JPS6116569B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a numerical control device having a thread cutting function, and an object thereof is to improve the thread cutting function.

A conventional numerical control device having a thread cutting function is shown in FIG. In the figure, 1 is a command discrimination register that determines the input machining program command, 2 is an F register that stores the commanded screw lead, 3 is an S register that commands the rotation of the workpiece (spindle), and 4 is the main shaft 5 is a feed rate control circuit that calculates the feed rate of the tool post, 6 is a pulse distributor, 7 is a remaining distance register that sequentially stores the remaining distance of the command, 8
is the servo control circuit.

Next, the operation will be explained. When the thread lead F, thread length L, and rotation speed S of the workpiece (spindle) are input as a thread cutting command from an input device such as a tape, the command discrimination register 1 indicates that the thread lead F is in the F register 2, Further, the thread length L is transferred to the remaining distance register 7, and the rotation speed S of the spindle is transferred to the S register 3, respectively, and a thread cutting command is turned on. The feed speed control circuit 5 sequentially calculates the feed speed of the tool post for cutting the commanded lead thread based on the contents of the F register 2 and the rotation pulse from the rotation encoder 4, and sends the feed speed to the pulse distributor 6. tell. The pulse distributor 6 generates a pulse train (pulses/second) for moving the turret according to the speed command from the feed speed control circuit 5 and sends it to the remaining distance register 7 and the servo control circuit 8. Remaining distance register 7 is command discrimination register 1
The pulse length L sent from the pulse distributor 6 is stored, and the pulse sent from the pulse distributor 6 is successively subtracted from this screw length L. When the value of the remaining distance register 7 becomes zero, the pulse distribution is stopped and the thread cutting command is terminated. The servo control circuit 8 controls the tool post feed motor using the pulse train sent from the pulse distributor 6. Therefore, by moving the tool rest at a speed determined by the screw lead F and the rotational speed S of the main shaft, thread cutting with a constant lead is performed.

In thread cutting using a conventional numerical control device, there may be a large error in the thread lead due to changes in the spindle rotation speed due to fluctuations in cutting load, distortion of the blade, distortion of the workpiece, etc. Particularly in the case of single-cut machining with high cutting loads,
The cutting load changes greatly between the start and end of thread cutting, and a phenomenon in which the lead deviates from the middle of the thread length appears, resulting in the inability to cut threads of a predetermined standard.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it is possible to externally set the screw lead correction value and correction point when cutting is performed such that the screw lead deviates from the middle of the screw length. The object of the present invention is to provide a numerical control device that can correct screw lead errors.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, so a description thereof will be omitted.

9 is a lead correction register for storing the screw lead correction value set from the outside; 10 is a correction point register for storing the screw lead correction start point set from the outside; 11 is the content of this correction point register 10. 12 is an AND gate that passes the data of the lead correction register 9 when the thread cutting position reaches the correction point, and 13 is the thread lead data and lead commanded by the program. a computing unit that computes correction data and creates new screw lead data; 14;
is an external setting switch.

Next, the operation of this inventive device will be explained. A thread cutting command, thread lead F, thread length L, and spindle rotation speed S are input as a machining program from the input device, and the thread lead correction value ±f is input from the external setting switch 14 to the lead correction register 9, and a correction start point is determined. If length 1 is set in the correction point register 10, the thread cutting command first moves the tool post at a speed calculated from the lead command F from the machining program and the spindle rotation speed S, and cuts the predetermined thread lead F. will be carried out.

The data in the remaining distance register 7 initially stores the screw length L, but as the command progresses, it is successively subtracted, and when the content of the remaining distance register 7 becomes equal to the data 1 in the correction point register 10, it is determined. The circuit 11 is turned on and correction starts. That is, the correction data ±f set in the read correction register 9 is sent to the arithmetic unit 13 through the AND gate 12. The calculator 13 calculates F±f using the screw lead F and the screw lead correction value ±f stored in the F register, and sends the result to the feed rate control circuit 5. Since this feed rate control circuit 5 calculates the lead command using F±f and the spindle rotation speed S, the speed command for moving the turret is corrected by ±f, and the lead F is corrected to F±f. This will allow you to cut threads.

This state will be explained with respect to the thread cutting pattern shown in FIG. The cutter moves from the start point A to the thread cutting start point B according to the command, and thread cutting is performed according to the command, but from this start point B to the correction point C, the thread is cut with the screw lead F, and from the correction point C to the end point D. Thread cutting is performed using the corrected lead F±f.
The command , is a command to return to the starting point A.

In the above embodiment, the read correction value and the correction point are each provided with an external setting switch, but they may be written into each register by input from a key switch. Alternatively, a means for setting the lead correction value and correction point as parameters in advance may be used.

As described above, in thread cutting, this invention allows the screw lead to be corrected from the middle of the thread length by external setting, so that deviations in the lead due to load fluctuations during cutting can be corrected, resulting in highly accurate thread cutting. It has the effect of obtaining.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a thread cutting function in a conventional numerical control device, Fig. 2 is a block diagram showing a thread cutting correction function in a numerical control device according to an embodiment of the present invention, and Fig. 3 shows a thread cutting lead correction function. It is a cutting pattern diagram. In the figure, the same reference numerals indicate the same or equivalent parts, 9 is a read correction register, 10 is a correction point register, 11 is a discrimination circuit, 12 is an AND gate,
13 is a computing unit, and 14 is an external setting switch.

Claims (1)

[Claims] 1 In a numerical control device having a thread cutting function, there is a lead correction register that stores the correction value of the screw lead, a correction point register that stores the correction start position of the screw lead, and a correction value of the screw lead and the screw lead in each register. a means for externally setting the correction start position of the screw lead, a means for determining the correction start position of the screw lead using the data of the correction point register, and a means for setting the correction start position of the screw lead by using the data of the correction point register, A numerical control device comprising: a calculator that calculates a screw lead command and a correction value for the screw lead, and also corrects the screw lead.