JPH11212618A - Work machining method for nc lathe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically perform correspondent working to plural kinds of works supplied to a lathe at random. SOLUTION: The plural work programs of different working forms are registered in a numerical controller(NC) for controlling the lathe, a work detecting member 12 is mounted on a turret 4, a work 14 is loaded on the lathe, a tool rest 5 is moved toward the work 14 while monitoring the load in a state of limiting the output torque of feeding motors 7 and 8 for moving the tool rest 5, the position of the tool rest 5 at the time, when the load of the feeding motors 7 and 8 exceeds a set level, is read by the NC and a branching instruction is executed while making a numerical range corresponding to the position of the tool rest corresponding to one of the plural registered work programs. Thus, one of the registered work programs is selected and executed. The load of a spindle rotating motor is detected in place of the load of the feeding motor corresponding to a work shape and the work program can be selected from the phase of the spindle at the time, when the load exceeds the set level, as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a numerical control (N
C) The method relates to a method of machining a work of a lathe controlled by an apparatus, and relates to a lathe capable of performing machining according to the shape of each work when works having different shapes are mixed and sequentially supplied to the lathe. It is.

[0002]

2. Description of the Related Art When machining a workpiece with an NC lathe,
Tools required for processing are mounted on a turret, a processing program including the tip commands of these tools is registered in advance in an NC device, and a lathe is loaded with a work. Then, the registered processing program is executed to execute processing. By changing the machining program of the NC lathe, it is possible to machine workpieces of various shapes. At a normal machining site, a machining plan for each lathe is taken into consideration, considering the type and number of workpieces to be machined and the delivery date. Stand up and execute machining according to the plan. In a lathe provided with an automatic work supply device (loader), a program used for machining and the number of workpieces to be machined by the machining program are registered in the NC machine.
A predetermined number of works having the same shape can be continuously processed. When processing multiple types of workpieces unattended at night, register multiple processing programs in the NC unit,
The work stocker that specifies the machining program to be used, the number of repetitions, and the order, while holding the work before machining waits, according to the machining order and number specified in the NC device, orders the corresponding work. Start machining the workpieces in a well-arranged state. If the operator is near the lathe during the working hours of the operator, the workpiece is randomly supplied to the lathe, the operator looks at the supplied workpiece, and specifies a machining program to be executed from the operation panel. May be processed one by one.

[0003]

A method of randomly supplying workpieces having different shapes to a lathe and letting an operator select a machining program corresponding to the supplied workpieces for performing unmanned operation at night without an operator. Sometimes, the operation cannot be performed and the operator cannot leave the vicinity of the work, so that the operator's work load is large. A method of presetting a machining program and the number of repetitions of a plurality of types of workpieces and performing a continuous machining of a plurality of types of workpieces can realize a long-time automatic machining without placing a burden on an operator.
If the setup before machining is incorrect, the machine may stop halfway, the tool may be damaged, or many defective products may be manufactured. That is, if there is an inconsistency between the processing order set in the NC device and the number or order of the workpieces prepared in the work stocker, the tool is brought into contact with the workpiece to break the tool, or a small-sized workpiece is processed to fail. Or generate good products. The occurrence of such a serious accident can be avoided by detecting the load on the feed motor and the spindle motor and stopping the machine instantaneously. It is not possible to avoid the problem that the scheduled machining is not completed due to the stop.

According to the present invention, a plurality of types of workpieces randomly supplied to a lathe can be machined according to each workpiece without providing a special device for determining the type of the workpiece supplied to the lathe. It is an object of the present invention to obtain a technical means capable of automatically performing the above.

[0005]

According to a first aspect of the present invention, a plurality of machining programs having different machining shapes are registered in a numerical control device for controlling a lathe.
A workpiece detection member 12 is mounted on the lathe, the workpiece 14 is loaded on the lathe, and the tool rest 5 is directed toward the workpiece 14 while monitoring the load while limiting the output torque of the feed motors 7 and 8 for moving the tool rest 5. The position of the tool rest 5 when the load of the feed motors 7 and 8 exceeds the set level is read by the numerical controller, and the numerical range corresponding to the position of the tool rest and the plurality of registered machining programs By executing a branch instruction corresponding to one of the above, one of the registered machining programs is selected and executed.

According to a second aspect of the present invention, a plurality of machining programs having different machining shapes are registered in a numerical control device for controlling a lathe, a workpiece detecting member 12 is mounted on a turret 4, and a workpiece is machined on the lathe. 14, the workpiece detection member 12 is advanced to a position close to the workpiece 14, the tool post 5 is stopped, and the spindle is rotated at a low speed while monitoring the load in a state where the output torque of the spindle rotation motor is limited. The phase of the spindle when the load of the rotary motor exceeds the set level is read by the numerical controller, and a numerical range corresponding to the phase of the spindle and one of the plurality of registered machining programs are read.
By executing a branch instruction corresponding to each of the machining programs, one of the registered machining programs is selected and executed.

[0007]

FIG. 1 is an explanatory view conceptually showing an embodiment of the present invention. When the work is supplied to the lathe and the processing operation is started, first, the NC device determines the work detection member 12 attached to the turret 4 and
After the workpiece 2 approaches the workpieces 14a and 14b, the output torque of the feed motor for moving the tool rest is limited to a low level, that is, when the workpiece detecting member 12 comes into contact with the workpieces 14a and 14b, the tool rest easily stops. The tool post is moved toward the work with a torque that is sufficient. When the workpiece detection member 12 abuts against the workpieces 14a and 14b, the load current of the feed motor and the positional deviation described later increase, so that the position of the tool post at that time can be read from the NC device.
The size and shape of the work can be measured from the stop position.

The NC device executes a corresponding machining program in accordance with the measured work size. That is, if the measured dimension is within the first dimension range, the first machining program corresponding to the dimension is executed to perform machining, and the second
If the dimension is within the range, the workpiece is machined by executing the corresponding second machining program. If the dimension of the workpiece does not correspond to any of the set dimension ranges, an alarm process is performed. This alarm processing is, for example, processing in which the workpiece is discharged to the outside without being processed. Processing of a plurality of workpieces is performed sequentially by automatically repeating the procedure shown from the start to the end in FIG. FIG. 1 schematically shows an example in which two types of workpieces are machined by selectively executing two types of machining programs registered in accordance with the lengths of the supplied workpieces 14a and 14b. ing. That is, when the length of the loaded workpiece 14a is long, the first processing program is executed to process a workpiece having a shape indicated by 15a in FIG.
When the length of the workpiece 14b is short, the second processing program is executed to process the second workpiece having the shape indicated by 15b in FIG.

In the example shown in FIG. 1, a machining program is selected by measuring the length of a work, that is, the dimension of the lathe in the main axis direction (Z-axis direction). As shown in FIG. The machining program can also be switched by measuring the dimension of the workpiece at a predetermined position in the direction perpendicular to the main shaft (X-axis direction). Further, as shown in FIG. 3, it is also possible to detect the shape of the work around the main axis (in the C-axis direction) and select a machining program. FIG.
When the output torque of the X-axis feed motor 8 of the tool post is restricted, the work detecting member 12 mounted on the turret 4 is
1 to measure the diameter of the workpiece from the position where the workpiece 14c, 14d abuts on the workpiece detection member 12 and the tool rest stops, and executes a machining program corresponding to the measurement range. 2 shows an example of selectively performing the processing of the shapes shown by 15c and 15d in FIG.
Further, FIG. 3 shows that the work detecting member 12 is advanced into a notch or a recess provided on the outer periphery of the work, and the main spindle motor is rotated at a low speed as shown by an arrow 42 in a state where the output torque of the main spindle motor is limited. The workpieces 14e and 14f abut on the workpiece detection member 12, and by measuring the phase of the spindle at the position where the spindle rotation has stopped, the workpiece shape is detected and a machining program corresponding to the detected workpiece shape is executed. This shows an example in which two types of shapes 15e and 15f are selectively processed. Next, a more specific embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the contact between the work detection member mounted on the turret and the work is detected by utilizing the increase in the position deviation generated in the servo control system of the tool post feed motor and the spindle motor. ing.

FIG. 4 is a block diagram showing a means for detecting an increase in the positional deviation of the servo system, taking the Z-axis feed motor of the tool rest as an example. The spindle 1 of the lathe is supported by a headstock 2 which is substantially integral with a bed (not shown), and a chuck 3 is mounted on the tip thereof. The tool rest 5 provided with the turret 4 is slidably mounted in a direction perpendicular to the main shaft (X-axis direction) on a slide stand 6 slidable in the main shaft direction (Z-axis direction). Are screwed with feed screws 9 and 10 driven forward and reverse by a Z-axis direction feed motor 7 and an X-axis direction feed motor 8, respectively. The turret 4 is provided with a work detecting member 12 made of a round bar machined to an accurate external dimension at one place of the tool mounting station. Z-axis and X-axis feed motors 7, 8
Are controlled by the servo controller 21.

The servo controller 21 includes a difference detector 24, a compensation circuit 25, and a power amplifier 26. The difference detector 24 is provided with a position command a given from the NC unit 22 and the pulse encoder 13 mounted on the feed motor 7. A difference signal (position deviation) c from the position feedback signal b given by the controller 25 is supplied to the compensation circuit 25, which calculates a speed command based on the position deviation c and converts the difference signal with the speed feedback signal into a power amplifier 26. Has given to. The current output from the power amplifier 26 is the maximum current setting unit 27
It is limited by the set value of. The NC device 22 increases or decreases this set value at a necessary timing. FIG. 4 shows only the servo control system of the Z-axis direction feed motor 7, but the X-axis direction feed motor 8 and a spindle indexing motor (not shown) are similarly controlled by a similar control system. Difference detector 24
Is detected by the position deviation detecting means 31. On the other hand, the set level d to be compared when detecting an increase or decrease in the position deviation is set in the position deviation setting means 32, and the set values + d and -d on the plus side and the minus side are individually set. The comparator 33 detects the detected position deviation c.
Outputs the control output e when reaches the set value d. NC
The device 22 reads the coordinates of the tool post 5 when the control output e is output (when the control target is a spindle indexing motor, the phase of the spindle) and stores it in a memory.

The position deviation detecting means 31, the position deviation setting means 32 and the comparing means 33 are actually configured as a program of the NC unit 22. When the position deviation c cannot be obtained from the servo control device 21, the NC device 22
The position command a and the position feedback signal b of the pulse encoder 13 and the like are input to the position deviation detecting means 31, and the position deviation c is detected as a difference between them.

As described above, as a method of detecting that the load of the motor has exceeded the set level, a method of detecting an increase in the current flowing through the motor is also possible in addition to the method of detecting an increase in the position deviation. However, the method using the above-described position deviation enables accurate load detection and is suitable for implementing the present invention.

The command for selecting a machining program corresponding to the position of the tool rest, the phase of the spindle, or the size, shape, and range of the work calculated from the detected position is set in the G code of the NC unit. You. This G code instruction is issued as an instruction having the following five parameters, for example.

Here, A : Servo motor shaft torque limit value at work detection B : Operation pattern: 1 is X axis, 2 is Z axis, 3 is C
The axes 4, 4 indicate the Y axis, and 5 indicates the dimension range in the B axis direction. C ： Feed speed at workpiece detection I : Work position range specification (start point) J : Work position range designation (end point) K : Program number to call

For example, an instruction G311 B2. C50. I0. J-10. K500
1. I-10. J-20. K5002. I-20. J-
30. K5003. Calls the machining program at address 5001 when the work detection position in the absolute coordinate system of the work is in the range of 0 to -10, and calls the machining program at address 5002 when the work detection position is in the range of -10 to -20. Call, -20
The range from to -30 indicates a branch instruction that calls the machining program at the address 5003.

FIG. 5 shows an example of a flowchart showing the execution procedure of the method of the present invention when the above-described position deviation and branch instructions are used. First, a work is loaded on a chuck of a lathe (S1), a work detection member is indexed via a turret (S2), and the indexed work detection member is moved to a first measurement start position (S3). Next, the shaft torque of the motor is limited (S4), and measurement movement, that is, low-speed movement of the tool rest or low-speed rotation of the spindle is started (S4).
5). If the shaft load of the motor exceeds a certain level during this movement, that is, if the position deviation increases and exceeds the set level, the process branches from the detection step S6 to release the limitation of the shaft torque (S7). Then, the work detection member is retracted (S8), and the work program specified by the branch instruction is called and executed to process the work (S9).

Although the measurement movement (S5) at a low speed with the shaft torque limited has been performed to a predetermined measurement end position, that is, the position set by the J parameter of the measurement command, the shaft load is not changed. If no increase is detected (S10), the limitation of the shaft torque is released (S11), and the process returns to step S12 for determining whether there is a next measurement range. This determination step S12 is a step of determining whether or not measurement of all branch conditions set in the branch instruction has been performed. In other words, if three measurement ranges of the work are specified in the above-described branch instruction, that is, if the branch instruction selects one of the three machining programs according to the shape of the work, step S3 to step S3 are performed.
When the branching due to the detection of the work in step S6 does not occur even if the procedure of steps 6 and 10 and 11 is performed three times, control branches to alarm processing step S13 in determination step S12, and a warning message is displayed on the display. Either the display is displayed to stop the machine, or the workpiece is directly discharged without executing the machining program, and the next workpiece is loaded.

By performing processing in such a procedure,
For example, when multiple types of workpieces are processed unattended at night, even if the workpieces are randomly arranged in the work stocker, the processing is performed by selecting a processing program according to the shape and dimensions of the workpiece supplied by the machine tool. Will give me N
There is no need to set the number of workpieces to be machined on the C device side, and it is no longer necessary for the work stocker to sort and align the work according to its shape. When there is a gap between the workpieces, it is possible to prevent a situation in which the machine stops and a predetermined number of workpieces are not processed, or a defective product is processed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment conceptually showing a method of the present invention.

FIG. 2 is an explanatory diagram showing a second example of a work detection direction.

FIG. 3 is an explanatory diagram showing a third example of a workpiece detection direction.

FIG. 4 is a block diagram of work detection using position deviation.

FIG. 5 is a flowchart showing a more specific embodiment for implementing the method of the present invention.

[Explanation of symbols]

 4 Turret 5 Turret 7 Z-axis feed motor 8 X-axis feed motor 12 Work detection member 14 Work

Claims (2)

[Claims] A plurality of machining programs having different machining shapes are registered in a numerical control device for controlling a lathe and a turret (4).
The work detection member (12) is mounted on the lathe, the work (14) is loaded on the lathe, and the load is monitored while the output torque of the feed motors (7, 8) moving the turret (5) is limited. Turret
Move (5) toward the work (14), read the position of the turret (5) when the load of the feed motor (7, 8) exceeds the set level with the numerical controller, and move it to the position of the turret. Executing one of the registered machining programs by executing a branch instruction in which a corresponding numerical range is associated with one of the registered machining programs; NC lathe work processing method. A plurality of machining programs having different machining shapes are registered in a numerical control device for controlling a lathe, and a turret (4)
The work detection member (12) is mounted on the lathe, the work (14) is loaded on the lathe, the work detection member (12) is advanced to the position near the work (14), the tool post (5) is stopped, and the spindle is rotated. The spindle is rotated at low speed while monitoring the load while the motor output torque is limited, and the phase of the spindle when the load of the spindle rotating motor exceeds the set level is read by the numerical controller to correspond to the phase of the spindle. NC lathe, wherein one of the registered machining programs is selected and executed by executing a branch instruction in which a numerical value range is associated with one of the registered machining programs. Work processing method.