Machine tool spindle speed adjustment system and spindle speed adjustment program

Abstract

To provide a main shaft rotating speed adjustment system and a main shaft rotating speed adjustment program for a machine tool capable of easily suppressing vibrations generated in a main shaft.SOLUTION: In a main shaft rotating speed adjustment system, a machine tool 1 for rotationally driving a main shaft 2 with a tool 3 mounted thereon, and driving the main shaft 2 in the axial direction of a rotational axis includes position measurement means 11 for measuring position data of the main shaft 2 in an axial direction, deviation calculation means 12 for changing a rotating speed of the main shaft 2 to measure the position data in the axial direction of the main shaft 2 in each rotating speed, and calculating a deviation amount in the axial direction of the main shaft 2 from the position data and a reference position, storage means 20 for storing the deviation amount in each rotating speed of the main shaft 2, and rotating speed adjustment means 13 for adjusting the rotating speed of the main shaft 2 to the rotating speed having the minimum deviation amount within an allowable range to a designated rotating speed during processing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spindle speed adjustment system and a spindle speed adjustment program for a machine tool, which are capable of suppressing vibrations occurring in a spindle. [Background technology]

[0002] In machine tools that machine workpieces by rotating a tool attached to a spindle, the deviation in the axial direction (Z-axis) of the spindle changes according to the commanded speed while the spindle is rotating. When machining with a high target surface roughness value, this machine tool is required to use a speed range that provides a small amount of Z-axis deviation.

[0003] For example, Patent Document 1 discloses a machine tool that includes a sensor that detects the vibration frequency of a spindle or a 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 compared to before the spindle rotation speed was changed as the set value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-107751 A Summary of the Invention [Problem to be solved by the invention]

[0005] The machine tool described in Patent Document 1 had to be provided with a sensor that detects the vibration frequency of the spindle or the tool in order to detect chatter vibration occurring in the spindle or the tool. This machine tool had a problem in that the structure was complicated because, for example, an acceleration sensor was provided in the housing.

[0006] Furthermore, when the machine tool described in Patent Document 1 detects that chatter vibration has occurred in the spindle or tool, it changes the spindle rotation speed and obtains the vibration intensity at each rotation speed, so it was necessary to limit the range of variation in the spindle rotation speed in order to shorten the search time.

[0007] Therefore, the present invention provides a spindle speed adjustment system and a spindle speed adjustment program for a machine tool, which can easily suppress vibrations generated in the spindle. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a spindle rotation speed adjustment system for a machine tool that rotates and drives a spindle on which a tool is attached and drives the spindle in the axial direction of the rotating shaft, the system comprising: position measurement means for measuring axial position data of the spindle; deviation calculation means for changing the rotation speed of the spindle, measuring axial position data of the spindle at each rotation speed, and calculating an axial deviation amount of the spindle from the position data and a reference position; storage means for storing the deviation amount at each rotation speed of the spindle; and rotation speed adjustment means for adjusting the rotation speed of the spindle during machining to the rotation speed at which the deviation amount is smallest within an allowable range for a specified rotation speed.

[0009] The spindle speed adjustment system for the machine tool also includes an allowable range setting means for setting the allowable range as a ratio to the spindle speed specified during machining and / or as an allowable speed.

[0010] In addition, in the spindle speed adjustment system of the machine tool, the allowable range setting means sets the narrower range of rotation speeds as the allowable range between the ratio of the spindle speed specified during machining and the allowable rotation speed.

[0011] In addition, in the spindle rotation speed adjustment system for a machine tool, the deviation calculation means measures position data in the axial direction of the spindle a predetermined number of times (two or more) to calculate the axial deviation of the spindle at each rotation speed, and stores the data with the largest deviation amount as deviation data.

[0012] The present invention also provides a spindle speed adjusting program for causing a computer to function as the spindle speed adjusting system for a machine according to any one of the above aspects. Effect of the Invention

[0013] The spindle rotation speed adjustment system of a machine tool of the present invention is a machine tool that rotates and drives a spindle on which a tool is attached and drives the spindle in the axial direction of the rotating shaft, and has position measurement means for measuring axial position data of the spindle, deviation calculation means for changing the rotation speed of the spindle to measure axial position data of the spindle at each rotation speed and calculates an axial deviation amount of the spindle from the position data and a reference position, storage means for storing the deviation amount at each rotation speed of the spindle, and rotation speed adjustment means for adjusting the rotation speed of the spindle during machining to the rotation speed at which the deviation amount is smallest within an allowable range for a specified rotation speed.Since the deviation amount for each rotation speed can be measured using 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, an effect of suppressing vibration generated in the spindle with a simple configuration is achieved.

[0014] Furthermore, the machine tool spindle rotation speed adjustment system of the present invention can measure and store the amount of deviation at each spindle rotation speed before the machine tool is put into operation or during a downtime, and therefore has the effect of being able to immediately adjust the rotation speed to one with a smaller deviation during operation.

[0015] Furthermore, the spindle rotation speed adjustment system for a machine tool of the present invention is provided with an tolerance setting means for setting the tolerance range as a ratio of the spindle rotation speed specified during machining and / or as an allowable rotation speed, thereby having the effect of adjusting the rotation speed to the smallest deviation amount within the allowable range for the specified spindle rotation speed.

[0016] Furthermore, in the machine tool spindle speed adjustment system of the present invention, the tolerance setting means sets the narrower range of rotation speeds between the ratio of the spindle speed specified during machining and the permissible rotation speed as the permissible range, thereby having the effect of adjusting the specified spindle speed to the rotation speed with the smallest deviation within a range that satisfies both the ratio and the permissible rotation speed.

[0017] Furthermore, in the machine tool spindle rotation speed adjustment system, the deviation calculation means measures axial position data two or more predetermined times to calculate the axial deviation of the spindle at each rotation speed, and stores the data with the largest deviation amount as the deviation data, thereby having the effect of being able to store the data with the largest deviation amount as the deviation data even when the deviation amount fluctuates over time.

[0018] Furthermore, the spindle speed adjustment program of the present invention, by functioning as a spindle speed adjustment system for the machine described in any one of the above, can measure the amount of deviation for each rotation speed using a position measuring means such as a scale that measures the axial position of the spindle, and can adjust the rotation speed to one with a small amount of deviation by the program, thereby having the effect of suppressing vibrations generated in the spindle with a simple configuration. [Brief description of the drawings]

[0019] [Figure 1] 1 is a configuration diagram showing an embodiment of a spindle rotation speed adjustment system according to the present invention; [Diagram 2] 4 is a flowchart showing an embodiment of a Z-axis deviation amount measuring means of the present invention. [Diagram 3]4 is a flowchart showing an embodiment of a spindle rotation speed adjusting unit of the present invention. [Figure 4] 1 is a perspective view showing an embodiment of a machine tool to which the present invention is applied; [Diagram 5] FIG. 4 is a diagram showing an example of a screen of the spindle rotation speed adjustment system according to the present invention. [Figure 6] FIG. 4 is a diagram showing an example of a screen of the spindle rotation speed adjustment system according to the present invention. [Figure 7] A graph showing the change in Z-axis deviation of a machine tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings. Machine tool of the present invention In The spindle speed adjustment system is a machine tool 1 that rotates a spindle 2 on which a tool 3 is attached and drives the spindle 2 in the axial direction of the rotation axis. In a position measuring means 11 for measuring axial position data of the spindle 2; a deviation calculating means 12 for measuring axial position data of the spindle 2 at each rotation speed by changing the rotation speed of the spindle 2 and calculating an amount of deviation in the axial direction of the spindle 2 from the position data and a reference position; a storage means 20 for storing the amount of deviation at each rotation speed of the spindle 2; Specified The rotation speed of the spindle , applicable and a rotation speed adjusting means for adjusting the rotation speed to the rotation speed at which the deviation amount is the smallest within an allowable range for a specified rotation speed.

[0021] In machine tool 1, deviation occurs in the axial direction (Z-axis) of spindle 2 according to the command rotation speed due to vibration caused by the rotation of spindle 2. The amount of Z-axis deviation changes differently for each machine, as shown in Figures 5 and 6, 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 over the entire range of rotation speeds for each machine in advance, and fine-tunes the rotation speed of spindle 2 around the command rotation speed so as to reduce vibration of machine tool 1. EXAMPLES

[0022] Fig. 1 is a configuration diagram showing an embodiment of a spindle speed adjustment system according to the present invention, Fig. 4 is a perspective view showing an embodiment of a machine tool using the present invention.

[0023] 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, and the like.

[0024] As shown in Fig. 4, spindle head 2a, on which spindle 2 is rotatably mounted, is driven in the Z-axis direction along guide 7. Scale 5 is provided in parallel with guide 7 on the main body of machine tool 1, and serves as a reference for reading the position on the Z-axis when spindle head 2a is driven. Position measurement means 11 is composed of this scale 5 and a detection unit 6 provided on spindle head 2a, and measures the position of spindle 2 in the Z-axis direction from scale 5 by detection unit 6. It should be noted that 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]

[0025] The spindle speed adjustment system 10 comprises position measuring means 11 which measures position data of the spindle 2 in the Z-axis direction using a scale 5 and a detection unit 6, deviation calculating means 12 which changes the rotation speed of the spindle 2 to measure position data of the spindle 2 in the Z-axis direction at each rotation speed and calculates the amount of deviation of the spindle 2 in the Z-axis direction from the position data and a reference position, rotation speed adjusting means 13 which adjusts the rotation speed of the spindle 2 during machining to the rotation speed which has the smallest deviation within the allowable range for a specified rotation speed, and tolerance range setting means 14 which sets the allowable range in terms of the allowable rotation speed and the ratio to the rotation speed of the spindle 2 specified during machining.

[0026] 1, reference numeral 20 denotes a storage means which stores position data in the Z-axis direction of the spindle 2 measured by the position measurement means 11, the amount of deviation calculated by the deviation calculation means 12, the allowable range set by the allowable range setting means 14, etc. The storage means 20 stores the amount of deviation calculated by the deviation calculation means 12 in association with the rotation speed of the spindle 2.

[0027] The position measurement means 11 is provided in a general machine tool 1 to detect position data in the Z-axis direction of the spindle 2, 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 amount of deviation based on the position data measured by the position measurement means 11. As shown in FIG. 7, the amount of deviation in 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 in the Z-axis direction of the spindle 2 at each rotation speed, and stores the data with the largest amount of deviation in the storage means 20 as the deviation data.

[0028] In this embodiment, the deviation calculation means 12 performs measurement for a predetermined time (about 1 second) at a predetermined sampling period for each rotation number 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 measurement 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.

[0029] The deviation calculation means 12 may be configured to store data of an area with the largest deviation amount among the data measured for a sufficiently long time (1 to 2 minutes) for one rotation number region as deviation data in the storage means 20. 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 measurement for a predetermined time (approximately 1 second) at regular intervals as in this embodiment.

[0030] The deviation calculation means 12 sets the step-up width to, for example, 100 min -1 The rotation speed of spindle 2 is set to 100 min -1 5 and 6, the deviation calculation means 12 measures the deviation at the maximum rotation speed of the spindle 2 of 40,000 min -1 Until 100min -1 The Z-axis deviation amount is measured for each rotation speed range. 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, the tool 3 that can rotate at the maximum rotation speed is attached to the spindle 2.

[0031] In this embodiment, the allowable range setting means 14 sets the narrower range of rotation speeds as the allowable range between the ratio of the rotation speed of the spindle 2 specified during machining and the allowable rotation speed. In the example shown in FIG. 5, the command rotation speed is 10,000 min-1 The allowable rate of change is set at ±5%, and the corresponding tolerance is ±500 min -1 The set tolerance is ±1,000 min. -1 Therefore, the tolerance setting means 14 is ±500 min -1 is set as the tolerance.

[0032] In the example shown in Figure 6, the command speed is 26,000 min -1 Since the allowable rate of change is set to ±10%, the corresponding allowable range is ±2,600 min -1 The set tolerance is ±2,000 min. -1 Therefore, the tolerance setting means 14 is ±2,000 min -1 is set as the allowable range. The allowable range setting means 14 may set the allowable range either as a ratio to the rotation speed of the spindle 2 or as an allowable rotation speed.

[0033] 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 command rotation speed to 10,000 min -1 Tolerance range ±500min -1 The rotation speed with the smallest deviation (9,800 min -1 In the example shown in FIG. 6, the rotation speed adjusting means 13 adjusts the command rotation speed to 26,000 min -1 Tolerance range is ±2,000min -1 The rotation speed with the smallest deviation (25,050 min -1 ) has been adjusted. [Diagnostic system function]

[0034] Next, the operation of the machine tool spindle speed adjustment system according to the present invention will be described. Fig. 2 is a flow chart showing an embodiment of the Z-axis deviation measurement means of the present invention, and Fig. 3 is a flow chart showing an embodiment of the spindle speed adjustment means of the present invention.

[0035] As shown in FIG. 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 calculated by a predetermined step-up width (100 min in this embodiment) from the minimum rotation speed. -1 The minimum RPM can be set to any RPM, and the step-up width is 100 min. -1 may be set to

[0036] 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 region (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.

[0037] 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 with 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 once per rotation speed region, for example. The deviation calculation means 12 calculates the amount of Z-axis deviation from the Z-axis position data measured in step S4 and a reference position (step S5).

[0038] 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 region being measured stored in the temporary storage area of ​​the storage means 20 (step S6), and if the Z-axis deviation amount calculated in step S5 is larger, it replaces the calculated Z-axis deviation amount as the Z-axis deviation data of the rotation speed region and stores it 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 an 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 region 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.

[0039] 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), and then 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, and adds a step-up width of 100 min to the rotation speed (R) of the spindle 2. -1 and the process returns to step S4. The deviation calculation means 12 measures the Z-axis deviation amount in a rotation speed range of a predetermined step-up width until the rotation speed (R) of the spindle 2 reaches the maximum rotation speed (Rmax).

[0040] The spindle speed adjustment system 10 of this embodiment can 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 by the deviation calculation means 12, calculate deviation data in the Z-axis direction, and store it in the storage means 20. In this way, the spindle speed adjustment system 10 can 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.

[0041] Next, the flow of automatic adjustment of the spindle speed will be described with reference to FIG.

[0042] When machining a workpiece with machine tool 1, as shown in FIG. 3, spindle speed adjustment system 10 checks whether or not an allowable range has been set for the command speed of spindle 2, and if an allowable range has been set, compares the allowable range with the step-up width (step S11).

[0043] The allowable rate of change (ratio to the command speed) and the amount of change (allowable speed) are step-up widths (100 min -1 ), the allowable range setting means 14 sets the allowable rate of change or the amount of change, whichever has a narrower range for the number of rotations, as the allowable range (step S12). On the other hand, if either the allowable rate of change or the amount of change is smaller than the step-up width, the rotation speed adjustment means 13 determines that the automatic control of the rotation speed is invalid, and rotates the spindle 2 at the command rotation speed (step S22).

[0044] 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 the region of the rotation speed corresponding to the step-up width (100 min -1 Each width is assigned a number of 1.

[0045] The rotation speed adjustment means 13 checks whether the Z-axis deviation data stored in the storage means 20 includes Z-axis deviation data in the current region number set in step S13 (step S14). If the current region number includes Z-axis deviation data, the rotation speed adjustment means 13 adds a number obtained by dividing the allowable range (range) by the step-up width to the current region number (r_cur) to set the upper limit region number (r_max) of the allowable range. The rotation speed adjustment means 13 also subtracts a number obtained by dividing the allowable range (range) by the step-up width from the current region number (r_cur) to set the lower limit region number (r_min) of the allowable range (step S15), and proceeds to step S16. On the other hand, if the current region number does not include 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).

[0046] In step S16, the rotation speed adjustment means 13 stores the maximum measurable value as the initial value of the Z-axis deviation amount (min_zerr) of the adjusted rotation speed in a temporary storage area of ​​the storage means 20. 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.

[0047] 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 also 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.

[0048] On the other hand, if the Z-axis deviation data of 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.

[0049] In step S20, the rotation speed adjustment means 13 compares the region number i with the upper limit region number (r_max) of the allowable range. If the region number i is equal to or smaller than the upper limit region number (r_max) of the allowable range, the rotation speed adjustment means 13 returns to step S17 and continues searching for a region number (rotation speed region) with smaller Z-axis deviation data.

[0050] On the other hand, if the region number i is greater than the upper limit 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 described above, the spindle rotation speed adjustment system 10 can automatically adjust the rotation speed of the spindle 2 during machining to the rotation speed at which the Z-axis deviation of the spindle 2 is smallest within the allowable range for the specified rotation speed. [Explanation of symbols]

[0051] 1 Machine tools 2 main shaft 3 tools 4 Tables 5. Scale 6. Detection section 7 Guide 10 Spindle speed adjustment system 11 Position measurement means 12. Deviation calculation method 13 Rotation speed adjustment means 14 Means of setting tolerance 20 Memory means

Claims

1. 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 the 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.

2. 2. A spindle speed adjustment system for a machine tool according to claim 1, further comprising an allowable range setting means for setting the allowable range by a ratio of the spindle speed specified during machining and / or an allowable speed.

3. 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, one of the ratio of the spindle speed specified during machining and the allowable speed, whichever has a narrower range of rotation speeds.

4. 4. The spindle rotation speed adjustment system for a machine according to claim 1, wherein the deviation calculation means measures axial position data of the spindle a predetermined number of times or more to calculate the axial deviation of the spindle at each rotation speed, and stores the data with the largest deviation amount as the deviation data.

5. 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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