JPH0832392B2 - Tool unbalance check method and removal method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for checking and removing an imbalance of a tool mounted on a spindle of a machine tool.

(Prior Art) Since the spindle of a machine tool rotates at high speed, an imbalance in the spindle itself causes machine vibration or the like. Therefore, the unbalance of the spindle is checked by the field balance. Further, since the spindle rotates at high speed with various miscellaneous tools mounted, if the tool itself is unbalanced, it may be dangerous because the tool may fall off or be damaged. Therefore, before mounting the tool on the automatic tool changer (ATC),
The unbalance of each tool is checked by the balancing machine.

(Problems to be solved by the invention) Since the above-mentioned conventional tool unbalance check is performed for each tool, it takes too much time, and even if the tool itself is balanced, depending on the shape and weight of the tool, the spindle There is a possibility that the natural frequency of is close to the number of rotations in use, and if machining is performed in this state, the spindle resonates, which is dangerous.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of checking the imbalance of a tool in a state where the tool is mounted on a spindle and a method of removing the imbalance. It is in.

(Means for Solving the Problems) The present invention relates to a method for checking and removing an unbalance of a tool mounted on a spindle of a machine tool, and the above object of the present invention is to mount the spindle on a machine tool. When checking the unbalance of the tool, the spindle is rotated at a predetermined rotation speed in each case when the standard tool is mounted on the spindle and when the command tool is mounted, and the vibration amplitude of the spindle is measured for a predetermined time. Then, the average value of the peak values is obtained, and when the average value when the command tool is attached is larger than the average value when the standard tool is attached, it is unbalanced, and when it is smaller or equal, there is no unbalance. In addition, when removing the imbalance of the tool attached to the spindle of the machine tool, each of the case where the standard tool is attached to the spindle and the instruction tool is attached. For the case, the spindle is rotated at a predetermined number of revolutions, the vibration amplitude of the spindle is measured for a predetermined time, and the average value of the peak values thereof is obtained. When it is larger, the unbalance position is indexed based on the shape of the command tool, and the unbalance amount is calculated based on the average value when the standard tool is mounted and the average value when the command tool is mounted. The unbalance at the position is achieved by removing the unbalance amount by the unbalance removing means.

(Operation) The unbalance check method and the removal method of the tool of the present invention are the vibration when the standard tool is attached to the spindle by the vibration measuring means and the command tool is attached to the spindle and rotated. Vibration and vibration are measured, and whether or not the command tool is unbalanced is checked based on the mutual difference and the unbalance is removed, so that safe machining can be started quickly.

(Embodiment) FIG. 1 is a block diagram showing an example of an apparatus for realizing the tool unbalance checking method of the present invention, which is generated by the rotation of a spindle equipped with a tool instructed by an NC unit 2. The vibration is detected by a vibrometer 10 including an acceleration pickup 1, a charge amplifier 11, a double integrator 12, a bandpass filter 13, and an A / D converter 14. When the sampling command SS is sent from the NC (numerical control) device 2 to the comparison / calculation device 3, the vibration detected by the vibrometer 10 is sampled by the comparison / calculation device 3 according to the sampling command SS. Then, the average value of the sampled peak values of the vibration amplitude is obtained, and the average value and the vibration amplitude of the standard tool (a tool of the same kind as the command tool and balanced to the maximum allowable value) of the vibration amplitude of the pre-stored standard tool are calculated. The average value of the peak values is compared, and the machining permission / non-permission (alarm) command SCY / SCN is sent to the NC device 2 according to the comparison result.

In such a configuration, an operation example thereof will be described with reference to the flowchart of FIG. 2. The ATC selects a standard tool according to a command from the NC device 2 and mounts it on the spindle (step S1). NC
Device 2 is the number of rotations for unbalance check of the spindle.
Rotate at R _c (rpm) (step S2), sampling command (sampling time; T (sec), sample rate; 60 / 2R
_c (seconds or less) SS _c is sent to the comparison / arithmetic unit 3. The comparison / arithmetic unit 3 is amplified by the charge amplifier 11, integrated by the double integrator 12, and is band-pass filtered to R _c / 60 (Hz).
Filtered by a bandpass centered at
Vibration command A / D converted by D converter 14 sampling command SS _c
Sampling according to (step S3), NC device 2
Stops the spindle (step S4). Then, the comparison / calculation device 3 converts the sampled peak value of the vibration amplitude into a positive number and obtains and stores the average value P _{ave (c)} thereof (steps S5 and S6).

Subsequently, the NC device 2 rotates the main spindle at the rotation speed R _u (rpm) used (step S7), and the sampling command (sampling time; T ′ (seconds), sample rate; 60 / 2R _u (seconds) or less) SS _u is sent to the comparison / arithmetic unit 3. The comparator / arithmetic unit 3 is amplified by the charge amplifier 11, integrated by the double integrator 12, filtered by a bandpass filter centered at R _u / 60 (Hz) by a bandpass filter, and the A / D converter 1
When the vibration A / D converted in 4 is sampled according to the sampling command SS _u (step S8), the NC device 2 stops the spindle (step S9). Then, the comparison / calculation device 3 makes the peak value of the sampled vibration amplitude a positive number, obtains the average value P _{ave (u)} thereof, and stores it (steps S10, S1).
1). Then, the NC device 2 confirms the presence or absence of the tool selection command (step S12). If there is no tool selection command, all the processing is terminated, and if there is a tool selection command, step S1.
Proceed to 3.

The ATC selects a command tool and mounts it on the spindle according to a command from the NC device 2 (step S13). The NC device 2 rotates the spindle at the number of revolutions R _c (rpm) for unbalance check (step S14), and the sampling command (sampling time; T (sec), sample rate; 60/2 R _c (sec) or less. ) Send SS _c to the comparison / arithmetic unit 3. The comparison / arithmetic unit 3 is amplified by the charge amplifier 11 and integrated by the double integrator 12,
When the vibration filtered by the bandpass filter centered on R _c / 60 (Hz) by the bandpass filter and A / D converted by the A / D converter 14 is sampled according to the sampling command SS _c (step S15), the NC device 2 stops the spindle (step S16). Then, the comparison / calculation device 3 converts the sampled peak value of the vibration amplitude into a positive number to obtain an average value P _{sump (c)} thereof (step S17), and obtains the average value P _{sump (c)} when the command tool is attached. The size is compared with the average value P _{ave (c)} when the standard tool was stored, which was previously stored (step S1
8). When the average value P _{sump (c)} when the command tool is attached is larger than the average value P _{ave (c)} when the standard tool is attached, the machining non-permission (alarm) command SCN is sent to the NC device 2 (step S
19). The NC device 2 issues an alarm and uses the ATC to eliminate the command tool (step S20), and ends all processing.

On the other hand, when the average value P _{sump (c)} when the command tool is attached is smaller than the average value P _{ave (c)} when the standard tool is attached, the NC device 2
Rotate the spindle at the operating speed R _u (rpm) (step S2
1), sampling command (sampling time; T ′
(Seconds), sample rate: 60 / 2R _u (seconds or less) SS _u is sent to the comparison / arithmetic unit 3. The comparator / arithmetic unit 3 is amplified by the charge amplifier 11, integrated by the double integrator 12, filtered by a bandpass filter centered at R _u / 60 (Hz) by a bandpass filter, and the A / D converter 14 When the A / D converted vibration is sampled in accordance with the sampling command SS _u (step S22), the NC device 2 stops the spindle (step S23). Then, the comparison / calculation device 3 converts the sampled peak value of the vibration amplitude into a positive number to obtain an average value P _{sump (u)} thereof (step S24), and obtains the average value P _{sump (u)} when the command tool is attached. The size is compared with the average value P _{ave (u)} with the standard tool stored in advance (step S2
Five). When the average value P _{sump (u)} when the command tool is attached is larger than the average value P _{ave (u)} when the standard tool is attached, the machining non-permission (alarm) command SCN is sent to the NC device 2 (step S
19). The NC device 2 issues an alarm and uses the ATC to eliminate the command tool (step S20), and ends all processing.

On the other hand, when the average value P _{sump (u)} when the command tool is attached is smaller than the average value P _{ave (u)} when the standard tool is attached, the machining permission command SCY is sent to the NC device 2 (step S26) and the machining is performed. To execute. Then, after this processing is completed, the process returns to step S12 and the above-described operation is repeated.

FIG. 3 is a block diagram showing an example of an apparatus that realizes the tool unbalance removal method of the present invention, corresponding to FIG. 1, and the same components will be assigned the same reference numerals and description thereof will be omitted. This device is provided with a device 4 for removing the unbalance of the tool in accordance with the unbalance removal command (unbalance position and unbalance amount of the tool) SA from the NC device 2. The means for removing the unbalance is, for example, a grindstone. And drills are used.

In such a configuration, the operation example will be described with reference to the flowchart of FIG. 4. The ATC selects a standard tool according to a command from the NC device 2 and mounts it on the spindle (step S31). N
The C device 2 rotates the main shaft at the rotational speed R _c (rpm) for the unbalance check (step S32), and the sampling command (sampling time; T (second), sample rate; 60 /
2 R _c (seconds or less) SS _c is sent to the comparison / arithmetic unit 3. The comparator / arithmetic unit 3 is amplified by the charge amplifier 11 and integrated by the double integrator 12, and is then passed through the bandpass filter to obtain R _c / 60 (H
z) is filtered by the band pass, and the A / D converted vibration is sampled by the A / D converter 14 according to the sampling command SS _c (step S33).
The device 2 stops the spindle (step S34). And
The comparison / calculation device 3 converts the sampled peak value of the vibration amplitude into a positive number and obtains and stores the average value P _{ave (c)} thereof (steps S35, S36). Then, the NC device 2 confirms the presence / absence of the tool selection command (step S37). If there is no tool selection command, all processing is terminated, and if there is a tool selection command, the process proceeds to step S38.

The ATC selects a command tool according to a command from the NC device 2 and mounts it on the spindle (step S38). The NC device 2 rotates the spindle at the number of revolutions R _c (rpm) for unbalance check (step S39), and the sampling command (sampling time; T (sec), sample rate; 60/2 R _c (sec) or less. ) Send SS to the comparison / calculation unit 3. The comparison / arithmetic unit 3 is amplified by the charge amplifier 11 and integrated by the double integrator 12,
When the vibration filtered by the bandpass filter centering on R _c / 60 (Hz) by the bandpass filter and A / D converted by the A / D converter 14 is sampled according to the sampling command SS _c (step S40), the NC device 2 stops the spindle (step S41). Then, the comparison / calculation device 3 obtains the average value P _{ave (c)} of the peak values of the sampled vibration amplitudes by positive numbers (step S42), and calculates the average value P _{sump (c)} when the command tool is attached. The size is compared with the average value P _{ave (c)} when the standard tool was stored, which was previously stored (step S4).
3). If the average value P _{sump (c)} with the command tool attached is smaller than the average value P _{ave (c)} with the standard tool attached, the machining permission command S
CY is sent to the NC device 2 (step S44) to execute the machining. Then, after this processing is completed, the process returns to step S37 and the above-described operation is repeated.

On the other hand, when the average value P _{sump (c)} when the command tool is attached is larger than the average value P _{ave (c)} when the standard tool is attached, the machining non-permission (alarm) command SCN is sent to the NC device 2 (step S
45). The NC unit 2 issues an alarm and indexes the unbalanced position based on the shape of the command tool (step S4
6) _{Calculate the} unbalance amount based on the average value P _{sump (c)} when the command tool is attached and the average value P _{ave (c)} when the standard tool is attached (step S47) It is sent to the removing device 4. When the unbalance removing device 4 removes the unbalance at the unbalance position of the command tool by the unbalance amount (step S4
8), returning to step S39, the above-described operation is repeated until processing is permitted.

Here, a method of calculating the above-mentioned unbalance amount will be described. For example, when there is an unbalance amount of m at the unbalanced position at a distance r from the rotation axis of the tool, the vibration amplitude Δx of the spindle system including the bearing with the tool is expressed by the following equation (1).

K · Δx ∝ mrω ² (1) where K; spring constant ω; angular velocity Therefore, the spring constant K of the spindle system including the bearing with the tool K,
Assuming that the angular velocity ω and the unbalance position r are equal, if the unbalance amount m _ave of the standard tool is obtained in advance, the unbalance amount m _sump of the command tool can be obtained by the following equation.

Therefore, the unbalance amount to be removed is m _sump −m _ave .

(Effect of the invention) As described above, according to the tool unbalance check method and tool removal method of the present invention, the tool unbalance can be checked and removed while the tool is mounted on the spindle. Not only can the number of man-hours be significantly reduced, but also highly accurate and safe machining can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an apparatus for realizing the tool unbalance checking method of the present invention, FIG. 2 is a flowchart explaining an operation example thereof, and FIG. 3 is a tool unbalance removal of the present invention. FIG. 4 is a block diagram showing an example of an apparatus that realizes the method, and FIG. 4 is a flowchart explaining an example of the operation. 1 ... Acceleration pickup, 2 ... NC device, 3 ... Comparison / calculation device, 4 ... Unbalance removal device, 10 ... Vibrometer, 11 ... Charge amplifier, 12 ... Double integrator, 13 ... …
Bandpass filter, 14 …… A / D converter.

Claims (2)

[Claims] 1. When checking the imbalance of a tool mounted on a spindle of a machine tool, the spindle is rotated at a predetermined rotation speed in each case of mounting a standard tool and a command tool on the spindle. Rotate and measure the vibration amplitude of the spindle for a predetermined time to obtain the average value of its peak values.If the average value when the command tool is attached is larger than the average value when the standard tool is attached, it means that there is an imbalance, and it is small. Or, when they are equal, the tool is unbalanced so that the tool is unbalanced. 2. When removing an imbalance of a tool mounted on a spindle of a machine tool, the spindle is rotated at a predetermined rotation speed in each case of mounting a standard tool and a command tool on the spindle. When rotated, the vibration amplitude of the spindle is measured for a predetermined time to obtain the average value of the peak values, and when the average value when the command tool is mounted is larger than the average value when the standard tool is mounted, the shape of the command tool Unbalance position is calculated based on, the unbalance amount is calculated based on the average value when the standard tool is mounted and the average value when the command tool is mounted, and the unbalance at the unbalance position is unbalanced by the unbalance removing means. A method for removing unbalance of a tool, wherein the amount of unbalance is removed.