JPH07195256A - Control unit and machine tool therewith as well as torque measuring instrument and tool breakage detector - Google Patents

Abstract

PURPOSE:To shorten a span of machining time as well as to improve the accuracy of finishing by preventing an undue torque from being imposed on a tool, and prolonging the extent of tool life. CONSTITUTION:A spindle rotating mechanismic part 4 rotating a drill 10 attached to a tip free of detachment shifts forward and backward to and from a work 11 by means of feed machanismic part 3. Machining torque added to the drill at the time of machining is detected by a magnetostrictive torque sensor 16, transmitting it to a torque controller 15 in which the given torque desired value is compared with the machining torque, and when three is a difference between them, a feed rate for according them with each other is found out, thereby outputting a speed command signal to a feed motor driver 12. In this way, the machining torque is accorded with the torque desired value. Therefore, no excessive torque is added to the drill and thereby the progress of deterioration becomes retarded. In addition, the drill is fed at a high speed under the condition that suchlike excessive torque is not added at all.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device, a machine tool using the same, a torque measuring instrument and a tool breakage detecting device.

[0002]

BACKGROUND OF THE INVENTION In a machine tool that performs various kinds of processing such as drilling, milling machine, drilling machine and the like by rotating tools such as drilling, milling machine and drilling machine, the above tool is detachably attached to the machine tool body and predetermined processing is performed. It is like this. This machine tool main body is provided with a spindle rotating mechanism for rotating a spindle to which the tool is attached, and a feed mechanism for moving the entire spindle rotating mechanism or a workpiece (workpiece) forward and backward. In the above, the tool is moved forward relative to the workpiece at a predetermined constant speed while the spindle is rotated at a constant speed. The speed is determined in consideration of the material of the work and the tool, the diameter of the tool, and the like.

By the way, at the time of processing, a reaction force from a work (work) is received and a torque is applied to the tool. Therefore, if the speed of each motor is set incorrectly, the chips / machining chips are clogged, or the tool is worn, the torque applied to the tool becomes large, and the tool breaks if a torque above a certain value is applied. There is a risk. On the other hand, in consideration of such a situation, if a predetermined margin is set in advance and the speed is set to be low, the processing efficiency will be deteriorated.

Therefore, there is required a technique for detecting the torque applied to the tool during machining, controlling the machine tool so as not to apply a torque above a certain value, and preventing breakage of the tool.

Further, in the past, when the tool is broken, the tool must be replaced, but since it is not possible to know the degree of wear, it is difficult to detect the proper tool replacement timing. As a result, wear progresses and deteriorates, and machining efficiency is poor, but the machining accuracy of the finished product is poor due to continued use, or it breaks during processing, ruining the product being processed or broken tools. Debris may fly and create a danger. In order to eliminate this, if you exchange it quickly,
Although it can be used, it is discarded because it is thrown away.
Furthermore, since it is unknown when it will be unusable, it is necessary to prepare a large amount of tools in advance, which is a waste.

Further, in order to control so as not to apply an excessive torque, it is necessary to set a target torque, but the setting tends to be a know-how. Furthermore, if the tool is controlled so that it will not break, the tool will not be overloaded depending on the machining situation at that time, but then the degree of tool deterioration and the machining situation will be set as specified. It becomes difficult to detect whether or not there is (abnormality).

Further, in order to prevent breakage of the tool,
It is necessary to perform accurate torque measurement, but it has been difficult for a conventional general torque sensor to detect the instantaneous torque fluctuation that occurs with breakage.

The present invention has been made in view of the above background, and an object of the present invention is to prevent an excessive torque from being applied to a tool, suppress breakage of the tool, and prevent deterioration (wear). By delaying the advance to extend the usable time of the tool, shorten the machining time and improve the machining accuracy, efficient machining can be performed, safe and highly accurate machining can be performed, The target torque value can be automatically set to a value that is suitable for the actual usage situation, and abnormalities during machining (abnormal tool conditions such as wear and breakage, incorrect machining conditions such as erroneous workpiece setting) It is also possible to know the wear condition of the tools used in the machine tool, and it is possible to accurately and easily know when the replacement time is approaching, or when it is time to replace the service life (remaining remaining To provide a control apparatus and a machine tool using the same capable of obtaining the number of times).

Another object of the present invention is to provide a torque measuring instrument and a tool breakage detecting device capable of accurately estimating torque in real time even if the machining load varies little with respect to the spindle motor capacity and in real time. It is in.

[0010]

In order to achieve the above-mentioned object, in a control device according to the present invention, a spindle rotating mechanism for rotating a tool detachably attached to the tip, and the spindle rotating mechanism are machined. A control device used in a machine tool having a feed mechanism for moving the object forward and backward, for controlling the feed speed of the feed mechanism, and a torque detection means for detecting a torque applied to the tool, and at least a setting. A feed speed calculation means for obtaining the feed speed based on the torque target value obtained and the torque detected by the torque detection means, and an output of the feed speed calculation means so that the calculated feed speed is obtained. It comprises a feed mechanism control means for controlling the feed mechanism.

Preferably, in addition to the above configuration, a torque target value generating means for determining a torque target value based on the feed position of the tool is further provided, and the feed speed calculating means outputs from the torque target value generating means. That is, the feed rate is obtained based on the torque target value.

In this case, as the target value generation means, for example, a target value point sequence storage means for storing a target value point sequence consisting of torque target value pairs for a plurality of feed positions and the target value point sequence storage means are stored. It can be composed of a stored predetermined target value point sequence and a target value torque calculating means for calculating a current torque target value based on the current feed position. Further, when the target value point sequence is generated on the basis of the processing torque waveform during normal processing and the target value point sequence generation means for storing the target value point sequence storage means is further provided, the torque target value is automatically determined. It is more preferable because it can be generated.

Further, a speed control means for controlling the feed speed to a constant speed set value is added to any one of the above-mentioned constitutions, and by the switching processing by the switching means,
It is more preferable to selectively execute either the speed control for keeping the speed constant or the torque control for keeping the output of the feed speed calculating means, that is, the torque constant. The switching timing of the switching means in such a case can be determined based on at least the feed position, for example.

Further, in the above-mentioned various configurations, an abnormality signal is issued when the feed rate determined by the feed rate calculation means becomes faster than a fixed upper limit value or lower than a fixed lower limit value. It is advisable to further provide detection means.

Preferably, a work completion time detecting means for detecting a work completion time required for one machining, and a replacement request signal when the work completion time exceeds or exceeds the maximum delay time required for tool replacement. It is to output.

Further, a work completion time detecting means for detecting a work completion time required for one machining, a current and a predetermined past work completion time detected by the work completion time detecting means, and a tool replacement are required. It is more preferable to further include a prediction unit that calculates the life of the tool in use based on the maximum delay time.

In the machine tool according to the present invention, a spindle rotating mechanism for rotating a tool detachably attached to the tip, a feed mechanism for moving the spindle rotating mechanism forward and backward with respect to a workpiece, and the above various types. With a control device consisting of
That is, the control device controls the feeding mechanism.

In the torque measuring instrument according to the present invention, the torque for estimating the torque applied to the tool attached to the machine tool by using the observer theory based on the current and the rotation speed value of the spindle motor mounted on the machine tool. A calculation means was provided. A torque measuring instrument used for a machine tool, wherein a spindle load torque estimating means for estimating a torque value applied to the spindle based on a current and a rotation speed value of a spindle motor mounted on the machine tool. And storage means for storing the torque of the spindle that is rotating during non-machining, which is obtained by the spindle load torque estimating means, and the torque applied to the spindle being machined, which is obtained by the spindle load torque estimating means. From the torque stored in the storage means,
You may comprise from the arithmetic means which calculates the torque applied to the tool attached to the said processing machine.

Further, in the tool breakage detecting device according to the present invention,
A torque measuring device having the above configuration is provided, and a breakage state of the tool is detected using the torque measurement value output by the torque measuring device, and a control unit is provided for controlling the operating state of the machine tool based on the detection result. Configured.

[0020]

The torque applied to the tool during machining is directly or indirectly detected by using the torque detecting means. And
Compared with the set torque target value, the feed rate is controlled in real time so that the machining torque matches the torque target value. Since the detected processing torque is directly compared, the control is performed with high accuracy.

When the torque target value generating means is provided (claims 2 to 4), the above control can be performed based on the optimum torque target value at that time according to the feed position and the like, so that the control can be performed with higher accuracy. Therefore, the processing accuracy is improved. Then, as in claim 3, the torque target value is defined by a plurality of target value point sequences, and the target value point sequences are interpolated based on the data, so that the processing processing is performed with a small storage capacity and a simple configuration. A desired torque target value is set throughout. Further, when the target value point sequence is automatically generated based on the machining torque waveform obtained during the actual machining as claimed in claim 4, even a person who has no know-how can use the environment of use at that time. Since the target value point sequence suitable for the condition is determined, the control performed based on it is also good.

Further, in the case where the feed rate is controlled by using the control function which is appropriately selected by the switching means and which has the speed control function and the torque control function (claim 5,
6) Since the control suitable for the use condition at that time can be performed, more accurate control is performed.

Further, in the case where an anomaly detecting means for issuing an anomaly signal is provided when the calculated feed speed becomes faster than a certain upper limit value and / or becomes less than a certain lower limit value (claim 7, In 8), if the processing torque increases, the feed rate decreases. Therefore, even if the tool is not broken, there is severe wear, or there is an abnormality such as lubricating oil not being supplied or chips being caught. If so, the speed becomes lower than the lower limit value.

Further, if a material different from the set workpiece is set and an attempt is made to process it, if the material is harder than the mistakenly set material, the processing torque is large. Similarly, the speed becomes lower than the lower limit value. On the contrary, if the material is softer than the one set by mistake, the processing torque is small and the speed becomes lower than the upper limit value. In this way, various abnormalities are detected. In particular, if an abnormal signal is provided when the value exceeds the upper limit, the set error can be detected as described above.
Further, if the feed rate becomes excessively high, it becomes dangerous, but a warning by an abnormal signal is received before that, so that the device and the user can be protected.

Further, when the work completion time detecting means is provided to output the replacement request signal when the work completion time exceeds or exceeds the maximum delay time (claim 9), it is time to replace the tool. You can know that exactly. As a result, the tool is replaced at an appropriate timing.
Moreover, when the work completion time detecting means and the predicting means are provided (Claim 10), it is possible to know that the replacement time is approaching in advance, which is a standard for preparing a tool for replacement, which is a waste. You no longer need to stock up.

A machine tool according to the present invention (claim 1
In 1), since it is controlled by the above various control devices, safe and efficient machining can be performed in a short time.

Further, the torque measuring device according to the present invention (claims 12 and 13) determines the spindle load torque estimating means from the rotation speed and the current of the spindle motor which is rotating at a constant speed before machining without load. Then, the spindle load torque at that time is calculated and stored in the storage means. Then, since the cutting torque is zero in this case, the value stored in the storage means is
The torque is generated based on friction and inertia of the spindle motor spindle. Similarly, the spindle load torque when the tool is actually brought into contact with the workpiece to perform the predetermined machining process is calculated and sent to the calculation means. In addition to the torque component based on the friction of the main spindle,
The value also includes the torque applied to the actual tool.
Therefore, the arithmetic unit reads out the torque data stored in the storage means, subtracts the two from each other, calculates the torque applied to the tool, and outputs the calculated torque. Also, when estimating the torque from the above current and rotation speed,
The torque applied to the tool can be estimated directly from the current and rotation speed by modeling with consideration of viscosity and friction and establishing an estimation calculation formula.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a control device, a machine tool using the same, a torque measuring instrument and a tool breakage detecting device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of a torque control device for a machine tool according to the present invention. In this example, as the machine tool to be controlled,
A drilling machine is used. This drilling machine
Posts 2 formed upright on the upper surface of the work holding table 1
In addition, a spindle rotation mechanism unit 4 is attached so as to be able to move up and down via the feed mechanism unit 3.

That is, the feed mechanism section 3 includes the feed motor 5
And a guide rail 6 composed of a ball screw for stably raising and lowering the spindle rotation mechanism portion 4 based on the output of the feed motor 5. Further, the spindle rotation mechanism section 4 includes a spindle motor 7, a chuck 8 attached to the tip of a spindle (not shown) connected to the output of the spindle motor 7,
A connecting member 9 that supports the main shaft motor 7 and the rotation transmitting mechanism such as the main shaft and the chuck 8 and connects to the guide rail 6.
It has and. Then, the drill 10 as a tool is detachably attached to the chuck 8.

Therefore, when the main shaft motor 7 is driven to rotate, the rotational force of the main shaft 7 and the chuck 8 is applied to the drill 1.
It reaches 0 and rotates at a predetermined speed. When the feed motor 5 is normally rotated in this state, the rotational force is transmitted to the guide rail 6 made of a ball screw, and the connecting member 9, that is, the main spindle rotating mechanism portion 4 is moved downward. As a result, the drill 10 is brought into contact with the workpiece 11, which is the workpiece placed on the upper surface of the workpiece holding table 1 below the drill 10,
Cutting process. When the feed motor 5 is rotated in the reverse direction,
The main shaft rotation mechanism section 4 moves upward. The motors 5 and 7 are connected to the feed motor driving device 1 respectively.
2. The rotation speed (speed) is controlled by the amount of electric power supplied from the spindle motor drive device 13.

Here, in the present invention, the spindle motor drive device 1
3 controls to rotate at a constant speed based on a spindle motor speed command from the spindle motor control device 14. Further, the feed motor drive device 12 rotates the feed motor 5 at a predetermined rotation speed based on a feed motor speed command given from the torque control device 15 which is a feed speed calculation means so that the descending movement speed becomes the command value. Control to do.

The torque control device 15 determines the feed rate so that the machining torque (torque applied to the tool during machining) reaches the given torque target value (a specific function will be described later). There is. Then, the processing torque is generated by the torque sensor 16 arranged on the outer periphery of the drill 10 and the amplifier 17 connected to the output of the torque sensor 16.
The processing torque value is detected by being amplified by and is sent to the torque control device 15.

As the torque sensor 16, for example, a magnetostrictive torque sensor can be used. That is, for example, 4
A torque sensor configured by winding an excitation coil and a detection coil around each leg of a core with a book leg is arranged with the leg open side of the core close to the outer surface of the rotating shaft. To do.

With such a configuration, when an AC signal is supplied from the power source (not shown) to the exciting coil, an induction voltage is induced on the detection coil side by electromagnetic induction and a predetermined AC signal is output. At this time, when torque is applied to the rotating shaft, the magnetic permeability of the rotating shaft changes due to the inverse magnetostrictive effect, so that the coupling coefficient between both coils changes. Therefore, the amplitude of the signal output from the detection coil changes. By detecting this amplitude, it is possible to know the magnitude of the torque applied to the rotating shaft.

Although the torque applied to the drill is directly detected in this example, the present invention is not limited to this, and a torque sensor is attached inside the chuck or in the middle of the spindle to indirectly detect the processing torque. Alternatively, a cutting dynamometer that can be attached to the work holding table 1 and can measure the torque during processing can be used. Further, a torque measuring device for estimating the processing torque from the current or the rotation speed of the spindle motor 7 (an example of obtaining the processing torque by this estimation will be described later) may be used.
The point is that anything that can detect the processing torque may be used.

On the other hand, the specific processing function of the torque control device 15 for determining the speed of the feed motor on the basis of the processing torque and the target torque value is as shown in the flowchart of FIG. That is, the basic feed speed f set in advance is set in a state where the drill 10 is rotated at a constant speed when the machining is started.
A speed command is output so that it moves downward at 0 (ST
1). And the drill tip position (feed position) h [mm]
Is measured, and the basic feed speed f0 is maintained until the tip of the drill 10 contacts the upper surface of the work 11 (h = 0) (ST2, ST3). In this example, since the main shaft rotating mechanism 4 moves up and down along the guide rail 6 formed of a ball screw, the distance that the feed motor 5 moves up and down is constant for each rotation, so the initial position (for example, the uppermost position). position)
The feed position can be calculated by obtaining the integrated number of rotations of the feed motor 5 from.

When the tip of the drill 10 comes into contact with the work 11 (h = 0), the actual drilling is performed thereafter. Therefore, the feed rate adjustment control according to the machining conditions after step 4 is performed. I do. That is, the rotation speed N of the spindle
[Rpm] (fixed) and processing torque value τ [kgf · cm]
To get. The processing torque value is detected by the torque sensor 16 (ST4).

Considering the processing torque value τ,
The torque τc [kgf · cm] generated by the drill 10 scraping the work 11 and the friction torque τf [kgf · c] between the drill 10 and the inner surface of the already drilled hole.
m]. And, τc is proportional to the square of the drill diameter D, and is proportional to the feed f of the drill 10 (amount [mm / rev] that the drill advances / retracts when the drill makes one revolution), and thus can be expressed by the following equation. .

Τc = kcfD ² km is a value that depends on the material (strictly, it also depends on the feed f). Also, τf is the rotational speed N of the drill and the depth h of the already cut hole. Since they are proportional to each other, τf = kf · N · h kf becomes a value depending on the material.

Therefore, the processing torque τ detected during processing
Is τ = kc · f · D ² + kf · N · h, and the speed of the feed motor is constant (speed control)
As an example of the machining torque detected over time, the machining torque also increases as the hole depth increases, as shown by the solid line in FIG. Therefore, in this example, paying attention to the fact that the processing torque τ depends on the feed f, the processing torque τ and the feed f are approximated by a proportional relationship as shown by the broken line in the figure, and control is performed based on the approximated curve. There is.

The torque target value τd serving as a control reference is externally given to the torque control device 15. In this example, when the feed speed and the drill rotation speed are constant as shown in FIG. Based on the machining torque waveform for the passage of time (during speed control) (drilling depth h),
The peak value is determined as the torque target value and that value is set. Since this peak value is the processing torque at each time during normal operation, if it is within the processing torque, the torque applied to the drill will not be overloaded and will not break.

Therefore, the deviation τe between the current machining torque τ obtained in step 4 and the preset torque target value τd is calculated (ST5).

Τe = τd-τ Then, the feed correction amount fm is calculated based on the calculation result. Specifically, it is calculated by the following formula (ST6).

Fm = Kpτe where Kp is a proportional constant, and the feed correction amount fm is the differential value of the torque deviation τe,
It may be calculated by using the integrated value and substituting it in the following formula. That is, it may be calculated using the PID control method (or PI, PD control method).

[0045]

[Equation 1] Furthermore, when the value of τe is a continuous quantity (analog value),
The correction amount fm is obtained by the above-mentioned arithmetic expression. However, when controlling using a microcomputer or the like, τe is a discrete amount (digital amount), so the correction amount fm at the kth sample from the start of control. (K) is

[0046]

[Equation 2] Becomes

Next, the feed amount f [mm / rev] is calculated by adding the correction amount fm obtained above to the reference feed amount f0, and the feed rate of the drill is calculated by multiplying the calculation result f by the drill rotation speed N. Calculate F [mm / min]. And
The rotation speed of the feed motor 5 for the feed speed of the spindle rotation mechanism 4 (drill 10) to reach the calculated F is obtained by the following formula, and the calculation result is output as a feed speed command to the feed motor drive device 12 ( ST7 to ST10).

V = Kv × F where Kv is the feed rate / motor speed command conversion coefficient. Therefore, if the boring process is started as shown by the solid line in FIG. 5, the machining torque is the torque target value (indicated by the broken line in the figure). (Shown) is almost the same. That is, the torque τc can be increased at the beginning of drilling with a small friction torque τf, that is, the feed f can be increased. In addition, near the end of drilling where the friction torque τf increases, the speed is slowed (almost equal to the feed speed in the speed control (control to keep the feed speed constant) shown by the chain double-dashed line in the figure) Open processing. This makes it possible to increase the machining speed without applying excessive torque to the drill 10.
As is clear from the figure, the processing can be performed in a shorter time than the speed control. When the processing torque exceeds the torque target value, the feed speed is reduced to protect the drill.

Then, the torque control (step 4 to step 10) is carried out to the drilling end position (ST11,
12) When the drilling end position is reached, a drill return command is output (ST13). Based on this return command, the feed motor driving device 12 supplies electric power so as to rotate the feed motor 5 in the reverse direction. If the drill moves up to the original initial position, the process ends (ST14,
15).

According to the above construction, the machining torque applied to the drill during machining is detected, and based on this, the feed speed is controlled to be increased or decreased in real time, whereby the actual machining torque can be made equal to the torque target value. it can. Therefore, the processing torque does not become excessive and damage to the drill (tool) can be prevented. Further, even if the tool wear progresses, the machining torque is not increased (in this case, the machining speed becomes slow as a whole), so that the tool is not subjected to excessive torque and the life is extended. Furthermore, the tool can be machined for a long period of time and at a feed rate adapted to the condition of the tool. Further, since the fluctuation of the processing torque is small, various effects such as improvement of the processing accuracy can be obtained.

FIG. 6 and FIG. 7 show a second control device according to the present invention.
An example is shown. Torque control device 15 shown in FIG.
Receives the processing torque applied to the tool during processing, and controls the feed speed so that the torque value becomes the torque target value. It has the same configuration as that shown in FIGS. 1 and 2 above. Is used.

In this embodiment, a machining abnormality detecting device is provided, the output of the torque control device 15 (feed motor speed command) is received, the machining state is judged, and if there is an abnormality, the feed motor drive device 12 is judged. A stop signal is output to this. Specifically, it has two reference values, an upper threshold and a lower threshold, and the input signal (feed motor speed command value) exceeds the upper threshold or becomes smaller than the lower threshold. Comparing device 2 that outputs an abnormal signal in some cases
It consists of zero. Then, this comparison device 20
It may be processed by software in the U or may be configured by hardware such as a window comparator.

That is, for example, as shown in FIG. 7, when chips produced by, for example, drilling work are clogged in the blade portion of the drill, the processing torque becomes extremely large. Then, as described above, the torque control device 15 gives an instruction to reduce the feed speed so that the processing torque becomes the torque target value. Therefore, the instructed feed rate becomes less than or equal to the lower limit threshold. Further, the same thing occurs, although the cutting oil is supplied during the processing, but the processing torque increases even when the supply of the cutting oil is stopped or the supply amount is insufficient, so that the same phenomenon occurs.

When the boring process is continued as it is in such a state, not only the machining time becomes long and the machining efficiency is deteriorated, but also the machining precision (finishing precision) of the work is deteriorated, and the tool is damaged. It causes wear. Therefore, when the feed speed becomes too low as in this example, it is determined that there is an abnormality, a stop hand stop signal is output to the feed motor drive device 12, and the feed motor (not shown) is stopped.

Also, in the case of an abnormal situation in which a work of a material different from the set one is inserted and a hole is to be drilled,
This can be detected by the abnormality detection device of this embodiment. In other words, if you set a standard feed rate or torque target value assuming that you will drill a hole in an aluminum workpiece, and insert a harder stainless steel workpiece,
When machining is performed up to the standard feed speed, the machining torque generated becomes extremely large and is detected by the same principle as above. As a result, it is possible to prevent a situation in which a wrong work is performed.

On the other hand, contrary to the above, when stainless steel is assumed and aluminum workpieces are supplied, the machining torque generated during machining at the standard feed speed is small, so It is controlled to make the speed very fast. In that case, the feed motor is stopped because the controlled feed speed exceeds the upper limit threshold value. As a result, it is possible to prevent a situation in which a wrong work is performed.

In the above embodiment, two thresholds, the upper limit and the lower limit, are set so that the detection is performed when any of the thresholds is exceeded. However, the present invention is not limited to this, and one of the thresholds is used. Set a threshold value, 2 above / below the threshold
Value control may be performed.

FIG. 8 shows an embodiment of the torque measuring device according to the present invention for estimating the torque from the current supplied to the spindle motor 7 and the rotation speed. By using this torque measuring device instead of the torque sensor shown in FIG. 1, the above-mentioned various controls and abnormality detection can be performed.

As shown in the figure, a drill 10 is detachably attached to a spindle motor 7 mounted on a main body of a processing machine via a chuck 8 attached to the tip of an output shaft 7a thereof. In the illustrated example, the spindle motor 7 is used for convenience.
Although the state where the chuck 8 of the output shaft 7a is attached is shown, the output shaft 7a is actually connected to the main shaft, and the chuck is attached to the lower end of the main shaft. The spindle motor 7 is a spindle motor driver (spindle motor driving device) 1
The control signal (current) from No. 3, that is, the current value allows operation at a desired rotation speed.

In the present invention, the spindle motor 7 is provided with the rotation detector 21 for measuring the rotation speed of the output shaft 7a, and the rotation speed ω detected by the rotation detector 21 and the spindle motor driver (spindle motor drive The output of the device 13 or the motor current im is applied to the torque measuring device 22 according to the present invention.

The torque measuring device 22 is equipped with a torque estimating section 23 for estimating the spindle load torque applied to the spindle (output shaft 7a) of the motor 7 according to the observer theory based on the above two input data. A storage device 24 for temporarily storing the output of the torque estimation unit 23 and a machining torque applied to the tool (in this example, since the tool is a drill,
Hereinafter, the cutting torque is referred to as “cutting torque”) and is connected to a cutting torque calculation unit 25. Furthermore, the data stored in the storage device 24 is read out and given to the torque calculation unit 25.

In the torque estimation unit 23, the rotational speed is y, the current is u, the observer gain is K (matrix (AK)
C) is selected so as to be stable), and the estimated vector of x is obtained by the following formula, and the estimated vector of x is [0
The spindle load torque TL is estimated by multiplying by 1].

[0063]

[Equation 3] Each coefficient in the above equation (1) is obtained as follows based on the following equation of motion of the motor (equation (2)).

[0064]

[Equation 4]

[0065]

[Equation 5] Therefore, as shown in FIG. 9, the rotational speed and the current of the spindle motor 7 in the unloaded state (the state in which the drill 10 is not in contact with the work (cutting torque = 0) and is rotating at a constant speed) before the machining are torque It is input to the estimation unit 23, the spindle load torque TL1 at that time is calculated, and it is stored in the storage device 24. Then, since the cutting torque is zero in this case,
The value stored in the storage device 24 is used as the output shaft 7 of the spindle motor 7.
The torque is generated based on friction with respect to a, inertia, and the like. This completes the initial setting.

Next, as shown in FIG. 10, the rotational speed and the current of the spindle motor when the drill 10 is actually brought into contact with the work 11 for cutting are input to the torque estimating section 23, and the spindle load at that time is input. The torque TL2 is calculated and given to the torque calculator 25. Then, the spindle load torque TL2 at this time is the sum of the torque due to the above-mentioned friction of the shaft and the torque applied to the tool by cutting. Therefore, the cutting torque calculation unit 25 reads the torque data TL1 stored in the storage device 24 and subtracts both (TL2−
TL1) to calculate the cutting torque and output it.

If there is no significant difference between the rotational speeds before and during the machining, the torque component due to friction during the machining is almost equal to FL1 which is obtained in the initial setting and stored in the storage device 24. As a result, it is possible to obtain an accurate cutting torque without friction of the shaft. That is, in this example, since the torque estimation and subtraction processing can be performed in a short time, the processing can be performed in real time.

On the other hand, the torque estimating unit 23 estimates the torque applied to the main shaft of the motor from the rotation speed and the current of the motor. However, assuming that the torque generated by friction is the viscosity / friction term proportional to the speed, The equation of motion of the motor can be set as the following equation.

[0069]

[Equation 6] Then, the equation (3) in the introduction process of the above-described embodiment becomes the following equation.

[0070]

[Equation 7] Then, when the observer is configured based on the above equation (corresponding to the equation (3) in the above-described embodiment), each coefficient in the equation (4) is determined in a state in which the torque component due to friction is taken into consideration. Therefore, the torque due to friction is subtracted, and the estimated torque TL is obtained purely by the tool. The storage unit and the torque calculation unit shown in the above-described embodiment are unnecessary, and the torque estimation unit is configured by the torque estimation unit (different calculation formulas) shown in FIG. 8 alone. In this example, the observer does not need to be redesigned even if the motor parameters fluctuate due to aging, etc., and is resistant to aging.

Here, the viscosity / friction coefficient D in the above equation (4)
Can be experimentally obtained, for example. That is, the parameter identification method is used, and an example is obtained from the response to the step input. That is, if im in the above formula (4) is i0 (constant), the solution of the formula (4) is obtained by solving a differential equation,

[0072]

[Equation 8] Becomes Then, from the above equation (5), the final value of the output ω (t) is G, and ω (T) at time t = T is 63.
It turns out that it reaches 2%.

Therefore, the step input i0 is applied to the motor, and the output ω at that time is measured as the time response data.
The maximum value G is obtained at the time when is converged and regarded as a constant value.
Then, D can be obtained from D = Km · i0 / G. In addition, J can be obtained from J = DT by obtaining the time T that is 63.2% of G. As a result, the coefficient in the equation (4) is determined. Note that J can also be calculated by physical calculation from various characteristics.

FIG. 11 and FIG. 12 show an example of a signal processing device for the output of each of the above-mentioned torque detection sensors which is the third embodiment of the control device according to the present invention. As shown in the figure, the drill 1
Spindle motor 7 for rotating 0 forward and reverse, and drill 10
Feed motor 5 for vertically moving (spindle motor 7)
Both motors 5 and 7 are controlled in their rotations by drivers 12 and 13 that receive a speed command from the cutting torque control device 26. This allows the spindle motor 7 to rotate the drill 10 forward at a predetermined speed,
Cutting (drilling) is performed by operating the feed motor 5 to move the drill 10 downward and bringing it into contact with the work 15 at a predetermined pressure.

At this time, if the rotation output of the feed motor 5 is increased, the machining time is shortened, but the reaction force received by the drill 10 from the work 15 is strong and a large torque is applied, which may cause breakage. If the output of the drill 10 is reduced, the risk of breakage of the drill 10 is reduced as much as possible, but the processing time is extended. That is, when the rotation speed of the drill 10 is constant, the torque applied to the drill 10 is the feed amount (down speed).
Depends on.

Therefore, in this example, the drill 10 is provided with the cutting torque estimator 22 according to the present invention, and the output of the cutting torque estimator 22 is sent to the cutting torque control device 26, and the drill 10 is subjected to a torque above a certain torque by feedback control. The cutting process is done in such a way that it does not come into contact.

That is, as shown in FIG. 12, a cutting torque control device (corresponding to the torque control device 15 shown in FIG. 1) 2
6 is a PID controller 26a and a feed rate calculation unit 26
b and a spindle rotation control unit 26c, and a signal based on the torque applied to the drill 10 estimated and calculated by the cutting torque estimator 22 in the PID controller 26a,
Input the signal difference based on the set load. Here, the set load is a value with a predetermined margin for the torque that breaks the drill 10. In addition,
The spindle rotation control unit 26c is configured to issue a control signal to the spindle motor driver 13 so as to rotate the spindle motor 7 at a constant speed.

In this state, the PID controller 26a determines the descending speed of the drill 10, that is, the feed amount, from the positive / negative of the input signal and its absolute value. In other words, when the input signal is negative, the torque applied to the drill 10 exceeds the set load and there is a high possibility of breakage, so it is necessary to reduce the feed amount or reverse the feed (raise the drill). On the other hand, when the input signal is positive, the torque applied to the drill 10 is smaller than the set load, so even if the torque applied to the drill 10 is increased a little, the drill is less likely to break, so the feed amount is increased. Increase processing efficiency by increasing the number. Then, the increase / decrease amount is PI
It is determined by the absolute value of the input signal to the D controller 26a. Then, the determined feed amount is sent to the next-stage feed speed calculation unit 26b, the speed of the feed motor 5 required to obtain the feed amount is obtained, and the decided speed is output to the feed motor driver 12 as a control signal. .

With such a structure, the torque (load) applied to the drill 10 during cutting can be kept below the breakage level. Further, since the drill is not unduly loaded, the life of the drill can be extended.

13 and 14 show an embodiment of the tool breakage detecting device according to the present invention. That is, the work 15
In the case of the cutting process for making a hole in the hole, an excessive torque is applied at the moment of breaking, so that the change in torque with respect to the change in time t is abnormal (breakage), as shown in FIG. A value (torque (sensor output) that cannot be obtained if normal) is set, and if the threshold value is exceeded, it is determined that the breakage has occurred and a predetermined output is performed.
That is, as shown in FIG. 14, a tool breakage detection device 27 is provided in place of the cutting torque control device 26, and the reference torque (the above threshold value) set by the detection device 27 is provided.
And the estimated torque are compared with each other, and when the estimated torque becomes large, it is determined to be abnormal.

When the tool breakage detection device 27 detects an abnormality, it outputs an abnormality signal (spindle rotation stop command) to the spindle motor driver 13. Then, the spindle motor driver 13 stops the current supply to the spindle motor 7. At the same time, a return command is issued to the feed motor driver 12, the feed motor 5 is rotated in the reverse direction, and the drill 10 is pulled up. The command to the spindle motor 7 is not the above stop command, but
It may be a reverse rotation command, or may be kept rotated.

FIG. 15 shows a fourth embodiment of the control device according to the present invention. This embodiment is based on the control device shown in FIG. 1 described above, and further, by changing the target torque value according to the machining position, it is possible to perform highly accurate control according to the situation. That is, although the torque target value is fixed in the first embodiment, the torque control device 1 is used in this embodiment.
The torque target value given to No. 5 is determined by the torque target value generation device 30 based on the drill position (feed position), and given from the torque target value generation device 30.

That is, since the tip of the drill 10 is sharp, when the tip of the drill abuts the work 11 and starts drilling, the diameter of the contact is small and the depth of drilling is also small. , Τf are both small. Therefore, if the target torque value is kept constant, excessive feed may occur in the initial stage of machining. Further, when the tip of the drill 10 projects toward the back surface of the work 11 when forming a through hole, the torque τc generated by machining decreases. Therefore, if the torque target value is kept constant, the feed rate becomes sharp after penetration. May rise to. Even if the resistance becomes small due to the penetration, if a relatively large processing torque is maintained and the material is sent at high speed, the possibility of burrs increases, which is even more dangerous. On the other hand, during normal drilling after the tip of the drill 10 has entered the work 11, the finish is better if it is processed with a constant torque as much as possible.

Therefore, in the present example, when machining a blind hole, as shown in FIG. 16 (A), after the tip 10a of the drill 10 comes into contact with the work 11 (h = 0), the tip portion 10b thereof is reached. The target torque value is gradually increased until the point is completely filled (h = hm), and then the final drilling position (h
= T) until the constant torque target value τm.

When a through hole is to be machined, the tip 1 of the drill 10 is attached to the work 11 as shown in FIG.
The target torque value is gradually increased after the contact of 0a (h = 0) until the leading end portion 10b of the contact point 0b completely (h = hm). After that, the constant torque target value τm is set until the tip 10a reaches the back surface (h = t) of the work 11. Then, after that, the target torque value is gradually decreased, and the target torque value is set to 0 when the tip portion 10b is completely projected.

The constant torque target value τm is determined from the strength of the drill 10 and the material of the work, as in the above embodiments. Further, the position at which the target torque value τm is reached, that is, the length hm of the tip portion 10b of the drill 10 is hm = D / (when the diameter of the drill is D and the tip angle is θ, as shown in FIG. tan (θ / 2)).

Then, the tip position (feed position) h of the drill 10 is acquired during machining, and the torque target value of the tip position h is determined. However, in this example, in order to reduce the memory capacity, FIG. A plurality of representative points (drill position, torque target value) representing the characteristics among the characteristics shown in (1) are determined, and the representative points (discretely extracted) are stored in the target value point sequence storage device 31. Taking FIG. 16 (B) as an example, the stored target value point sequence is

[0088]

[Equation 9] As shown in. That is, it is possible to obtain the characteristics shown by connecting each target value point sequence with a straight line. In addition, in the case of FIG.

Then, if the current feed position h is given to the torque target value calculation device 32 in the torque target value generation device 30, a predetermined value 2 stored in the target value point sequence storage device 31 is set.
The data regarding the representative point (in this example, the representative points adjacent to both sides of the current feed position) is read out, and the torque target value at the current feed position is calculated, and the torque control device 1
I am going to send it to 5.

In the torque target value calculation device 32, the target value is calculated by interpolating between the read two points. In this example, the interpolation is performed by a straight line. Thus, for example, the calculation formula for calculating the torque target value τd at the position h between (h1, τ1) and (h2, τ2) is

[0091]

[Equation 10] Becomes Therefore, the feed position h in the example of FIG.
The target value τd for is as shown in the table below.

[0092]

[Table 1] Although four target value point sequences are extracted in the above embodiment, a complicated target value can be easily generated by increasing the number of target point sequences used. Further, when performing the interpolation, in the above-mentioned embodiment, the interpolation is performed by the straight line connecting the two representative points, but it can be set by a quadratic function, a cubic function, or the like. The other configurations and effects are the same as those of the above-described embodiment, and therefore the same reference numerals are given,
Detailed description thereof will be omitted.

FIG. 18 shows a fifth embodiment of the control device according to the present invention. In this example, based on the above-described fourth embodiment, the target value point sequence data to be stored in the target value point sequence storage device 31 is automatically generated and stored.

That is, the torque target value generation device 30 'in this example has a target value point sequence storage device 31 and a torque target value calculation device 32 having the same functions as those of the above-described embodiment, and a target value point sequence generation device 33. And the generator 33
The target value point sequence data is generated on the basis of the data given in step S1 and stored in the target value point sequence storage device 31.

The function of the target value point sequence generator 33 will be described. As shown in FIG. 19, first, speed control is performed to control the feed speed to be constant, and machining is performed once. The processing torque applied to the drill 10 is detected by the torque sensor 16, and the processing torque waveform is stored (ST20). As a result, for example, the waveform shown in FIG. 20A is stored. It should be noted that the processing may be performed a plurality of times, and the average value of the obtained plurality of processing torque waveforms may be calculated and stored.

Next, the sequence of target value points to be extracted is determined (S
T21). Specifically, a position (h1) at which the processing torque starts to be applied, a position (h2) advanced from the position h1 by the distance of the tip portion of the drill 10, a position (h4) at which the processing torque becomes zero, and the position h4. A position h3 that is returned by the distance of the tip portion is determined (see FIG. 20A). In the case of a blind hole, if h1 is determined from the change in processing torque, h2 and h3 are determined based on the position.

From the stored machining torque waveform, the machining torque at each of the determined feed positions h1 to h4 is detected, and the machining torque is used as a torque target value to form a pair of target value points P1 to P4 with the corresponding feed position. Target value point sequence storage device 3 in the next stage
It is stored in 1 (ST22). As a result, the target value point sequence storage device 31 stores the coordinate data (feed position, torque target value) of each point P1 to P4 shown in FIG. 20B, and based on this data. As described above, since the torque target value calculation device 32 interpolates between the points, the polygonal line waveform shown by the solid line in FIG. 20B eventually becomes the torque target value at each position, and the target value is set to this target value. The feed amount is controlled by the torque control device 15.

Further, in extracting the target value point sequence in step 22, in the case of FIG. 20 as an example, each of the positions h1 to h4
Although the processing torque in the above was used as it is, for example, P2, P3
When deciding, the constant section (H
a, Hb) may be set, the average of the processing torque in the section may be calculated, and the average value may be used as the torque target value. Thereby, a more accurate target value can be obtained.

With such a configuration, the target value point sequence is automatically set based on the actually measured data, so that a value that is simple and suitable for the use condition / situation at that time is determined, and the torque control is more efficient. You can do it well.

Further, in order to obtain the target value point sequence as shown in FIG. 16 (B), the peak of the machining torque waveform during speed control is detected and the peak value is set as the torque target value of P2 and P3. This can be handled by setting (drill feed positions h2 and h3 are the same as above) (see FIG. 22 (A)).

As a result, since a constant target value is set between P2 and P3, as shown by the solid line in FIG. 7B, the actual machining torque gradually increases at the beginning and then After drilling around the peak torque value, the tip of the drill protruded from the back surface of the work (h = 3)
If so, the torque is gradually reduced to suppress the occurrence of burrs.
That is, the processing time can be shortened as in the first embodiment described above.

Further, as shown in FIG. 23 (A), if the speed control is performed under the same conditions for a new drill and a wear drill in which the blade part of the drill has worn due to use, the machining torque of the wear drill becomes extremely large. . Therefore, in determining the torque target value when controlling P2 to P3 so as to have a constant torque target value, from the machining torque waveform obtained by performing the speed control of the new drill as shown in the drawing, Of the processing torque at the shallow position (small h) of
You may set to the torque target value of 2 and P3. In such a case, as shown in FIG. 6B, even a worn tool can be machined with reasonable torque, and tool (drill) breakage due to wear can be prevented.

Furthermore, in the case where a hole is formed in a work in which a plurality of works made of different materials are stacked, the following target value point sequence can be set.
That is, as shown in FIG.
If different speeds are controlled by stacking different types of materials (for example, aluminum and SUS) and setting the speed according to the hard SUS (speed becomes slower), the processing time will be as shown by the dashed line in the figure. become longer. On the other hand, if soft aluminum is used, the processing speed becomes high as indicated by the chain double-dashed line in the figure, but the processing torque for cutting SUS becomes excessive and there is a risk of breakage.

Therefore, the feed rate is determined in accordance with SUS and the speed is controlled, and the target torque values P2 and P3 are determined in accordance with the obtained SUS machining torque (see FIG. 9B). Then, when torque control is performed based on the target value point sequence thus obtained, as shown in FIG. 7C, when machining aluminum, a hole is punched with a machining torque larger than the original setting. Since it is processed in a short time, and the SUS thereafter is processed under the optimum conditions, it is possible to prevent the processing time from becoming longer than necessary without applying an excessive torque to the drill. It should be noted that the target value point sequence may be further added to one or two feed positions in place of aluminum to SUS, and the optimum processing torque for each material may be set to the torque target value.

In any of the above examples, the target value point sequence can be automatically determined based on the data actually processed (which kind and pattern of determination is used in advance. ) Moreover, since the determined target value point sequence has a value suitable for the situation of use at that time, it is possible to perform control with high accuracy and improve machining accuracy. Furthermore, since it is simple and clear, setting mistakes are eliminated. Note that the configuration and operational effects other than the determination of the target value point sequence described above are the same as those of the above-described fourth embodiment, so description thereof will be omitted.

FIG. 25 shows a sixth embodiment of the control device according to the present invention. In this embodiment, the fourth and fifth embodiments described above are used.
Unlike the embodiment, the torque target value generation device 30 ″ substitutes a feed position given during machining into a predetermined function without using a target value point sequence consisting of a torque target value for a specific feed position. Thus, the torque target value is determined.

Specifically, for example, assuming that the target torque value for each feed position is as shown in FIG. 26 (the same as the target value for the blind hole in FIG. 16A), the tip of the drill is Let hm be the position that completely enters the work (control start position that keeps the torque value constant) and τm be the target torque value at that time. At present, the following min calculation (choose the smaller of the two numerical values) is performed. By substituting the tip position (feed position) h of the drill, the torque target value at that position can be obtained.

Τd = min (τm, (τm / hm) × h) FIG. 27 shows a seventh embodiment of the control device according to the present invention. As shown in the figure, in this embodiment, both the speed control mechanism for controlling the feed speed to be constant and the torque control mechanism for changing the feed speed so that the torque shown in each of the above-described embodiments becomes the torque target value. And one of the two control mechanisms is selected according to the feed position of the drill to perform predetermined control.

That is, considering the case where a through hole is formed, the positional relationship between the work and the drill is as shown in FIG.
There are five types shown in (E). And drill 10
Before the front end 10a of the workpiece reaches the work 11 ((A) in the figure)
Has no processing torque, and the tip 10 of the drill 10
After b is completely projected from the back side of the work 11 ((E) in the figure), the processing torque is due only to the friction torque (there is no cutting torque), and the distance in contact with the drill (depth of the hole). ), Which is constant at t, shows a substantially constant value regardless of the feed position (the position of the tip 10a of the drill 10). In any case, the cutting torque is smaller than the processing torque at the time of 0 <x <t + hm ((B) to (D) in the figure).

Therefore, a simple speed control of the control system is performed in the sections (A) and (E), and torque control is performed in the sections (B) to (D). That is, as shown in FIG. 27, the feed mechanism unit 3 feeds the spindle rotation mechanism unit 4 at a predetermined speed based on the rotation control signal sent from the feed motor driving device 12. At this time, the torque sensor 16 detects the processing torque applied to the drill, and the torque control device 15
To enter. The output of the torque control device 15 is given to the feed motor drive device 12 via the changeover switch 35. Also, this changeover switch 3
The target speed value at the time of speed control is given to the feed motor driving device 12 via 5.

On the other hand, the feed position sensor 36 provided side by side with the feed mechanism section 3 detects the current position of the tip of the drill (feed position), and the detected feed position is selected by the switch 37 and the target torque value generator. I am trying to input 30. Then, the switch 37 switches the changeover switch 35 according to the feed position, and either the feed speed output from the torque control device 15 or the speed target value for speed control is selected and given to the feed motor drive device. To be

In the torque control in this example, the actual processing torque is set to the torque target value as shown in FIG. That is, the torque target value generation device 3
In this example, 0 has the same structure as that shown in the fourth embodiment (feed positions 0, hm, t, t + hm.
Each torque target value at the time of is stored as a target value point sequence, the torque is constant from hm to t, and is interpolated by a predetermined arithmetic expression (quadratic function, etc.) in other sections), feed A desired torque target value is output to the torque control device 15 so that the position has the torque target value characteristic as shown in FIG. 29, and the torque control device 15 causes the detected machining torque to match the torque target value. Control. Note that the specific processing of this torque control is the same as that in each of the above-described embodiments, and therefore will be omitted. Further, as the torque target value generating device to be used, those shown in the fifth and sixth embodiments may be used.

Further, as shown in FIG. 30, the switch 37 is first connected to the speed control side, switched when the feed position is 0 and connected to the torque control side, and the feed position is t + hm.
If it becomes, it will switch again and connect to the speed control side.

As a result, the feed rate does not become excessive in the above sections (A) and (E) where the load is small and the processing torque is small, and in particular, in such section (E), the feed rate is relatively low. Since there are few burrs and the speed does not increase rapidly, it is safe because the drill does not break due to excessive force when the speed changes.

In this example, the torque target value is also changed in accordance with the feed position in the sections (B) and (D). However, as in the first embodiment described above, the sections (B) to (D). The target torque value may be kept constant over the period.

FIG. 31 shows the essential parts of an eighth embodiment of the control device according to the present invention. This embodiment is similar to the seventh embodiment in that both speed control and torque control can be switched appropriately.

In this example, as shown in FIG. 32, the changeover timing of the changeover switch 35 by the changeover device 37 is a section in which the tip of the drill is completely inside the work (feed position is from hm to t). Only the torque control (to maintain a constant torque value) is performed, and the speed is controlled in other sections.

Then, the speed target value during the speed control is
As shown in FIG. 33, it is changed according to the feed position. The solid line portion in the figure is the section in which the speed is controlled. That is, the drill is not in contact with the work before the feed position becomes 0, so the drill is moved at high speed. Then, at the feed positions 0 to hm where the drill starts the actual drilling of the work, the speed is reduced so that excessive drilling torque is not applied to the drill.

In this example, the speed change point is set to the feed position 0.
A little earlier, I tried to reduce the speed before the drill touches the work, but this takes into account the error of the feed position and the work size, and the deceleration is completed before the drill reaches the work reliably. This is to keep it. Then, the two speed target values and the speed change points are stored, and one of the speed target values is output based on the feed position information given from the feed position sensor (not shown).

Further, as shown in FIG. 33, the drill is fed at a constant speed even after the feed position t where the tip of the drill projects from the back surface of the work, but the speed target value at this time is torque control immediately before that. The feed speed at that time is received from the torque control device 15, and the given feed speed is determined as a speed target value and output. As a result, when the torque control is switched to the speed control, the feed speed does not suddenly change and the control becomes discontinuous, and mechanical vibration is not generated. In addition, the vibration may cause damage to the drill and decrease in machining accuracy, but since the speed does not change when the control is switched, continuous smooth switching can be performed and drill breakage can be prevented. The accuracy can be improved.

As can be seen from the figure, the speed is controlled so that the feed position is maintained at the above-mentioned target speed value further than t + hm (the speed change point is after t + hm). Similar to the above, this is because it is possible to reliably maintain a constant speed until the drill penetrates the work in consideration of errors in the feed position and the work size.

On the other hand, in the torque target value generator 39, the torque at that time is based on the feed position given so as to have the characteristic of the torque target value with respect to the feed position as shown in FIG. The target value is sent to the torque control device 15. Here, in this example, since the torque control performs control to keep the processing torque from the feed position hm to t indicated by the solid line in the figure constant, the torque stored in the internal memory during the relevant section is received. Since the target value is output, a complicated function such as a calculation means is unnecessary.

Further, the torque target value stored in the memory is appropriately changed according to the processing conditions at that time. That is, receiving the actual machining torque obtained while performing speed control immediately before switching (immediately before the feed position hm),
The processing torque is stored in the memory. As a result, similar to the above, when the speed control is switched to the torque control, the torque applied to the drill does not suddenly change, and smooth switching is performed.

35 to 37 show a ninth embodiment of the control device according to the present invention. In this example, a machine tool is applied to a drilling machine. As shown in the figure,
The basic structure is the same as that of the various embodiments described above, and a drill 10 as a tool is attached to the tip of the output shaft of the spindle motor 7 via a chuck 8. When the feed motor 5 is rotated forward while the spindle motor 7 is rotating at a constant speed, the spindle motor 7, the chuck 8 and the drill 10 are advanced toward the work 11 for drilling.

During this machining, the torque sensor 16 'detects the machining torque applied to the drill 10 and applies the machining torque to the torque control device 15. As the torque control device 15, those shown in the various embodiments described above can be applied, and the feed rate of the drill is determined so that the processing torque becomes a torque target value given from the outside. The applied torque target value may be constant throughout the machining process, or may be a value (variable) generated by a torque target value generation device (not shown) based on the feed position. Then, the feed motor 5 is adjusted so that the feed speed determined by the torque control device 15 is achieved.
Rotates at a predetermined rotation speed. Although not shown, each motor is provided with a motor driving device (see FIG. 1 and the like). Further, in the illustrated example, the torque applied to the output shaft (spindle) of the spindle motor 7 (substantially equal to the torque applied to the drill) is detected, but as in each of the above-described embodiments, a torque sensor is provided around the drill. May be provided, or the torque may be estimated from the current supplied to the spindle motor 7, and various types can be used.

Here, in this embodiment, the marker 40 which moves with the movement of the spindle motor 7 etc. is provided, and the first and second detectors are provided at predetermined positions of the guide rail 6 for guiding the movement of the spindle motor 7 etc. 41a and 41b are provided to detect the passage of the marker 40. Each detector 41
The specific installation positions of a and 41b are as follows: the first detector 41a detects the marker 40 when the drill reaches the machining start position, and the second detector 41 when the drill reaches the machining end position.
b is set at a position where the marker 40 is detected.
Each of the detectors 41a and 41b can use, for example, a proximity switch or the like, and the installation position thereof can be moved. As a result, the dimensions and shape of the drill 10 and work 11 used and the processing conditions (through hole / blind hole)
The work area can be changed according to.

Then, the work start trigger output from the first detector 41a and the work start trigger output from the second detector 41b are applied to the wear detector 42, at which the degree of wear of the drill 10 is determined. To determine whether or not the replacement time has come, and if the replacement time has come, the output device 43
A replacement request signal is output to the. Then, the output device 43 lights the alarm lamp or sounds an alarm based on the replacement request signal to notify the user that the replacement time has come.

Next, the wear detector 42 will be described. The internal structure thereof is as shown in FIG. That is, the triggers output from each of the detectors 41a and 41b are both input to the reference timer 42a, and the reference timer 42a starts timing by inputting a work start trigger and stops timing by inputting a work end trigger. To do. As a result, one working time T required for actual drilling
Is measured.

Then, the work time T thus obtained is sent to the determination unit 42b at the next stage, and compared therewith to the work maximum delay time ST given from the outside, and ST <
If it is T, it is judged that it is time to replace it. Then, a change request signal is sent to the output device via the tool change signal output unit 42c, and a sending stop command is sent to the torque control device 15.

That is, as described in each of the above-mentioned embodiments, when the torque is controlled, the machining time becomes long as the drill wears (see FIG. 37). Therefore,
Focusing on the processing time required for the work, if the processing time exceeds a predetermined value ST, it can be determined that the degree of wear is severe and the replacement time has come. Therefore, in this example, when the working time T is equal to or longer than the maximum working delay time ST (hatching in FIG. 37), it is assumed that the drill has reached the end of its life and is replaced.

With this structure, it is possible to prevent breakage of the tool due to wear. Furthermore, since the wear is judged in the form of the time until the end of work, the order of set devices is clear and easy to use.

37 and 38 show a tenth embodiment of the control device according to the present invention. In this example, the ninth embodiment described above is further improved so that not only the tool life (replacement time) is notified, but also how many more times the replacement time comes can be predicted. ing. FIG. 37
The wear predictor 44 shown in FIG.
It is mounted on a machine tool in place of the wear detector 42 of 5), and the time from receiving the work start trigger sent from each of the detectors 41a and 42a by the timer 44a to the work end trigger (work completion). Time) T is measured, and the work completion time T is stored in the storage device 44b. In this example, the work completion time currently detected and the work completion time detected one time before are stored and held in the storage device 44b as work histories. In addition, the number of operations up to now is also stored.

For each predetermined number of times of work, the difference calculation unit 44 between the current and previous work completion times stored in the storage device 44b.
The difference between the two, that is, the increment ΔT of the work completion time is obtained there, and the calculation result is given to the remaining number operation unit 44d of the next stage. In addition, the remaining number calculation unit 4
The current work completion time T is given from the storage device 44b to 4d. In addition, the maximum work delay time S is previously
T is set. Then, the remaining number calculation unit is configured to calculate the remaining number M by the following formula based on the given three data.

M = (ST-T) / ΔT That is, as shown in FIG. 39, the work completion time becomes longer as the number of works increases. When the difference ΔT between the current work completion time and the previous work completion time is known, assuming that the time will be longer than the current work completion time T by ΔT each time work is performed in the future, the prediction line indicated by the broken line in the figure is I can withdraw.
Therefore, the maximum work delay time ST and the current work completion time T
The remaining number of times can be predicted by dividing the difference of 1 by the difference ΔT.

Then, the remaining number M obtained in this way
Is sent to the display availability determination unit 44e in the next stage and compared therewith with a preset alarm display count (reference value for starting display of the remaining count) SM, and if the remaining count is equal to or less than the alarm display count, The remaining number M calculated via the remaining number output unit 44f is displayed on an output device (not shown).
The output of the remaining number calculation unit 44d is also connected to the tool replacement signal output unit 44g, and when M = 0, a replacement request signal is output as in the above-described embodiment, and the user comes to the replacement time. It is supposed to let you know.

With such a configuration, in addition to the effects of the ninth embodiment described above, it is possible to notify the user of the future replacement time and the usage period, rather than suddenly notifying the user of the replacement time. , It is not necessary to stock replacement tools (drills) more than necessary. On the other hand, it is possible to suppress the occurrence of a situation in which there is no tool for replacement even though it is time to replace the tool, and it is possible to efficiently operate the tool.

The calculation of the remaining number of times is not limited to the above-mentioned arithmetic expression. For example, when all the work completion time up to the present is stored in the storage device and the remaining time is obtained, a graph as shown in FIG. 39 is used. Create a prediction line (straight line or curve) that passes through the peak of the work completion time of each time,
Various methods can be used in addition to finding the intersection between the predicted line and the maximum work delay time, detecting the number of times of work at that time, and subtracting the current number of times of work from the number of times of work to obtain the remaining number of times. .

The remaining number of times can be displayed by outputting a specific numerical value, or by only turning on a warning lamp indicating that the time for replacement is approaching. Any method can be used. Then, when the warning and the lamp are turned on, a plurality of reference values (SM) are provided, and the lamp is turned on step by step as the replacement time approaches (color change,
The number may be changed).

In each of the above-mentioned embodiments, an example in which a drill is used as a tool has been described, but the tool (machine tool) to which the present invention is applied can be applied to various things other than a drill. Of course.

[0140]

As described above, in the control device according to the present invention, since the feed speed is controlled in real time so that the machining torque matches the torque target value, excessive torque is applied to the tool. Can be prevented, and breakage of the tool can be suppressed. When the actual machining torque is smaller than the target torque value, the feed rate increases, so that the machining rate can be improved without applying an excessive force to the tool. Further, since no excessive force is applied to the tool in this way, it is possible to prolong the deterioration (wear) of the tool and extend the usable time of the tool.

When the torque target value generating means is provided (claims 2 to 4), the above control can be performed based on the optimum torque target value at that time according to the feed position and the like, so that the control can be performed with higher accuracy. Therefore, the processing accuracy is further improved. Then, as in claim 3, the torque target value is defined by a plurality of target value point sequences, and the target value point sequences are interpolated based on the data, so that the processing processing is performed with a small storage capacity and a simple configuration. A desired torque target value can be set throughout. Further, as in claim 4, when the target value point sequence is automatically generated based on the machining torque waveform obtained during actual machining, even a person who does not have know-how
A target value point sequence suitable for the use environment / condition at that time can be determined.

Further, when the speed control function and the torque control function are provided and the feed speed is controlled by using the control function appropriately selected by the switching means (claim 5,
6) Since the control suitable for the use condition at that time can be performed, more accurate control is performed. In particular, if a section with little torque fluctuation is controlled by the speed control function, the control system is simple and can operate at high speed.

Further, in the case where the abnormality detecting means for issuing an abnormality signal is provided when the calculated feed speed becomes faster than a certain upper limit value or becomes lower than a certain lower limit value (claim 7, In 8), it is possible to know an abnormality at the time of machining (abnormality of tool such as wear and breakage, mistake of machining condition such as erroneous setting of workpiece). As a result, it is possible to suppress the occurrence of defective products due to repeated processing in the wrong state.

Further, when the work completion time detecting means is provided and the replacement request signal is output when the work completion time exceeds or exceeds the maximum delay time (claim 9), it is time to replace the tool. You can know that exactly. As a result, the tool can be replaced at an appropriate timing. When the work completion time detecting means and the predicting means are provided (Claim 10), it is possible to know that the replacement time is approaching in advance. You no longer need to stock up.

Since the machine tool according to the present invention is controlled by the above-mentioned various control devices, safe and efficient machining can be performed in a short time and the usability is improved.

Further, since the torque measuring device according to the present invention estimates the torque value, not the torque variation, it can be accurately performed even if the variation of the machining load is small, and its calculation is relatively easy and the torque can be calculated in real time. Can be estimated. Also, calculate the calculation formula that takes viscous friction into consideration and calculate based on it, or calculate the output load torque when the tool is not applied to find the error due to friction, etc. Since it is subtracted from, the torque applied to the tool can be accurately measured.

Further, in the tool breakage detecting device for monitoring the output (estimated torque) of the torque measuring instrument of the present invention and adjusting the operating state of the machine tool in accordance with the torque value, the presence or absence of breakage of the tool is detected. You can predict breakage,
When broken, the tool can be moved away from the work piece smoothly, and prediction can be performed for efficient processing.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a control device according to the present invention.

FIG. 2 is a flowchart illustrating the function of a torque control device that is a main part of the first embodiment.

FIG. 3 is a diagram for explaining the operation of the first embodiment.

FIG. 4 is a diagram illustrating the operation of the first embodiment.

FIG. 5 is a diagram for explaining the operation of the first embodiment.

FIG. 6 is a diagram showing a main part of a second embodiment of the control device according to the present invention.

FIG. 7 is a diagram for explaining the operation of the second embodiment.

FIG. 8 is a diagram showing an embodiment of a torque measuring device according to the present invention.

FIG. 9 is a diagram for explaining the operation of one embodiment of the torque measuring device.

FIG. 10 is a diagram for explaining the operation of one embodiment of the torque measuring device.

FIG. 11 is a diagram showing a third embodiment of the control device according to the present invention.

FIG. 12 is a diagram showing a third embodiment of the control device according to the present invention.

FIG. 13 is a diagram for explaining the operation principle of an embodiment of the tool breakage detection device according to the present invention.

FIG. 14 is a diagram showing an embodiment of a tool breakage detection device according to the present invention.

FIG. 15 is a diagram showing a fourth embodiment of the control device according to the present invention.

FIG. 16 is a diagram for explaining the operation of the fourth embodiment.

FIG. 17 is a diagram for explaining the operation of the fourth embodiment.

FIG. 18 is a diagram showing a main part of a fifth embodiment of the control device according to the present invention.

FIG. 19 is a flowchart illustrating the function of a target value point sequence generation device that is an essential part of the fifth embodiment.

FIG. 20 is a diagram for explaining the operation of the fifth embodiment.

FIG. 21 is a diagram for explaining the operation of the fifth embodiment.

FIG. 22 is a diagram for explaining the operation of the fifth embodiment.

FIG. 23 is a diagram for explaining the operation of the fifth embodiment.

FIG. 24 is a diagram for explaining the operation of the fifth embodiment.

FIG. 25 is a diagram showing a main part of a sixth embodiment of the control device according to the present invention.

FIG. 26 is a diagram for explaining the operation of the sixth embodiment.

FIG. 27 is a diagram showing a main part of a seventh embodiment of the control device according to the present invention.

FIG. 28 is a diagram illustrating a positional relationship between a drill and a work.

FIG. 29 is a diagram showing an example of a torque target value given to the torque control device of the seventh embodiment.

FIG. 30 is a diagram showing a switching timing of the switch of the seventh embodiment.

FIG. 31 is a diagram showing a main part of an eighth embodiment of the control device according to the present invention.

FIG. 32 is a diagram showing a switching timing of the switch of the eighth embodiment.

FIG. 33 is a diagram showing an example of speed target values for feed positions output from the speed target value setting device of the eighth embodiment.

FIG. 34 is a diagram showing an example of a torque target value given to the torque control device of the eighth embodiment.

FIG. 35 is a diagram showing a ninth embodiment of the control device according to the present invention.

FIG. 36 is a block diagram showing an internal configuration of a wear detector which is a main part of the ninth embodiment.

FIG. 37 is a view for explaining the operation of the ninth embodiment.

FIG. 38 is a diagram showing a main part of a tenth embodiment of the control device according to the present invention.

FIG. 39 is a view for explaining the operation of the tenth embodiment.

[Explanation of symbols]

 7 Spindle Motor 10 Tool (Drill) 13 Spindle Motor Drive Device (Spindle Motor Driver) 16 Torque Sensor (Torque Detecting Device) 20 Comparison Device (Machining Abnormality Detecting Device) 21 Rotation Speed Detector 22 Cutting Torque Estimator (Torque Measuring Device) 23 Torque Estimating Unit (Spindle Load Torque Estimating Means) 24 Storage Device 25 Torque Calculating Unit (Calculating Means) 26 Cutting Torque Control Device (Speed Calculating Means) 27 Tool Breakage Detection Device (Control Means) 30, 30 ', 30 "Torque Target Value generation device 31 Target value point sequence storage device 32 Torque target value calculation device 42 Wear detector 44 Life estimation device

Front page continuation (72) Inventor Nobuchi Matsunaga 10 Odoron-cho, Hanazono Todo-cho, Ukyo-ku, Kyoto-shi, Kyoto Prefecture

Claims (14)

[Claims] 1. A machine tool comprising: a spindle rotating mechanism for rotating a tool detachably attached to a tip thereof; and a feed mechanism for moving the spindle rotating mechanism forward and backward with respect to a workpiece. A control device for controlling a feed speed of a feed mechanism, wherein the torque detection means detects a torque applied to the tool, at least a set torque target value, and the torque detected by the torque detection means based on the torque detection means. A control device comprising: a feed speed calculation unit that obtains a feed speed; and a feed mechanism control unit that receives the output of the feed speed calculation unit and controls the feed mechanism so that the calculated feed speed is obtained. 2. A torque target value generating means for determining a torque target value based on the feed position of the tool, wherein the feed speed calculating means is based on the torque target value output from the torque target value generating means. The control device according to claim 1, wherein the feed rate is obtained. 3. A target value point sequence storage means for storing a target value point sequence consisting of torque target value pairs for a plurality of feed positions, and a predetermined value stored in the target value point sequence storage means. 2. A target value torque calculating means for calculating a current torque target value based on the current feed position.
The control device according to 1. 4. The target value point sequence generating means for generating the target value point sequence on the basis of a machining torque waveform during normal machining and storing the target value point sequence in the target value point sequence storage means. Control device. 5. The speed control means for controlling the feed speed to a constant speed setting value, the output of the speed control means, and the output of the feed speed calculation means are selected to select The control device according to any one of claims 1 to 4, further comprising a switching unit that transmits to the feed mechanism control unit. 6. The switching timing of the switching means is
The control device according to claim 5, wherein the control device is determined based on at least the feed position. 7. The control device according to claim 1, further comprising an abnormality detection unit that outputs an abnormality signal when the feed speed becomes slower than a certain reference value. 8. The control device according to claim 1, further comprising an abnormality detection unit that outputs an abnormality signal when the feed speed becomes faster than a fixed reference value. 9. A work completion time detecting means for detecting a work completion time required for one machining, and a replacement request signal is output when the work completion time exceeds or exceeds a maximum delay time required for tool replacement. The control device according to claim 1, wherein the control device is configured as described above. 10. A work completion time detecting means for detecting a work completion time required for one machining, a present and a predetermined past work completion time detected by the work completion time detecting means, and a tool replacement. The control device according to any one of claims 1 to 9, further comprising: a predicting unit that determines a life of a tool in use based on the maximum delay time. 11. A spindle rotating mechanism for rotating a tool detachably attached to a tip thereof, and a feed mechanism for moving the spindle rotating mechanism forward and backward with respect to a workpiece, according to claim 1. A machine tool comprising the control device according to claim 1, wherein the feed mechanism is controlled by the control device. 12. A torque measuring instrument used in a machine tool, the tool being attached to the machine tool using observer theory based on a current and a rotation speed value of a spindle motor mounted on the machine tool. A torque measuring instrument comprising a torque calculating means for estimating the torque applied to the. 13. A torque measuring instrument used for a machine tool, wherein a spindle load for estimating a torque value applied to the spindle based on a current and a rotation speed value of a spindle motor mounted on the machine tool. A torque estimating means, a storage means for storing the torque of the spindle that is rotating during non-machining, which is obtained by the spindle load torque estimating means, and a spindle that is being machined that is obtained by the spindle load torque estimating means. A torque measuring device comprising a torque applied to the tool and a computing means for calculating the torque applied to the tool attached to the processing machine from the torque stored in the storage means. 14. A torque measuring device according to claim 12 or 13, wherein breakage of a tool is detected using a torque measurement value output by the torque measuring device, and the machine tool of the machine tool is detected based on the detection result. A tool breakage detection device comprising control means for controlling an operating state.