axis drive motor 5 using the feed pulse f from the AND gate 8a. By inputting the AE signal from the interpolator 8b that generates an output pattern for control and the position detecting means 20 or the contact detecting means 22, a counter inside the interpolator 8b indicates that the grindstone 1a of the tool 1 is lower than the reference plate 10. The position Y (Y
At the same time, the CPU (center It consists of an arithmetic processing unit) 8c and a storage device 8d connected to this CPU 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 explain the principle of the present invention when measuring the diameter of the grinding wheel 1a. In FIG. 6, when the main shaft 2 is at the starting point, the main shaft 2 and the reference plate 10 Distance (hereinafter referred to as reference distance)
When L ₀ is, the diameter of the grindstone 1a of the tool 1 is given by the following formula.

d=2(L ₀ −a) (1) Here, a indicates the moving distance of the grindstone 1a of the tool 1 to be measured. In other words, the position when it is at the starting point
If Y ₀ is the position of the main shaft 2 when the grinding wheel 1a contacts the reference plate 10, then a=|Y−Y ₀ |...(2) is obtained. This operation will be explained with reference to FIGS. 1 to 3.

First, the position Y ₀ of the starting point of the tool to be measured 1 is stored in the storage device 8d, and then when the tool to be measured 1 is moved along the Y axis, the grinding wheel 1a of the tool to be measured 1 is placed on the reference plate. 10, the position Y at that time is taken into the CPU 8c, and at the same time,
Stop axis movement. The CPU 8c calculates the moving distance a of the tool to be measured 1 from these detected positions Y ₀ and Y.

Further, the reference distance L ₀ in equation (1) is determined by the following equation.

L ₀ = d ₀ /2 + a ₀ ... (3) Here, d ₀ is the known diameter of the grinding wheel 12a of the reference tool 12, and a ₀ is the diameter of the grinding wheel 12a of the reference tool 12. and the tool to be measured 1
This is the moving distance of the reference tool 12 obtained by moving in the same manner as , and is obtained in the same manner as the moving distance a.

In this way, the reference distance L ₀ is measured in advance using the reference tool 12 having the grindstone 12 with a known diameter, and then the tool to be measured 1 is mounted on the spindle 2 and the tool travel distance a is measured. and 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 shaft 2 returned to the starting position Y ₀ ,
The automatic tool changer is activated to take out a reference tool 12 having a grindstone 12a with a known diameter d ₀ from a tool magazine (not shown) and attach it to the spindle 2.
The position Y ₀ at the starting point of the reference tool 12 is stored in the storage device 8d of the calculation means 8 (step
S1). Next, rotate the main shaft 2 (step
S2). Then, the main shaft 2 is moved in the Y-axis direction, and the reference tool 12 is moved downward in FIG. 1 at a high feed rate (step S3). Then, calculation means 8
The gate signal of the AND gate 8a 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 the feed pulse f, and the Y-axis drive motor 5 continues to operate.
When the grindstone 12a of the reference tool 12 enters the detection area of the photoelectric switch 20, the photoelectric switch 2
0 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), enters the CPU 8c of the calculation means 8.

When the CPU 8c receives this detection signal,
The gate signal of the AND gate 8a is turned OFF to stop inputting the feed pulse f to the interpolator 8b, and the Y-axis drive motor 5 is stopped. Thereafter, the Y-axis drive motor 5 is operated again to move the main shaft 2 in the Y-axis direction at a slow feed rate (step S5). Then, the grindstone 12a of the reference tool 12 is attached to the reference plate 10.
When the contact sensor 22 comes into contact with the
S6), enters the CPU 8c of the calculation means 8.

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

Furthermore, the CPU 8c calculates the travel distance based on the control program registered in the storage device 8d (step S9), and confirms that the tool inserted in the spindle 2 is the reference tool (step S10). , a reference distance L ₀ is calculated using the grindstone diameter d ₀ of the reference tool 12 registered in the storage device 8d and the control program (step S11), and this is registered in the storage device 8d (step S12). and,
Next, operate the automatic tool changer to exchange the reference tool 12 of the spindle 2 with the tool to be measured 1, and
Using almost the same procedure as in case 2, measure tool 1.
Measure the diameter of the grinding wheel. That is, the position _Y0 at the starting point of the tool to be measured 1 is stored in the storage device 8d (step S1). Next, the main shaft 2 is rotated (step S2). Then, the main shaft 2 is operated to rotate the tool 1 to be measured and move it downward in FIG. 1 at a high feed rate (step S3). At this time, the feed pulse f passes through the AND gate 8a and enters the interpolator 8b.
A control signal for the Y-axis drive motor 5 is output from b. The grindstone 1a of the tool to be measured 1 is a photoelectric switch 20
When the light enters the detection area, the signal processing section 21 detects a decrease in the amount of light by the photoelectric switch 20.
Send a contact signal to CPU 8 (step S4).

When the CPU 8c receives this detection signal,
The gate signal of the AND gate 8a is turned OFF, and the input of the feed pulse f to the interpolator 8b is stopped.
Stop the Y-axis drive motor 5. After that, Y again
The shaft drive motor 5 operates to move the main shaft 2 in the Y-axis direction at a slow feed rate (step S5). When the grindstone of the reference tool 12 comes into contact with the reference plate 10, the contact detection means 22 outputs an AE signal, which is detected by the signal processing section 23,
S6), enters the CPU 8c of the calculation means 8. CPU8c
When this contact signal is input, the pulse number of the feed pulse f is taken from the counter inside the storage device 8d as the position Y of the tool to be measured 1, and is registered in the storage device 8d (step S7), and the AND gate 8a Turn off the feed pulse f
The input to the interpolator 8b is stopped, and the Y-axis drive motor 1
5 is stopped and the tool to be measured 1 is returned to the starting point (step S8). In addition, the CPU 8c uses the storage device 8
The control program in d calculates the travel distance and confirms that the tool inserted in the spindle 2 is the tool to be measured (steps S9 and S10).
The grinding wheel diameter d of the tool to be measured 1 is determined by the reference distance _L0 stored in the storage device 8d and the control program.
is calculated (step S13). The calculated value is registered in the storage device 8d as the measured grindstone diameter d, and the process ends (step S14).

In the above, the movement of the grindstone is caused by the position detection means 20
After the grinding wheel is detected by the reference plate 10
The feed rate of the spindle 2 until it comes into contact with is 4
[mm/min], the rotation speed is set to 4000 [rpm], and the feed amount per rotation of the spindle 2 is 1 μm. Since the grindstone is brought into contact with the plate 10, even if the grindstone is eccentric, its influence is completely eliminated. 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 is set at 15 [m/min] until the movement of the grindstone from the starting point is detected by the position detection means 20.

When the target tool has a radius of 30 [mm] and is moved toward the reference plate 10 at a feed rate of 4 [mm/min],
The time T ₁ during which the smallest grindstone is in contact with the reference plate 10 is as follows: T ₁ = 30 [mm] ÷ 4 [mm/min] x 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 of 1 mm in front of the reference plate 10, the time ta required for the grindstone to be detected by the reference plate 10 from the starting point is ta= 29 [mm] ÷ (15 [m/min] x 10 ³ ) x 60 = 0.116 [sec] Also, the time from when the movement of the grinding wheel is detected by the position detection means 20 until the grinding wheel contacts the reference plate 10 tb is tb = 1 [mm] ÷ 4 [mm/min] x 60 = 15 [sec]. In the end, the total time T ₂ becomes T ₂ =15+0.116=15.116 [sec], which significantly reduces the measurement time.

For the second and subsequent measurements, use the reference plate 1.
0 in the X-axis direction or Z-axis direction,
The grindstone of the tool to be measured is brought into contact with the uncontacted portion of the reference plate 10. When the measurement is repeated and the measurement surface of the reference plate 10 is polished with each of the above-mentioned grindstones, and there are no uncontacted areas, the measurement surface is automatically polished with another grindstone, and the reference plate 10 can be used again. Do it like this.

In addition, above, we explained the case where the diameter of the grindstone is measured by moving the tool in the Y-axis direction, but it is also possible to measure the diameter of the grindstone by moving the tool in the X-axis direction (direction perpendicular to the paper in Figure 1). Alternatively, the length of the grindstone can be measured by moving the tool in the Z-axis direction (left-right direction in FIG. 1). In this case, it goes without saying that the reference plate 10 and the position detection means 20 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 resolution (1 μm), the level of the detected AE signal is high and a fast response speed is obtained. In this case, the contact signal is not limited to the AE 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
In a numerically controlled grinding machine configured to be moved by a drive motor in at least one direction of an axis, a Y axis, and a Z axis, a contact member that contacts a grindstone of the tool in a rotating state; a contact detection means for detecting contact of the grindstone; a position detection means for detecting that the grindstone has arrived at a position a certain distance away from the contact member and slowing down the feed speed of the main shaft by the drive motor; a calculation means for calculating the dimensions of the grindstone from the position of the spindle when the grindstone comes into contact with the grindstone; contact position moving means for changing the contact position with the contact member, the position detection means detects the movement of the grindstone, and the grindstone is configured to switch the feed speed from high speed to low speed and bring it into contact with the contact member. Therefore, the dimensions of the grindstone can be quickly measured even when the range of dimensions to be measured is wide. In addition, since the grinding wheel dimensions can be measured by effectively utilizing the functions of the NC grinding machine,
Measurements can be made quickly without interrupting the automatic operation of the NC grinding machine. Therefore, highly accurate grinding work can be performed 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. There are advantages.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a device for carrying out 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 the 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. DESCRIPTION OF SYMBOLS 1... Tool to be measured, 1a... Grinding wheel, 2... Main shaft, 8... Calculating means, 10... Contact member (reference plate), 12... Reference tool, 12a... Grinding wheel,
20... position detection means (photoelectric switch), 22...
...Contact detection means (AE sensor).

Claims (1)

[Claims] 1. A main shaft on which a tool having a grindstone is mounted,
In a numerically controlled grinding machine, the main shaft is configured to be moved by a drive motor in at least one of the X-axis, Y-axis, and Z-axis, a contact member that contacts the grindstone of the tool in a rotating state; contact detection means for detecting contact of the grindstone with the contact member; position detection means for detecting that the grindstone has arrived at a position a certain distance away from the contact member and slowing down the feed speed of the main shaft by the drive motor; , calculation means for calculating the dimensions of the grindstone from the position of the main shaft when the grindstone contacts the contact member; and for each dimension measurement, one of the contact member and the grindstone is moved, and the dimensions are measured. An automatic grindstone dimension measuring device for a numerically controlled grinding machine, comprising a contact position moving means for changing the contact position between the grindstone and the contact member at different times.