JP3421562B2 - Cutting tool runout detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool shake detecting method. For details, while the spindle of a numerically controlled machine tool is rotating, the height of the cutting edge of each cutting edge of a multi-blade tool is automatically measured to find the maximum and minimum values of the cutting edge height to detect the runout of the cutting tool. Is the way.

[0002]

2. Description of the Related Art Before using a multi-blade tool such as an end mill or a milling tool before fitting a tool onto a spindle, it is necessary to adjust the runout of the blade within a certain range. Each of multi-blade tools
The run-out of the cutting edge is also measured outside the machine as described above, but in addition to preventing blade setting defects, it also prevents premature wear of certain cutting edges and uneven machining and also extends the life of the cutting edges. Moreover, in order to reduce the variation in the height of the cutting edge, measurement is performed for each cutting edge.

However, the runout of the blade can be measured in advance by external measurement, and if there is a defect, the tool can be reset on the tool holder to adjust the runout small, but in reality it was difficult to measure the runout accurately. For example, in the case of the tool microscope method,
It is difficult to focus when rotating the tool on a commonly used tool presetter. Also, in the case of the dial gauge type, it is often necessary to rotate the tool many times to measure the high position of the blade.

By the way, all the above-mentioned methods for measuring the runout of the blade are out-of-machine measurements, and in any of these measurements, the runout of the tool alone without any runout of the spindle must be measured. Naturally, the influence on the machined surface should be evaluated by adding the deflection of the spindle. There is a method to measure the runout of each cutting edge with a dial gauge while rotating the spindle on the machine, but since it is not automatic measurement, it takes a lot of time and the measurement results show individual differences, etc. It is possible to measure the cutting edge of a tool with a laser beam, but there are drawbacks such as the time required for measurement increases if the main axis of each cutting edge of a multi-edged tool is stopped, which leads to automation of measurement and measurement control work. It is not suitable as a method for measuring the runout of the cutting edge of a machine tool.

[0005]

The method of measuring the deflection of the cutting edge of the tool mounted on the tool holder outside the machine described in the prior art does not measure the deflection of the blade including the deflection of the spindle. It has, and it does not adapt to automatic measurement when calculating with a dial gauge in the machine, and even when measuring with a laser beam inside the machine, the spindle rotation is stopped for each cutting edge and measurement is required Has the problem of becoming. The present invention has been made in view of such problems that the conventional technology has, the purpose is to measure the outside of the machine in advance after the multi-blade tool properly attached to the tool holder is attached to the spindle, An object of the present invention is to provide a method for measuring the maximum and minimum values of the cutting edge height of a multi-edged tool during rotation of a spindle by means of laser beam measuring means in the machine.

[0006]

Shake detection method of the cutting tool of the present invention in order to achieve the above object, according to an aspect of detects the deflection of the tool which is fixed a cutting edge mounted on numerically controlled machine tool spindle on a circle circumference Method, but when measuring the highest cutting edge,
From the outside of the tool to the center
With feed rate limited to the blade edge detection accuracy in the direction perpendicular to the axis
It is moved and aligned directly with the spindle axis of the detection means placed inside the machine.
The light beam output in the intersecting direction was interrupted even for a moment
Sometimes the sensor signal is output to the numerical control device and this signal
The lowest edge is calculated by calculating the highest edge position.
When measuring the tip, the number of rotations at which the tool edge can be detected
To rotate the tool from the center of the tool to the outside
When the cutting edge detection accuracy required in the direction perpendicular to the spindle axis is required,
Moved at the tool feed speed and the light beam passed even for a moment
The sensor signal is output to the numerical controller at an instant and this signal
Calculate the lowest cutting edge position based on
The shake of the cutting tool is obtained from the position data obtained by calculating the cutting edge and the lowest cutting edge . According to the method of the present invention, it is possible to automatically measure the runout of the rotary member including the spindle and the tool as the tip runout of the tool during the spindle rotation after mounting the milling tool on the spindle and before starting the machining work. Becomes

Further, the theoretical rotational speed S ₂ [min ^-1 ] when detecting the lowest cutting edge is 60 / (number of cutting edges × Δt) <
S ₂ <(60 × 2) / (number of cutting edges × Δt), and when the required accuracy of blade edge detection is P [μm], the tool feed speed F
[Mm · min ⁻¹ ] is the rotation speed S of the tool that can measure the position of the cutting edge during tool rotation, which is obtained by F = P × S × 10 ⁻³
The range of is the theoretical rotational speed S when detecting the highest cutting edge.
₁ [min ⁻¹ ] is S ₁ <60 ÷ Δt [Δt is the pulse width of the sensor output signal, second], and the theoretical rotation speed S ₂ [min ⁻¹ ] when detecting the lowest cutting edge is 60 / ( Number of cutting edges x
Δt) <S ₂ <(60/2 × Δt), and when the required accuracy of blade edge detection is P [μm], the tool feed speed F [mm
Min < ^-1 >] is a value obtained by F = P * S * 10 < ^-3 >. According to the present invention, it is possible to measure the blade edge position of a rotating cutting tool that is attached to the spindle, but the range of the rotational speed of the spindle that can detect a high blade edge and a low blade edge during spindle rotation is clarified in advance, and its range Since the feed rate of the spindle can be easily determined according to the accuracy of the position of the cutting edge to be detected at the selected rotation speed, automatic measurement becomes easy.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a laser measuring device 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 standing beside a bed (not shown) so that it can be positioned in the W axis direction parallel to the Z axis. The cross rail 1 is provided on the front surface in the Y axis direction. The 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 therein. There is. Attachment 4
A milling tool T, which is a tool to be measured and is gripped by the milling arbor 5, is detachably attached to the tip tapered hole.

A laser measuring device 6 is fixed near the Y-axis moving end portion of the lower surface of the cross rail 1 via a mount 7 so that the laser optical axis faces the X-axis direction. The laser measuring device 6 monitors that the laser light a emitted from the laser emitting portion 6a reaches the internal diode through the small window of the light receiving portion 6b, and cuts off when the tool passes the laser light a at right angles. When the shaded area becomes 90% of the small window, it outputs a sensor signal, the cable 8 is an electric wire for supplying the power supply voltage and the sensor signal to an NC device (not shown), and 9 is a protective cover.

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

In FIG. 2A, the cutting edge of the measured object is not detected when the measured object does not block the optical axis of the laser beam and no sensor signal is output. Figure 2 (b)
Indicates that the sensor signal is being output while the object to be measured is blocking the laser beam optical axis, but the cutting edge of the object to be measured is not detected. FIG. 2C shows that the sensor signal starts to output to detect the cutting edge of the measured object in any case when the optical axis of the laser beam is blocked or the tool cutting edge passes through the cutting edge of the measured object. Shows.

Next, a method for detecting the runout of the cutting edge by measuring the positions of the highest cutting edge and the lowest cutting edge of the milling tool using the measuring device configured as described above will be described.
First, the tool rotation speed S when detecting the highest cutting edge and the lowest cutting edge of the milling tool and the feed rate F that determines the detection accuracy of the cutting edge position will be described.

FIG. 3 (a) shows the positional relationship between the tool feed direction and the beam axis when the highest cutting edge is detected. t ₁ ~t ₄ shows a chip that is fixed on the milling tool. By moving the tool from the state shown in FIG. 3 (b) and cutting off the beam axis by the cutting edge [FIG. 3 (c)], the outermost cutting edge of the rotating milling tool can be detected. When cut off, the sensor of the light receiving unit outputs, for example, a pulse for 0.1 second and sends it as a skip signal to the numerical control device to store the position of the cutting edge at that time and instruct the shift to the next measurement process.

FIG. 4A shows the positional relationship between the tool feed direction and the beam axis when the lowest cutting edge is detected. In this case, the beam axis moves the tool from the position where it is blocked by the cutting edge of the milling tool [Fig. 4 (b)]. When the lowest cutting edge comes, the beam axis goes out of the cutting edge, and the light beam reaches the light receiving portion 6b. When the light reaches the light receiving unit, the light receiving unit outputs a constant pulse (for example, a pulse width of 0.1 seconds), and a skip signal is sent to the numerical controller. In this case, it is referred to as B-contact method (normally closed) signal processing here. When the light is blocked, for example, a sensor signal of 0.1 second is output and a skip signal is output. ) Signal processing.

Next, during tool rotation, the highest cutting edge and the lowest
A method of determining the rotation speed of the tool as a condition for detecting the position of the cutting edge will be described.

First, when detecting the position of the highest cutting edge , for example, a 0.1 second pulse of a sensor output signal is output for each cutting edge in FIGS. 6 and 7 . Assuming that the skip signal sampling interval on the NC side is 0.001 seconds, the 0.1-second pulse output that is output at the same time as detection is a sufficient value for skip signal detection. Therefore, in this case, there is no limitation on the number of revolutions, and only the limitation on the feed rate with respect to the detection accuracy occurs. That is, when the tool is rotated and the detection accuracy of the cutting edge is P μm, the final feed speed F ₀ of the tool is F ₀ = P × S × 10 ⁻³ (m
m · min ⁻¹ ). However, F ₀ is the final feed rate, and it is desirable that the feed rates of several stages are sequentially set in advance.

For example, the feed speed is gradually lowered to the final speed F ₀ at 3 to 4 times so as to improve the detection accuracy. An example of detecting a high blade edge with a final detection accuracy of 1 μm is shown below with S = 6000 min ⁻¹ . F ₀ = 1 × 6000 = 6.0 m when the target detection accuracy is 1 μm
Since m · min ⁻¹ , the first feeding speed F ₁ = 10
00, the tool position is returned 6.0 mm after the signal is turned on, and then the second feed speed F ₂ = 100 is set and 0.06 mm is also returned after the signal is turned on. Next, the third feed rate is F ₃ = 2
When the signal is turned ON, 0.01 is returned after the signal is turned ON, and the final fourth feeding speed is set to F ₀ = 6.0. When the signal is turned ON, detection is completed.

Next, the case of detecting the position of the lowest cutting edge will be described. In FIG. 8, since the beam is blocked when all the cutting edges pass, the sensor output signal of 0.1 pulse is output from the light receiving unit for all the cutting edges, and the sensor output signal is always NO. In this case, the skip signal is not output to the NC device.

When the tool position reaches the position shown in FIG. 4 (c), the beam reaches the light receiving portion beyond the lowest cutting edge and the detection signal detected for each cutting edge is lost, and the sensor output signal corresponding to this is lost. No longer output 0.1 second pulse
It FIG. 9 shows a state in which the detection signal t ₄ is missing. If the 0.1 second pulse with respect to t ₄ is not output, the sensor output signal S ₂ is partially turned off.

The tool rotation speed in which this state occurs indicates that it occurs when the time required for the cutting edges t ₃ and t ₁ adjacent to t ₄ to pass is longer than 0.1 seconds. Lower when in other words the two cutting edges time through come lowers the tool rotational speed is larger than the pulse width of the sensor output signal edge
It shows that the destination can be detected. Therefore, the tool rotation speed that can detect a low cutting edge is S ₂ <(2 × 60)
If Δt = 0.1 seconds and the number of cutting edges = 4 in / (Δt × the number of cutting edges), S ₂ <300 min ⁻¹ . However, it should be noted that there is a lower limit on the tool rotation speed for detecting the lowest cutting edge.

In FIG. 10, when the tool rotation speed is further reduced, the blade edge is detected and the 0.1 second pulse corresponding to the sensor output signals t ₁ , t ₂ and t ₃ output from the light receiving section is turned on.
A break occurs in the signal and an OFF state occurs. This OF
The F state can no longer be distinguished from the OFF state caused by t ₄ . The lower limit rotational speed at which a low blade edge can be detected means that it cannot be detected when the time taken for adjacent blade edges t ₁ and t ₂ to pass becomes longer than 0.1 seconds. Therefore, the rotational speed S _{1 of the} lower limit of the tool that can detect a low cutting edge
Is Δt ≧ (60 / S ₂ ) × (1 / number of cutting edges) ∴S ₂ ≧
[60 / (number of cutting edges × Δt)] For example, if Δt = 0.1 seconds and the number of cutting edges = 4, then S ₂ = 150 min ⁻¹ .

By summarizing the above, the following relational expression is obtained. (2 × 60) / (Δt × number of cutting edges)> S ₂ > 60 / (Δt × number of cutting edges) S ₂ satisfying the above relational expression is selected as the rotation speed and the final feed is performed by the method of determining the feed speed. If the speed is selected, it is possible to detect the position of the lowest cutting edge with the desired accuracy. By the way, the tool rotation speed is theoretically expressed as S = 60 / (number of blades × 0.1) min ⁻¹ , but when selecting the actual tool rotation speed, the signal delay time and the rotation speed of the tool rotation speed It is necessary to consider the margin by considering the error and the time loss of the skip signal acquisition timing on the NC device side, and it is possible to detect it in the range of the tool rotation speed higher than the theoretical value by dividing by the coefficient k. It can be displayed as follows. Lowest blade
The tool rotation speed S ₂ for detecting the tip is (k × 2 × 6
0) / (Δt × number of cutting edges)> S ₂ > 60 / Δt × number of cutting edges ×
k, here k is determined by the margin based on the loss time until the above-mentioned sensor output signal is processed by the NC device to drive the servo system and the rotational speed error of the tool rotational speed.

Next, the measuring method according to the present invention will be described with reference to the flowchart of FIG. At the start of measurement in step S1, a measurement beam is emitted to the light receiving side. In step S2, the position of the tool origin is stored. The first measurement is from the detection of the highest cutting edge of the cutting edges of the milling tool. In step S3, the circuit condition is selected so that the processing condition of the sensor output signal is processed by the A contact method (normally open). That is, this is to output a skip signal to the NC device when the sensor output signal is generated.

In step S4, the tool rotation speed S ₁ is set. In step S5, the moving direction of the tool is determined so as to move in the direction shown in FIG. In step S6, the tool feed speed F is set. The feed rate is related to the accuracy of detecting the height of the cutting edge . For example, when detecting the position of the cutting edge with an accuracy of 1 μm, the feed rate F is F = 1 μm × S ₁ × 10 ⁻³ (mm)
If it is set to, the detection method becomes extremely slow.
Therefore, as described above, starting from a high feed speed until reaching the final feed speed, a speed of about 3 stages is set in advance, and a fixed amount of the tool feed is returned every time the sensor light receiving unit detects the final feed speed. The blade edge is detected by the speed so that the detection accuracy can be satisfied.

When the tool feed reaches the final feed speed to detect the cutting edge in step S7, a 0.1 second pulse of the sensor output signal is output in step S8, and a skip signal is output to the NC device in step S9. The highest position of the cutting edge is calculated and stored from the data of step S10 and the data of the tool origin in step S2.

Next, the process moves to detection of the position of the lowest cutting edge . In step S12, the B contact method (normally closed) is selected for processing the sensor output signal. The B-contact method is a method of outputting a skip signal when the sensor output signal disappears. In step S13, the tool rotation speed S ₂ required to detect the next lower cutting edge during tool rotation is selected. The selectable range of S ₂ has certain conditions: 60 ÷ (number of cutting edges × Δt) <S ₂ <(2 ×
60) / (Δt × number of cutting edges) is selected from the range.

In step S14, the moving direction of the tool is shown in FIG.
Set to move in the direction shown in . Next step S1
In 5, the tool feed speed F is set. The process up to the final feed rate is the same as that for detecting the highest cutting edge . When the tool feed detects the cutting edge at the final feed speed in step S16, a 0.1 second pulse of the sensor output signal is output in step S17, and a skip signal is output to the NC device in step S18, the tool is output in step S18. The cutting edge position of is stored. In step S20, the position of the lowest cutting edge is calculated and stored from the data of step S18 and the data of the tool origin in step S2.
In step S21, the deflection of the tool blade is calculated from the data of steps S11 and S20, and the measurement is completed.

[0028]

As described above, since the method for detecting the shake of the cutting tool of the present invention operates as described above, it has the following effects. It restricts the use of the tool exceeding a certain threshold because the deflection of the numerically controlled machine tool of the milling tool can detect the position of the lowest edge and the position of the highest edge measured during tool rotation by a non-contact tool It is possible to extend the life and improve the roughness of the machined surface. Since the measurement is automated, it can be expected to improve the operation efficiency, and if it is measured before the work is started, it will be possible to perform the inspection of the tool preparation work until the tool holder is attached to the spindle.

[Brief description of drawings]

FIG. 1 is a perspective view of a laser measuring device and a spindle head portion attached to a cross rail of a machining center.

2A is an explanatory view showing a state where a laser beam is passing through a tool edge, FIG. 2B is an explanatory view showing a state where laser light is blocked by the tool edge, and FIG. 2C is a laser beam. FIG. 3 is an explanatory view of a state when the tool blade edge is blocked or the tool blade edge passes. In any case, the beam receiving unit outputs a Δt second pulse of the sensor output signal.

3A is an explanatory view of a state in which a tool approaches a laser beam axis direction while rotating, and FIG. 3B is an illustration showing that a cutting edge of the tool is apart from the laser beam before starting measurement. FIG. 1C is an explanatory diagram showing a state in which the tool moves and the highest cutting edge blocks the laser beam.

FIG. 4A is a diagram showing a state in which a tool moves in a direction away from a laser beam axis while rotating, and FIG. 4B shows a state where the laser beam is blocked by the cutting edge of the tool before the measurement is started. FIG. 6C is a diagram showing a state, and FIG. 7C is a diagram showing a state at the time when the laser beam passes through the tip of the lowest cutting edge due to the tool movement.

FIG. 5 is a graph showing a sensor detection signal Q ₁ and a sensor output signal Q2 when a laser beam is always received [FIG. 3 (b)].

6A and 6B are graphs showing that the sensor output signal can be detected when the highest blade edge is detected.

7 (a) and 7 (b) are graphs showing that the sensor output signal Q ₂ can be detected when the highest cutting edge is detected.

FIG. 8 is a graph showing a state in which a change cannot be detected in the B contact method (normally closed) because the sensor output signal Q ₂ is always present when the laser beam is always interrupted when detecting the lowest blade edge .

FIG. 9 is a graph showing that the sensor signal output Q ₂ cannot be detected unless the rotation speed is equal to or lower than a certain value when the lowest blade edge is detected.

FIG. 10 is a graph showing a state in which the blade edge cannot be identified by the output Q ₂ of the sensor output signal unless the rotation speed is equal to or more than a certain rotation when the lowest blade edge is detected.

FIG. 11 is a flowchart illustrating the order of measurement according to the present invention.

[Explanation of symbols]

T DUT (tool) a Laser beam 1 Cross rail 2 Spindle head 3 Spindle ram 4 Attachment 5 Milling arbor 6 Laser measuring instrument 6a Laser emitting part 6b Laser receiving part 7 Mounting base 8 Cable 9 Protective cover

Continuation of the front page (56) Reference JP-A-2-78904 (JP, A) JP-A-4-315556 (JP, A) JP-A 61-90858 (JP, A) JP-A-60-127441 (JP , A) JP 62-241639 (JP, A) JP 64-64752 (JP, A) JP 5-329751 (JP, A) JP 47-1276 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23Q 17/24 B23Q 17/09 G01B 11/00

Claims (2)

(57) [Claims] [Claim 1] A numerical control machine tool mounted on the machine spindle circle circumference on a method for detecting the deflection of the tool which is fixed to the cutting edge,
When measuring the highest cutting edge, use the rotated tool
Blade from the outside of the tool to the center in a direction perpendicular to the spindle axis
Move at the feed speed limited to the pre-detection accuracy and place it on the machine.
Output in the direction orthogonal to the main axis of the detection means.
The sensor signal is counted when the light beam is interrupted even for a moment.
Output to the value control device, and based on this signal, the highest blade
When calculating the lowest position by calculating the tip position
Is to rotate the tool at the number of rotations where the cutting edge can be detected.
Move the tool from the center of the tool to the outside and at a right angle to the spindle axis.
Moves at the tool feed speed when the required blade edge detection accuracy is
Let the sensor signal at the moment when the light beam passes even for a moment
Is output to the numerical control device, and the lowest
There determined by calculating the edge position, the lowest blade and highest cutting edge
A shake detection method for a cutting tool, which is characterized in that the shake of the cutting tool is obtained from the position data obtained by the above calculation . 2. The range of the rotational speed S of the tool when measuring the lowest cutting edge is the theoretical rotational speed S ₂ [min ⁻¹ ] when detecting the lowest cutting edge, which is 60 / (number of cutting edges × Δt). ) <
S ₂ <(60 × 2) / (number of cutting edges × Δt), and when the required accuracy of blade edge detection is P [μm], the tool feed speed F
The method for detecting a shake of a cutting tool according to claim 1, wherein [mm · min ⁻¹ ] is obtained by F = P × S × 10 ⁻³ .