JP4595227B2 - Tool abnormality detection device and tool abnormality detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tool abnormality detection device and a tool abnormality detection method used in a machine tool that performs machining by rotating a spindle to which a tool is attached.
[0002]
[Prior art]
Conventionally, in a machine tool that performs machining by rotating a spindle to which a tool is attached, whether or not an abnormality such as tool breakage (also referred to as tool breakage or simply breakage) has occurred in the machine tool in advance. The determination was made by touching the tool attached to the spindle to the touch sensor. That is, when tool breakage has occurred, the tool does not touch the touch sensor, so that it is determined that “tool breakage has occurred”.
[0003]
[Problems to be solved by the invention]
However, according to the above prior art, a touch sensor is required to determine tool breakage, and it is necessary to secure time for determining tool breakage separately from the machining time.
[0004]
As a different determination method, there is a technique for detecting tool breakage by monitoring a torque waveform generated by a controller during machining and detecting a disturbance of the waveform generated during tool breakage. In this case, although a touch sensor is not required, 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 disturbance due to a tool break that should be detected originally.
[0005]
The present invention has been made in view of such a problem, and an object thereof is to determine whether or not an abnormality such as tool breakage has occurred without being affected at all by a machining load.
[0006]
[Means for Solving the Problems and Effects of the Invention]
The present invention according to claim 1, which has been made to solve such a problem, 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 a tool is attached. Inertia detecting means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotation speed of the spindle motor in a state where the tool is attached, and the machining said comparing the detected inertia by inertia detection means before and after the inertia detected by the inertia detecting means after processing, has decreased from inertia detected by the inertia detecting unit before processing lever, wherein Tool breakage judging means for judging that the tool has broken is provided. .
[0007]
According to the tool abnormality detection device configured as described above, it is possible to determine whether or not tool breakage has occurred without being affected at all by the machining load.
According to a second aspect of the present invention, in the tool abnormality detection device according to the first aspect, the tool breakage determining means sets the time when the rotation of the main shaft is accelerated before the processing and the time when the rotation of the main shaft is decelerated. After the machining, the inertia of the spindle detected by the inertia detecting means is compared .
[0008]
According to the tool abnormality detection device configured as described above, it is possible to determine whether or not tool breakage occurs each time machining is performed, and it is not necessary to particularly secure a time for 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 a tool is attached, and at least the tool is attached, Based on a torque command signal for driving the spindle motor for rotating the spindle and the rotation speed of the spindle motor, an inertia detection means for detecting inertia of the rotating spindle, and an inertia detected by the inertia detection means, Clamp abnormality determining means for determining that a clamp abnormality of the tool has occurred when the main shaft fluctuates during rotation is provided.
[0009]
According to the tool abnormality detection device configured as described above, it is possible to detect whether or not a clamping abnormality has occurred by rotating the spindle. For example, if this is detected during processing, a detection time is particularly secured. Therefore, it is possible to detect a clamp abnormality.
[0010]
The present invention according to claim 4 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 a tool is attached, and at least the tool is attached, Based on a torque command signal for driving the spindle motor for rotating the spindle and the rotation speed of the spindle motor, an inertia detection means for detecting inertia of the rotating spindle, and an inertia detected by the inertia detection means, When there is substantially the same inertia as when the tool is not attached to the main shaft, there is provided tool-less determining means for determining that the tool is not attached to the main shaft.
[0011]
According to the tool abnormality detection device configured as described above, it is possible to detect whether or not a tool is attached to the main shaft by rotating the main shaft. For example, if this is detected during machining, a detection time is particularly secured. The tool-free state can be detected without doing so.
[0012]
According to a fifth aspect of the present invention, there is provided a tool abnormality detection device for detecting an abnormality of the tool of a machine tool that performs machining by attaching a desired tool to a main shaft from a plurality of tools and rotating the main shaft. Inertia detection means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotation speed of the spindle motor in a state where the tool is mounted, and inertia in advance the inertia detected by the inertia detecting means measured tool when attached to the main axis, as a result of comparing the detected inertia by the inertia detecting means of the spindle during rotation, have both inertia is different lever, and characterized in that incorrect tool with a tool determining means for detecting a is attached to the main shaft That.
[0013]
According to the tool abnormality detection device configured as described above, it is possible to detect that an erroneous tool is attached to the spindle (hereinafter referred to as a tool error) by rotating the spindle. If detected, a tool error can be detected without particularly securing a detection time.
[0014]
The present invention described in claim 6 is the tool abnormality detecting device according to any one of claims 1 to 5, wherein the machine tool, characterized in that the rotational speed of the spindle is to control the servo .
[0015]
According to the tool abnormality detection device configured as described above, the inertia can be detected without providing a special configuration for detecting the inertia.
In addition, what comprised the tool abnormality detection apparatus of Claims 1-6 as a tool abnormality detection method is this invention of Claims 7-12, respectively, and there exists an effect similar to a corresponding tool abnormality detection apparatus, respectively. be able to.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a substrate drilling machine 1 to which the present invention is applied. A spindle motor 7 that rotates the spindle of the substrate drilling machine 1 is attached to a head 9, and can be moved up and down together with the spindle by a Z-axis motor 11 that is also attached to the head 9. The head 9 is moved left and right along the two rails 17 as the Y-axis motor 13 rotates the ball screw 15. The table 19 to which the substrate is fixed is moved back and forth along the two rails 25 when an X-axis motor (not shown) rotates the ball screw 21.
[0017]
A block diagram of the substrate drilling machine 1 is shown in FIG. As shown in the figure, the substrate drilling machine 1 has a CPU 23, a ROM 25 in which basic programs to be decoded and executed by the CPU 23 are stored in advance, and various data storage functions such as a work area used in the programs. The RAM 27 and the NC control unit 29 for executing the motion command generated by the CPU 23 are mainly composed of a display 31 for displaying a program and the operation panel 33 for giving a command to the substrate drilling machine 1. It is configured. The CPU 23 reads and executes a program stored in the ROM 25, and controls the entire substrate 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 NC control unit 29 is connected to a spindle servo amplifier 35, an X-axis servo amplifier 37, a Y-axis servo amplifier 39, a Z-axis servo amplifier 41, and the like, and each of these servo amplifiers has a motor and an encoder E corresponding thereto. It is connected. The servo amplifiers 35 to 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.
[0018]
FIG. 3 shows a block diagram of the spindle control system. The control unit 51 receives a feedback of an actual speed (or actual acceleration) based on a signal from the encoder E (see FIG. 2) and outputs a torque command to the current amplifier 52 that drives the spindle motor 7. 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 estimation unit 53 estimates the inertia of the load 55 applied to the main shaft. When the inertia change determination unit 57 determines that the inertia estimated by the load inertia estimation unit 53 has changed, an error is detected. Each block of the control unit 51, the load inertia estimation unit 53, and the inertia change determination unit 57 is realized by the CPU 23, the NC control unit 29, the spindle servo amplifier 35, and the program executed by the CPU 23 in FIG.
[0019]
A flowchart of this process is shown in FIG. This process is started each time machining is performed using the spindle. First, in step (hereinafter simply referred to as S) 100, a rotation command is issued to the spindle. In subsequent S110, the spindle motor 7 is accelerated to the target speed. At this time, based on the torque command signal generated from the control unit 51 and the rotational speed of the spindle motor, the inertia of the tool is estimated in S120. The inertia estimated here is J1. In step S130, actual processing is performed. When the machining is completed, the spindle motor 7 is decelerated (S140). 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 J2.
[0020]
Then, it is determined in S160 whether tool breakage has occurred. Here, J2 is performed determination by examining or not smaller than the J1, it determines whether more specifically J1 is smaller than that Flip multiply the safety factor K to J2. For example, when the tool 61 that has been as shown in FIG. 5A before machining is broken as shown in FIG. 5B after machining, the inertia of the tool 61 ′ is smaller than that before machining. ing. If the safety factor K> 1 is set here, if there is no abnormality in the tool, J2 should be larger. When it is determined that J1 is smaller, that is, there is no abnormality in the tool, the process proceeds to S170 to prepare for the next operation, and this process is terminated. On the other hand, when it is determined that J1 is larger, the process proceeds to S180, it is determined that an abnormality has occurred in the tool, the process at the time of abnormality is performed, and this process is terminated. Examples of processing at the time of abnormality include generating an alarm sound and performing a display indicating the abnormality on the screen of the display 31.
[0021]
The difference in torque command between when the tool breaks and when it does not occur is shown in the graph of FIG. In this figure, the dotted line tcmd is a torque command when a breakage occurs, the alternate long and short dash line amo is the acceleration when a breakage occurs, the solid line tcmd2 is a torque command when no tool abnormality occurs, and the broken line amo2 is when no tool abnormality occurs Is a curve representing each acceleration signal (the horizontal axis is time). It should be noted that the two curves of the alternate long and short dash line amo and the broken line amo2 are almost overlapped as a result of the speed control by the servo loop, and the lowermost curve over the almost entire area of the graph is the overlap of these two curves. . In addition, since the tool is in the same state from time 1 to 113, the dotted line tcmd and the solid line tcmd2 also overlap.
[0022]
It is noted that the acceleration state is up to around time 65, the machining time is up to around time 113 (however, machining is not performed in this figure), and the deceleration state is up to around time 185. As shown in this graph, the absolute value of the broken line tcmd where the breakage occurs is considerably smaller during deceleration than the solid line tcmd2. This is because the torque required for deceleration is reduced as a result of the tool inertia being reduced due to breakage. In the tool abnormality detection process, the torque command value is compared at the time of acceleration and at the time of deceleration rather than comparing when the breakage occurs and when it does not occur. The signal waveforms of both do not generally match even if tool breakage does not occur.However, when the inertia is estimated in the above process, the inertia is calculated in consideration of the dynamic friction coefficient and viscous friction coefficient of the main shaft, and it still occurs. Since the possible error is absorbed by the safety factor K, it is a process for accurately determining the presence or absence of breakage.
[0023]
According to the substrate drilling machine 1 as described above, since tool breakage is determined based on inertia detected before and after machining, there is no influence of machining load. Moreover, every time machining is performed, it can be determined whether or not tool breakage has occurred, and there is no need to particularly secure time for determination.
[0024]
Here, the correspondence between the configuration of the present embodiment and the essential requirements of the present invention is shown. The processes of S120 and S150 correspond to the inertia detection means of the present invention, and the processes of S160 and S180 correspond to the tool breakage determination means of the present invention.
As described above, the substrate drilling machine 1 has been described as an embodiment to which the present invention is applied. However, the present invention is not limited to this embodiment, and can be implemented in various modes. For example, this tool abnormality detection device may be applied to a machine tool (eg, machining center) other than the substrate drilling machine 1. The inertia may be estimated based on signals and information other than the torque command value.
[0025]
Moreover, you may make it detect the abnormality of a tool by comparing with the inertia assumed beforehand. This process 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 check the occurrence of an abnormality. The assumed inertia (Ja) can be assumed from the previously estimated inertia J1 or the like. When the assumed inertia Ja is thus calculated, a rotation command is issued to the main spindle in S200. In step S210, the spindle motor 7 is accelerated to the target speed. At this time, based on the torque command signal generated from the control unit 51 and the rotational speed of the spindle, the inertia J1 of the tool is estimated in S220. The process so far is exactly the same as the tool abnormality detection process of FIG. And S230 in determines less or not than that J1 is Flip multiply safety factor K1 to Ja. If J1 is larger, the process proceeds to S240, it is determined that an abnormality has occurred in the tool, the process at the time of abnormality is performed, and this process is terminated. Possible causes of the abnormality detected here include a tool clamping abnormality (see FIG. 5D. The case of detecting this corresponds to the clamping abnormality determining means of the present invention), a tool error, and the like.
[0026]
J1 is small only lever towards (S230: YES), J1 determines whether larger or not than that Flip multiply safety factor K2 in Ja (S250). If J1 is smaller or the same, the process proceeds to S240, it is determined that an abnormality has occurred in the tool, the process at the time of abnormality is performed, and this process is terminated. Causes of the abnormality detected here include tool breakage, tool fall from the spindle (see FIG. 5 (c). The case where this is detected corresponds to the tool-less determining means of the present invention), tool error (The case where this is detected corresponds to the tool determining means of the present invention). If J1 is larger (S250: YES), that is, if J1 is within the range of Ja * K1 to Ja * K2, the process proceeds to S260 to prepare for the next operation (for example, processing) and perform this process. finish.
[0027]
According to the above process, the abnormality which generate | occur | produced in the tool is detectable before starting a process. When the clamping abnormality shown in FIG. 5 (d) has occurred, the inertia of the tool fluctuates during estimation, so even if it is determined that a clamping abnormality has occurred by detecting this fluctuation. good. 7 is activated by an operation from the operator, it may be performed each time processing is performed. In this way, it is not necessary to secure time for determining tool abnormality.
[0028]
The inertia estimation accuracy can be improved as follows. First, known values (spindle motor inertia Jm, coupling inertia Jc, spindle inertia Js) are set in the machine at the time of shipment from the factory, and the inertia Jk is obtained by Jk = Jm + Jc + Js. If necessary, the tool holder inertia Jh is also added.
[0029]
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 by Kb = (T2−T1) / V2 from the torque command value T2 at the time of rotation at a high constant rotational speed V2, and stored.
[0030]
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 using the processing of FIG. 4, the following equation is established from the actual acceleration A4 and the actual speed V4, with T4 being the torque command value for deceleration at the time of deceleration: Jt + Jk = (T4 + T1 + Kb * V4) / A4
To estimate tool inertia Jt. In this way, the inertia estimation accuracy 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 showing an example of an abnormality that has occurred in the tool.
FIG. 6 is a graph for explaining the principle of finding 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 | substrate drilling machine 7 ... Main shaft motor 9 ... Head 11 ... Z-axis motor 13 ... Y-axis motor 29 ... NC control part 35 ... Main-axis servo amplifier 51 ... Control part 53 ... Load inertia estimation part 55 ... Load 57 ... Inertia change Judgment part 61 ... Tool

Claims (12)

In a tool abnormality detection device for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
Inertia detection means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotational speed of the spindle motor at least in a state where the tool is attached;
Wherein comparing the inertia detected by said inertia sensing means before and after the processing, inertia detected by the inertia detecting means after processing, has decreased from inertia detected by the inertia detecting unit before processing lever Tool breakage determining means for determining that the tool attached to the spindle has broken.
A tool abnormality detection device comprising: In the tool abnormality detection device according to claim 1,
The tool breakage determination means,
And before the processing during acceleration of the rotation of the main shaft, the deceleration of the rotating of the spindle as later the processing, compare Inashi multichemistry spindle detected by the inertia detecting means
Tool abnormality detection device comprising a call. In a tool abnormality detection device for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
Inertia detection means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotational speed of the spindle motor at least in a state where the tool is attached;
Clamp abnormality detection means for determining that a clamp abnormality of the tool has occurred when the inertia detected by the inertia detection means fluctuates during rotation of the spindle. apparatus. In a tool abnormality detection device for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
Inertia detection means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotational speed of the spindle motor at least in a state where the tool is attached;
When the inertia detected by the inertia detection means is substantially the same as the inertia when no tool is attached to the main shaft, there is provided a toolless determination means that determines that the tool is not attached to the main shaft. Tool abnormality detection device. In a tool abnormality detection device for detecting an abnormality of the tool of a machine tool that performs machining by attaching a desired tool to a main shaft from a plurality of tools and rotating the main shaft,
Inertia detection means for detecting inertia of the rotating spindle based on a torque command signal for driving the spindle motor for rotating the spindle and the rotational speed of the spindle motor at least in a state where the tool is attached;
Pre inertia and inertia detected by the inertia detecting means of the tool measured when attached to the main axis, as a result of comparing the inertia detected by the inertia detecting means during rotation of the spindle, both inertia If there is a difference, a tool abnormality detection device comprising tool determination means for detecting that an erroneous tool is attached to the spindle. In the tool abnormality detection device according to any one of claims 1 to 5,
It said machine tool, the tool abnormality detecting device, characterized in that the rotational speed of the spindle and controls the servo. In a tool abnormality detection method for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
At least in a state where the tool is mounted, the inertia of the rotating spindle is detected based on a torque command signal for driving the spindle motor that rotates the spindle and the rotation speed of the spindle motor, and before and after the machining. The detected inertia is compared, and if the inertia detected after machining is smaller than the inertia detected before machining, it is determined that the tool attached to the spindle has broken. Tool abnormality detection method. In the tool abnormality detection method according to claim 7,
Wherein the time of acceleration of the rotation of the main shaft to the front the process, the deceleration of the rotating of the spindle as later the machining, the tool abnormality detecting method comprising comparing to Rukoto the Inashi catcher. In a tool abnormality detection method for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
At least in the state where the tool is attached, the inertia of the spindle to which the tool is attached is detected based on the torque command signal for driving the spindle motor that rotates the spindle and the rotational speed of the spindle motor , and the detection A tool abnormality detection method comprising: determining that a clamping abnormality of the tool has occurred when the inertia changed during rotation of the spindle. In a tool abnormality detection method for detecting abnormality of the tool of a machine tool that performs machining by rotating a spindle to which a tool is attached,
At least in the state where the tool is attached, based on the torque command signal for driving the spindle motor that rotates the spindle and the rotation speed of the spindle motor, the inertia of the rotating spindle is detected, and the detected inertia is tool abnormality detecting method characterized by determining that the inertia in a state where no attaching a tool to the spindle, have not been substantially attached tool is the spindle is at the same time. In a tool abnormality detection method for detecting an abnormality of the tool of a machine tool that performs machining by attaching a desired tool to a spindle from a plurality of tools and rotating the spindle,
At least in the state where the tool is mounted, the inertia of the rotating spindle is detected based on the torque command signal for driving the spindle motor that rotates the spindle and the rotation speed of the spindle motor, and the detected inertia the advance result a tool to measure the inertia and inertia and compared detected when attached to the main shaft, detecting the if both inertia different wrong tool is attached to the main shaft The tool abnormality detection method characterized by these. In the tool abnormality detection method according to any one of claims 7 to 11,
Tool abnormality detecting method, wherein the machine tool, the rotational speed of the spindle and controls the servo.

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