JPS6226041B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a numerical control method, and particularly to a numerical control method for controlling the movement of a movable object by setting a prohibited area within a movable range.

In numerically controlled machine tools, the maximum movable range of tools, tables, etc. (hereinafter referred to as movable objects) is determined based on the length of the ball and screw, etc., and the movable objects may go out of control due to a programming error or some other obstacle. However, if the movable object is exceeded (overtravel), this is immediately detected and the movable object is brought to an emergency stop.
In order to detect such overtravel, limit switches are usually installed at the maximum stroke points on the +X side, -X side, +Y side, and -Y side of the movable range, and dots are installed on the movable parts to detect overtravel. Overtravel is detected by detecting that the dock has stepped on the limit switch.

Incidentally, in a numerically controlled machine tool, there is a prohibited area into which movable objects cannot enter even if it is within the maximum movable range. FIG. 1 is an explanatory diagram illustrating the relationship between the prohibited area and the maximum movable range. In the figure, TA is an overtravel area, MA is a maximum movement area, and EPA ₁ and EPA ₂ are prohibited areas within the maximum movement area. No entry area EPA ₁ ,
EPA ₂ has almost the same shape as the chuck shape at the lathe, so that the tool does not enter the prohibited area EPA ₁ ,
When entering EPA ₂ , the tool and chuck will come into contact with each other, causing breakage and destruction of the tool and chuck.

Now, conventionally, there has been no easy means for detecting that a tool has entered this prohibited area.

For example, contact between a tool and a chuck, etc. can be detected by attaching a sensor, limit switch, etc. to the chuck, etc., but this method makes it difficult to attach the sensor, etc. to the chuck, etc., and complicates the chuck structure. , leading to high costs. Furthermore, with this method, when changing the prohibited area,
This has the disadvantage that modification work is complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method that can easily and reliably detect the entry of a movable object such as a tool into a prohibited area, and furthermore, can easily change the prohibited area by programming means.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 2 is a block diagram for realizing the numerical control method according to the present invention, Fig. 3 is a relationship diagram between the movable range and the prohibited area, and Fig. 4 shows the movable range divided into many small areas, and each small FIG. 5 is an explanatory diagram of the case where entry prohibition information is written in an area. FIG. 5 is an explanatory diagram of the relationship between each small area and a memory address when the entry prohibition information of eight small areas is stored as one word in the memory.

In the figure, reference numeral 1 denotes a parameter storage device, which is composed of a random access memory (RAM) and stores fast forward speed, acceleration/deceleration time constants,
It stores various parameters such as prohibited areas based on second and third limit information. Reference numeral 2 denotes a non-volatile memory such as a magnetic bubble memory, in which the above-mentioned parameters are written, and the parameters are read out to the parameter storage device at the same time as the power of the numerical control device is turned on. 3 is an arithmetic processing unit which calculates coordinate values (X, Z), (I, K), (X ₁ ,
Arithmetic processing is performed based on Z ₁ ), (X ₂ , Z ₂ ) (see Figure 3) to create entry prohibition information. That is, the overtravel area, maximum movable area MA, and prohibited areas EPA ₁ and EPA ₂ are set as shown in Fig. 3, and the maximum movable area MA is, for example,
If the maximum movable area MA is divided into 24 equal parts in the axial direction and 16 equal parts in the Z-axis direction, and the maximum movable area MA is divided into 24 x 16 small areas maij (see Figure 4), the calculation processing unit 3 Area maij (i = 1, 2, ... 16, j = 1, 2, ...
...24) is within the prohibited area EPA ₁ or EPA ₂ . Then, if the small area maij is an entry-prohibited area, it outputs "1", and if it is not an entry-prohibited area, it outputs "0". 4 is a write control circuit which converts the access prohibition information output from the calculation unit 3 into 8 bits (1
(words) are written to the memory 5, which will be described later. Reference numeral 5 denotes a memory for storing entry prohibition information, where one bit corresponds to one small area maij, and 8 bits are read/written in units of 8 bits. In addition, eight small areas {ma ₁ , ₁ ,
ma ₁ , ₂ , ...ma ₁ , ₈ }, {ma ₁ , ₉ , ma ₁ , ₁₀ ...
ma ₁ , ₁₆ }, {ma ₁ , ₁₇ , ma ₁ , ₁₈ , ...ma ₁ , ₂₄ }...
...{ma ₁₆ , ₁₇ , ma ₁₆ , ₁₈ ... ma ₁₆ , ₂₄ } 8-bit entry prohibition information forms one word, and each word is written to address A ₀ , A ₁ , A ₂ ...A ₄₇ of memory 5. (See FIGS. 4 and 5). 6 is a read control circuit, 7 is an address register, and 8-bit entry prohibition information is read/written to the memory address of the memory 5 specified by the address register 7. Reference numeral 8 denotes an output register that stores 8-bit entry prohibition information read out by the reading circuit 6. Reference numerals 9 and 10 are current position counters that indicate the current position of the movable object in the X-axis direction and the Z-axis direction, respectively, and feedback pulses XFp and ZFp are generated from a pulse coder (not shown) each time the movable object moves by a predetermined amount. The current position of the movable object is indicated by adding and reversing the numbers according to the direction of movement. In addition, instead of the feedback pulses XFp and ZFp, X, which is generated from a pulse distributor (not shown),
The Z-axis direction distribution pulse is sent to the current position counters 9 and 10.
It is also possible to add and inversely count. 9a is the small area maij
9b is an acceleration counter with a capacity of 8, and 9c is an acceleration counter with a capacity of 3. Therefore, the reversal counter 9c divides the length of the maximum movable area MA in the X-axis direction into three (X ₁ , X ₂ ,
X ₃ (Fig. 4), indicates in which region of X ₁ to X ₃ the movable object exists. Further, the reversal counter 9b indicates in which small region maij constituting the region (X ₁ , X ₂ , X ₃ ) the movable object is present;
The acceleration/reversal counter 9a is the X in the small area maij of the movable object.
Indicates the axial position. 10a and 10b are reversible counters constituting the current position counter 10, and the capacity of the counter 10a is equal to the length l _Z in the Z-axis direction of the small area maij.
(FIG. 4), and the capacity of the counter 10b is 16. Therefore, the reversible counter 10b indicates in which small area in the Z-axis direction the movable object is present, and the reversible counter 10a indicates the position of the movable object in the small area maij in the Z-axis direction. A decoder 11 decodes the contents of the current position counters 9 and 10, and sets the memory address corresponding to the small area maij where the movable object is present in the address register. 12 is a decoder, which converts the contents of the add/reverse counter 9b from binary to 10
Convert to decimal. That is, if the content of the addition/reversal counter 9b is i, the decoder 12 outputs a line li (i=1, 2...
8) outputs “1”. 13 is a gate circuit,
For example, eight AND gates 13a, 13b...
Consists of 13h and one or gate 13i,
Each AND gate 13a . Reference numeral 14 denotes a flip-flop, which is set by a preparation function command G23 from an operation panel or tape, and reset by a preparation function command G22. Note that the preparation function command G22 prohibits the tool from entering the set entry-prohibited area,
G23 is a command that allows the tool to enter the set prohibited area. 15 is an AND gate which takes the AND of the set output of the flip-flop 14 and the output of the OR gate 13i, and when G22 is commanded, the tool enters the prohibited area EPA.
If you enter the emergency stop signal
Output EMS.

Now, in the present invention, the overtravel region
Settings for TA, prohibited area EPA ₁ , and EPA ₂ include coordinate values that can identify the boundary line of the area, information indicating the inside and outside of the boundary, and the set prohibited area.
This is done by inputting preparation function commands G22 and G23 that prohibit or permit access to tools into EPA ₁ and EPA ₂ . In the following example, it is assumed that the overtravel area TA and the prohibited entry areas EPA ₁ and EPA ₂ are all rectangular, and each area is
Information indicating OTA, EPA ₁ , and EPA ₂ is called first limit information, second limit information, and third limit information.

The first limit information is a value indicating the maximum stroke length of the machine in the ±X and ±Z directions, and is input from a manual data input switch (hereinafter referred to as MDI) provided on the operation panel. In other words, the first limit information is the maximum stroke point of the machine in the ±X and ±Z directions as parameters, and the MDI is
, and is set in the nonvolatile memory 2.
Then, the area outside the set maximum stroke point automatically becomes the overtravel area. Note that once this parameter is set by the machine manufacturer, it should not be changed thereafter.

The second limit information is the coordinate values (X ₁ , Z ₁ ), (X ₂ , Z ₂ ) of points P ₃ and P ₄ (see Figure 3) that specify the boundary of the prohibited area EPA ₁ (however, X ₁ >X ₂ , Z ₁ >Z ₂ ), etc., and is set in the nonvolatile memory 2 by inputting the above coordinate values as parameters from the MDI. The area inside the set boundary automatically becomes a prohibited area. Note that by commanding the preparation function command G22, it is possible to prohibit the entry of tools into the set no-entry area EPA ₁ , and by commanding G23, it is possible to allow tools to enter the no-entry area EPA ₂ . .

The third limit information is the coordinate values (X, Z), (I, K) of points P ₁ and P ₂ (see Figure 3) that specify the boundary of the prohibited area EPA ₂ (X>I, Z> K), etc., and is set in the non-volatile memory 2 by inputting the above coordinate values in response to instructions from the MDI or from a tape or the like. Then, either the inside or outside of the set boundary becomes a prohibited area, and the inside or outside of the set boundary becomes a prohibited area.
The parameter ``outside'' is input in advance from the MDI as a parameter and set in the non-volatile memory 2. Further, similarly to the second limit area EPA ₁ , the tool can be prohibited from entering the prohibited area in G22, and the tool can be allowed to enter the prohibited area in G23. Note that setting or changing the third limit area EPA ₂ by command is performed by the following command.

G22 X…Z…I…K…＊ Next, the operation of the present invention will be explained.

Prior to machine operation, first, second,
Third limit information, fast forwarding speed, etc. are input as appropriate parameters and written into the non-volatile memory 2.
First, when the numerical control device is powered on, parameters set in the nonvolatile memory 2 are read out to the parameter storage device 1 by a processing device (not shown).

Then, based on the first limit information, second limit information, and third limit information, the arithmetic processing section 3 performs 8
The entry prohibition information of the small areas {ma ₁ , ₁ , ma ₁ , ₂ . . . ma ₁ , ₈ } is calculated and an 8-bit entry prohibition information group IIG is output. Since the address register 7 is initially reset to zero, the write control circuit 4
writes the entry prohibition information group IIG to address _A0 of the memory 5, and at the same time increments the contents of the address register 7 by one step. Thereafter, the arithmetic processing unit 3 sequentially calculates {ma ₁ , ₉ ,
...ma ₁ , ₁₆ }, {ma ₁ , ₁₇ ...ma ₁ , ₂₄ }...
The entry prohibition information of {ma ₁₆ , ₁₇ , ...ma ₁₆ , ₂₄ } is calculated and an 8-bit access prohibition information group IIG is sequentially output, and the write control circuit 4 stores this IIG at address _A1 of the memory 5 . Address A ₂ ...Write to address A ₄₇ . This results in
The writing operation of the prohibited areas EPA ₁ and EPA ₂ to the memory 5 is completed. Incidentally, the flip-flop 14 is reset when the power is turned on. Further, for convenience of explanation, point RP (see FIG. 3) will be used as the machine origin from now on.

When the write operation of the entry-prohibited area to the memory 5 is completed, the processing becomes possible, and the numerical control device performs numerical control processing according to the processing program stored in the processing tape or the non-volatile memory 2. When the tool moves in the X-axis direction or Z-axis direction as a result of this numerical control process, a feedback pulse is generated every time the tool moves in the X-axis direction or Z-axis direction by a predetermined amount.
XFP and ZFP are generated from a pulse coder (not shown) and input to current position counters 9 and 10, respectively. Current position counters 9 and 10 add and invert XFP and ZFP according to the moving direction of the tool. Therefore,
The current position counters 9 and 10 always store the current position of the tool. Current position counter 9,1
The content of 0 is input to the decoder 11, where it is converted into a memory address corresponding to the small area maij where the tool exists, and is set in the address register 7. The read control circuit 6 reads out 8-bit entry prohibition information from the memory address indicated by the address register 7 and sets it in the output register 8.

On the other hand, the contents of the addition/reversal counter 9b are determined by the decoder 12.
is input and converted from binary to decimal.

Now, if the small area where the tool exists is ma ₄ , ₁₀ (Fig. 4), the count value of the reversal counter 9b is 1.
Therefore, “1” is output only to the output line _l2 of the decoder 12.
is output, and "0" is output to the other output lines _l1 , _l3 to _l8 . Further, 11111000 is read out from the memory address A ₁₀ (see FIG. 5) and stored in the output register 8. AND gate group 13a to 13h
are the contents of the 1st, 2nd...8th bits of the output register 8 (access prohibition information for small areas _ma4 , ₉ , _ma4 , ₁₀ ... _ma4 , ₁₆ ) and the decoder output lines _l1 , _l2 ... ...l Since it is configured to output the AND of ₈ , the output of the AND gate 13b becomes "1",
The output of the OR gate 13i also becomes "1". At this time, since the flip-flop 14 has been reset, the output of the AND gate 15 becomes "1", an alarm signal EMS is output, and the tool immediately stops. Note that if the tool does not exist in the prohibited area, the output of the OR gate 13i becomes "0" and the alarm signal EMS is not output.

In addition, there is a prohibited area set within the movable area.
If G23 is commanded to allow the tool to enter EPA ₁ and EPA ₂ , the flip-flop 14 is set and the AND gate 15 is closed, so as long as the tool is within the movable area, the alarm signal EMS will not be generated.

FIG. 6 is an explanatory diagram illustrating an application example of the present invention. In lathing, the tailstock is moved back and forth in the Z-axis direction depending on the length of the workpiece, and the prohibited area EPA ₂ for tools changes depending on the position of the tailstock.
Therefore, in the present invention, the prohibited area EPA ₂ is set as a third limit area, and this area is changed depending on the position of the tailstock. This change can be easily made by inputting G22X...Z...I...K...* as described above.

7 to 9 are explanatory diagrams of other embodiments of the present invention. FIG. 7 is an explanatory diagram in which the movable range is divided into small areas according to the shape of the prohibited area, and FIG. FIG. 9, which is an explanatory diagram when entry prohibition information is written, is a block diagram for realizing the numerical control method according to the present invention. In the figure, the same parts as in FIGS. 2 and 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, 31 is an arithmetic processing unit that indicates coordinate values (X, Z), (I,
K), (X ₁ , Z ₁ ), (X ₂ , Z ₂ ), the entire area is divided into 8 in the Z-axis direction and 7 in the X-axis direction, and the area is divided into 56
It divides into small areas 00, 01...0F...37, calculates entry prohibition information for each small area 00, 01...0F, 11, 12...37, and stores the entry prohibition information in memory.
write to. That is, one bit is assigned to the memory 5 corresponding to each small area as shown in FIG. “0” is written to. In addition, 00, 01, ...37 are hexadecimal values, and 00, 01 ...37 in Figures 7 and 8
correspond to each other. In addition, the arithmetic processing unit 31
Based on the contents of the current position counters 9 and 10 in the axial and Z-axis directions, that is, based on the current position of the movable part, it is calculated which bit in the memory 5 is to be referred to.

Next, the operation shown in FIG. 9 will be explained. Now, if a movable part (for example, a tool) exists at point AP (small area 11) in FIG.
X ₀₂ (=X ₁ ) and current tool position Xp, and when moving in the -X direction, boundary value X ₀₁ (=X) and Xp, +
When moving in the Z direction, the boundary value Z ₀₁ (=K) and the current tool position Zp are compared, and when moving in the −Z direction, the boundary value Z ₀₀ and Zp are compared. If the boundary line in the X direction is crossed, the contents of the register (11) indicating the current address of the memory 5 will be incremented by ±8 according to the direction of movement, and if the boundary line in the Z direction is crossed, the content of the register (11) indicating the current address of the memory 5 will be increased by ±8 according to the direction of movement. Similarly, the result of the calculation is set to the address register 7 by ±1. For example, border
If X ₀₂ is exceeded, address register 7 contains 19 (= 11
+8) is set, and if the boundary line _X01 is crossed, 09 (=11-8) is set in address register 7,
If it crosses the boundary line Z ₀₁ , 12 is written to address register 7.
(=11+1) is set, and the current address corresponding to each small area where the tool exists is set in the address register 7. Note that when the tool simultaneously moves in the X and Z axes directions, the arithmetic processing unit 31 calculates the X and Z direction boundaries and Xp, depending on the direction of movement.
Zp is constantly compared and the contents of the address register 7 are updated each time the boundary line is crossed.

Therefore, the tool is now moving in the +Z direction to the boundary line.
If Z ₀₁ is exceeded, 12 is set in the address register 7, and the read control circuit 6 reads the fifth data from the memory 5.
The contents ("1") of the shaded area in the figure are read out, and it is detected that the tool has entered the prohibited area, thereby generating an alarm and lighting up the alarm lamp of the numerical control device. Further, when the tool moves in the +X direction and exceeds the boundary value _X02 , 19 is set in the address register 7 and "0" is read from the memory 5.

In the above explanation, the movement control of tools, tables, etc. in a machine tool has been explained, but the present invention is not limited to this, but can also be applied to movement control of a robot arm, etc. Further, in the embodiment, the shape of the prohibited area is rectangular, but it may be triangular or circular. Further, in the embodiment, for convenience of explanation, the overstroke point RP (FIG. 3) has been described as the mechanical origin, but the mechanical origin may be located anywhere within the movable region. In addition, in the embodiment, the entry prohibition information was calculated and obtained after the power was turned on to the numerical control device, and was stored in the memory (RAM). It is also possible to read out the data from the non-volatile memory and store it in the RAM, thereby omitting the arithmetic processing after the power is turned on. Furthermore, in the examples,
Although hardware is provided for each function, it is also possible to configure the system to be processed by a microprocessor or the like. Further, the prohibited entry areas set by the first to third limit information may overlap each other.

As described above, according to the present invention, the prohibited area can be easily set by the programming means without using limit switches, sensors, etc., and the prohibited area can also be changed by the programming means. Furthermore, it is possible to reliably determine whether a movable object such as a tool has entered the prohibited area. Further, in the present invention, the movable area is divided into a large number of small areas, entry prohibition information is calculated for each small area, the calculation results are stored in memory, and the entry prohibition information is calculated according to the current position of the movable object. Since the entry-prohibited information is read from the memory and it is determined whether or not the entry is allowed into the entry-prohibited area, there is no need to calculate whether or not a movable object exists in the entry-prohibited area. The above determination can be made quickly and without increasing the burden on the processing device.

Furthermore, the above-mentioned no-entry area can be invalidated or validated by simply issuing the preparation function commands G23 and G22.
Further, the prohibited area can be easily changed and set.

The position of the tool to be checked for trespassing is the position of the tool on the program path, and if the tool diameter has been corrected correctly, it will be the tip of the tool.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram explaining the relationship between the no-entry area and the maximum movable range, Fig. 2 is a block diagram for realizing the numerical control method according to the present invention, and Fig. 3 is the relationship between the movable range and the no-entry area. Figure 4 is an explanatory diagram when the movable range is divided into many small areas and entry prohibition information is written in each small area, and Figure 5 is an explanatory diagram of the case where the entry prohibition information of 8 small areas is written as one word. FIG. 6 is an explanatory diagram illustrating the relationship between each small area and a memory address when storing it in a memory, and FIG. 6 is an explanatory diagram illustrating an application example of the present invention.
7 to 9 are explanatory diagrams of other embodiments of the present invention. FIG. 7 is an explanatory diagram in which the movable range is divided into small areas according to the shape of the prohibited area, and FIG. FIG. 9, which is an explanatory diagram when entry prohibition information is written, is another block diagram for realizing the numerical control method according to the present invention. DESCRIPTION OF SYMBOLS 1... Parameter storage device, 2... Non-volatile memory, 3, 31... Arithmetic processing unit, 4... Write control circuit, 5... Memory, 6... Read control circuit, 7...
...Address register, 8...Output register, 9,
10...Current position counter, 11, 12...Decoder, 13...Gate circuit, 14...Flip
Flop.

Claims (1)

[Scope of Claims] 1. In a numerical control method that controls the movement range of a movable object by setting a prohibited area within the movement range of the movable object, there is provided a means for dividing the movement range of the movable object into a large number of small areas. , an entry-prohibited area setting means that is capable of setting a movable range of the movable object as an entry-prohibited area of the movable object by a program means, and the entry-prohibited area is variable by the program means; and a coordinate value of the small area; a calculation means for calculating whether or not the small area is a prohibited area based on the information from the prohibited area setting means; and a storage means for storing the prohibited entry information obtained by the calculation; A numerical control method characterized in that the movement of the movable object is controlled by reading entry prohibition information of a small area in which the movable object is located from a storage means that stores entry prohibition information based on information of the small area in which the movable object is located. 2. The numerical control method according to claim 1, wherein the set prohibited area is invalidated by a command.