JP2002292543A - Tool abnormality detection device and tool abnormality detection method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To determine whether or not an abnormality such as tool breakage has occurred without being affected by a processing load. A tool inertia J1 when the spindle motor 7 is accelerated in S110 and a tool inertia J2 when the spindle motor 7 is decelerated in S140 are estimated, and J2 becomes smaller than J1. If it is determined that the tool is broken, it is determined that the tool has been broken, and processing for an abnormal condition is performed (S18).
0) This process ends. According to such processing, the determination of the presence or absence of tool breakage is performed when machining is not performed, so that the determination is performed without being affected by the processing load and without particularly securing time for the determination. No detection time is required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool abnormality detecting device and a tool abnormality detecting method used for a machine tool that performs machining by rotating a main spindle on which a tool is mounted.

[0002]

2. Description of the Related Art Conventionally, in a machine tool that performs machining by rotating a spindle on which a tool is mounted, it is determined whether or not an abnormality such as tool breakage (also referred to as tool breakage or simply breakage) has occurred. The determination is made by touching a tool attached to the spindle with a touch sensor provided in advance on the machine tool. That is, if a tool break has occurred, the tool does not touch the touch sensor, so that it is determined that "tool break has occurred".

[0003]

However, according to the above prior art, a touch sensor is required to determine a tool break, and a time for determining a tool break needs to be secured separately from a machining time. There is.

As a different determination method, there is a technique of monitoring a torque waveform generated by a controller during machining and detecting a tool break by detecting a disturbance of a waveform generated at the time of tool break. In this case, although a touch sensor is not necessary, there is a problem that it is difficult to distinguish between a noise waveform due to various disturbances applied to the spindle during machining and a waveform distortion due to a tool break which should be detected.

The present invention has been made in view of the above problems, and has as its object to determine whether or not an abnormality such as a tool break has occurred without being affected by a processing load at all.

[0006]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, there is provided a machine tool for machining by rotating a main shaft on which a tool is mounted. In a tool abnormality detection device for detecting an abnormality of a tool, at least in a state where the tool is attached, inertia detection means for detecting inertia of the rotating main spindle, and inertia detected by the inertia detection means before machining. Tool inertia detecting means for comparing the inertia detected by the inertia detecting means after machining and determining that the tool has broken if the inertia is reduced.

[0007] According to the tool abnormality detecting device thus configured, it is possible to determine whether or not a tool break has occurred without being affected by the machining load at all. Claim 2
According to the present invention, in the tool abnormality detection device according to claim 1, the tool breakage determination unit detects the inertia of the main shaft detected by the inertia detection unit at the time of acceleration of the rotation of the main shaft at the time of deceleration of the same rotation. The inertia of the main shaft detected by the inertia detecting means is compared with the main shaft, and if the inertia is reduced, it is determined that a tool attached to the main shaft has broken.

[0008] According to the tool abnormality detecting device configured as described above, it is possible to determine whether or not a tool break has occurred each time machining is performed, and it is not necessary to particularly secure a time for the determination. The present invention according to claim 3 is a tool abnormality detection device that detects an abnormality of the tool of a machine tool that performs machining by rotating a spindle to which the tool is attached, in a state where at least the tool is attached, Inertia detecting means for detecting inertia of the rotating main spindle, and when the inertia detected by the inertia detecting means fluctuates during rotation of the main spindle, it is determined that an abnormal clamping of the tool has occurred. And a clamp abnormality determining means.

According to the tool abnormality detecting device thus configured, it is possible to detect whether or not a clamp abnormality has occurred by rotating the main shaft. , It is possible to detect a clamp abnormality without securing the same.

According to a fourth aspect of the present invention, there is provided a tool abnormality detecting device for detecting an abnormality of a tool of a machine tool which performs machining by rotating a spindle on which the tool is mounted, wherein at least the tool is mounted. In the state, when the inertia detecting means for detecting the inertia of the rotating main spindle and the inertia detected by the inertia detecting means are substantially the same as the state where the tool is not mounted on the main spindle, the tool is mounted on the main spindle. It is characterized by comprising a tool-free determination means for determining that there is no tool.

[0011] According to the tool abnormality detecting device constructed as described above, it is possible to detect whether or not a tool is attached to the main shaft by rotating the main shaft. The tool-less state can be detected without securing time.

According to a fifth aspect of the present invention, there is provided a tool abnormality detecting apparatus for detecting an abnormality of a tool of a machine tool which performs a machining by attaching a desired tool from a plurality of tools to a spindle and rotating the spindle. In at least the state in which the tool is attached, the inertia detecting means for detecting the inertia of the rotating main spindle, and the inertia detecting means are detected when the tool whose inertia is measured in advance is attached to the main spindle. Tool inertia is compared with inertia detected by the inertia detecting means while the spindle is rotating, and if different, tool determination means for detecting that an incorrect tool is attached to the spindle is provided. .

[0013] According to the tool abnormality detecting device configured as described above, the fact that an erroneous tool is attached to the main spindle (hereinafter referred to as a tool error) can be detected by rotating the main spindle. If this is sometimes detected, a tool error can be detected without securing a particularly long detection time.

According to a sixth aspect of the present invention, in the tool abnormality detecting device according to any one of the first to fifth aspects, the machine tool controls a rotation speed of the main shaft by a servo. The inertia detecting means detects the inertia based on the rotation speed of the main shaft and a torque command signal output by the servo.

According to the tool abnormality detecting device configured as described above, the inertia can be detected without providing a special configuration for detecting the inertia. It is to be noted that the tool abnormality detecting devices according to claims 1 to 6 are configured as a tool abnormality detecting method, respectively, according to the present invention described in claims 7 to 12, and have the same effects as the corresponding tool abnormality detecting devices. be able to.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a substrate drilling machine 1 to which the present invention is applied. A spindle motor 7 for rotating the spindle of the substrate drilling machine 1 is attached to the head 9,
Similarly, a Z-axis motor 11 attached to the head 9 can move up and down together with the main shaft. Head 9
The Y-axis motor 13 is moved left and right along the two rails 17 by rotating the ball screw 15. The table 19 to which the substrate is fixed is provided with two rails 25 by rotating a ball screw 21 by an X-axis motor (not shown).
Is moved back and forth along.

FIG. 2 shows a block diagram of the substrate punch 1. As shown in FIG.
A ROM 25 pre-stored with a basic program to be decoded and executed by the CPU 23, a RAM 27 having various data storage functions such as a work area used by the program, and an NC for executing a motion command generated by the CPU 23. The control unit 29 is mainly composed of a display 31 for displaying a program or the like and an operation panel 33 for giving a command to the board drilling machine 1. The CPU 23 reads and executes a program stored in the ROM 25, and controls the entire board drilling machine 1 such as decoding of a machining program, generation of a motion command, and user interface processing via the display 31 and the operation panel 33. The spindle controller 35, the X-axis servo amplifier 37, the Y-axis servo amplifier 39, the Z-axis servo amplifier 41, and the like are connected to the NC control unit 29. Each of the servo amplifiers has a corresponding motor and encoder E. It is connected. Servo amplifier 35
41 control the current value supplied to the corresponding motor from the speed command output from the NC control unit and the actual number of revolutions per unit time fed back from the encoder E. Reference numeral 43 denotes an X-axis motor.

FIG. 3 is a block diagram showing a control system of the spindle. The control unit 51 is an encoder E (see FIG. 2)
Amplifier 5 that drives the spindle motor 7 by receiving feedback of the actual speed (or actual acceleration) based on the signal from the
2 to output a torque command. Based on the torque command signal generated from the control unit 51 and the actual number of revolutions per unit time fed back from the encoder E,
The load inertia estimating unit 53 estimates the inertia of the load 55 applied to the main shaft. Load inertia estimator 5
When the inertia change determination unit 57 determines that the inertia estimated by the step 3 has changed, it is detected as an error. Each block of the control unit 51, the load inertia estimating unit 53, and the inertia change determining unit 57 includes the CPU 23 of FIG.
NC controller 29, spindle servo amplifier 35, and CPU
23 is realized by a program to be executed.

FIG. 4 shows a flowchart of this process. This process is performed every time machining is performed using the spindle.
Is activated. First, step (hereinafter simply referred to as S) 10
At 0, a rotation command is issued to the spindle. Then, in subsequent S110, the spindle motor 7 is accelerated to the target speed. At this time, the inertia of the tool is estimated in S120 based on the torque command signal generated from the control unit 51 and the rotation speed of the spindle motor. The inertia estimated here is assumed to be J1. Then, actual processing is performed in S130. When the machining is completed, the spindle motor 7 is decelerated (S140). At this time, the inertia of the tool is estimated again based on the torque command signal and the rotation speed of the spindle motor (S150). The inertia estimated here is assumed to be J2.

Then, it is determined in step S1 whether the tool has been broken.
The determination is made at 60. Here, the determination is made by checking whether J2 is smaller than J1. More specifically, it is determined whether J1 is smaller than the value obtained by multiplying J2 by the safety coefficient K. For example, before processing, FIG.
When the tool 61 is broken as shown in FIG. 5B after machining, the inertia of the tool 61 ′ is smaller than before the machining. Here, if the safety coefficient K> 1 is set, J2 should be larger if there is no abnormality in the tool. If it is determined that J1 is smaller, that is, it is determined that there is no abnormality in the tool, the process proceeds to S170, where preparation for the next operation is made, and this processing ends. On the other hand, when it is determined that J1 is larger, the process proceeds to S180, where it is determined that an abnormality has occurred in the tool, and a process at the time of abnormality is performed, followed by termination of the present process. Examples of the processing at the time of abnormality include generation of an alarm sound, display on the screen of the display 31 indicating an abnormality, and the like.

FIG. 6 is a graph showing the difference between the torque commands when the tool is broken and when it is not broken. In this figure,
The dotted line tcmd indicates the torque command when breakage occurs, and the dashed line am
o is a curve representing each signal of the acceleration at the time of breakage, solid line tcmd2 is a curve representing a torque command when no tool abnormality has occurred, and dashed line amo2 is a curve representing each signal of the acceleration when no tool abnormality has occurred (the horizontal axis is time). . Note that the dashed line amo and the dashed line a
The two curves of mo2 almost overlap as a result of the speed control by the servo loop, and the lowermost curve over almost the entire area of the graph is the overlap of these two curves. In addition, since the state is the same as that of the tool from time 1 to time 113, the dotted line tcmd and the solid line tcmd2 also overlap.

It is to be noted that the acceleration state is until about time 65, the processing time is until about time 113 (however, no processing is performed in this figure), and the deceleration state is about until time 185.
As shown in this graph, broken line tcmd
Has a significantly smaller absolute value during deceleration than the solid line tcmd2. This is because the torque required for deceleration is reduced as a result of the inertia of the tool being reduced due to breakage. In the tool abnormality detection processing, the torque command value is compared between the time of acceleration and the time of deceleration, instead of comparing the time when breakage occurs and the time when breakage does not occur.
Although the signal waveforms of the two do not generally match even if tool breakage does not occur, in the above process, when estimating the inertia, the inertia is calculated in consideration of the kinetic friction coefficient and the viscous friction coefficient of the main shaft. Error to the safety factor K
Therefore, the presence or absence of breakage is accurately determined.

According to the substrate drilling machine 1 as described above, since the tool break is determined based on the inertia detected before and after the processing, there is no influence from the processing load. Moreover, each time machining is performed, it can be determined whether or not a tool break has occurred, and it is not necessary to secure a time for the determination.

Here, the correspondence between the configuration of the present embodiment and the essential requirements of the present invention will be described. The processing of S120 and S150 corresponds to the inertia detecting means of the present invention, and the processing of S160
The processing of S180 corresponds to the tool breakage determination means of the present invention. As described above, the substrate drilling machine 1 has been described as one embodiment to which the present invention is applied. However, the present invention is not limited to this embodiment at all and can be implemented in various modes. For example, a machine tool other than the board drilling machine 1 (eg,
This tool abnormality detection device may be applied to a machining center. Further, the inertia may be estimated based on signals or information other than the torque command value.

Further, the abnormality of the tool may be detected by comparing with a presumed inertia. This processing will be described with reference to the flowchart of FIG. This process is started when the operator operates the operation panel 33 when it is desired to inspect the occurrence of an abnormality. The assumed inertia (referred to as Ja) is the inertia J1 estimated last time.
And so on. When the assumed inertia Ja is calculated in this way, a rotation command is issued to the main shaft in S200. And S
At 210, the spindle motor 7 is accelerated to the target speed. At this time, the inertia J of the tool is determined in S220 based on the torque command signal generated from the control unit 51 and the rotation speed of the spindle.
Estimate 1. Up to this point, the processing is completely the same as the tool abnormality detection processing of FIG. Then, in S230, it is determined whether or not J1 is smaller than Ja multiplied by the safety coefficient K1. J
If the value of 1 is larger, the process proceeds to S240, where it is determined that an error has occurred in the tool, and a process at the time of the abnormality is performed, and the present process ends. The cause of the abnormality detected here may be a tool clamping abnormality (see FIG. 5D. The case where this is detected corresponds to the clamping abnormality determining means of the present invention), a wrong tool, and the like.

If J1 is larger (S230: YE
S), it is determined whether J1 is greater than Ja multiplied by the safety coefficient K2 (S250). If J1 is smaller or the same, the process proceeds to S240, where it is determined that an error has occurred in the tool, and processing for the time of abnormality is performed, followed by terminating the present processing.
The causes of abnormalities detected here are, in addition to tool breakage,
The tool falls from the spindle (see FIG. 5 (c). The case where this is detected corresponds to the tool-free determination means of the present invention), and the tool error (the case where this is detected corresponds to the tool determination means of the present invention). ) Etc. are conceivable. If J1 is larger (S2
50: YES), that is, J1 is Ja * K1 to Ja * K2
If the value falls within the range, the process proceeds to S260, where preparation (for example, processing) for the next operation is performed, and this processing ends.

According to the above-described processing, an abnormality occurring in a tool can be detected before starting machining. In addition,
If the clamping abnormality shown in FIG. 5D has occurred, the inertia of the tool fluctuates during the estimation, and this variation may be detected to determine that the clamping abnormality has occurred. Although the process of FIG. 7 is started by the operation of the operator, it may be performed each time processing is performed. In this case, it is not necessary to secure time for determining a tool abnormality.

The accuracy of inertia estimation can be improved in the following manner. First, known values (spindle motor inertia Jm, coupling inertia Jc, and spindle inertia Js) are set in the machine at the time of shipment from the factory.
Inertia Jk is obtained by k = Jm + Jc + Js.
If necessary, the inertia Jh of the tool holder is also added.

Next, the dynamic friction torque T1 is calculated from the torque command value Tx at the time of constant low-speed rotation such as when the spindle is oriented, and stored. The viscous friction coefficient Kb is calculated from the torque command value T2 at the time of rotation at a high constant rotation speed V2 by Kb =
It is calculated by (T2-T1) / V2 and stored.

From the above values, the torque command value T3 during acceleration, the actual acceleration A3, and the actual speed V3, the following equation is established. Jt + Jk = (T3-T1-Kb * V3) / A3 From this, the tool inertia Jt is estimated. When used in the processing of FIG. 4, at the time of deceleration, T4 is set as a torque command value at the time of deceleration, and the following equation is established from the actual acceleration A4 and the actual speed V4. . By doing so, the accuracy of estimating the inertia can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of a substrate drilling machine 1 to which the present invention is applied.

FIG. 2 is a block diagram showing an outline of a substrate drilling machine 1;

FIG. 3 is a block diagram showing a control system of the substrate drilling machine 1;

FIG. 4 is a flowchart of a tool abnormality detection process.

FIG. 5 is an explanatory diagram illustrating an example of an abnormality that has occurred in a tool.

FIG. 6 is a graph for explaining a principle of detecting a tool abnormality by a tool abnormality detection process.

FIG. 7 is a flowchart of a second tool abnormality detection process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Board drilling machine 7 ... Spindle motor 9 ... Head 11 ... Z-axis motor 13 ... Y-axis motor 29 ... NC control part 35 ... Spindle servo amplifier 51 ... Control part 53 ... Load inertia estimation part 55 ... Load 57 ... Inertia change Judgment part 61 ... Tool

Claims (12)

[Claims] 1. A tool abnormality detecting device for detecting an abnormality of a tool of a machine tool that performs machining by rotating a spindle to which the tool is attached, wherein the spindle is rotating at least in a state where the tool is attached. Comparing the inertia detected by the inertia detecting means before the machining with the inertia detected by the inertia detecting means after the machining, and if the inertia is reduced, the tool breaks. A tool breakage detection method, comprising: a tool breakage determination unit that determines that the occurrence of the tool breakage. 2. The tool abnormality detection device according to claim 1, wherein the tool breakage determination unit is configured to: when the rotation of the main shaft is accelerated, is reduced by the inertia of the main shaft detected by the inertia detection unit. A tool abnormality detecting device for comparing the inertia of a main shaft detected by a detecting means and determining that a tool attached to the main shaft has broken if the inertia is reduced. 3. A tool abnormality detecting device for detecting an abnormality of a tool of a machine tool that performs machining by rotating a spindle to which a tool is attached, wherein the spindle is rotating at least in a state where the tool is attached. Inertia detecting means for detecting the inertia of, and the inertia detected by the inertia detecting means,
A tool abnormality detection device, comprising: a clamp abnormality determination unit that determines that a clamp abnormality of the tool has occurred when the fluctuation occurs during rotation of the spindle. 4. A tool abnormality detecting device for detecting an abnormality of a tool of a machine tool that performs machining by rotating a spindle to which a tool is attached, wherein the spindle is rotating while at least the tool is attached. Inertia detecting means for detecting the inertia of, and the inertia detected by the inertia detecting means,
A tool abnormality detection device comprising: a tool-free determination unit that determines that a tool is not mounted on the spindle when the tool is substantially not mounted on the spindle. 5. A tool abnormality detecting device for detecting an abnormality of a tool of a machine tool which performs a machining by attaching a desired tool from a plurality of tools to a spindle and rotating the spindle, wherein at least the tool is attached. In the state, the inertia detecting means for detecting the inertia of the rotating main spindle, the inertia detected by the inertia detecting means when a tool whose inertia is measured in advance is attached to the main spindle, and while the main spindle is rotating. A tool abnormality detecting device, comprising: a tool determining unit that compares the inertia detected by the inertia detecting unit and detects that a wrong tool is attached to the spindle if the inertia is different. 6. The tool abnormality detection device according to claim 1, wherein the machine tool controls a rotation speed of the spindle by a servo, and the inertia detection unit is configured to detect the inertia of the spindle. Detection,
A tool abnormality detection device which performs the operation based on a rotation speed of the spindle and a torque command signal output by the servo. 7. A tool abnormality detection method for detecting an abnormality of a tool of a machine tool which performs machining by rotating a spindle on which a tool is mounted, the method comprising the steps of: detecting inertia of a spindle detected before machining; A tool abnormality detection method comprising: comparing inertia with a tool; and determining that the tool on the spindle has broken if the inertia has decreased. 8. The tool abnormality detection method according to claim 7, wherein the inertia of the main spindle detected at the time of acceleration of the rotation of the main spindle is compared with the inertia of the main spindle detected at the time of deceleration of the same rotation, and the inertia decreases. And determining that a tool attached to the spindle has broken. 9. A tool abnormality detection method for detecting an abnormality of a tool of a machine tool that performs machining by rotating a spindle to which a tool is attached, comprising: detecting an inertia of the spindle to which the tool is attached; When the value fluctuates during the rotation of the spindle, it is determined that a clamping abnormality of the tool has occurred. 10. A tool abnormality detection method for detecting an abnormality of a tool of a machine tool that performs machining by rotating a spindle on which a tool is mounted, comprising: detecting an inertia of a rotating main spindle; A tool abnormality detecting method, wherein it is determined that a tool is not attached to the spindle when the state is substantially the same as the state where the tool is not attached to the spindle. 11. A tool abnormality detecting method for detecting an abnormality of a tool of a machine tool which performs machining by attaching a desired tool from a plurality of tools to a spindle and rotating the spindle, wherein inertia is measured in advance. Compare the inertia detected when the tool is attached to the spindle and the inertia detected during rotation of the spindle, and if different, detect that the wrong tool is attached to the spindle. Characteristic tool abnormality detection method. 12. The tool abnormality detecting method according to claim 7, wherein the machine tool controls a rotation speed of the spindle by a servo, and detects the inertia of the spindle. A tool abnormality detection method which is performed based on a rotation speed and a torque command signal output by the servo.