JPH0197540A - numerical control machine tools - Google Patents

Abstract

PURPOSE:To prevent the occurrence of overcutting, by a method wherein, when it is discriminated that a relative position between a tool and a workpiece is attains a preset movable limit, through control of a drive means, further movement is prohibited. CONSTITUTION:A control part 108 being a signal generating means generates a signal by means of which a tool mount 101 or a work is moved by a given distance at one pulse at a time, and a CPU 105 drives drive motors 102 and 103 through the working of a servo control part 104. The moving position of the tool mount 101 is detected by means of encoders mounted to the two motors 102 and 103, and a shape is computed from a manual input or a program from an input device 109. When a relative position between a tool and a workpiece attains a relative movable limit stored in a memory part 106, the CPU 105 decides it to stop the drive of the two motors 102 and 103. This constitution enables execution of a rapid cutting work without being nervous about overcutting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a numerically controlled (hereinafter referred to as NC) machine tool, and in particular to an NC machine tool characterized by control of the position of a cutting edge of a tool.

[Conventional technology] FIG. 3 is a diagram showing a chuck portion of a general lathe.

In not only NC lathes but also general lathes, etc., it is necessary to precisely shape the green jaws 3 of the chuck portion 4 for holding the material to be cut before cutting the material to be cut. The green jaws 3 (hereinafter simply referred to as jaws 3) of the chuck portion 4 are rotated by a screw or the like around the main shaft 5 of the lathe in order to hold or release the material to be cut. Here, the claws need to be replaced depending on the workpiece, but since errors occur during attachment, it is necessary to reshape the attachment afterward. Therefore, in actual shaping of the pawl 3, after the pawl 3 is mounted on the chuck portion 4, the final shaping process is performed using the tool 2 of the lathe itself.

The procedure of such a conventional manual nail shaping process will be explained with reference to FIGS. 2(a) and 3.

(1) Bring the cutting edge 2a of the tool 2 into contact with the front end surface 3a of the jaw 3, and reset the digital counter etc. displayed on the monitor using this position as a reference in the Z-axis direction (here, the direction of the main shaft 5 of the lathe is is the Z-axis, and the direction perpendicular to the main axis 5 is the X-axis.
The axis. The origin position in the X-axis direction is the main axis 5).

(2) Move the tool stand 1 a distance corresponding to a predetermined depth of cut in the X-axis direction. Next, the tool stand 1 is moved in the Z-axis direction by an amount obtained by subtracting the finishing allowance from the target finishing dimension in the Z-axis direction while watching a scale on a counter or the like, and the claws 3 are cut.

(3) When the cutting depth reaches the amount obtained by subtracting the finishing allowance from the finishing dimension mentioned above, return the tool rest l slightly to the origin in the X-axis direction, and while watching the scale on the counter in the Z-axis direction, Return to the origin.

(4) Further, steps (2) and (3) are repeated until the depth of cut in the X-axis direction reaches the amount obtained by subtracting the finishing allowance from the target finished dimension in the X-axis direction.

(5) Adjust the rotation speed of the lathe and the depth of cut of the tool cutting edge 2a to achieve the final finish to the target finished dimensions.

In addition, when using an NC lathe that uses an NC program or uses an MDI (manual data input) method, the procedures and machining conditions (such as lathe rotation speed and tool feed rate) explained above can be manually or programmed to operate the NC lathe. Needless to say, this can be done by manually controlling the control section.

[Problems to be solved by the invention] In the manual nail shaping process described above, the operator must move the tool stand while looking at the counter scale on the monitor, and during the rough cutting stage, Machining must be carried out using the amount obtained by subtracting the finishing allowance from the target finished dimensions as a guide, and there is a problem that over-shaving often occurs, and work must be done carefully to prevent over-shaving. However, there was a problem in that it took a long time to process.

Furthermore, although NC lathes that use programs etc. do not have the above-mentioned problems, the jaws 3 of the chuck section 4 are generally made of a hard material such as steel, so the cutting edge 2a of the tool 2 often gets damaged during cutting. It has the problem that it lacks.

Therefore, tools must be replaced, and automatic machining of pawls using a program is extremely difficult in NC lathes.

This invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a numerically controlled machine tool that can accurately form nail shapes with simple operations.

[Means for Solving the Problems] A numerically controlled machine tool according to the present invention includes a signal generating means for moving a tool or a workpiece, a driving means for driving the tool or a workpiece, and a drive member for the tool. a position detection means for detecting a relative position with respect to the workpiece; a movement limit setting means for setting a movable limit of the tool relative to the workpiece; and a movement limit setting means for setting a relative movable limit of the tool with respect to the workpiece; and a control means for controlling the drive means so as not to move any further in the direction when the relative position of the tool with respect to the workpiece reaches the movable limit.

[Operation] The signal generating means generates a pulse signal to move the tool stand or the workpiece a predetermined distance, such as 1 μm or 10 μm, for example, every 1 pulses.

The driving means drives a motor or the like to move the tool or the workpiece a predetermined distance every time it receives a pulse signal.

The position detection means calculates the relative position of the tool with respect to the workpiece based on the output of an encoder or the like provided on a motor or the like, and outputs a signal corresponding to the position.

The movement limit setting means calculates and stores the relative movable limit of the tool with respect to the workpiece based on the manually input or programmed shape of the workpiece.

The determining means determines whether the relative position of the tool to the workpiece has reached a movable limit by successively comparing the tool or the workpiece each time the tool or the workpiece moves.

The control means controls the driving means to prevent the tool from moving further relative to the workpiece in the direction in which the movable limit is reached when the relative position of the tool with respect to the workpiece reaches the movable limit. Outputs a signal to prevent motors, etc. from being driven.

[Examples] The present invention will be described below based on drawings showing examples thereof.

FIG. 1 shows the configuration of an embodiment of a numerically controlled machine tool according to the present invention.

In FIG. 1, for example, in the case of an NC lathe, a tool stand 101
In order to be driven in the main axis (Z) and the direction (X) perpendicular to the main axis, the screw type feed mechanism is connected to a drive mechanism, ie, a servo motor or a stepping motor, 102 and 103 through screw feed mechanisms 01a and 101b. There is. Some NC milling machines have a movable workpiece table on which the workpiece is fixed, and in this case, 101 corresponds to the workpiece table. The motors 102 and 103 are provided with a pulse generator such as a rotary encoder as a position detection means, and output feedback to the servo control unit 104 as to how many times the motors have rotated in which direction. A known microcomputer can be applied to the central processing unit 105, which sequentially executes predetermined programs. A well-known RAM (Random Access Memory) or the like can be applied to the storage unit 106 as well. The display unit 107 is a known digital or CRT type display, and the central processing unit 105 indicates the position of the cutting edge of the tool by the motor 102.10.
Calculated from the output of the rotary encoder No. 3 and displayed on the display section 107.
to be displayed. The operation unit 10B as a signal generating means has a pulse that moves the tool stand 101 (or tool) by 1 mm in one rotation and generates 100 pulses or 1000 pulses in one rotation, for example, in order to have commonality with the feeding mechanism of a conventional lathe. It is a generator. This pulse generator is
They are provided respectively in the axial direction. Human power device 10
9 is connected to the central processing unit 105 and is connected to the tool stand 10.
It consists of a keyboard as a movement limit setting means for inputting the movable limit of 1, ie, the shape of the target workpiece, etc., and also has a function of resetting the display on the display section 107.

By the way, in general machining in which a round bar is cut into a predetermined shape using an NC lathe, the shape of the target workpiece or the movement of the tool stand 101 (or the cutting edge of the tool) for shaping it into the shape is pre-centered. The program may be input to the calculation unit 105, stored in the storage unit 106, and executed under automatic control. However, when manufacturing a simple jig or the like, or when shaping the jaws 3 of the chuck section 4 of a lathe as shown in Fig. 3, manual operation at the operating section 10B is preferable to automatic control by creating a program. It is preferable to

Next, the present invention will be explained in detail by taking as an example the case where the claws 3 of the chuck portion 4 shown in FIG. 3 are shaped.

In this case, as mentioned above, the material of the claw 3 is hard and the cutting edge 2a of the tool 2 is likely to chip, making it the least suitable case for automatic control.

First, a pulse signal is generated by the operating section 10B, and the pulse signal is manually input to the servo control section 104 via the central processing section 105. The servo control unit 104 controls, for example, the 18 m tool stand 101 every l pulse according to the number of pulses of the pulse signal.
drive motor 103 that moves the motor in the Z-axis (main axis) direction. The motor 103 moves the tool stand 101 by 1 μm. The motor 103 feeds back a pulse signal to the servo control section 104 according to its rotation speed or rotation angle. The servo control unit 104 calculates the movement amount of the tool stand 101 based on the pulse signal from the Mi-Yu 103, and the central calculation unit 10
Output to 5. The central processing unit 105 stores the position of the tool stand 101 in the storage unit 106 as an absolute position with respect to a certain reference point of the NC lathe or as a relative position from the previously reset position.
and simultaneously display it on the display unit 107. In this way, when the cutting edge 2a of the tool 2 attached to the tool stand 101 (corresponding to number l in FIG. 3) comes into contact with the front end surface 3a of the claw 3, by pressing the reset button of the input device 109 A reference point in the axial direction is set, and at the same time, the distance display in the X-axis direction on the display 107 is reset to "sail 00". Although similar operations are possible in the X-axis direction (direction perpendicular to the main axis), in principle, the origin is the main axis in the X-axis direction.

Next, the final dimensions of the claw 3 are diameter φ100mm,
When the depth is 10 mm, the human power device 109 calculates X=
By inputting 100 and Z=-10 and pressing the setting button of the input device 109, the target value (i.e., the relative movable limit value of the tool with respect to the workpiece) is stored in the storage unit 106 via the central processing unit 105. be remembered. Similarly, human powered device 1
09, the finishing allowance in the X-axis and X-axis directions is set to 0.
A tool stand with a diameter of 1 mm, for example, XF=0.1, ZF=0.
1 and human power. As a result, the rough cutting target value (X = 99.9
00, Z=-9,9).

Next, the main spindle 5 and the chuck part 4 are rotated at a predetermined number of rotations, and as roughly shown in FIG. Generates pulses in the axial direction and controls the motor 102 via the central processing unit 105 and servo control unit 104.
to drive.

Then, the operation unit 108 generates a pulse in the X-axis direction to drive the motor 103 so as to move the tool stand 101 to the left in FIG. 2 until it reaches Z=-9,90. The motor 103 feeds back the number of rotations or the rotation angle to the servo control unit 104 every moment according to its rotation, and the servo control unit 104 calculates the position of the tool rest 101 (or the cutting edge 2a of the tool 2) and sends it to the central calculation unit 105. Output.

The central arithmetic unit 105 serving as a determination means is connected to the tool stand 101 (
Alternatively, it is determined whether the position of the cutting edge 2a) of the tool 2 has reached a target value (limit value for relative movement of the tool with respect to the workpiece) set in the storage unit 106. When the position of the tool stand 101 (or the cutting edge 2a of the tool 2) reaches the target value of Z=-9,90, even if pulse manual input is continued from the operation unit 108, the central processing unit 105 as a control means ignores this pulse input and does not output any signal to the servo control section 104, and the servo control section 104 does not output a signal for driving the motor 103. At the same time, the central processing unit 105 outputs an alarm such as a buzzer to inform the operator that the workpiece has been cut to a predetermined rough cutting dimension.

Next, when the operator returns the tool stand 101 slightly in the opposite direction in the X-axis direction and returns it in the opposite direction beyond the origin in the Release and prepare for the next cutting operation.

Furthermore, move the workbench 101 a predetermined amount in the X-axis direction, and
Repeat the above procedure until reaching 99.90 and Z=-9,90.

There is also an alarm for determining the position of the tool in the X-axis direction and the target value (limit value of the tool's ability to move in the X-axis direction with respect to the workpiece).
The same is true for the axial direction.

In this way, when X=99.90 and Z=-9.90 are reached, the rough machining ends, and then the finishing machining begins.

When the rotation speed of the chuck part 4 of the NC lathe is changed, the central processing unit 105 sets the target values X=99.90 and Z=-9,9.
0 is canceled and the new final shaping size is set to X=-50,
00 and Z=-10,00 are read from the storage unit 10B. Note that if you directly set only X = 99.90 and Z = -9,90, here X = -50,00 and Z = -10,
Reset the update setting to 00. Then, the servo control section 104
The motors 102 and 103 are driven in response to pulsed human power from the operation unit 108 via the X=100 and Z=-10,
The tool stand 101 is moved until it reaches 00.

In the above embodiment, when rough machining is completed and the next transition is to finish machining, for example, a change in the rotation speed of the chuck section 4 is detected and the target value (limit value of tool movement) is changed. Alternatively, the manual device 109 must be used to directly set a fixed target value. However, when performing finishing machining, there are cases where it is desired to perform finishing machining directly following rough machining without taking the trouble of changing the movable limit value. This embodiment will be explained next.

In this case, the movement amount parameter PAx of the tool 2 in the direction opposite to the cutting direction in the X-axis direction and the Z-axis direction is set in advance.
and PAz, for example 0.2mm (PAx=0.2.PA
z=0.2), and the cutting direction movement amount parameters PBX and PBz as the finishing allowance are each set to, for example, 0.1 (PBx-0, 1, PBz=0.1).
Set.

As mentioned earlier, when the cutting edge 2a of the tool 2 reaches the set value
=99.90 or Z=-9,90°, an alarm will sound and the servo control unit 104 will stop the motor 102
Alternatively, 103 is not driven.

Now, when the tool 2 is moved slightly in the direction opposite to the cutting direction, the central processing unit 105 receives in this state that the tool 2 is returned in the opposite direction within the movement amount parameter PAx or PAz, that is, 0.2 mm. do.

As a result, the alarm is canceled and the set value X=99.90 or Z=
-9,90 is the movement amount parameter in the cutting direction PB
The set value is automatically changed so that it can be moved by x or PBz, that is, 0.1 mm. That is, the function of the central processing unit 105 is substantially based on the target value of X=100.
．． It exhibits the same function as when OO and Z=-10,00 are newly set.

Therefore, it is easy to cut further to finish by PBx or PBz.

In addition, in order to perform the undercut machining 3b as shown in FIG. 2(b), the time when the finishing machining is finally completed, that is
100. When the cutting edge 2a of the tool 2 reaches the position indicated by OO, Z = -10,00, the cutting edge 2a of the tool 2 is moved again to the specified position in the direction opposite to the cutting direction in either the X-axis or Y-axis direction. Parameter ff1PA has set value X=100.00. only when moved within PAZ. Z=-10,00
The program of the central processing unit 105 may be set so that the cutting edge 2a of the cutting tool 2 can be moved by a predetermined amount.

The above explanation has been about shaping the jaws of the chuck part on an NC lathe, but it can also be applied to manually cutting a workpiece material such as a round bar held by the jaws of the chuck part into a predetermined shape. Needless to say, numerically controlled machine tools are not limited to NC lathes, but can also be applied to NC milling machines and other types of machines.

[Effects of the Invention] As described above, the numerically controlled machine tool according to the present invention can set the relative movable limit of the tool with respect to the workpiece, and the relative position of the tool with respect to the workpiece can be set within the movable limit. When the limit is reached, even if the operator accidentally moves the tool further, the tool will not move relative to the workpiece, allowing quick cutting without worrying about overcutting. It has this effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a numerically controlled machine tool according to the present invention, FIG.
Figure (b) is a side view of the jaw for explaining undercut machining, and Figure 3 is a side view showing the configuration of the chuck section of a general lathe. In the figure, 101 is a work table, 102 and 103 are drive means (motors), 104 is a servo control unit, 105 is a central processing unit,
106 is a storage section, 107 is a display section, 10B is a signal generation means (operation section), and 109 is a movement limit setting means (input device).
It is. Applicant Mori Seiki Co., Ltd. Agent Patent Attorney Matsu 1) Michi Masaru

Claims (1)

[Claims] (1) signal generating means for generating a signal for moving the tool relative to the workpiece at least in a main axis and a direction perpendicular to the main axis; In a numerically controlled machine tool comprising a driving means for driving, and a position detecting means for detecting a relative position of the tool with respect to the workpiece, the movement sets a relative movable limit of the tool with respect to the workpiece. a limit setting means, and a relative position of the tool with respect to the workpiece detected by the position detection means reaches a relative movable limit of the tool with respect to the workpiece set by the movement limit setting means. a discriminating means for discriminating whether the tool has moved relative to the workpiece; A numerically controlled machine tool comprising: control means for prohibiting the driving means from moving further relative to the workpiece.