JPH0466661B2 - - Google Patents

Description

[Detailed description of the invention] (a). TECHNICAL FIELD OF THE INVENTION The present invention relates to a drive control method for a steady rest device installed in a numerically controlled lathe for the purpose of preventing chatter of a workpiece.

(a). TECHNICAL FIELD OF THE INVENTION Normally, when machining a long rod-shaped workpiece in lathe machining, a steady rest device is used to prevent chatter that occurs during machining and to perform highly accurate machining.

(c). Prior Art and Problems Conventionally, when a steady rest device is used in a numerically controlled lathe, it has been necessary for an operator to manually position it. However, if you try to use the steady rest device during machining, it is extremely difficult to correctly set the steady rest device in the optimal position, and in reality, it is impossible to operate the steady rest device during machining. It was hot.

Therefore, operators have no choice but to change cutting conditions, tools, etc. through trial and error to eliminate chatter, and are forced to perform extremely inefficient work.

(d). Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the present invention provides a method for controlling the drive of a steady rest device in a numerically controlled lathe, which allows the numerically controlled lathe to properly position the steady rest device at a predetermined position. The first purpose is a steady rest device for numerically controlled lathes that allows the machine to determine whether or not the steady rest device can be used without the operator having to give any special instructions regarding the use of the steady rest device in the machining program. A second object of the present invention is to provide a drive control method.

(e). Structure of the Invention That is, the present invention provides a memory that stores a workpiece flat part table indicating the position of the flat part during machining of the workpiece, and sequentially rewrites the contents of the workpiece flat part table in accordance with the progress of machining.
During machining based on the machining program, it is calculated and determined whether the total length of the workpiece is longer than a predetermined length relative to the diameter of the workpiece, and as a result, if it is determined that the length is longer than the predetermined length, searches the workpiece flat part table in the memory to determine the flat part of the workpiece to be machined, and moves and positions the steady rest device to the determined flat part to support the workpiece being machined. It is composed of

(f). Embodiments of the Invention Hereinafter, embodiments of the present invention will be specifically described based on the drawings.

FIG. 1 is a control block diagram showing an example of a numerically controlled lathe to which the drive control method for a steady rest device according to the present invention is applied, FIG. 2 is a side view showing an example of a three-point steady rest device, and FIG. A side view showing an example of a two-point support steady rest device, FIG. 4 is a schematic diagram showing a workpiece flat part table stored in a workpiece flat part shape memory, and FIGS. 5 to 9 show control modes of the steady rest device. The figure shown in FIG. 10 is a diagram showing each dimensional relationship when determining the encounter point of the tool and steady rest device in follow-up control.

As shown in FIG. 1, the numerically controlled lathe 1 has a main control section 2, and the main control section 2 is connected via a bus line 3 to a keyboard 5, a workpiece flat part shape memory 6, and a machining program memory 7. , steady rest control section 9, mechanism operation control section 10, etc. are connected. Two steady rest devices 11 are connected to the steady rest control section 9 so that their drive can be freely controlled by the steady rest control section 9, and the steady rest devices 11 are connected to the steady rest control section 9 according to the support mode of the workpiece 15 as shown in FIG. As shown in FIG. 3, there is a three-point support steady rest device that supports the workpiece 15 with three support rollers 11a, and a two-point support steady rest device that supports the workpiece 15 with two support rollers 11a as shown in FIG. There is a device. Incidentally, the steady rest devices 11 can be selectively used as appropriate by attaching them to the bed 16 of the lathe as necessary. In addition, the steady rest device 11 is attached to the bed 16.
The two-point steady rest device is provided so as to be movable and driven in the Z-axis direction, that is, in the direction perpendicular to the plane of the paper in FIGS. It is also provided so that it can be driven freely. The three-point support steady rest device 11 includes three support arms 11b to which support rollers 11A are attached.
is provided to be openable and closable in the directions of arrows A and B, and by opening and closing the support arm 11b,
It is possible to support the workpiece 15 and prevent interference between the support arm 11b and a tool that approaches during machining. The mechanism operation control unit 10 also includes a first
As shown in the figure, a main shaft 12, a tool rest 13, etc. are connected to each other so as to be freely controllable.

Since the numerically controlled lathe 1 has the above configuration, when machining, the machining program PRO is called from the machining program memory 7 to the main control section 2, and
output to the mechanism operation control section 10, and the mechanism operation control section 1
0 controls the drive of the tool rest 13 and the spindle 12 based on the machining program PRO, but as machining progresses, if machining using the steady rest device 11 is instructed during the machining program PRO. , the main control unit 2 runs the machining program PRO.
The steady rest device 11 is driven and controlled based on this to position the steady rest device 11 at a predetermined position.

That is, if the Z coordinate value Z1 at which the steady rest device 11 should be positioned is specified in the machining program PRO, the main control section 2 immediately moves the steady rest device 11 to a predetermined position via the steady rest control section 9. The workpiece 15 is positioned at the Z coordinate Z1 and supported at that position, and processing is started. In addition, steady rest device 11
As shown in Fig. 5, since two machines are provided for one lathe 1, the machining program PRO
If the coordinate value Z1 supported in the workpiece 15 is larger than L/2 of the total length L of the workpiece 15 or larger than the parameter value preset in the steady rest control section 9 (therefore, the coordinate value Z1 is (if located on the side)
is the steady rest device 11 on the chuck 17 side in FIG.
A to the coordinate value Z1, and if not (therefore, if the coordinate value Z1 is located on the tail stock side), move the steady rest device 11B on the tail stock 19 side to the coordinate value Z1 to perform positioning. conduct. Further, the steady rest device 11 used may, of course, be supported by either two-point support or three-point support, as described above.

Next, if the coordinate value Z1 for positioning the steady rest device 11 is not specified in the machining program PRO, or if machining using the steady rest device 11 is not specifically instructed, the main control unit 2
First, workpiece 15 in the machining program PRO
Based on the material diameter D and total length L, determine whether the processing should be performed using the steady rest device 11 (1)
Calculations are made based on the formula (that is, the main control unit 2 controls the steady rest device 11 for all machining operations instructed in the machining program PRO except for those for which the positioning coordinate value Z1 of the steady rest device 11 is specified). Use equation (1) to determine whether or not it should be used.)

L<αD ……(1) (α is a parameter set in advance in the numerically controlled lathe 1) If it is determined that L<αD, the material diameter D is sufficiently large compared to the total length L, so Steady rest device 1
1 during machining, and therefore, the main control unit 2 starts machining without using the steady rest device 11 during machining based on the machining program PRO.

If it is determined that L>αD, by using the steady rest device 11, it is possible to effectively suppress the chatter that occurs during machining. A command is given to position the device 11 to a predetermined position.

That is, the steady rest device 1 performed by the steady rest control section 9
1, automatic positioning control includes a steady rest device 11
moves following the movement of the machining tool in the Z-axis direction. (1) Follow-up control and simply two steady rest devices 1
Processing is performed by positioning at least one of the steady rest devices 11 at a predetermined position. (2) There are two types of support position optimization control.

(1) Follow-up control is used when the machining specified by the machining program PRO is a machining other than thread cutting or grooving, and the length of the machining area in the Z-axis direction is set in advance as a parameter in the numerically controlled lathe 1. This is a control method that is performed when the value is greater than or equal to the specified value, and provides the most accurate machining with the least chatter.

That is, when performing follow-up control, the steady rest control unit 9 searches the workpiece flat part shape memory 6,
The current flat part of the workpiece 15, that is, the parallel bar-shaped part (for example, the part SA in FIG. 9,
(SC, SE, etc.), determine the coordinate values of the parts where the steady rest device 11 can be set. As shown in FIG. 4, the workpiece flat part shape memory 6 stores the coordinate values of the flat part 15a of the workpiece 15 to be machined, which has a width in the Z-axis direction that allows the anti-sway device 11 to be set, to the starting point and the coordinate value of the flat part 15a. It stores a workpiece flat part table TABL which stores the Z coordinate values Z _S , Z _E of the end point, and the diameter D (corresponding to the X coordinate value) of the relevant part. Therefore, the steady rest control unit 9 Workpiece flat part table of workpiece flat part shape memory 6
By searching TABL, it is possible to immediately know the distribution of flat portions 15a on which the steady rest device 11 can be set for the workpiece 15 to be machined. The contents of this workpiece flat part table TABL are rewritten as the machining by the machining program PRO progresses.
The tool path during machining, that is, the trajectory of the tool calculated by (The existence of the flat portion 15a whose X coordinate does not change and the formation condition are immediately known.) Therefore, the formation condition of the flat portion 15a of the workpiece 15 is immediately calculated by the main control unit 2, and based on the result, the main control unit Step 2 rewrites the contents of the workpiece flat part table TABL. ],
The steady rest control part 9 always has the latest flat part 15a on the claw.
You can know the formation status of.

As shown in FIG. 4, when the length L1 of the flat part 15a is equal to or less than a predetermined value, the workpiece flat part table TABL has a If the dimension ZR (see Figures 5 and 7) is smaller than the sum of the predetermined parameter values, it is assumed that the steady rest device 11 cannot follow the tool in synchronization with the workpiece flat table. An "x" indicating that tracking is not possible is placed in the tracking capability flag storage area FA in TABL.
Set the flag FLG. In addition, the length L1 is the dimension ZR of the support portion of the steady rest device 11 in the Z-axis direction.
If the value is larger than the value obtained by adding the predetermined parameter value to
In the tracking enable/disable flag storage area FA in TABL, a "○" flag FLG indicating that tracking is possible.
stand up.

Therefore, the steady rest control section 9 controls the steady rest device 1.
1B, the mechanism operation control unit 10 controls the tool rest 1.
3 to perform machining on the workpiece 15 based on the machining program PRO using the tool 20 mounted on the tool post 13, the movement is controlled in the direction of arrow C, for example, as shown in FIG. The workpiece 15 being machined was supported by the support roller 11a in the C direction at a feed rate equal to the feed rate of the tool 20 in the Z-axis direction, with respect to the flat part 15a machined by the tool 20, with a slight delay from the tool 20. Move and hold the shape. As a result, the steady rest device 11B is moved and driven in synchronization with the feed of the tool 20 on the almost opposite side of the tool 20 that is performing the machining operation, so that the workpiece 15 does not cause vibration in the steady rest device 11B. It is supported reliably and the machining is performed with high precision.

Also, since the parts SB, SD, etc. in FIG. 9 are tapered parts, the tool 20 of the steady rest device 11B
Since it is impossible to perform follow-up control when facing the workpiece 15, the support of the workpiece 15 by the steady rest device 11B is temporarily suspended, and the steady rest device 11A on the other chuck 17 side is moved to the workpiece 15 to be machined by the tool 20. Move to the position ZP closest to the machining part SB in the flat part 15a of the part SE closest to the part SB within a predetermined distance or more, where the flag FLG in the followability flag storage area FA is set to "○". let me,
The workpiece 15 is supported at the position ZP. In this state, the steady rest device 11B is separated from the workpiece 15 and the tool 20 is made to process the part SB.
The positioning operation for the next flat portion 15a of B starts. That is, the flat portion 15a to be processed next by the tool 20
is part SC, therefore, when the tool 20 moves from part SB to processing SC, steady rest device 11B
must be positioned at a predetermined position in the portion SC. This positioning position of the steady rest device 11B is called the encounter point MP, and the coordinate position of the encounter point MP is as follows.
As shown in FIG. 10, it is determined from equation (2).

l ₃ +K/f=2l ₁ +l ₂ +l ₃ +l ₄ /F+T ………(2) f: Tool feed speed (mm/min) F: Rapid feed speed of steady rest device (mm/min) l ₁ : Relief amount (Constant) (mm) l ₂ : Distance between the tool and the steady rest (mm) l ₃ : Distance to the encounter point (mm) l ₄ : Radius difference - clearance amount (mm) K: Distance of the steady rest with respect to the tool Follow-up delay amount (mm) T: Time constant (minutes) In other words, the distance _l3 from the tool 20 to the encounter point MP is _l3 = f( _2l1 + _l2 ++ _l4 )+F(fT-K)/F-f Based on the distance _l3 , the steady rest control unit 9 can calculate the Z coordinate value for positioning the steady rest device 11B (the current position of the tool 20 at the time of the distance _l3 calculation is known). ). As a result, the steady rest device 11B is positioned at the encounter point MP of the portion SC, the tool 20 finishes machining the portion SB and begins machining the portion SC, and the tool 20 further locates the Z coordinate position corresponding to the encounter point MP. After passing through and proceeding to the left in FIG. 10 by an amount corresponding to the predetermined delay amount K, the steady rest device 11B is moved in the X-axis direction by an amount equivalent to the clearance amount to support the workpiece 15, and the tool 20 is immediately moved. Follow-up control linked to feed in the Z-axis direction (in this case, arrow C direction) is entered. Note that when calculating the distance l ₃ , the distance l ₂ between the tool and the steady rest device is the distance at the time of calculating the distance l ₃ .
Furthermore, at the time of calculation of distance l ₃ (that is, the sampling time of distance l ₂ ), the steady rest device 11B is
Of course, equation (2) changes depending on whether or not the steady rest device 11B leaves the part SA before the steady rest device _11B leaves the part SA. The Z coordinate for positioning the steady rest device 11B is determined from the distance l ₃ at .

In this way, when the steady rest device 11B enters the follow-up control again, the steady rest control section 9
The steady rest device 11A that was supporting the workpiece 1
5 and move it to a predetermined standby position. In addition, in order to avoid calculations for determining the encounter point MP of the steady rest device 11B and complicated control such as positioning to the encounter point MP, the unfollowable portion SB,
If the flat portion 15a held by the SD is less than a predetermined value, the portion SC is also treated as an unfollowable portion, and the portions SB, SC, and SD are all supported by the steady rest device 11A. Of course, it is also possible to do so.

Next, we will discuss (2) support position optimization control, which is used in cases other than follow-up control.
In this case, the steady rest control unit 9 searches the workpiece flat part table TABL in the workpiece flat part shape memory 6, and if the position is the closest to the machining area to be performed and there are two of them, the A nearby flat portion 15a that does not interfere with the movement of the tool 20 during machining is found, the steady rest device 11 is moved to the found flat portion 15a to support the work 15, and machining is started.

At this time, if the determined distance d to the flat part 15a is d<L/2 with respect to the total length L of the workpiece 15, as shown in FIGS. The steady rest device 11B is moved to the flat portion 15a to support the workpiece 15, and if d≧L/2, the steady rest device 11A on the chuck 17 side is moved as shown in FIGS. 6 and 8.
is moved to the flat portion 15a, the workpiece 15 is supported in that state, and machining is started.

In addition, as shown in FIG. 5 and FIG. 6, when the three-point support steady rest device 11 is used, the above-mentioned
Position the predetermined steady rest device 11A or 11B on the flat portion 15a determined under the conditions shown in ,
Yet another steady rest device 11B or 11A
When the steady rest device 11A is set at the flat portion 15a determined under the conditions shown in ,
As shown in FIG. 6, the steady rest device 11B is positioned at a flat portion 15a at a distance of l _c from the chuck 17 within αD and closest to αD. When the steady rest device 11A is set at the flat portion 15a determined by the conditions, the steady rest device 11A is set at the flat portion 15a at the position _closest to αD when the distance from the tail stock 19 is within αD, as shown in FIG. Position the workpiece 1.
5 can be supported by two steady rest devices 11. Note that the workpiece 1 is supported by two such steady rest devices 11.
When the total length L of 5 is αD≦L<2αD−l (l is the distance in the Z-axis direction between the two steady rest devices 11A and 11B when they are closest to each other), that is, the workpiece When the total length L of 15 is not long, it is particularly effective in increasing the machining accuracy.

(g). Effects of the Invention As described above, according to the present invention, a memory such as the workpiece flat part shape memory 6 storing the workpiece flat part table TABL indicating the position of the flat part 15a during processing of the workpiece 15 is provided, and the workpiece flat part shape memory 6 or the like is provided. The contents of the workpiece flat part table TABL are sequentially rewritten according to the progress of machining, and when machining is performed based on the machining program PRO, it is checked whether the total length of the workpiece 15 is longer than a predetermined length with respect to its diameter such as D. As a result, if it is determined that the length is longer than a predetermined length, the workpiece flat part table TABL in the memory is searched to determine the flat part 15a of the workpiece 15 to be machined. Since the steady rest device 11 is moved and positioned on the determined flat portion 15a to support the workpiece 15 being machined, the operator has not given any instruction to use the steady rest device 11 in the machining program PRO. In both cases, the numerically controlled lathe 1 automatically determines the necessity and drives and controls the steady rest device 11, so that the workpiece 15 can be machined with high precision without causing chatter. Furthermore, steady rest device 1
1 is a positioning position (not necessarily a fixed position) based on the workpiece flat table TAB, which is rewritten as the machining progresses.As already mentioned, during follow-up control, the steady rest device 11 is The steady rest device 11 is driven to move in the Z-axis direction in synchronization with the movement of the tool 20, and therefore its positioning position has a certain width in the Z-axis direction. It is positioned at an appropriate position and can perform efficient processing.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an example of a numerically controlled lathe to which the drive control method for a steady rest device according to the present invention is applied, FIG. 2 is a side view showing an example of a three-point steady rest device, and FIG. A side view showing an example of a two-point support steady rest device, FIG. 4 is a schematic diagram showing a workpiece flat part table stored in a workpiece flat part shape memory, and FIGS. 5 to 9 show control modes of the steady rest device. The diagram shown in FIG. 10 is a diagram showing the dimensional relationships when determining the encounter point between the tool and the steady rest device in follow-up control. 1... Numerical control lathe, 6... Memory (work flat part shape memory), 11, 11A, 11B... Steady rest device, 15... Work, 15a... Flat part, D... Diameter (diameter), L ...Full length, PRO...Machining program, TABL...Workpiece flat part table.

Claims (1)

[Claims] 1. In a numerically controlled lathe in which one or more steady rest devices are movably provided, a memory is provided that stores a workpiece flat part table indicating the position of the flat part during machining of the workpiece, and the contents of the workpiece flat part table are stored. is sequentially rewritten according to the progress of machining, and when machining based on the machining program, it is calculated and determined whether the total length of the workpiece is longer than a predetermined length with respect to the diameter of the workpiece, and as a result, If it is determined that the length exists, search the workpiece flat part table in the memory to determine the flat part of the workpiece to be machined;
A drive control method for a steady rest device in a numerically controlled lathe, the steady rest device being configured to move and position the steady rest device on the determined flat portion to support a workpiece being machined.