JPH0256683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a spindle control method applied when performing simultaneous machining with two tool rests using a four-axis numerically controlled lathe.

(b) Background of the technology When machining is performed simultaneously using two turrets using a 4-axis numerically controlled lathe, determining the rotational speed of the main spindle is a big problem. For example, when machining the outer diameter, in order to control the circumferential speed to be constant, it is necessary to increase the rotation speed as the workpiece is cut and the diameter becomes smaller, but at the same time, the inner diameter To process at a constant rate, it is necessary to lower the rotational speed as the diameter increases through cutting.

(c) Conventional technology and problems Conventionally, in such cases, one of the turrets was focused on, and the rotational speed of the main shaft was adjusted so that the circumferential speed was constant at a speed suitable for cutting the blade of that turret. Either a control method was used, or a control method was used to control the rotation speed to be constant considering both tool rests.

However, in the former case, if you try to perform outer diameter machining on one turret and inner diameter machining on the other, the outer diameter machining will gradually change as the machining progresses. It is desirable for the rotational speed to increase, and the opposite is true for internal diameter machining, so giving priority to machining using one turret has the disadvantage that machining on the other turret tends to be difficult.

In the latter case, for the entire processing process,
A constant rotational speed is often maintained based on the turret with a lower circumferential speed, but in this case, although it is easier to create a machining program, it is inevitable that the machining efficiency will deteriorate. Furthermore, in order to increase machining efficiency, specifying the number of rotations in detail for each process requires a complicated program and requires a lot of time to create.

(d) Purpose of the invention In order to eliminate the above-mentioned drawbacks, the present invention aims to perform simultaneous machining using two turrets at an appropriate circumferential speed for both turrets without deteriorating machining efficiency. The object of the present invention is to provide a spindle control method for a four-axis numerically controlled lathe that allows the following.

(e) Structure of the Invention That is, the present invention provides a circumferential speed setting memory that stores speed data such as maximum and minimum values of circumferential speed depending on the type of machining and the part to be machined. Read the speed data corresponding to the type of machining to be performed and the part to be machined on each turret from the speed setting memory, calculate and determine the target speed from the constant speed data, and calculate the circumferential speed of the cutting edge of the tool in each turret. The average value should basically match the target speed, and in any case, the circumferential speed of the cutting edge of each tool post should be located between the maximum and minimum values of the circumferential speed of the read speed data. The rotation speed of the main shaft is controlled so as to

(f) Examples of the invention Examples of the invention will be described below based on the drawings.

Fig. 1 is a block diagram showing an example of the control section of a 4-axis numerically controlled lathe to which the present invention is applied, and Fig.
A diagram showing an example of the turret area of a numerically controlled axis lathe, Figure 3 is a flowchart showing an example of a circumferential speed determination program, Figure 4 is a sectional view showing a workpiece held in a chuck, and Figure 5 is a diagram showing two pieces. FIG. 6 is a diagram showing the maximum, minimum, and optimum circumferential speed of each machining performed on the tool post, and FIG. 6 is a diagram showing the relationship between the machining position and the spindle rotation speed.

The 4-axis numerically controlled lathe 1, as shown in FIG.
The main control unit 2 includes a program memory 3, a main axis control unit 5, a feed axis control unit 6,
Display 7, keyboard 9, circumferential speed calculation section 1
0, a circumferential speed setting memory 11, a circumferential speed determination control section 8, and the like are connected via a bus line 12. Further, a spindle drive motor 13 is connected to the spindle control section 5.
Two feed shaft drive motors 15 each having a transducer 16 attached thereto are connected to the feed shaft control section 6 .

On the other hand, as shown in FIG. 2, the lathe 1 has a chuck 17 attached to the main spindle, and a chuck 17 on which a tool 20 is attached, sandwiching the axis of the main spindle, that is, the Z axis 14. Two turrets 19A and 19B are Z axis 1
Arrows A and B directions parallel to 4 and X perpendicular to the Z axis
It is provided so as to be freely movable and driveable in the axial direction, that is, in the directions of arrows C and D.

Since the 4-axis numerically controlled lathe 1 has the above configuration, when machining the workpiece 21 using the lathe 1, the main control is performed via the keyboard 9 with the workpiece 21 mounted on the chuck 17. Command unit 2 to start machining. Then, the main control unit 2 reads the machining program PRO corresponding to the workpiece 21 held in the chuck 17 from the machining program memory 3, and based on the machining program PRO,
The main shaft drive motor 13 and the feed shaft drive motor 15 are drive-controlled via the main shaft control section 5 and the feed shaft control section 6 .

That is, during the machining program PRO, the type of machining (bar machining, profile machining, thread machining, drilling machining, groove machining, etc.) that each tool rest 19A, 19B should perform, the machining area (outer diameter, inner diameter, end face, etc.) ), workpiece material, tools used, degree of machining (rough machining or finishing machining)
Since the machining start position and the like are stored as machining information, the feed axis control unit 6 moves each tool rest 19 in the directions of arrows A, B or C, D, so that the tool rest 19 is attached to each tool rest 19A, 19B. The cutting edge of the tool 20 is positioned at the machining start position. On the other hand, the main control section 2 searches the circumferential speed setting memory 11 from the machining information of the machining program PRO, reads out the circumferential speed according to the type, part, and degree of machining, and the circumferential speed calculation section 10 and the circumferential speed determination control section Output to 8. The circumferential speed setting memory 11 stores circumferential speeds according to the type of machining, the degree of machining, and the part to be machined as speed data VDT in three categories: maximum value, minimum value, and optimum value. , the type, degree and location of processing are programmed.
When read from PRO, the circumferential speed suitable for the relevant machining is immediately output as the maximum, minimum, and optimum values.

Suppose that the inner and outer peripheries of a hollow cylindrical workpiece 21 as shown in FIG.
(machining 1), and when machining from point H to point G (machining 2) with the tool rest 19B, peripheral speed setting memory 1
Maximum circumferential speed of machining 1 and machining 2 read from 1
Assuming that V ₁ max, V ₂ max, minimum circumferential speeds V ₁ min, V ₂ min, and optimum circumferential speeds V ₁ opt, V ₂ opt have the relationships shown in FIG. , calculation section 1
The target peripheral speed Vc during machining is determined according to the peripheral speed determination program VPRO stored in 0.

That is, as shown in FIG. 3, in the circumferential speed determination program VPRO, machining 1 is
and machining 2 maximum circumferential speed V ₁ max, V ₂ max and minimum circumferential speed
As shown in Fig. 5, it is determined whether the areas sandwiched by V ₁ min and V ₂ min have overlapping portions PRT, and if they do not have overlapping portions PRT, the cutter It is determined that simultaneous machining of machining 1 and machining 2 using tables 19A and 19B is impossible, and the process proceeds to step S3.
The alarm is displayed on the display 7. If there is an overlapping portion PRT, step S4 is entered and the target circumferential speed Vc is determined as Vc=(V ₁ opt + V ₂ opt)/2... (1) That is, the optimum circumferential speed V ₁ opt in machining 1 and 2 is determined.
It is determined by taking the average of V ₂ opt. Target peripheral speed
Once Vc is determined, steps S5, S6, S7
The maximum circumferential speed Vmax of the overlapping portion PRT is determined in steps S8, S9, and S10, and the minimum circumferential speed Vmin of the overlapping portion PRT is determined in steps S8, S9, and S10. Next, if the target circumferential speed Vc obtained in step S4 is Vmin≦Vc≦Vmax (if the circumferential speed Vc is included in the overlapped portion PRT), the target circumferential speed Vc can be obtained by equation (1). However, if Vc<Vmin, the circumferential speed of equation (1) is used as is.
If Vc is located to the left of the overlapping part or PRT in Figure 5), steps S11, S12, and S13:
As the target circumferential speed Vc, the minimum circumferential speed of the overlapped portion PRT
Vmin is adopted, and if Vc > Vmax (when the circumferential speed Vc in equation (1) is located to the right of the overlapped portion PRT in Fig. 5), the overlapped portion is determined in step S14.
The maximum circumferential speed Vmax of PRT is adopted as the target circumferential speed Vc, and is output to the circumferential speed determination control section 8.

In this way, the target peripheral speed Vc is determined by the peripheral speed determination program.
Once determined based on VPRO, the main control section 2 rotates the drive motor 13 via the spindle control section 5 to move the workpiece 21 along with the chuck 17 to Z.
The tool rests 19A and 19B are rotated around the shaft 14.
Start processing based on.

On the other hand, the transducer 16 attached to the feed shaft drive motor 15 outputs position pulses PL1 and PL2 to the feed shaft control section 6 at every predetermined rotation angle of the motor 15, and the control section 6 outputs the pulses PL1 and PL2. By integrating the tool 2 mounted on the tool rests 19A and 19B, and therefore on each tool rest 19A and 19B.
The positions of the cutting edges 0 and 20 in the directions of arrows C and D with respect to the Z-axis 14, that is, in the direction of the X-axis, can be immediately known. The control unit 6 notifies the circumferential speed determination control unit 8 of the cutting edge position PX of each tool 20 in the X-axis direction. Since the current rotation speed of the spindle and therefore the workpiece 21 is outputted to the control section 8 from the spindle control section 5, each of The peripheral speeds Vt ₁ and Vt ₂ of the cutting edge of the tool 20 are calculated, and Vt=(Vt ₁ +Vt ₂ )/2 (2) is the target peripheral speed determined by the peripheral speed calculation unit 10.
The spindle rotation speed Ns is calculated so as to be equal to Vc, and is output to the spindle control section 5. As a result, the main spindle, and therefore the workpiece 21, is
The circumferential speed of the cutting edge of the tool 20 attached to B is Vt ₁ , Vt ₂
The rotation is controlled so that the average value Vt of is equal to Vc.

By the way, even if the rotation speed Ns of the spindle is controlled so that the average value Vt of the circumferential speeds Vt ₁ and Vt ₂ of the cutting edge of the tool 20 becomes Vc, depending on the size of the workpiece 21 etc., each tool rest 19A, 19B The circumferential speed of the cutting edge of the tool 20 is
Since there is a possibility that the circumferential speed exceeds the maximum value read from the circumferential speed setting memory 11 or falls below the minimum value, the circumferential speed determination control unit 8 determines the circumferential speed Vt of the cutting edge of each tool 20 from the cutting edge position PX. ₁ , when calculating Vt ₂ ,
The circumferential speeds Vt ₁ and Vt ₂ are the minimum circumferential speeds V ₁ min and V ₂ min and the maximum circumferential speeds V ₁ max,
It is determined whether or not the peripheral speed Vt 1 of the tool 20 of the tool post 19A that performs machining 1 is determined between V ₂ max and Vt ₁
The turret 1 that raises V ₁ max and performs machining 2
If the circumferential speed Vt ₂ of the tool 20 of 9B exceeds V ₂ max, the rotational speed Ns of the spindle is reduced. Also, conversely,
If the circumferential speed Vt ₁ falls below V ₁ min or Vt ₂ falls below V ₂ min, increase the rotational speed Ns and reduce the wind speed Vt ₁ ,
Determine the rotation speed Ns so that Vt ₂ is always V ₁ min≦Vt ₁ ≦V ₁ max ……(3) V ₂ min≦Vt ₂ ≦V ₂ max ……(4)
The spindle drive motor 13 is controlled via the main shaft drive motor 13. In addition,
If equations (3) and (4) cannot be satisfied even if the rotation speed Ns is adjusted, an alarm signal ALM is output to the main control unit 2, and the main control unit 2 outputs an alarm signal that indicates that simultaneous machining is not possible. This is notified to the operator via the display 7, and the drive of the spindle drive motor 13 and the feed axis drive motor 15 is stopped via the spindle control unit 5 and feed axis control unit 6 to interrupt machining, and the operator takes appropriate action. have appropriate treatment.

FIG. 6 shows the relationship between the spindle rotation speed Ns and the position of the cutting edge of the tool 20, ie, the machining positions of the tool rests 19A and 19B, when machining the workpiece 21 shown in FIG. 4. In the case of outer diameter machining (referred to as "machining 1"), as the machining position advances from point E to point F, the workpiece outer diameter D1 decreases, so the circumferential speed V ₁ max, V ₁ opt,
In order to maintain V ₁ min, the rotation speed Ns needs to be gradually increased. Conversely, in the case of internal diameter machining (referred to as "machining 2"), as the work progresses from point H to point G, the workpiece's internal diameter D2 increases, and the circumferential speed V ₂ max,
In order to maintain V ₂ opt and V ₂ min, it is necessary to gradually reduce the rotation speed Ns.

Therefore, first, the target circumferential speed Vc is determined by equation (1) using the circumferential speed determination program VPRO, and the main axis is set at the machining starting points E and H of each tool rest 19A and 19B.
The rotational speed is controlled by the circumferential speed determination control unit 8 so that the average value Vt of the circumferential speeds Vt ₁ and Vt ₂ becomes Vt=Vc.
Ns ₁ is determined, but as it is, the turret 19
Since the circumferential speed Vt ₂ of B is lower than the minimum circumferential speed V ₂ min,
The rotational speed Ns is increased from Ns ₁ to Ns ₂ where Vt ₂ =V ₂ min, and machining is started with formulas (3) and (4) satisfied (at this point, Vt>Vc). During machining, the inner and outer diameters of the workpiece 21 constantly change due to machining, so the circumferential speed determination control section 8 controls the tool post 19.
The cutting edge positions PX of the blades A and 19B in the X-axis direction are periodically input from the control unit 6, and the rotation speed Ns is controlled so that Vt ₂ =V ₂ min. As processing progresses,
The inner diameter D2 expands, and the average value Vt gradually reaches the target circumferential speed.
It approaches Vc and finally becomes Vt=Vc. From that point P1, the rotational speed Ns is controlled so that Vt=Vc (however, in any case, equations (3) and (4) must be satisfied). Processing progresses,
When the inner diameter D2 becomes larger, Vt ₂ > V ₂ max at the rotation speed Ns controlled by Vt = Vc, so Vt ₂
From the point P2 when = V ₂ max, Vt ₂ = V ₂ max
Gradually reduce the rotational speed Ns while maintaining
Processing is performed up to point F and point G.

In addition, in the above-mentioned embodiment, the circumferential speed setting memory 11
In addition, speed data such as maximum, minimum, and optimum circumferential speeds are provided for each type of machining, degree of machining, and location to be machined.
As described above, the case where VDT is stored, if the memory 11 stores at least the maximum and minimum values of circumferential speed according to the type of machining and the part to be machined, it is possible to determine the optimum value and the degree of machining. The corresponding circumferential speed etc. can be easily obtained by multiplying the maximum value and minimum value by a predetermined coefficient.

Also, when calculating the average value Vt of the target circumferential speed Vc and the actual circumferential speeds Vt ₁ and Vt ₂ , it is not just the average of both as shown in equations (1) and (2), but a certain amount of Of course, it is also possible to calculate it by weighting one of the machining speeds or the peripheral speed of the turret.

Further, in the above embodiment, the outer diameter of the workpiece 21 is cut with one tool rest 19A, and the inner diameter of the workpiece 21 is cut with the other tool rest 19B.
In the present invention, as long as simultaneous processing is performed, each tool rest 19
Of course, any combination of the processed parts (inner diameter, outer diameter, end face, etc.) of A and 19B can be applied.

(g) Effect of the Invention As explained above, according to the present invention, the circumferential speed setting memory 11 is provided which stores speed data VDT such as the maximum value and minimum value of the circumferential speed depending on the type of machining and the part to be machined. , speed data corresponding to the type of machining to be performed on each tool rest 19A, 19B and the machining part.
VDT is read from the memory 11, and the target circumferential velocity Vc is calculated and determined from the uniform velocity data VDT, and the tool 2 in each tool rest 19A, 19B is
In principle, the average value Vt of the circumferential speeds Vt ₁ and Vt ₂ of the cutting edge of 0 is made to match the target circumferential speed Vc, and in any case, the circumferential speeds Vt ₁ and Vt ₂ are in the center of the speed data VDT. Since the spindle rotation speed Ns is controlled so that it is located between the maximum and minimum circumferential speed,
Simultaneous processing using two tool rests 19A and 19B,
It is now possible to perform both machining within the appropriate circumferential speed range, eliminating the need for unreasonable machining on one turret and the need to specify the rotation speed of the spindle in detail on the machining program, as was the case in the past. . Note that the rotation speed Ns is controlled to change continuously as the machining progresses so that it basically matches the target circumferential speed Vc. It is possible to prevent the deterioration of machining efficiency that occurs when machining is performed at a constant low rotational speed based on , and to perform highly efficient machining.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the control section of a 4-axis numerically controlled lathe to which the present invention is applied, and Fig.
A diagram showing an example of the turret area of a numerically controlled axis lathe, Figure 3 is a flowchart showing an example of a circumferential speed determination program, Figure 4 is a sectional view showing a workpiece held in a chuck, and Figure 5 is a diagram showing two pieces. FIG. 6 is a diagram showing the maximum, minimum, and optimum circumferential speed of each machining performed on the tool post, and FIG. 6 is a diagram showing the relationship between the machining position and the spindle rotation speed. 1...4-axis numerical control lathe, 11...peripheral speed setting memory, 19A, 19B...turret, 21...work, V ₁ max, V ₂ max...maximum value, V ₁ min,
V ₂ min...minimum value, VDT...speed data, Vc...
...Target speed, Vt ₁ , Vt ₂ ...Cirferential speed of cutting edge, Vt...
Average circumferential speed of the cutting edge, Ns: Spindle rotation speed.

Claims (1)

[Claims] 1. In a 4-axis numerically controlled lathe that has two turrets and simultaneously processes workpieces mounted on the main spindle, the circumferential speed can be adjusted according to the type of machining and the part to be machined. A circumferential speed setting memory is provided that stores speed data such as maximum and minimum values, and when performing simultaneous machining, speed data corresponding to the type of machining to be performed and the machining area on each turret can be retrieved from the circumferential speed setting memory. In addition to calculating and determining the target speed from the read and constant speed data, the average value of the circumferential speed of the cutting edge of the tool in each tool post should basically match the target speed, and in any case, each tool post should A four-axis numerically controlled lathe configured to control the rotation speed of the main spindle so that the circumferential speed of the cutting edge is between the maximum value and the minimum value of the circumferential speed corresponding to the read speed data. spindle control method.