JPS6299020A - Thread cutting control system - Google Patents

Abstract

PURPOSE:To recut a rough cut thread in the same phase, by inputting outputs from a read circuit and a phase shift arithmetic circuit to a thread cutting cycle circuit while a tool locus, generated by correcting a phase shift, to a cutting machine. CONSTITUTION:A sum of a phase shift quantity deltai, correction quantity ST of delay time and a Diff quantity SD and a feed quantity F from a read circuit 1 are input to a phase shift arithmetic circuit 9. A true phase shift quantity deltat is obtained from the residue of (deltai+ST+SD)/F. The circuit 1 and the quantity deltat of the circuit 9 are input to a thread cutting cycle circuit 2, and its output is input to a cutting machine 10 via a circuit 3. By this input of a corrected tool locus, a threaded part is recut and finished in the same phase when roughing is performed.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) This invention relates to a control method for thread cutting performed using a machine tool such as a numerically controlled (Me) lathe (technical background and problems thereof) Conventionally, when threading a workpiece using an HrJ machine, etc., there is no problem if the threaded part of the workpiece is processed consistently from rough machining to finish machining, but if the workpiece is removed once during the process, it may have to be cut again. When installed, the phase of the threaded portion shifts, and this phase alignment becomes a problem. In fact, depending on the workpiece, a separate process is required in the middle of the process of machining the threaded part, so the workpiece whose threaded part has been roughly machined is removed, and the workpiece that has undergone the separate process is reinstalled and the rough machined part is processed. When finishing a threaded part or finishing a threaded part that has been roughly machined using another machine tool, the above-mentioned phasing becomes a big problem, and it is necessary to use a special jig for phasing. A phase shift occurs, which places a heavy burden on workers to align the phases.

(Object of the invention) This invention was made under the above circumstances,
The purpose of this invention is to perform NC processing of a workpiece whose threaded portion has been roughly machined.
It is an object of the present invention to provide a thread cutting control system that is attached to a lathe or the like and allows easy phase alignment without using a special jig when finishing thread cutting on a workpiece.

(Summary of the Invention) The present invention relates to a thread cutting control method when a workpiece whose threaded portion has been roughly machined is mounted on a numerically controlled machine tool and the threaded portion is reprocessed. The phase shift of the thread groove is measured, and the delay of the servo system of the numerically controlled machine tool and the calculation delay time of the numerical control device are calculated and determined, and the phase shift determined by the above measurement and
Based on the calculated delay of the servo system and the calculated calculation delay time, the threaded part is reprocessed by matching the phase of the threaded part.

(Embodiment of the invention) As mentioned above, when reprocessing a workpiece whose threaded portion has been roughly machined to an NC lathe or the like for finishing the threaded portion, there are differences in the mounting method and the processing machine. As a result, the phase of the threaded part deviates from that during the original rough machining. Figure g2 shows how to measure the amount of phase shift that occurs in this type of installation, and as shown in the figure. The threaded portion of the workpiece 100 has been subjected to rough thread cutting at a pitch p. Therefore, this workpiece IOQ is attached to an NC lathe, and the main spindle is stopped at a predetermined marker position. Then, after moving the cutting edge of the tool (bite) 101 to the thread cutting start point PG, from this point PO along the axial direction (Z-axis) of this screw, the pitch P is multiplied by n (where n is a positive integer). becomes JJ=pX
The cutting edge is moved to a point moved by n minutes. Then, from this point P1, align the cutting edge of the workpiece 101 with the thread groove of the workpiece 100 by hand-feeding or manually operating the pulse handle. If the position of the cutting edge of the cutting tool 101 at this time is point P2, then if the distance between this point P2 and the above point P1 is measured,
The above reinstallation is performed by the amount of phase shift δl (m
m) is found.

However, simply correcting this phase shift amount δl cannot completely correct the above phase shift, and the process from detection of the d shift of the machine tool's servo system (mouth 1ff) and pulse data of the spindle rotation speed to completion of calculation. Because of the delay time,
Furthermore, it is necessary to add corrections to these.

FIG. 1 is a block diagram schematically showing a control section used in an NC lathe or the like that implements the thread cutting control method of the present invention, and the present invention will be described in detail below with reference to the same figure.

In Fig. 1, the reading circuit 1 reads an NG program created on an NG tape or the like or inputted from the operation panel, moves the cutting edge of 101 to the above-mentioned predetermined thread cutting start point PO, and moves the cutting edge of 101 to the above-mentioned phase by rapid traverse. Point P for measuring the deviation
1 (see the amount of movement), then stop this NG program once, move the blade tip to the point P2 by manual operation as described above, and store the phase shift amount δ1 in the phase shift memory. Measure and store in circuit 8. Thereafter, the above-mentioned NG program is returned to the above-mentioned thread cutting start point PG, and after rapidly forwarding the cutting edge of 101, the thread cutting process is started. Therefore, when the reading circuit 1 reads the thread cutting command, the delay time correction circuit 6 and Di
A feed command (feed amount F (■ m/rev) is given to the n calculation circuit 7 and the 1 phase shift calculation circuit 9. On the other hand, the spindle rotation speed calculation circuit 5 always reads the information from the REV pulse counter 4 attached to the spindle. soldered pulse data rp (pulse /
sec), the rotational speed of the main shaft of this NC lathe is measured, and the measured value R (r, p, s) is input to the delay time correction circuit 6 and the Diff calculation circuit 7.

Here, this delay time correction circuit 6 is as follows.

Correction Fa based on the delay time ΔT (sec) from detection of the input feed amount F, spindle rotation speed B, and pulse data of the spindle rotation speed to completion of calculation
st (+u+) is calculated using the following equation.

S+= (R/80)XFXΔDing ・・・・・・(
1) Also, the Diff calculation circuit 7 calculates its DiFfm based on the input feed riF and rotation aR of the main shaft.
so (am) is calculated using the following equation. put it here,
Kυ indicates the speed deviation of the servo system.

Therefore, the phase shift calculation circuit 9 calculates that the above-mentioned mounting measured and stored in the phase shift storage circuit 8 is the above phase shift amount δl.
, the delay time correction MS calculated by the above equation (1)
The true phase shift amount δt is obtained from the remainder obtained by dividing the sum of + and DiffQSp calculated by the above formula (2) by the feed IF commanded from the reading circuit 1.

That is, the remainder of (δH+S++So)/F is found as the distance δt (am) of the true phase shift amount.

Therefore, the true phase shift value δ1 obtained above is input to the thread cutting cycle circuit 2, which starts the thread cutting cycle in response to the command from the reading circuit 1, and the true phase difference δ1 with respect to the thread cutting start point PO is After correcting the deviation amount δ[,
A function generating circuit 3 generates a function of the corrected machining locus of the cutting tool. The trajectory of the cutting tool with this phase shift corrected is shown in FIG. 3, and the cutting edge of the cutting tool 101 is as follows.
Move from the thread cutting start point PIG to the point P2o that is close to the workpiece 100 in the direction perpendicular to it, and move to the point pH corrected by the above correction amount δ[, and cut the threaded part of the workpiece lOO at a predetermined pitch to the point of the incomplete threaded part. After cutting the thread to PI2, it is pulled to point P13 and returns to the starting point PIG.

When the bite trajectory generated with the phase shift corrected in this way is input, machining filO will re-process the threaded part using the same phase as when it was first rough-machined, even if it is a reinstalled screw. It will be possible.

(Effects of the Invention) As described above, according to the thread cutting control method of the present invention,
Even when a workpiece whose threaded portion has been rough-machined and once removed is reinstalled on an NG lathe and the workpiece is finished with thread cutting, phase alignment can be easily performed without using special jigs, making the work easier. Threading can be easily performed without placing any burden on the operator.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an outline of a control device that implements the thread cutting control method of the present invention, FIG. 2 is a diagram for explaining the force method for measuring phase shift in thread cutting, and FIG.
The figure shows the locus of the cutting tool in the thread cutting process in which the phase shift is corrected according to the present invention. 1...Reading circuit, 2...Thread cutting cycle circuit, 3
...Function generation circuit, 4...REV pulse counter,
5... Main shaft rotation speed calculation circuit, 6... Delay time correction circuit, 7... D i f f flij calculation circuit, 8...
- Phase shift storage circuit, 9... Phase shift calculation circuit, 10
···Processing machine. 100...work, lot...part-time job. Figure 3

Claims (1)

[Claims] When a workpiece whose threaded portion has been roughly machined is mounted on a numerically controlled machine tool and the threaded portion is reprocessed, a phase shift of the thread groove of the threaded portion that occurs during the installation is measured, and
The delay of the servo system of the numerically controlled machine tool and the calculation delay time of the numerical control device are calculated and calculated, and the measured phase shift, the calculated delay of the servo system, and the calculated calculation delay time are calculated. A thread cutting control method characterized in that the threaded portion is reprocessed by matching the phase of the threaded portion based on the above.