JPS60228019A - Method of cutting controllably multiple thread screw in numerical control lathe - Google Patents

Abstract

PURPOSE:To minimize idle cutting in working a multiple thread screw by locating a tool in a certain position and delaying the start of working the multiple thread screw from the certain position by a time lag due to the lag of working start timing. CONSTITUTION:When a multiple thread screw is cut by a numerical control lathe, the working of the multiple thread screw is indicated during the working program. In working each thread of the multiple thread screw, a tool 7 is located in a certain position such as cut starting point in the direction of Z axis. Also, a lag of start timing of cutting each thread relative to that from the start point of cutting the screw having the reference number of threads is calculated as a time lag. And the start timing of working this screw is delayed by a time corresponding to the time lag. Thus, the working of each thread is controlled so that the working is started from a certain position such as cutting start point.

Description

Detailed Description of the Invention (a) 0 Technical Field of the Invention The present invention provides the following advantages:
This invention relates to a method for controlling the cutting of multi-thread threads in a numerically controlled lathe, which can greatly suppress the occurrence of unnecessary idle cutting parts, and can also easily machine threads with large pitches and a large number of threads.

(b), Background of the technology In recent numerically controlled lathes, a series of related machining is treated as one fixed cycle, and machining/program creation is done simply by inputting the fixed cycle from the keyboard etc. A so-called automatic program that can do this has been developed and put into practical use.

Although these automatic programs have made it possible for operators to create and input cannibal programs while referring to production drawings, there are still many points that need to be improved in these automatic programs.

(C), Prior Art and Problems Conventionally, when cutting a thread in this type of numerically controlled lathe, the feed of the tool is started by a one-rotation signal output from the spindle encoder. The rotation angle and tool position were synchronized. Therefore, when cutting a multi-thread thread, the rotation angle of the -spindle and the tool position are synchronized by shifting the cutting start position of the tool one pitch at a time in the +Z direction when cutting the second and third threads. I was letting it happen.

However, if the cutting start position is shifted in the +Z direction, there is a problem that the idle cutting portion from the start of feeding until the tool actually cuts the thread increases accordingly, and the machining time becomes longer. Furthermore, by shifting the cut II4 starting position in the +Z direction, the tool may hit the tail stock or go beyond the +Z direction S) low limit of the tool post, making machining impossible. This tendency becomes more pronounced as the pitch becomes larger and the number of threads becomes larger, and a countermeasure from the side is desired.

(d) 0 Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the present invention eliminates the need to shift the cutting start position in the +Z direction according to the number of threads to be machined when machining a multi-thread thread, and therefore: A numerically controlled lathe that can minimize the occurrence of unnecessary idle cutting parts, and eliminates interference between the tool and tailstock, and the turret exceeding the stroke limit, making machining impossible. The object of the present invention is to provide a method for controlling the cutting of multi-thread sewage.

(e) Structure of the invention 0 In other words, the present invention provides that when machining of multiple threads is instructed in the machine program, when machining each thread of the multiple threads, the tool is moved in the Z-axis direction. At the same time as positioning at a certain position, the deviation of the processing start timing of each thread from the fixed position of the reference number of threads is calculated as a delay time, and the processing start timing of the processing of the thread is calculated as a delay time. By delaying the time corresponding to the delay time, processing of each thread is started from the fixed position.

(f) 3 Embodiments of the Invention Hereinafter, embodiments of the present invention will be specifically described based on the drawings.

Fig. 1 is a diagram showing an example of a numerically controlled lathe to which the cutting control method for multi-start webbing according to the present invention is applied, Fig. 2 is a control block diagram of the numerically controlled lathe shown in Fig. 1, and Fig. 3 is FIG. 4 is a flowchart showing an example of a multi-thread thread cutting cycle program, and FIG. 5 is a cross-sectional view of a two-thread thread cutting process.

Numerical control lathe 1.1. t% As shown in Figure 1, main axis 2
The chuck 3 is rotatably provided with its center aligned with the chuck 3, and a workpiece 5 to be cut into a multi-thread thread is gripped and fixed to the chuck 3. A tail stock 6 is provided on the right side of the workpiece 5 in the figure to push and support the workpiece 5 against the chuck 3 side, and the main shaft 2,
Therefore, above the Z-axis in the figure, the tool rest 9 on which a plurality of tools 7 are mounted is aligned with the Z-axis in the figure, that is, in the direction of arrows A and B, and the X-axis, that is, in the direction perpendicular thereto, in the direction of arrows C and D. It is provided so that it can be freely moved and driven. Note that the tool rest 9 is indicated by arrows E and F.
The tool 7 is provided so as to be rotatable and fixed at every 90° in the direction, and a tool 7 suitable for machining the workpiece 5 can be selected and used.

As shown in FIG. 2, the numerically controlled lathe 1 has a main control section 9, and the main control section 10 includes a cutting nib program memory 11 and a multi-thread cutting nib program memory. 14,
A main axis control section 12, a feed axis control section 13, a starting signal output control section 15, and a delay time calculation section 16 are connected. A main shaft drive motor 17 is connected to the main shaft control unit 12.
A spindle encoder 19 is connected to the spindle drive motor 17 and is capable of outputting a one-rotation signal $1 for each rotation of the spindle drive motor 17 . Further, a feed shaft drive motor 20 is connected to the feed shaft control section 13 .

Since the numerically controlled lathe 1 has the above-described configuration, the main control unit 10 reads out the cannibal program PRO stored in the cannibal program memory 11 during machining, and executes the program assigned to the cannibal nib 4-gram PRO. Processing is performed using the steps described below. That is, the spindle drive motor 17 is rotated via the spindle control unit 12 at a predetermined rotation speed indicated in the machine program PRO, and the workpiece 5 is thereby rotated via the chuck 3.
is similarly rotated at a predetermined rotation speed, and further the feed axis control section 1
3 to drive the feed shaft drive motor 20 to move the tool rest 9
is appropriately moved in directions A, B, C, and D, and the tool 7 executes the predetermined machining shown in the cutting program PRO.

At this time, when cutting the workpiece 5 with multiple threads is instructed in the cutting nib 4-gram PRO, the main control unit 1
0 immediately searches the multiple thread cutting angle nib program memory 14, reads out and executes the multiple thread cutting angle program PS'P.

(Margins below) Normally, when cutting a thread, as shown in Fig. 3, the tool 7 moves from the end surface 5a of the workpiece 5 to an acceleration distance L1 required to reach a speed tj (t) suitable for cutting. Right side (
+2 direction), set the tool 7, then move the cutting edge 7a of the tool 7 in the D direction (-X direction) by an amount equivalent to the depth of cut D1 per cut, and position it at the cutting start point SP. do.

In this state, the spindle 2, and thus the workpiece 5, is rotationally driven via the spindle drive motor 17, and as a result, the spindle x;7:y-
When the one rotation signal s1 is output from the motor 19 (the one rotation signal is 360 degrees from the reference point where the spindle 2, therefore the workpiece 5 is located)
The blade will be cut when it rotates to 0. ), the start signal output control unit 15 immediately outputs the start signal s2 to the feed axis control unit 13, and in response to this, the feed axis control unit 13 drives the feed axis drive motor 2o, and the tool post 9 and the tool 7 begins to be fed in the incoming direction at a predetermined cutting speed. After idle cutting of the acceleration distance @Ll, the tool 7, which has reached the predetermined feed speed, cuts the screw 5b into the workpiece 5 with the depth of cut D1, as shown in FIG.
continue to form. The tool 7 moves in the A direction and when the predetermined range of thread cutting is completed, the tool 7 is retracted in the C direction and fast forwarded in the B direction to increase the acceleration distance iL1 again and the depth of cut further than the previous cutting. D1 [cutting amount D1 is
Normally, it is often different for each pass (a path in which cutting is performed from the cutting start point SP with a predetermined depth of cut, and then returns to the cutting start point SP again is called a "pass". The same applies below). . ] The tool 7 is positioned at the cutting start point sp where the cutting edge 7a is moved in the direction D, and as described above,
The screw 5b is machined by a start signal S2 output in synchronization with the one-rotation signal S1. In this way, when the cutting is performed a predetermined number of times, the cutting depth D2 of the workpiece 5 reaches the predetermined cutting depth DP, and cutting of the cutting edge 5b is completed.

By the way, when cutting a multi-thread thread, the above-described cutting operation is performed by changing the machining start timing at which the tool 7 starts to be fed from the cutting start point sp. That is, as shown in FIG. 4, the multi-thread thread cutting cycle program PSP starts with a parameter xSm (x is a parameter indicating the number of threads to be cut, and m is a parameter in the thread to be cut) in step S1. This is a parameter indicating the number of cuts.

), and in steps s2 and s3, first 1
Settings are made for the first cutting of the thread thread (X-1, m=1), and in step S4, from the cutting start point SP to the tool 7
The output timing of the activation signal S2 to start feeding is calculated. In this calculation, the spindle control section 12 drives the delay time calculation section 16 to calculate the calculation, and the result is calculated as the delay time D.
It is output to the activation signal output control section 15 as T.

Now, let us explain the case of cutting a double thread thread shown in Fig. 5.The first thread thread 5b and the second thread thread 5b
2, there is a difference of 180° in the rotation angle of the main shaft 2,
The difference in machining start timing, that is, the delay time rIIIDT of the start signal S2 with respect to the one-rotation signal S1, causes the spindle rotation speed to
[r, p, m, ], '(Equation 11 %Equation % Therefore, the starting signal output control unit 1.5 controls the cutting of the first thread with the output from the spindle encoder 19 of the 1-rotation signal S1. At the same time, the starting signal S2 is output to the feed axis control unit 13, but the cutting of the second thread is performed by the one-rotation signal S1.
After the time corresponding to the delay time DT shown in equation (1) has elapsed since the start signal S2 is output, the axis control unit 1
Control the output to 3. Then, the tool 7 positioned at the cutting start point SP on the right side of FIG. 3 by the acceleration pressure iL1 has its machining start timing delayed by an amount corresponding to 1800 rotation times of the workpiece 5, so that the second thread 5b
As shown in FIG. 5, the thread 5b is cut from an angular position shifted by 180° from the first thread 5b, thereby forming a two thread thread.

This statement also applies to multiple threads of four or more threads, and in this case, the equation showing the delay time DT per thread is shown in equation (2).

Therefore, when cutting an X thread (1≦X≦n), the delay time DT of the activation signal S2 with respect to the one rotation signal S1 is as shown in equation (3).

That is, after the delay time DT determined by equation (3) has elapsed, the start signal S2 is output to the feed axis control section 13.

In this way, when the output timing of the activation signal S2 for each strip is calculated in step S4, step S5
In step S6, the cutting depth D2 is updated by adding the cutting depth fiDl newly cut in the current processing (pass) to the previously processed cutting depth D2, and in step S6, the updated cutting depth is D2 is the predetermined depth D
Determine whether or not P has been reached, and check if the predetermined depth DP is still reached.
If the number of cuts has not been reached, the number of cuts is updated in step Sll, and the actual machining operation begins in step 310.

This machining operation is almost the same as that already described for machining a general thread. That is, regardless of the number of threads to be machined, the tool 7 is moved to a predetermined cutting start point S determined by the cutting depth D2 and the acceleration pressure IILI.
P, and from that position, after a predetermined delay time DT (including the case where DT=0) with respect to the one-rotation signal S1, a start signal S2 is outputted to drive the feed shaft control unit 13 and the feed shaft drive motor 20. The feeding of the tool 7 is started via the , and n-thread threads are machined.

In this way, the machining is performed, and if it is determined in step S6 of the multi-thread cutting cycle program PSP that the cutting depth D2 will reach the cutting depth DP in the next cut, the process proceeds to step S7. In step S8, it is determined how many threads the thread is currently being machined, and if the final thread is to be machined, step SIO is immediately entered to machine the final thread. If not, update the number of machining threads X in step S9,
Furthermore, initialize the number of cuts and proceed to step 510.
Start cutting.

Note that the one-rotation signal S output from the main shaft encoder 19
1 does not necessarily have to be of a type that outputs a signal every 360 degrees of the main shaft 2, and may of course be of a type that outputs a signal every predetermined angle. In short, any signal that can determine the 360° rotation of the main shaft can be employed as the one-rotation signal S1.

In addition, the tool rest 9 is equipped with an E
, it goes without saying that any type can be used in addition to the type that rotates in the F direction.

(g) 0 Effects of the Invention As explained above, according to the present invention, when machining of multiple threads is instructed in the Kani program PRO, processing of each thread of the multiple threads is possible. At this time, the tool 7 is positioned at a certain position such as the cutting start point SP in the Z-axis direction, and
Cutting start point S of the thread number that is the standard for the first thread etc.
The deviation in the machining start timing of each thread with respect to the machining start timing from P is calculated as a delay time DT, and the machining start timing of machining the thread is calculated as the delay time DT.
By delaying the time corresponding to , machining of each thread is started from the above-mentioned fixed position, so regardless of the number of threads to be cut, the tool 7 can be cut at a fixed position in the Z-axis direction. Machining can be performed by positioning at the starting point SP, and tool 7 can be adjusted according to the number of machining threads, unlike conventional methods.
It is no longer necessary to shift the cutting start position of Not only can this be suppressed, but also screws with a large pitch and a large number of threads can be machined without interference between the tool rest 9 and the tail stock 6, and without causing the stroke limit of the tool rest 9 to be exceeded.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a numerically controlled lathe to which the cutting control method for multi-start lathe according to the present invention is applied, Fig. 2 is a control block diagram of the numerically controlled lathe shown in Fig. 1, and Fig. 3 FIG. 4 is an enlarged view showing the state of cutting, FIG. 4 is a flowchart 1 showing an example of a multi-thread thread cutting cycle program, and FIG. 5 is a cross-sectional view of a double thread thread. 1 Numerical control lathe 5b Neshi SP/ Fixed position (cutting start point) DT...Delay time PRO...Kani program applicant Yamazaki Iron Works Co., Ltd. Agent Patent attorney Phase 1) Shinji (and 1 other person)

Claims (1)

[Claims] In a numerically controlled lathe whose drive is controlled based on the cutting nib program, when machining a multi-thread thread in the cutting nib program is instructed, when machining each thread of the multi-thread thread,
The tool is positioned at a constant position in the Z-axis direction, and the deviation in the machining start timing of each thread with respect to the machining start timing from the fixed position of the reference thread number is calculated as a delay time. A method for controlling the cutting of a multi-thread thread in a numerically controlled lathe, the processing start timing of which is delayed by a time corresponding to the delay time, so that processing of each thread is started from the fixed position.