JPH11327624A - Numerical controller with feed speed controlling function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a numerical controller with a feed speed controlling function capable of performing machining at an optimum feed speed at all times. SOLUTION: The upper limit value Vmax. of the feed speed of a cutting tool is stored in a CMOS memory corresponding to the moving direction of the cutting tool. Whether or not it is during machining is judged by detecting the load of a servo motor for performing feed to the cutting tool (S1-S2), the moving direction of the cutting tool is calculated only in the case that it is during machining (S3), the upper limit value Vmax. of a tool feed speed corresponding to the moving direction is obtained (S4) and only in the case that a command feed speed V exceeds the upper limit value Vmax., the upper limit value Vmax. is outputted instead of the command feed speed V and the tool feed speed is limited (S5-S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical controller having a feed speed limiting function.

[0002]

2. Description of the Related Art There is known a numerical controller for performing cutting by feeding a tool or a work based on a machining program or a movement command from a manual pulse generator or a guidance operation handle.

[0003] In the case of performing cutting by playing back a machining program in this type of numerical controller, an optimized tool feed speed is given in advance by the machining program. Problem does not occur, but when cutting is performed by manually feeding a tool or workpiece with a manual pulse generator or guidance operation handle, etc. The feed rate of the workpiece may exceed the allowable range and increase, resulting in so-called heavy cutting, which may lead to abnormal biting or excessive cutting of the tool into the workpiece, or accidents such as breakage of the tool .

[0004] In particular, such as a tool such as a cutting tool used for turning, there is a remarkable difference in a cutting feed speed depending on a cutting direction of a cutting edge with respect to a workpiece, or a cutting tool in which an area where cutting is impossible occurs. In some cases, the maximum feed speed at which normal cutting can be performed varies in various ways depending on the direction of tool movement.Therefore, cutting is performed by manually feeding the tool or workpiece with a manual pulse generator or guidance operation handle. In such a case, it becomes very difficult to adjust the feed speed.

For example, in the case of turning, it is possible to use the same tool to perform both cylindrical cutting and end face cutting, depending on the shape of the cutting tool. There is a difference in the maximum feed rate that is allowed in the case, and even when performing cylindrical cutting using a special cutting tool, the outer shape of the rotating body draws a quadratic curve. Strictly speaking, the angle formed by the cutting tool and the workpiece fluctuates depending on the cutting location. There is a problem that a portion is cut off.

Naturally, if the tool feed speed is set lower for safety, machining is prolonged. If the tool feed speed is set higher, cutting is performed at a specific location where the cutting amount relatively increases. The adverse effects such as occurrence of such a problem occur.

Further, even in the case where cutting is performed by playing back a machining program, since the speed command of the machining program is set in block units, the outer shape draws a quadratic curve. In the case of processing such a rotating body, for example, in the case of processing an arc portion or the like, similarly to the above, there is a problem that the angle formed by the cutting tool and the workpiece varies depending on the cutting location, and partial heavy cutting is performed. There is a possibility that shaving occurs.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a numerical controller having a feed speed limiting function capable of solving the above-mentioned drawbacks of the prior art and always performing cutting at an optimum feed speed. It is in.

[0009]

According to the present invention, a moving direction calculating means for calculating a moving direction of a tool or a work in real time, and an upper limit value of a feed speed of the tool or the work corresponding to the moving direction of the tool or the work. The stored regulation value storage means, and the present value of the feed speed exceeds the upper limit value based on the moving direction of the tool or the work calculated by the movement direction calculation means and the upper limit value stored in the regulation value storage means. The above object has been achieved by a configuration characterized by comprising a feed speed restricting means for restricting a feed speed of a tool or a work so as not to cause the problem.

[0010] In addition, by providing regulation value storage means for each tool type, selecting the regulation value storage means according to the type of the installed tool and regulating the feed speed of the tool or work, it is possible to perform various processing. I can deal with it.

Further, by restricting the feed speed of the tool or the work only during the cutting operation, the tool operation is not unnecessarily restricted at the time of the idle feed or the approach operation of the tool, and the overall operation is prevented. Improved processing efficiency.

The determination as to whether or not cutting is being performed can be achieved, for example, by detecting the load of a servomotor that feeds a tool or a work, and comparing that value with a set value.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a numerical controller 10 having a feed speed limiting function according to an embodiment of the present invention and a main part of a machine tool, for example, a lathe, which is driven and controlled by the numerical controller 10.

The processor 11 is a processor that controls the numerical controller 10 as a whole, and
The system program stored in M12 is read, and the numerical controller 10 is entirely controlled according to the system program. The RAM 13 is a memory for temporary storage.

The CMOS memory 14 is configured as a non-volatile memory that is backed up by a battery (not shown) and retains the stored state even when the power of the numerical controller 10 is turned off. The upper limit value storage file stored corresponding to the moving direction is also stored in the CMOS memory 14.

The interface 15 is an interface for an external device, to which an external device 72 such as a paper tape reader and a paper tape puncher is connected. The NC program is read from the paper tape reader, and the NC program edited in the numerical controller 10 can be output to the paper tape puncher.

A PMC (programmable machine controller) 16 controls the machine tool by a sequence program stored in the numerical controller 10. That is, in accordance with the functions instructed by the NC program, these sequence programs convert the signals into necessary signals on the machine tool side, and output the signals from the I / O unit 17 to the machine tool. Various actuators on the machine tool are operated by this output signal. Also,
A signal from a limit switch or the like on the machine tool is received, necessary processing is performed, and the signal is passed to the processor 11.

The current position of each axis, alarm, parameter,
An image signal such as image data is transmitted to a CRT / MDI unit 70.
Is sent to the display. The interface 18 receives data from the keyboard of the CRT / MDI unit 70 and passes the data to the processor 11. The interface 19 is connected to a manual pulse generator group 71 composed of three manual pulse generators for X-axis, Z-axis and guidance, and receives pulses from these manual pulse generators.

The three manual pulse generators for the X-axis, the Z-axis, and the guidance are mounted on the operation panel 113 on the machine tool side as shown in FIG. Operating handle 108, Z axis operating handle 1
09, a guidance operation handle 111 is attached.

The X-axis operation handle 108 and the Z-axis operation handle 109 are operation handles for complete manual operation. When one of them is operated, the tool is moved to the X-axis according to the operation amount and the handle rotation speed. If the tool is moved in the axial direction or the Z-axis direction, and the X-axis operation handle 108 and the Z-axis operation handle 109 are simultaneously operated, the tool moves in the XZ plane in proportion to the operation amount and the handle rotation speed ratio. Move with.

The selection switch 110 operates the guidance operation handle 111 to move the tool along the machining path in the machining program, or causes the tool to perform an approach operation by operating the guidance operation handle 111. The direction selection key 112 is used to select the guidance operation handle 111.
Is used to specify the forward / reverse direction of the tool feed direction when moving the tool along the machining path by operating.

When the former function is selected by the selection switch 110 and the guidance operation handle 111 is operated, the feed direction of the tool is regulated by the machining path in the machining program, and only the moving speed of the tool is controlled by the guidance operation handle. It changes according to the steering wheel rotation speed of 111.

The operation panel 113 further includes a spindle switch 101 for starting rotation of the spindle, a spindle stop switch 102 for stopping the rotation, and a coolant switch 10 for supplying a machining fluid to the tip of the tool.
3. Coolant stop switch 104 for stopping the supply of coolant, tool change switch 105 for automatically changing the tool of the tool rest, teaching switch 106 for storing the machining path generated by manual operation as a machining program, teaching A playback switch 107 and the like for executing the processed machining program are provided. Signals from these switches are transmitted to the I / O unit 17 and P
It is passed to the processor 11 via the MC 16.

The axis control circuits 30 and 31 receive a movement command pulse for each axis from the processor 11 and
41. The servo amplifiers 40 and 41 receive the command and drive the servo motors 50 and 51 of each axis. X,
The Z-axis servo motors 50 and 51 have built-in pulse coders for detecting position and speed, and feedback signals from these pulse coders are fed back to the axis control circuits 30 and 31. Further, each of the servo control CPUs incorporated in the axis control circuits 30 and 31 performs each processing of a position loop, a speed loop, and a current loop based on these feedback signals and the above-described movement command, and performs final drive control. Current command for each axis is calculated for each axis,
The positions and speeds of 0 and 51 are controlled.

The spindle control circuit 60 outputs a spindle speed signal to the spindle amplifier 61 in response to a spindle rotation command and a command such as spindle orientation. Upon receiving the spindle speed signal, the spindle amplifier 61 rotates the spindle motor 62 at the commanded rotation speed. Further, the rotational position of the spindle motor 62 is positioned at a predetermined position in accordance with the orientation command.

FIG. 4 is a conceptual diagram showing an example of an upper limit value storage file (restriction value storage means) stored in the CMOS memory 14.

In this embodiment, assuming that the cutting tool 1 as a tool moves vertically and horizontally in the XZ plane as shown in FIG. 2, the moving direction is classified into eight directions at a pitch of 45 °. The upper limit value of the cutting feed speed allowed for each direction is stored in the upper limit value storage file as a regulation value.

Needless to say, the direction in which cutting can be performed and the cutting feed speed allowed for each feed direction vary depending on the type of cutting tool such as the cutting tool 1 and the like. It is necessary to determine the angle and whether the division is to be performed at an equal pitch or an unequal pitch, depending on the type of each tool. For each tool,
An optimized upper limit value storage file is created in advance and registered in the CMOS memory 14 in association with the tool number and the like.

FIG. 6 shows a speed limiting process which is executed when the processor 11 receives a machining program and a movement command from the various handles 108, 109, 111 and calculates a movement command (= speed) of each axis at a predetermined cycle. It is a flowchart which shows an outline.

The actual position, speed, and current loop processes are the same as those in the related art, and therefore will not be described here.

The processor 11 which has started the speed limiting process
First, the X, Z axis servo motors 50,
The values of the drive currents Ix and Iz at 51, in other words, the values of the loads Ix and Iz acting on the X and Z axis servomotors 50 and 51 for feeding the byte 1 are read (step S).
1) It is determined whether or not the combined load Ix ² + Iz ² exceeds the set value Is ² (step S2).

The set value Is ² is a set value for determining whether or not the cutting tool 1 is cutting the work material 2. The setting operation Is ² is an approach operation, a rapid feed operation of the cutting tool 1 outside the processing path, and processing has already been completed. X when tracing the bytes 1 against it has a plane, and is set slightly larger than the load Ix ₀ ² + Iz ₀ ² acting on the servomotor 50 and 51 of the Z-axis.

Therefore, regardless of whether the machining program is being played back, the operation handle 111 for guidance, the operation handle 108 for X-axis, the operation handle 1 for Z-axis,
If the result of the determination in step S2 is false regardless of whether the operation is in operation 09 or not, the approach operation, the rapid traverse operation of byte 1 outside the machining path, or the byte 1 with respect to the face that has already been machined is performed. Means that the sending operation for tracing is performed, and if the result of the determination in step S2 is true, the byte 1
Means that the actual cutting operation is performed.

When the result of the determination in step S2 is false, since the actual cutting operation by the cutting tool 1 is not performed, it is not necessary to limit the tool feed speed. Alternatively, the guidance operation handle 111 or the X-axis operation handle 10
8. The movement command V corresponding to the operation amount and operation speed of the Z-axis operation handle 109 is directly output to the axis control circuits 30 and 31 of the X and Z axes to drive and control the feed of the byte 1 (step S7). ).

Accordingly, the limitation of the tool feed speed does not affect the approach operation of the cutting tool 1 and the rapid traverse operation of the cutting tool 1 outside the machining path, and the movement of the cutting tool 1 to the machining start position and the movement to the next machining position. The movement of the cutting tool 1 can be performed at a high speed in accordance with the speed specified by the machining program or the operation speed of the guidance operation handle 111, the X-axis operation handle 108, and the Z-axis operation handle 109.

If the result of the determination in step S2 is true and it is detected that cutting is being performed, the processor 11 operates the machining handle or guidance operation handle 111, the X-axis operation handle 108, or the Z-axis operation handle. The moving direction of the cutting tool 1 is calculated in real time based on the operation amount and operation speed of the operation handle 109 (step S).
3) In addition, the cutting tool 1 currently mounted on the tool post
Referring to the tool number of byte 1, that is, the tool number of byte 1 designated by the immediately preceding tool change command, the upper limit value storage file as shown in FIG.
3 and the upper limit value Vmax. Of the cutting feed speed stored corresponding to the moving direction calculated in the process of FIG. Is read (step S4), and the magnitude relation with the movement command V given by the machining program or the handle operation is compared (step S4).
5).

Then, the movement command V given by the machining program or the handle operation is changed to the upper limit value Vmax. If not, the movement command V given by the machining program or the handle operation is output as it is in the same manner as described above (step S7), and the movement command V given by the machining program or the handle operation is changed to the upper limit value Vmax. .
Is exceeded (step S) instead of the movement command V given by the machining program or the handle operation.
6), the upper limit value Vmax. Of the safe tool feed speed allowed for the current tool and the tool feed direction. Is output (step S7).

Therefore, when the operator performs a cutting operation while manually feeding the cutting tool 1 using the guidance operation handle 111, the X-axis operation handle 108, or the Z-axis operation handle 109, Even if an excessive cutting feed rate is set by mistake as the feed rate of the workpiece, heavy cutting exceeding the cutting ability may cause cutting into the workpiece 2 or breakage of the cutting tool 1 There is no.

In the case where the outer shape of the rotator draws a quadratic curve, the cutting tool 1 which varies depending on the machining position is used.
, The upper limit value Vmax. Of the feed speed determined for each moving direction. Therefore, even if the contour of a quadratic curve such as an arc is machined under program control, it is possible to prevent inadvertent heavy cutting and achieve precise machining. it can.

When the feed rate is designated by the machining program, the minimum machining unit for which the feed rate can be designated is limited to one block. Therefore, no matter how the commanded feed rate in the machining program is adjusted, one block is required. It is not possible to cut the contour of a quadratic curve such as an arc specified by the above at the optimum feed rate over the entire section. However, in the case of the present embodiment, the movement of the tool is performed in real time for each calculation cycle of the tool movement command. Since the direction is determined and the maximum value of the tool feed speed is regulated in accordance with the direction of movement, it is not limited to the command feed speed setting unit such as one machining block, but always responds to the tool feed direction. It is possible to perform cutting at the optimum tool feed speed.

For example, as shown in the example of FIG. 3, in the case where a circumferential groove of 1/4 arc is formed on the outer peripheral portion of the end face of the cylindrical processing material 2, the arc section AB is 1 in the machining program.
Since it is defined as one machining block, only a single feed speed can be specified for this one block, and there is no other choice but to apply the same tool feed speed to the section.

Therefore, if the maximum feed speed is 0.5 m / min. In accordance with the section shown in FIG.
, A feed speed of 0.5 m / min. Is inevitably applied to the section. However, in practice, the maximum feed rate that can be applied in a section is 0.
It is 1 m / min., And the section of heavy machining may cause machining abnormalities such as cutting.

If a feed speed of 0.1 m / min. Is set for the circular arc section AB with priority given to performing normal machining in the section, the 0.1 m / min.
n. The feed speed of n. will be applied, and the arc section AB
There is a problem that the machining time is redundant as a whole.

In this embodiment, the feed rate having the larger value among the sections and the maximum feed rate applied to the section, that is, the maximum feed rate 0.5 m /
min. or a value larger than min.
If you set it as a feed rate on the machining program,
For the section of FIG. 3 in which the tool moving direction is in the range of 315 ° to 360 °, the upper limit value of the section is 0.5 m / mi.
n. The feed rate of cutting is applied, and the tool moving direction is 2
Since the cutting feed rate of 0.1 m / min, which is the upper limit of the section, is applied to the section of FIG. 3 in the range of 70 ° to 315 °, cutting by heavy cutting is performed. It is possible to eliminate the problems that occur and make the entire processing time redundant, thereby achieving precise and smooth processing.

In FIG. 4, the tool moving direction is 180
Although the upper limit of the cutting feed rate is set as 0 m / min. For the direction of the range of ° to 225 ° and the direction of the tool moving direction of the range of 225 to 270 °, The purpose of this is to prevent a tool feed to an area where cutting using the cutting tool 1 is impossible, for example, to prevent an erroneous operation of cutting the work material 2 in a portion without a blade.

Naturally, operations such as feeding in the natural direction and cutting the tool 1 and letting the cutting tool 1 escape in the direction after cutting, or feeding in the direction and cutting and cutting the tool 1 in the direction after cutting are performed. However, when the cutting tool 1 is retracted from the workpiece 2, a substantial cutting load does not act on the cutting tool 1, so that the determination result of step S <b> 2 in FIG. In other words, the tool feed in the direction and the direction is allowed.

As described above, the cutting process using the cutting tool 1 has been described as an example of the embodiment. As described above, the upper limit value storage file is created for each type of tool attached to the lathe driven and controlled by the numerical controller 10. CMOS memory 1
4, the optimum machining control can always be performed according to the type of the tool mounted on the tool rest.

Of course, the present invention may be applied to a machine tool having three or more feed shafts, such as a milling machine.

[0049]

According to the present invention, it is possible to carry out cutting at an optimum feed speed at all times according to the moving direction of the tool and the type of the tool. Even when the tool feed speed set in the program is inappropriate, it is possible to prevent the occurrence of cutting due to heavy cutting and perform a smooth machining operation.

Further, since the limitation of the tool feed speed is applied only at the time of cutting, the approach operation and the rapid traverse of the tool outside the machining path can be carried out at a high speed by the usual handle operation as before. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a numerical control device with a feed speed limiting function according to an embodiment to which the present invention is applied and a lathe driven and controlled by the numerical control device.

FIG. 2 is a conceptual diagram illustrating an example of division in a tool feed direction.

FIG. 3 is a conceptual diagram showing an example of a tool feed speed applied in the case of arc cutting.

FIG. 4 is a conceptual diagram illustrating an example of an upper limit value storage file serving as a regulation value storage unit.

FIG. 5 is a view showing the appearance of an operation panel equipped with a tool feed handle.

FIG. 6 is a flowchart illustrating an outline of a speed limit process.

[Explanation of symbols]

 1 byte 2 Work material 10 Numerical control device with feed rate limiting function 11 Processor 12 ROM 13 RAM 14 CMOS memory 15 Interface 16 Programmable machine controller 17 I / O unit 18 Interface 19 Interface 21 Bus 30, 31 Axis control circuit 40, 41 Servo amplifier 50, 51 Servo motor 60 Spindle control circuit 61 Spindle amplifier 62 Spindle motor 70 CRT / MDI unit 71 Manual pulse generator group 72 External equipment 101 Spindle switch 102 Spindle stop switch 103 Coolant switch 104 Coolant stop switch 105 Tool change switch 106 Teaching switch 107 Playback switch 108 Operation handle for X-axis 109 Z Axis operation handle 110 Selection switch 111 Guidance operation handle 112 Direction selection key 113 Operation panel

Claims (5)

[Claims] 1. A numerical control device having a function of giving a relative movement between a tool and a work based on a movement command, a moving direction calculating means for calculating a moving direction of the tool or the work in real time, a tool or a work. Control value storage means for storing the upper limit value of the feed speed in correspondence with the movement direction of the tool or the work, and the movement direction of the tool or work calculated by the movement direction calculation means and the control value stored in the control value storage means. A feed rate limiting means for limiting a feed rate of a tool or a work based on the upper limit value so that a current value of the feed rate does not exceed the upper limit value. . 2. The apparatus according to claim 1, further comprising a restriction value storage means for each tool type, wherein the restriction value storage means is selected according to the type of the installed tool to regulate the feed speed of the tool or the workpiece. The numerical control device with a feed speed limiting function according to claim 1. 3. The numerical controller according to claim 1, wherein the feed speed of the tool or the workpiece is restricted only during cutting. 4. The apparatus according to claim 1, wherein a load of a servomotor for feeding the tool or the workpiece is detected, and a value thereof is compared with a set value to determine whether or not cutting is being performed. 3. A numerical controller with a feed speed limiting function according to 3. 5. The method according to claim 1, wherein the feed speed of the tool or the workpiece is regulated during execution of the machining program and / or manual operation by operating the handle. Numerical control unit with feed speed limit function.