JP7636770B2 - Machine tool spindle speed adjustment system and spindle speed adjustment program - Google Patents

Description

The present invention relates to a machine tool spindle speed adjustment system and spindle speed adjustment program that can suppress vibrations that occur in the spindle.

In machine tools that machine workpieces by rotating a tool attached to the spindle, the deviation in the axial direction (Z-axis) of the spindle changes according to the commanded rotation speed while the spindle is rotating. When machining with a high target surface roughness value, this machine tool is required to use a rotation speed range that provides a small amount of Z-axis deviation.

For example, Patent Document 1 discloses a machine tool that includes a sensor that detects the vibration frequency of the spindle or tool, a calculation unit that calculates the vibration intensity of chatter vibration occurring in the spindle or tool based on the vibration frequency, and an adjustment unit that adjusts a set value for controlling the spindle rotation speed, and that determines a fluctuation range of the spindle rotation speed based on the occurrence of chatter vibration, changes the spindle rotation speed within the fluctuation range while obtaining vibration intensity for each of the multiple rotation speeds, and uses, among the multiple rotation speeds, the rotation speed at which the vibration intensity is relatively smaller than before the spindle rotation speed was changed as the set value.

JP 2019-107751 A

The machine tool described in Patent Document 1 had to be provided with a sensor that detects the vibration frequency of the spindle or tool in order to detect chatter vibration occurring in the spindle or tool. This machine tool had the problem of being complicated in structure because, for example, an acceleration sensor was provided in the housing.

In addition, when the machine tool described in Patent Document 1 detects chatter vibration in the spindle or tool, it changes the rotation speed of the spindle to obtain the vibration intensity at each rotation speed, so it was necessary to limit the range of variation in the rotation speed of the spindle in order to shorten the search time.

Therefore, the present invention provides a machine tool spindle speed adjustment system and spindle speed adjustment program that can easily suppress vibrations that occur in the spindle.

To solve the above problems, the present invention provides a machine tool spindle speed adjustment system for a machine tool that drives a spindle to which a tool is attached in rotation and drives the spindle in the axial direction of the rotating shaft, the machine tool having a position measurement means for measuring axial position data of the spindle, a deviation calculation means for measuring the axial position data of the spindle at each rotation speed by changing the rotation speed of the spindle and calculating the amount of deviation in the axial direction of the spindle from the position data and a reference position, a storage means for storing the amount of deviation at each rotation speed of the spindle, and a rotation speed adjustment means for adjusting the rotation speed of the spindle during machining to the rotation speed at which the amount of deviation is smallest within the allowable range for a specified rotation speed.

The spindle speed adjustment system of the machine tool also includes a tolerance setting means for setting the tolerance range as a percentage of the spindle speed specified during machining and/or as an allowable speed.

In addition, the spindle speed adjustment system of the machine tool is such that the allowable range setting means sets the narrower range of rotation speeds between the ratio of the spindle speed specified during machining and the allowable rotation speed as the allowable range.

In addition, in the spindle speed adjustment system for a machine tool, the deviation calculation means measures the position data in the axial direction of the spindle two or more times to calculate the deviation in the axial direction of the spindle at each rotation speed, and stores the data with the largest deviation amount as the deviation data.

The present invention also provides a spindle speed adjustment program for causing a computer to function as a spindle speed adjustment system for a machine described in any one of the above.

The spindle speed adjustment system of the machine tool of the present invention is a machine tool that drives a spindle to which a tool is attached in rotation and drives the spindle in the axial direction of the rotating shaft, and has a position measurement means that measures the axial position data of the spindle, a deviation calculation means that changes the rotation speed of the spindle to measure the axial position data of the spindle at each rotation speed and calculates the axial deviation of the spindle from the position data and a reference position, a storage means that stores the deviation at each rotation speed of the spindle, and a rotation speed adjustment means that adjusts the rotation speed of the spindle during processing to the rotation speed at which the deviation amount is smallest within the allowable range for a specified rotation speed.By having this, the deviation amount for each rotation speed can be measured using a position measurement means such as a scale that measures the axial position of the spindle, and the rotation speed can be adjusted to the rotation speed with the smallest deviation amount, so that it is possible to suppress vibrations generated in the spindle with a simple configuration.

The machine tool spindle speed adjustment system of the present invention can measure and store the deviation amount at each spindle speed before the machine tool starts operating or during downtime, so that during operation, the speed can be immediately adjusted to a speed with a small deviation amount.

The spindle speed adjustment system for the machine tool of the present invention is also equipped with an allowable range setting means for setting the allowable range as a percentage of the spindle speed specified during machining and/or as an allowable speed, thereby making it possible to adjust the speed to the one with the smallest deviation within the allowable range for the specified spindle speed.

The spindle speed adjustment system for the machine tool of the present invention has the effect that the allowable range setting means sets the ratio of the spindle speed specified during machining and the allowable speed, whichever has the narrower range of speeds, as the allowable range, thereby making it possible to adjust the specified spindle speed to the speed with the smallest deviation within a range that satisfies both the ratio and the allowable speed.

In addition, the spindle speed adjustment system for machine tools has an advantage that the deviation calculation means measures the position data in the axial direction of the spindle two or more times to calculate the deviation in the axial direction of the spindle at each rotation speed, and stores the data with the largest deviation amount as the deviation data, so that even if the deviation amount fluctuates over time, the data with the largest deviation amount can be stored as the deviation data.

The spindle speed adjustment program of the present invention, by functioning a computer as a spindle speed adjustment system for a machine described in any one of the above, can measure the deviation amount for each rotation speed using a position measurement means such as a scale that measures the axial position of the spindle, and the program can adjust the rotation speed to a small deviation amount, which has the effect of suppressing vibrations occurring in the spindle with a simple configuration.

1 is a configuration diagram showing an embodiment of a spindle rotation speed adjustment system according to the present invention; 4 is a flowchart showing an embodiment of a Z-axis deviation amount measuring means of the present invention. 4 is a flowchart showing an embodiment of a spindle rotation speed adjusting unit of the present invention. 1 is a perspective view showing an embodiment of a machine tool to which the present invention is applied; FIG. 4 is a diagram showing an example of a screen of the spindle rotation speed adjustment system according to the present invention. FIG. 4 is a diagram showing an example of a screen of the spindle rotation speed adjustment system according to the present invention. FIG. 13 is a graph showing a change in Z-axis deviation of a machine tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings.
The spindle rotation speed adjustment system in a machine tool of the present invention, in a machine tool 1 which drives and rotates a spindle 2 on which a tool 3 is attached and drives the spindle 2 in the axial direction of the rotating shaft, comprises: position measurement means 11 which measures axial position data of the spindle 2; deviation calculation means 12 which changes the rotation speed of the spindle 2 to measure axial position data of the spindle 2 at each rotation speed and calculates an axial deviation amount of the spindle 2 from the position data and a reference position; storage means 20 which stores the deviation amount at each rotation speed of the spindle 2; and rotation speed adjustment means 13 which adjusts the rotation speed of the spindle specified during machining to the rotation speed at which the deviation amount is smallest within an allowable range for the specified rotation speed.

In machine tool 1, vibrations caused by the rotation of spindle 2 cause deviations in the axial direction (Z-axis) of spindle 2 according to the commanded rotation speed. As shown in Figures 5 and 6, the amount of Z-axis deviation varies differently for each machine, and is particularly large around the rotation speed of spindle 2 where the natural vibration of machine tool 1 occurs. Therefore, the inventors of the present application have devised a function that measures the amount of Z-axis deviation in the entire rotation speed range for each machine in advance, and fine-tunes the rotation speed of spindle 2 around the commanded rotation speed so as to reduce vibrations of machine tool 1.

Figure 1 is a diagram showing an embodiment of a spindle speed adjustment system according to the present invention. Figure 4 is a perspective view showing an embodiment of a machine tool using the present invention.

In this embodiment, the machine tool 1 is a machining center, and has a table 4 on which a workpiece is placed, and a spindle 2 on which a tool 3 is attached and driven to rotate. The table 4 is driven in the X-axis and Y-axis directions perpendicular to the rotation axis of the spindle 2, and the spindle 2 is driven in the axial direction of the rotation axis (Z-axis direction). The machine tool 1 has the tool 3 attached to the tip of the spindle 2, and while rotating the tool 3, it moves it relative to the workpiece in the X-, Y-, and Z-axis directions to machine the workpiece into a desired shape. The machine tool 1 also has a control device (not shown) that numerically controls the machining trajectory of the tool 3, an operation panel for inputting instructions such as machining conditions, tool replacement, and coordinate settings, and a monitor for displaying machining information, position information, etc.

As shown in Fig. 4, the spindle head 2a on which the spindle 2 is rotatably mounted is driven in the Z-axis direction along a guide 7. A scale 5 is provided in parallel with the guide 7 on the main body of the machine tool 1, and serves as a reference for reading the position on the Z-axis when the spindle head 2a is driven. The position measuring means 11 is composed of this scale 5 and a detector 6 provided on the spindle head 2a, and measures the position of the spindle 2 in the Z-axis direction from the scale 5 by the detector 6. It should be noted that the machine tool 1 is not limited to the configuration shown in the figure, and the present invention can be applied to various machine tools such as other vertical machining centers, horizontal machining centers, drilling machines, boring machines, milling machines, grinding machines, etc.
[Configuration of spindle speed adjustment system]

The spindle speed adjustment system 10 includes a position measurement means 11 that measures the position data of the spindle 2 in the Z-axis direction using a scale 5 and a detection unit 6, a deviation calculation means 12 that changes the rotation speed of the spindle 2 to measure the position data of the spindle 2 in the Z-axis direction at each rotation speed and calculates the deviation amount of the spindle 2 in the Z-axis direction from the position data and a reference position, a rotation speed adjustment means 13 that adjusts the rotation speed of the spindle 2 during machining to the rotation speed with the smallest deviation amount within the allowable range for the specified rotation speed, and an allowable range setting means 14 that sets the allowable range by the ratio to the rotation speed of the spindle 2 specified during machining and the allowable rotation speed.

In FIG. 1, 20 is a storage means, which stores the position data in the Z-axis direction of the spindle 2 measured by the position measurement means 11, the deviation amount calculated by the deviation calculation means 12, the tolerance range set by the tolerance range setting means 14, etc. The storage means 20 stores the deviation amount calculated by the deviation calculation means 12 in association with the rotation speed of the spindle 2.

The position measurement means 11 is provided in a general machine tool 1 to detect the position data of the spindle 2 in the Z-axis direction, and detects the position data using a scale 5 such as a linear scale and a detector 6. The deviation calculation means 12 calculates the deviation from a reference position as the deviation amount based on the position data measured by the position measurement means 11. As shown in FIG. 7, the deviation amount of the Z-axis may change over time (the depth of FIG. 7 is the time axis). Therefore, it is preferable that the deviation calculation means 12 measures the position data in the Z-axis direction two or more times to calculate the deviation of the spindle 2 in the Z-axis direction at each rotation speed, and stores the data with the largest deviation amount in the storage means 20 as the deviation data.

In this embodiment, the deviation calculation means 12 performs measurements for a predetermined time (approximately 1 second) at a predetermined sampling period for each rotation speed region, and calculates the Z-axis deviation amount from the measured Z-axis position data and the reference position. The deviation calculation means 12 performs measurements six times for each region, and stores the largest Z-axis deviation amount as deviation data in the storage means 20. As the Z-axis reference position, for example, the average or median of the measured Z-axis position data, position data before the rotation of the spindle 2, etc. can be used.

The deviation calculation means 12 may also be configured to store in the storage means 20 as deviation data the data of the area with the largest deviation amount among the data measured for a sufficiently long time (1 to 2 minutes) for one rotation speed region. In this case, the deviation calculation means 12 divides the measured position data into areas of approximately 1 second each, and calculates the deviation amount from the reference position for each area. Note that, since the amount of measured position data can be reduced and the calculation load of the Z-axis deviation amount can be suppressed, it is preferable that the deviation calculation means 12 is configured to perform measurements for a predetermined time (approximately 1 second) at regular intervals, as in this embodiment.

The deviation calculation means 12 sets the step-up width to 100 min ^-1 , for example, and measures the rotation speed of the spindle 2 by stepping up every 100 min ^-1 , up to the maximum rotation speed of the spindle 2. In the embodiment shown in Figs. 5 and 6, the deviation calculation means 12 measures the Z-axis deviation amount every 100 min ^-1 up to the maximum rotation speed of the spindle 2 of 40,000 min ^-1 . The storage means 20 stores the largest Z-axis deviation amount for each rotation speed range as deviation data within all rotation speed ranges. In this embodiment, when the Z-axis deviation amount of the spindle 2 is measured, a tool 3 that can rotate at the maximum rotation speed is attached to the spindle 2.

In this embodiment, the tolerance setting means 14 sets the narrower range of rotation speed as the tolerance range between the ratio of the rotation speed of the spindle 2 specified during machining and the tolerance speed. In the example shown in Fig. 5, the tolerance rate is set to ±5% for a command rotation speed of 10,000 min ^-1 , and the corresponding tolerance range is ±500 min ^-1 . In addition, since the set tolerance range is ±1,000 min ^-1 , the tolerance setting means 14 sets ±500 min ^-1 as the tolerance range.

6, the allowable rate of change is set to ±10% for a command speed of 26,000 min ^-1 , so the corresponding allowable range is ±2,600 min ^-1 . Also, since the set allowable range is ±2,000 min ^-1 , the allowable range setting means 14 sets ±2,000 min ^-1 as the allowable range. Note that the allowable range setting means 14 may set the allowable range either as a ratio to the speed of spindle 2 or as the allowable speed.

The rotation speed adjusting means 13 adjusts the rotation speed of the spindle 2 designated during machining to the rotation speed with the smallest deviation within the allowable range for the designated rotation speed. In the example shown in Fig. 5, the rotation speed adjusting means 13 adjusts the rotation speed (9,800 min ^-1 ) with the smallest deviation within the allowable range of ±500 min ^-1 for a command rotation speed of 10,000 min- ¹ . In the example shown in Fig. 6, the rotation speed adjusting means 13 adjusts the rotation speed (25,050 min-1) with the smallest deviation within the allowable range of ±2,000 min ^-1 for a command rotation speed of 26,000 min ^{- 1} .
[Diagnostic system function]

Next, the operation of the machine tool spindle speed adjustment system according to the present invention will be described. Figure 2 is a flow chart showing one embodiment of the Z-axis deviation measurement means of the present invention, and Figure 3 is a flow chart showing one embodiment of the spindle speed adjustment means of the present invention.

2, the deviation calculation means 12 first reads the minimum rotation speed as the rotation speed (R) of the spindle 2 for measuring the deviation amount (step S1). The rotation speed (R) is increased from the minimum rotation speed by a predetermined step-up width (100 min ^-1 in this embodiment). The minimum rotation speed can be set to any rotation speed, and may be set to the step-up width of 100 min ^-1 .

The deviation calculation means 12 compares the rotation speed (R) of the spindle 2 read in step S1 with the maximum rotation speed (Rmax) of the machine tool 1 (step S2), and if the rotation speed (R) is equal to or lower than the maximum rotation speed (Rmax), inputs "1" to the number of measurements n for each rotation speed range (step S3). On the other hand, if the rotation speed (R) of the spindle 2 read in step S1 exceeds the maximum rotation speed (Rmax) of the machine tool 1, the deviation calculation means 12 converts the unit of all Z-axis deviation data into mm, stores it in the normal memory of the storage means 20, and ends the measurement.

The deviation calculation means 12 rotates the spindle 2 at a rotation speed (R) and measures the position data of the spindle 2 in the Z-axis direction using the position measurement means 11 (step S4). The deviation calculation means 12 performs measurement for a predetermined time (about 1 second) at a predetermined sampling period per rotation speed region, for example. The deviation calculation means 12 calculates the Z-axis deviation amount from the Z-axis position data measured in step S4 and the reference position (step S5).

The deviation calculation means 12 compares the Z-axis deviation amount calculated in step S5 with the Z-axis deviation amount of the rotation speed area being measured stored in the temporary storage area of the storage means 20 (step S6). If the Z-axis deviation amount calculated in step S5 is larger, the calculated Z-axis deviation amount is replaced as the Z-axis deviation data of the rotation speed area and stored in the temporary storage area of the storage means 20 (step S7). The Z-axis deviation data before measurement is stored with "0" or the minimum measurable value as the initial value. On the other hand, if the Z-axis deviation amount calculated in step S5 is the same as or smaller than the Z-axis deviation amount of the rotation speed area being measured stored in the temporary storage area of the storage means 20, the deviation calculation means 12 proceeds to step S8 without rewriting the Z-axis deviation data temporarily stored in the temporary storage area of the storage means 20.

The deviation calculation means 12 compares the number of measurements n for each rotation speed region with a predetermined number of measurements N (six in this embodiment) (step S8). If the number of measurements n has not reached the predetermined number of measurements N, the deviation calculation means 12 adds "1" to the number of measurements n (step S9), returns to step S4, and repeats the measurement of Z-axis deviation data in the same rotation speed region. On the other hand, if the number of measurements n has reached the predetermined number of measurements N, the deviation calculation means 12 proceeds to step S10, adds 100 min ^-1 , which is a step-up width, to the rotation speed (R) of the spindle 2, and returns to step S4. The deviation calculation means 12 measures the Z-axis deviation amount in the rotation speed region of the predetermined step-up width until the rotation speed (R) of the spindle 2 reaches the maximum rotation speed (Rmax).

The spindle speed adjustment system 10 of this embodiment uses the deviation calculation means 12 to measure the position data in the Z-axis direction of the spindle 2 a predetermined number of times or more in the entire range of rotation speeds up to the maximum rotation speed (Rmax) of the machine tool 1, calculate deviation data in the Z-axis direction, and store it in the storage means 20. This allows the spindle speed adjustment system 10 to measure the Z-axis deviation data of the spindle 2 before the machine tool 1 is shipped from the factory or during a time period when the machine tool 1 is not in operation.

Next, the flow of automatic adjustment of the spindle speed will be explained based on Figure 3.

When machining a workpiece with the machine tool 1, as shown in FIG. 3, the spindle speed adjustment system 10 checks whether an allowable range has been set for the command speed of the spindle 2, and if an allowable range has been set, compares the allowable range with the step-up width (step S11).

When the allowable rate of change (ratio to the command speed) and the amount of change (allowable speed) are equal to or larger than the step-up width (100 min ^-1 in this embodiment), the allowable range setting means 14 sets the allowable rate of change or the amount of change, whichever has a narrower range in speed, as the allowable range (step S12). On the other hand, when either the allowable rate of change or the amount of change is smaller than the step-up width, the speed adjustment means 13 determines that the automatic speed control is invalid, and rotates the spindle 2 at the command speed (step S22).

Next, the rotation speed adjusting means 13 divides the command rotation speed by the step-up width to set a region number (r_cur) (step S13). The region number is assigned a number of 1 for each rotation speed region corresponding to the step-up width (100 min ^-1 width in this embodiment).

The rotation speed adjustment means 13 checks whether the Z-axis deviation data stored in the storage means 20 contains Z-axis deviation data in the current area number set in step S13 (step S14). If the current area number contains Z-axis deviation data, the rotation speed adjustment means 13 adds the allowable range (range) divided by the step-up width to the current area number (r_cur) to set the upper limit area number (r_max) of the allowable range. The rotation speed adjustment means 13 also subtracts the allowable range (range) divided by the step-up width from the current area number (r_cur) to set the lower limit area number (r_min) of the allowable range (step S15), and proceeds to step S16. On the other hand, if the current area number does not contain Z-axis deviation data, the rotation speed adjustment means 13 determines that the automatic rotation speed control is disabled and rotates the spindle 2 at the command rotation speed (step S23).

In step S16, the rotation speed adjustment means 13 stores the maximum measurable value in the temporary storage area of the storage means 20 as the initial value of the Z-axis deviation amount (min_zerr) of the adjusted rotation speed. In addition, the rotation speed adjustment means 13 stores the lower limit area number (r_min) set in step S15 in the temporary storage area of the storage means 20 as the area number (min_no) with the smallest Z-axis deviation data, and also stores it in the temporary storage area of the storage means 20 as area number i.

The rotation speed adjustment means 13 compares the Z-axis deviation data of the region number i stored in the storage means 20 with the Z-axis deviation amount (min_zerr) stored in the temporary region (step S17). If the Z-axis deviation data of the region number i is smaller than the Z-axis deviation amount (min_zerr), the rotation speed adjustment means 13 replaces the Z-axis deviation amount (min_zerr) with the Z-axis deviation data of the region number i and stores it in the temporary storage region of the storage means 20, and replaces the region number (min_no) with the region number i and stores it in the temporary storage region of the storage means 20 (step S18). The rotation speed adjustment means 13 also adds "1" to the region number i (step S19) and proceeds to step S20.

On the other hand, if the Z-axis deviation data for area number i is equal to or greater than the Z-axis deviation amount (min_zerr), the rotation speed adjustment means 13 adds "1" to area number i in step S19 without replacing the Z-axis deviation amount (min_zerr) and area number (min_no), and proceeds to step S20.

In step S20, the rotation speed adjustment means 13 compares the area number i with the area number (r_max) of the upper limit of the allowable range. If the area number i is equal to or smaller than the area number (r_max) of the upper limit of the allowable range, the rotation speed adjustment means 13 returns to step S17 and continues searching for an area number (rotation speed area) with a smaller Z-axis deviation data.

On the other hand, if the region number i is greater than the upper region number (r_max) of the allowable range, the rotation speed adjustment means 13 rotates the spindle 2 at the spindle rotation speed of the region number (min_no) (step S21). As a result, the spindle rotation speed adjustment system 10 can automatically adjust the rotation speed of the spindle 2 during machining to the rotation speed that minimizes the Z-axis deviation of the spindle 2 within the allowable range for the specified rotation speed.

REFERENCE SIGNS LIST 1 machine tool 2 spindle 3 tool 4 table 5 scale 6 detector 7 guide 10 spindle speed adjustment system 11 position measurement means 12 deviation calculation means 13 speed adjustment means 14 tolerance setting means 20 storage means

Claims (5)

In a machine tool that rotates a spindle on which a tool is attached and drives the spindle in an axial direction of a rotation axis,
a position measuring means for measuring axial position data of the spindle;
a deviation calculation means for measuring axial position data of the spindle at each rotation speed while changing the rotation speed of the spindle, and calculating an amount of deviation in the axial direction of the spindle from the position data and a reference position;
a storage means for storing the deviation amount at each rotation speed of the spindle;
a rotation speed adjusting means for adjusting the rotation speed of the spindle designated during machining to a rotation speed at which the deviation amount is smallest within an allowable range for the designated rotation speed;
A system for adjusting the spindle speed in a machine tool having the above structure. The spindle speed adjustment system for a machine tool according to claim 1, further comprising a tolerance setting means for setting the tolerance range as a percentage of the spindle speed specified during machining and/or as a permissible speed. 3. The spindle speed adjustment system for a machine tool according to claim 2, wherein the allowable range setting means sets as the allowable range a narrower range of rotation speeds among the ratio of the spindle speed specified during machining and the allowable rotation speed. The spindle speed adjustment system for a machine according to any one of claims 1 to 3, wherein the deviation calculation means measures the axial position data two or more times to calculate the axial deviation of the spindle at each rotation speed, and stores the data with the largest deviation as the deviation data. 5. A spindle speed adjusting program for causing a computer to function as the spindle speed adjusting system for a machine tool according to claim 1.

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