JPH0736975B2 - Machine tool automatic return device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a numerically controlled machine tool that automatically performs machining such as drilling and tapping, and in particular, the machine tool is brought to an emergency stop during machining. The present invention relates to an automatic return device for a machine tool that can automatically return to a processing tool and a member to be processed without any trouble.

(Prior Art) In general, due to advances in automation technology in recent years, in various manufacturing plants, for example, there are cases where drilling, tapping, etc. are automatically performed by a so-called numerically controlled machine tool. Has a numerically controlled machine tool as shown in FIGS. 5 and 6, for example.

The illustrated machine tool 1 is a so-called turret type machine tool for drilling, and a turret 16 for selecting a drill 5 to be used is attached to a movable table 15 which can be moved up and down, left and right, and back and forth. There is. Then, the drill 5 connected to a spindle (not shown) provided inside the turret 16 moves in the above-mentioned three-dimensional direction with respect to the workpiece 3 installed on the work table 2 to form a workpiece. 3 can be drilled at any position.

The moving table 15 includes an X-axis moving mechanism (hereinafter, simply referred to as X-axis) 6 for moving the drill 5 in the front-back direction with respect to the workpiece 3, and a Y-axis moving mechanism (hereinafter, simply called Y-axis) for moving the drill 5 in the left-right direction. .) 7 and a Z-axis moving mechanism (hereinafter, simply referred to as Z-axis) 4 for moving in the vertical direction, and each axis has an X-axis motor 8, Y for driving the respective axis.
The axis motor 9 and the Z-axis motor 10 are attached, and the X-axis position detector 11, the Y-axis position detector 12, and the Z-axis position detector 13 for detecting the position of each axis are respectively motors 8, 9,
Installed on 10.

Then, these motors 8, 9, 10 and each position detector 1
Each of 1, 12, and 13 is connected to a control device (not shown) that controls the machine tool 1 in a comprehensive manner, and this control device performs so-called feedback control on each axis to move the drill 5 to the work piece 3. It is possible to position it at any position with respect to.

The turret 16 has a tool motor for driving the drill 5.
14 is attached, and this tool motor 14 is also connected to the control device, and the control device controls the tool motor 14 while detecting the current value supplied to this tool motor 14. The rotation of the drill 5 is controlled to control the drilling of the workpiece 3.

Then, in the machine tool 1 for such a drilling process, each axis is operated by the control device to move the drill 5 to an arbitrary processing position of the workpiece 3, and at that position, the tool motor is operated.
While driving 14 to rotate the drill 5, each axis is moved according to the machining direction of the drill 5 to automatically perform drilling.

(Problems to be Solved by the Invention) However, in such a conventional machine tool,
When an emergency stop occurs due to a power outage during machining, the excitation of each axis motor is lost, and the turret may be displaced by its own weight or by the cutting reaction force of the drill.
If you try to extract the drill from the work piece by rotating the drill attached to the spindle of the turret as it is, the hole diameter will be expanded during processing, resulting in poor machining or load on the drill There was a problem such as breakage.

Further, for this reason, in such a case, for example, an operator removes the drill from the turret, and after pulling out the drill from the member to be machined by a driving force, the work such as mounting the drill on the turret again is performed. There was a problem that it took time to recover from an emergency stop and production efficiency decreased.

The present invention has been made in order to solve such a conventional problem, and when the machine tool is brought to an emergency stop during machining, the optimum position of the spindle for extracting the machining tool from the workpiece is set. Automatically search and move the spindle to its optimum position,
An object of the present invention is to provide an automatic return device for a machine tool that can automatically return the machine tool by extracting it from a member to be processed without damaging the work tool.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention provides a spindle moving means for moving a spindle of a machine tool having a spindle mounted with a machining means for machining a member to be machined; Position detecting means for detecting a position, machining driving means for driving the machining means, driving force detecting means for detecting a driving force when the machining driving means drives the machining means, and the machine tool for emergency stop The emergency stop detecting means for detecting that the machine tool has made an emergency stop, and the spindle moving means causes the spindle moving means to slightly move the machining means with respect to the workpiece. And a minute drive signal that causes the machining driving means to minutely drive the machining means when the machine tool is stopped due to the emergency stop detection means. Signal output from the machining control means and the emergency stop detection means when the machine tool has made an emergency stop, based on the position detection means and the driving force detection means, the minimum drive while the spindle is slightly moving. A return control means for detecting an appropriate position of the spindle corresponding to the force and outputting an appropriate position signal for moving the spindle to the appropriate position to the machine tool control means.

(Operation) The present invention configured as described above operates as follows.

When the machine tool is brought to an emergency stop, the emergency stop detection means outputs an emergency stop signal to the machine tool control means, the machining control means and the return control means.

Then, the machine tool control means, which has received this emergency stop signal, outputs to the spindle moving means a minute movement signal for slightly moving the machining means with respect to the workpiece, so that the spindle is slightly moved with respect to the workpiece. To move. Similarly, the processing control means, which receives the emergency stop signal, outputs a minute drive signal to the processing drive means to minutely drive the processing means.

Then, the return control means sequentially stores, via the position detecting means and the driving force detecting means, the driving force of the machining driving means corresponding to the position of the spindle during the minute movement of the spindle, and sets the driving force to the minimum value. By obtaining the proper position of the corresponding spindle and outputting the proper position signal for moving the spindle to this proper position to the machine tool control means, the machine tool control means operates the spindle movement means to move the spindle to the proper position. To move.

Therefore, the spindle moves to a position during machining before the emergency stop or a position near it, and the machining means can be pulled out from the workpiece in the proper direction, and the workpiece becomes defective. Without doing so, and there is no fear that the processing means will be damaged, it will automatically return.

(Example) Below, the automatic return device of the machine tool which concerns on this invention is demonstrated in detail based on drawing.

FIG. 1 is a schematic configuration diagram of an automatic return device for a machine tool according to the present invention. In the figure, for example, when a machine tool similar to the machine tool described in the related art stops in an emergency during machining. , An automatic return device capable of automatically returning this machine tool is shown. Note that the machine tool that is automatically returned is the same as the machine tool described in the related art, and the description thereof is omitted here. Further, the same members as those described in the related art are designated by the same reference numerals.

As shown in the figure, this automatic recovery device is provided with an emergency stop detector 20 that detects this emergency stop state when the machine tool is in an emergency stop due to a power failure or the like and outputs an emergency stop signal indicating this state. This emergency stop detector
20 outputs the emergency stop signal to each of the machine tool controller 21, the tool motor controller 22, and the return controller 23.

The X-axis position detector 11, the Y-axis position detector 12, and the Z-axis position detector 13 that detect the position of each axis of the machine tool are connected to the machine tool control unit 21 that inputs this emergency stop signal, The machine control unit 21 controls an X-axis motor, a Y-axis motor 9 and a Z-axis motor 10 that drive each axis based on these position detectors, and positions a spindle to which a machining tool (here, a drill) is attached. It is designed to control.

Note that this positioning control is performed by so-called NC control, and a detailed description of this control is omitted because it is not related to the present invention.

Then, when the emergency stop signal is input, the machine tool control unit 21 is configured to control each axis motor so that the spindle is slightly moved within a predetermined range with respect to the workpiece. There is.

This situation will be described with reference to FIG. In the figure, for example, when the drill attached to the spindle of the machine tool is positioned at the point A and the machine tool is stopped during the drilling of the workpiece, the spindle of the machine tool is stopped. Is displaced by its own weight or by the cutting reaction force of the drill, and the position of the spindle is displaced to point B. That is, the tip of the drill is at the point A and the attachment end is at the point B, and is in a deformed or broken state.

Therefore, when the machine tool control unit 21 inputs an emergency stop signal, it drives each axis motor to move the spindle within a small predetermined range D-E shown in the drawing at a predetermined interval (for example, 1/100 mm to 3 mm).
/ 100mm) to make a small zigzag movement, and move the drill from B to C to search for the original point A or an appropriate position close to this point. That is, when the emergency stop signal is input, the machine tool control unit 21 inputs the current position of the spindle by each of the position detectors 11, 12 and 13, and the predetermined range D in which the spindle is moved based on this position. -E is set, and the main axis is slightly moved within this predetermined range along a predetermined path.

Further, like the machine tool control unit 21, the tool motor control unit 22 that inputs an emergency stop signal from the emergency stop detector 20 supplies power of a predetermined voltage to the tool motor 14 that drives the drill to drive the machining tool. As a result, predetermined processing is performed on the member to be processed. Furthermore, the tool motor control unit 22 is connected to a current detector 24 that detects a current value flowing in the tool motor 14, and the tool motor control unit 22 is based on the current detector 24, for example,
If the current value flowing in the tool motor 14 is greater than or equal to a predetermined value,
The power supply voltage is appropriately controlled for the tool motor 14 by controlling the voltage of the power supply.

When the emergency stop signal is input, the tool motor control unit 22 supplies the tool motor 14 with electric power of a predetermined minute voltage to rotate the tool motor 14 slightly. That is, the spindle is slightly moved as described above while the tool motor 14 applies a slight rotational load to the drill.

Further, the return control unit 23, which also inputs the emergency stop signal, includes the X-axis position detector 11, the Y-axis detector 12, the Z-axis detector 13,
And a current detector 24 are connected to each other, and the recovery control unit 23
When an emergency stop signal is input, the position of the spindle that slightly moves and the current value that flows in the tool motor 14 in accordance with that position are input via each position detector and current detector 24, and that position and The current value is sequentially stored in the internal memory according to the minute movement of the spindle. And
When the spindle completes its minute movement, the return control unit 23 determines the minimum current value among the stored current values, and determines the position (each position of the X axis, Y axis, and Z axis) corresponding to this minimum current value. I am asking for it. In other words, when the drill is deformed due to being pushed into the work piece, the position of the spindle that minimizes the load on the tool motor 14 (the value of the current flowing in the tool motor 14) is the proper position to extract the tool from the work piece. Therefore, the return control unit 23 determines the appropriate position where the load (current value) applied to the tool motor during the minute movement of the spindle is minimized.

Then, the return control unit 23 outputs the obtained proper position to the machine tool control unit 21, and the machine tool control unit 21 moves the spindle to this proper position.

This situation will be explained with reference to FIG. 2. When the drill deforms due to an emergency stop, if the spindle slightly moves from point B to point C along the dotted line, it will return to the original position A on the route before the emergency stop. When the spindle moves, the shape of the drill returns to its original shape, and the load on the tool motor 14 is minimized. Therefore, the position of point A has the minimum current value, and the return control unit
23 outputs the position of the point A to the machine tool control unit 21 based on this minimum current value, so that the machine tool control unit 21
Move the spindle to point A. In addition, even on such a route that does not pass through the original point A, the spindle can be positioned at an appropriate position near the point A, that is, with a small amount of deformation of the drill.

When the machine tool control unit 21 moves the spindle to the proper position, the machine tool control unit 21 outputs a movement end signal indicating that the spindle has been moved to the proper position to the return control unit 23. The control unit 23, the tool motor control unit 22,
A return drive signal for rotating the tool motor 14 in the direction for pulling the drill out of the workpiece is output, and a return movement signal for moving the spindle in the opposite direction to the machining progress direction of the tool is output to the machine tool control unit 21. Output to the control unit 21.

As a result, the tool motor control unit 22 that receives this return drive signal rotates the tool motor 14 in that direction, and at the same time the machine tool control unit 21 that receives the return movement signal moves the spindle in the opposite direction, It is possible to automatically return the machine tool by removing the drill from the work piece.

Further, when the drill breaks due to displacement of the spindle due to an emergency stop, the current value input by the return control unit 23 does not change even if the spindle slightly moves, and the tool motor 14 is broken because the tool is broken. Since no load is applied to the current value, this current value becomes equal to or less than a predetermined minute current value. Thus, when the current value is equal to or less than the predetermined minute current value and is constant,
The return control unit 23 determines that the drill is broken,
An alarm signal is output to the alarm device 25 that warns of drill abnormality,
This alarm device 25 is activated to warn the operator that there is something wrong with the drill.

Further, when the drill is difficult to work, even if the spindle moves slightly, the current value flowing through the tool motor 14 becomes a constant high current value, so the return control unit 23 causes the spindle to move slightly. If the input current value does not change during the operation, it is judged that the drill is too difficult to work on and the automatic recovery is not possible. Similarly, an abnormal signal is output to the alarm device 25 and the alarm device 25 This alerts the operator that the drill is abnormal.

The automatic restoration device according to the present invention configured as described above operates based on the operation flowcharts shown in FIGS. 4. FIG. 4 is a subroutine flowchart of step 2 of the main flowchart shown in FIG.

The machine tool controller 21, the tool motor controller 22, and the return controller 23 wait until the emergency stop detector 20 detects an emergency stop of the machine tool (step 1), and the emergency stop detector 20 detects the emergency stop. By detecting and outputting an emergency stop signal to the respective control units, the respective control units operate based on a subroutine flowchart shown in FIG. 3 described later, and minutely drive the tool motor 14 and minutely move the spindle. Move
The operation of setting the proper position of the spindle for automatic return is performed (step 2).

Then, the return control unit 23 does not change the input current value while the spindle is slightly moving during the operation of setting the proper position, and the current value is equal to or less than the predetermined minute current value. Then, it is judged whether or not the tool motor 14 is rotating with no load (step 3), and if the current value is constant below a predetermined minute current value, it is judged that the drill is broken, An alarm signal is output to the alarm device 25 to warn the operator that the drill is abnormal (step 4).

Further, when the return control unit 23 determines that the current value input in step 3 is not constant below a predetermined minute current and the drill is not broken, whether the input current value is constant or not is determined. Judgment (step 5), and if it is constant, it is judged that the load applied to the tool motor 14 is constant and the drill is embedded in the work piece, and the process proceeds to step 4.

On the other hand, in step 5, when the input current value is not constant, the return controller 23 determines that the machine tool can be automatically returned, and the load applied to the tool motor during the fine movement of the spindle ( The proper position where the electric current value) is minimized is obtained, and this proper position is output to the machine tool controller 21, and the machine tool controller 21 moves the spindle to this proper position (step 6).

Then, when the machine tool control unit 21 moves the spindle to the proper position, it outputs a movement end signal to the return control unit 23, and the return control unit 23 causes the tool motor control unit 22 to move the drill from the workpiece. In addition to outputting a return drive signal for rotating the tool motor 14 in the direction of extraction, the machine tool control unit 21
A return movement signal for moving the spindle in a direction opposite to the direction in which the drill is processed is output to the machine tool controller 21. And
The tool motor control unit 22 rotates the tool motor 14 in that direction, and at the same time, the machine tool control unit 21 moves the spindle in the opposite direction, extracts the drill from the workpiece and automatically returns the machine tool (step 7).

Next, the operation of setting the return position in step 2 will be described with reference to FIG.

The machine tool control unit 21 which has input the emergency stop signal inputs the current position of the spindle through each of the position detectors 11, 12 and 13, and slightly moves the spindle according to the current position of the spindle. Set a predetermined range (step 10).

Similarly, the tool motor controller 22 that has input the emergency stop signal
Sets the power of a minute voltage that drives the tool motor 14 minutely (step 11).

Then, the machine tool control unit 21 drives each axis motor,
The main axis is moved in a zigzag at predetermined intervals within the set predetermined range, and is slightly moved along a predetermined path. At the same time, the tool motor control unit 22 supplies the tool motor 14 with electric power of a predetermined minute voltage set, and minutely drives the tool motor 14 (step 12).

Then, the return control unit 23 determines the position of the spindle that slightly moves via the X-axis position detector 11, the Y-axis position detector 12, the Z-axis position detector 13, and the current detector 24, and the position in accordance with this position. Input the current value flowing in the tool motor 14, and store the position and current value in the internal memory sequentially according to the movement of the spindle,
Return to step 2 (step 13).

Therefore, the spindle misaligned due to an emergency stop is positioned at a position during machining before the misalignment, or a position close to this position, if the drill is not broken or is not inserted into the work piece, and the drill is Since the amount of deformation is reduced and it is automatically extracted from the work piece, the load that breaks or breaks is not applied to the drill by this extraction, and the drill is automatically extracted from the work piece Can be automatically restored.

If the drill breaks due to the displacement of the spindle due to an emergency stop, or if the work piece is difficult to insert, the alarm 25 warns of an abnormality in the tool, so such a condition is automatically detected. It will also happen.

Incidentally, in the present embodiment, a machine tool for drilling a workpiece is exemplified, but such a machine tool,
It is needless to say that the machine tool is not limited to the processing content, and may be a machine tool that performs tap processing, milling processing, or the like.

(Effects of the Invention) As is clear from the above description, the present invention has the following effects.

Corresponds to the position of the spindle while the spindle is moving slightly, by moving the spindle misaligned due to the machine tool's emergency stop to a small amount relative to the work piece while supplying a minute driving force to the machining means. Sequentially storing the driving force of the processing drive means,
Find the proper position of the spindle corresponding to the minimum value of this driving force,
Since the spindle is moved to this proper position, the spindle will move to the position during machining before the emergency stop or near this position, and the machining means can be extracted from the workpiece in the proper direction. Thus, it becomes possible to automatically return the machine tool without making the member to be machined defective and without damaging the machining means.

Also, it is possible to automatically return the machine tool,
You can shorten the time from emergency stop to return,
The operating rate of machine tools is improved and productivity is improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an automatic return device for a machine tool according to the present invention, FIG. 2 is an operation explanatory diagram of an automatic return device for a machine tool according to the present invention, and FIG. 3 is an automatic machine tool according to the present invention. An operation flowchart of the restoring device, FIG. 4 is a subroutine flowchart of step 2 shown in FIG. 3, FIG. 5 and FIG.
The figure is an explanatory view of a conventional machine tool for drilling. 8 ... X-axis motor (spindle moving means), 9 ... Y-axis motor (spindle moving means), 10 ... Z-axis motor (spindle moving means), 11 ... X-axis position detector (position detecting means), 12 ……
Y-axis position detector (position detection means), 13 ... Z-axis position detector (position detection means), 14 ... Tool motor (processing drive means), 20 ... Emergency stop detector (emergency stop detection means), twenty one
...... Machine tool control section (machine tool control means), 22 ...... Tool motor control section (machining control means), 23 …… Return control section (return control means), 24 …… Current detector (driving force detection means) , 25 …… Alarm.

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Claims (1)

[Claims] Claim: What is claimed is: 1. A spindle moving means for moving a spindle of a machine tool comprising a machining means for machining a workpiece, a position detecting means for detecting a position of the spindle, and a machining means for driving the machining means. Machining drive means, drive force detection means for detecting a drive force when the machining drive means drives the machining means, emergency stop detection means for detecting that the machine tool has made an emergency stop, and emergency stop detection. A machine tool control means for outputting a minute movement signal for minutely moving the machining means with respect to a workpiece to the spindle moving means when the machine tool is stopped due to an emergency stop detecting means. Based on this, when the machine tool is in an emergency stop, the processing drive means outputs a minute drive signal for minutely driving the processing means, and the emergency stop detection means. Then, when the machine tool is in an emergency stop, the proper position of the spindle corresponding to the minimum driving force during the minute movement of the spindle is detected based on the position detecting means and the driving force detecting means, and the appropriateness is detected. An automatic return device for a machine tool, comprising return control means for outputting an appropriate position signal for moving the spindle to a position to the machine tool control means.