JP3729956B2 - Screw rework method in lathe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw reworking method in a lathe.
[0002]
[Prior art]
Thread cutting on a lathe needs to prevent a phase shift from occurring in the screw's spiral trajectory, even when the cutting is divided into several times, such as roughing or finishing. In particular, it is important to synchronize the rotation angle of the workpiece and the automatic feed of the tool in the spindle axis direction. For this reason, the threading start position in the main shaft axis direction is always made coincident, and the tool's automatic feed is started in the main shaft axis direction after the main shaft rotation signal is detected, so that the screw thread locus coincides. I am doing so.
[0003]
Therefore, as long as the workpiece is not removed from the chuck, it is possible to always match the screw's spiral trajectory no matter how many times the cut is made. In practice, however, the shape of the processed screw is strictly checked. In such a case, it may be necessary to remove the screw from the chuck and perform measurement with a dedicated screw gauge or the like.
[0004]
Of course, if it is known that the cutting is insufficient as a result of the measurement, it is necessary to reattach the workpiece to the chuck and perform recutting, but it is very difficult to attach the once removed workpiece to the chuck under the same conditions. This is because the relative rotational position of the chuck and the workpiece and the protruding amount of the workpiece with respect to the chuck must be reproduced in exactly the same state as before removal.
[0005]
If the relative rotation position of the chuck and the workpiece and the protrusion amount of the workpiece relative to the chuck change, even if exactly the same conditions are applied to the threading start position, the automatic feed speed of the tool in the spindle axis direction, etc. It becomes impossible to make the re-processed spiral locus coincide with the spiral locus engraved by the machining.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to eliminate the disadvantages of the prior art and perform threading along the same spiral trajectory as before removing the workpiece from the chuck, even when the workpiece is once removed from the chuck and remounted. An object of the present invention is to provide a method for reworking a screw in a lathe.
[0007]
[Means for Solving the Problems]
According to the present invention, the tip of the tool is manually aligned with an arbitrary screw groove, and then synchronized with the manual operation to rotate the spindle and feed the tool in the direction of the spindle until the rotation signal of the spindle is detected. The amount of movement of the tool in the spindle axis direction is calculated, and when the tool is retracted and automatic synchronous feeding of the tool for reworking is started, at least until the tool contacts the workpiece and reaches the screw shape start point The tool feed correction corresponding to the amount of movement is given in the spindle axis direction.
[0008]
Alternatively, instead of obtaining the amount of tool movement in the spindle axis direction by aligning the tip of the tool with an arbitrary screw groove and then synchronizing it manually to rotate the spindle and feed the tool in the spindle axis direction, When the spindle rotation amount until one rotation signal is detected, the tool is retracted and a cut is made for re-machining to start automatic synchronous feed of the tool, the spindle rotation amount is used as the cutting feed direction of the tool. If the main shaft is rotated by the amount of rotation of the main shaft after the rotation signal of the main shaft is detected, automatic synchronous feeding of the tool is started from the threading start point, and the amount of rotation of the main shaft is calculated. When the tool is obtained by moving the tool in the direction opposite to the cutting feed direction, after detecting the main shaft rotation signal, the main shaft rotates by an amount obtained by subtracting the main shaft rotation amount from the main shaft rotation amount. Automatic tool synchronization from the threading start point It was to carry out the re-processing of the screw to start Ri.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 7 is a diagram illustrating the principle of the screw reworking method according to the present invention. FIG. 7A is an operation explanatory diagram when the threading is first performed on the workpiece W. FIG. When the tool T is positioned at the threading start position Ps and one rotation signal is output every time the main shaft (work W) makes one rotation, the tool T moves in the Z-axis direction in synchronization with the rotation of the main shaft. And threading the workpiece W. In FIG. 7A, a virtual shape obtained by extending the shape of the workpiece W to the threading start position is indicated by a broken line. When the tool T moves in synchronization with the rotation of the main spindle (work W), the tip of the tool T passes through the locus indicated by the broken line in the work virtual shape and comes into contact with the work at the screw shape start point a of the work W from this position. A screw is processed for the workpiece W.
[0010]
Thus, when the first threading process is completed, the workpiece W is removed from the chuck, and the workpiece W is mounted on the chuck to perform the machining again, as shown in FIG. When the protruding amount of W from the chuck is different from the initial machining state shown in FIG. 7 (a) and the phase of the screw is different from that at the first machining, the tool T is moved from the threading machining start position Ps to the spindle. When the movement in the Z-axis direction is started after receiving one rotation signal in synchronization with the rotation of, the position of the threading start point becomes the position a ′ in FIG. The position of the point a is shifted.
[0011]
Therefore, the shift amount α or β between the screw groove position and the reception position of the single rotation signal is measured (the shift amount α is a single rotation signal obtained when moving from the screw groove position in the machining direction (left direction in FIG. 7). The deviation amount with respect to, β is the deviation amount when moving in the opposite direction) This measuring method will be described later.
[0012]
At the time of re-machining, the tool is moved to a position advanced in the Z-axis machining direction by a deviation amount β from the threading start position Ps or moved to a position opposite to the Z-axis machining direction by a deviation amount α from the threading start position Ps. If T is positioned and the tool T starts moving in synchronization with the rotation of the spindle when receiving one rotation signal from this position, the tool T comes into contact with the workpiece W and the screw shape start point a, and rework is performed from this position. Will do.
[0013]
Alternatively, the tool T is positioned at the threading start position Ps, and after receiving one rotation signal, the shift amount α (where Z = ZR tool movement amount (lead) at one rotation signal generation interval is ZR, α = ZR− β, and the amount of deviation α can also be obtained from the amount of deviation β), when the movement of the tool T is started in synchronization with the rotation of the spindle, The screw is reworked along the obtained screw groove.
[0014]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram showing a main part of a control device 100 for driving and controlling an NC lathe to which the method of the present invention is applied.
[0015]
The processor 11 of the control device 100 is a processor that controls the control device 100 as a whole. The processor 11 reads a system program stored in the ROM 12 via the bus 21 and controls the control device 100 as a whole according to the system program. Control. The RAM 13 stores temporary calculation data, display data, various data input by the operator via the CRT / MDI unit 70, and the like.
[0016]
The CMOS memory 14 is configured as a non-volatile memory that is backed up by a battery (not shown) and retains the memory state even when the power of the control device 100 is turned off. The machining program or CRT / MDI unit read via the interface 15 A machining program or the like input via 70 is stored.
[0017]
In the ROM 12, various system programs for executing processing required for creating and editing the machining program and processing for automatic operation are written in advance.
[0018]
The interface 15 is an interface for an external device that can be connected to the control device 100, and is connected to an external device 72 such as a floppy cassette adapter. A machining program or the like is read from the external device 72, and the machining program edited in the control device 100 can be stored in a floppy cassette or the like via the external device 72.
[0019]
A PMC (programmable machine controller) 16 controls an auxiliary device on the NC lathe side, for example, an actuator such as a robot hand for tool change, by a sequence program built in the control device 100. That is, according to the M function, S function, and T function instructed by the machining program, these sequence programs convert the signals into necessary signals on the auxiliary device side and output them from the I / O unit 17 to the auxiliary device side. Auxiliary devices such as various actuators are activated by this output signal. In addition, it receives signals from various switches on the operation panel provided in the main body of the NC lathe, performs necessary processing, and passes it to the processor 11.
[0020]
Image signals such as the current position of each axis of the NC lathe, alarms, parameters, and image data are sent to the CRT / MDI unit 70 and displayed on its display. The CRT / MDI unit 70 is a manual data input device provided with a display, a keyboard, and the like. The interface 18 receives data from the keyboard of the CRT / MDI unit 70 and passes it to the processor 11.
[0021]
The interface 19 is connected to the Z-axis manual pulse generator 71 and receives a pulse from the manual pulse generator 71. The manual pulse generator 71 is mounted on the operation panel of the NC lathe, and is used to precisely position the turret of the NC lathe by controlling each axis by a distribution pulse based on manual operation. The same applies to the X-axis manual pulse generator 73 and the interface 20. Note that the Z-axis is a feed in the main shaft axis direction, and the X-axis is a feed in a direction (cutting direction) orthogonal to the main shaft.
[0022]
The axis control circuits 30 and 31 for the Z and X axes for moving the turret of the NC lathe receive a movement command for each axis from the processor 11 and output the command for each axis to the servo amplifiers 40 and 41. In response to this command, the servo amplifiers 40 and 41 drive the servo motors 50 and 51 of each axis of the NC lathe. The servomotors 50 and 51 for each axis incorporate a position / speed detector, and a position / speed feedback signal is fed back from the position / speed detector. In FIG. 1, description of the feedback of the position signal and the feedback of the velocity is omitted.
[0023]
The interface 23 is connected to the manual pulse generator 74 of the main shaft and receives a pulse from the manual pulse generator 74. The spindle control circuit 32 is connected to the bus 21. The spindle control circuit 32 has a position loop control circuit and a speed loop control circuit. Usually, the speed command output from the processor 11 and the speed detection provided in the spindle motor 62 are detected. Based on a feedback signal from a device (not shown), the spindle motor 62 is speed-controlled via a spindle amplifier 42, is rotated at a commanded rotational speed, and the work W caught on the chuck is rotationally driven. A position coder 63 is coupled to the spindle motor 52 by a gear or a belt, and the position coder 63 outputs a feedback pulse (including a single rotation signal) in synchronization with the rotation of the spindle. The feedback pulse passes through the interface 22. And read by the processor 11.
[0024]
When the rotational position of the main shaft is controlled (in the case of so-called C-axis control), the position loop of the spindle control circuit 32 starts its function, and the position loop control is performed by the movement command from the processor 11 and the feedback pulse from the position coder 63. To control the rotational position of the spindle (workpiece). In relation to the present invention, when the manual pulse generator 74 for the main shaft is operated, the main shaft is driven based on the pulse from the manual pulse generator 74.
[0025]
Hereinafter, the processing in the rework mode in the case where the work once removed from the chuck is mounted on the chuck again and reworking such as driving in the cutting amount is performed will be described with reference to the flowcharts shown in FIGS.
[0026]
First, the operator who has attached the workpiece to the chuck again operates the CRT / MDI unit 70 of the control device 100 to switch the operation mode of the device to the rework mode, and uses the manual pulse generators 71, 73, 74. As shown in FIG. 5, each of the manual pulse generators 71, 73, and 74 of the Z axis (feed direction), the X axis (cutting direction), and the main axis (workpiece rotation) is operated. Is positioned in the groove portion of the screw serving as a workpiece, and after confirming the completion of positioning, the positioning completion key of the CRT / MDI unit 70 is pressed.
[0027]
The portion for positioning the tip of the tool may be anywhere as long as it is a groove portion of the screw. In addition, in order to accurately position the tip of the tool in the groove portion of the screw, the contact between the tip of the tool and the screw groove is visually confirmed by a projection microscope, or the tip of the tool and the groove of the screw are Insert a thin paper sheet between them and check the degree of crushing.
[0028]
The process shown in steps S1 to S6 is a flowchart showing an outline of the process performed by the processor 11 in response to the operation of the operator at the above stage.
[0029]
That is, the processor 11 that has detected the switching to the rework mode by the operator can first manually control the Z-axis and X-axis servomotors 50 and 51 and the spindle motor 52 by the manual pulse generators 71, 73 and 74. The axis mode is set (step S1), and the following processes are performed in accordance with manual operations of the manual pulse generator 73 (operation detected at step S2) and 71 (operation detected at step S4).
[0030]
First, when a movement command is input by operating the manual pulse generator 73 (step S2), the processor 11 sends the tool in the X-axis direction according to the movement command ΔX (step S3). The movement command ΔX from the manual pulse generator 73 includes a sign corresponding to the rotation direction of the operation handle. The feed direction when the operation handle is rotated in the positive direction is the + X direction, and the operation handle is The feed direction when rotated in the reverse direction is the -X direction (both see FIG. 5).
[0031]
The processing when the manual pulse generator 71 is operated (step S4, step S5) is the same as that of the manual pulse generator 73 (step S2, step S3). However, the feed of the tool is in the Z-axis direction, and there is still a distinction between forward and reverse in the feed direction.
[0032]
Independent manual control of the servomotors 50 and 51 by the manual pulse generators 71 and 73 can be performed at any time until the positioning completion key of the CRT / MDI unit 70 is operated (step S6).
[0033]
When the operator who has completed the positioning by the manual pulse generators 71 and 73 presses the positioning completion key of the CRT / MDI unit 70, the processor 11 detects this operation in the process of step S6 and stores it in the positioning completion position storage register Z1. The current position Zn stored in the Z-axis current position register is stored (step S7), and a value 0 for requesting detection of the amount of positional deviation is set in the flag F (step S8). In short, the value of the positioning completion position storage register Z1 is the value of the Z axis when the tip of the tool is accurately positioned in the groove portion of the screw.
[0034]
Next, the operator synchronizes the rotation of the spindle 52 and the tool feed in the Z-axis direction, moves the tool in the Z-axis direction by manual operation, and the tool in the Z-axis direction until one rotation signal of the spindle 52 is detected. Is moved by the control device 100.
[0035]
In order to synchronize the rotation of the main shaft 52 and the tool feed in the Z-axis direction, a method of operating the Z-axis manual pulse generator 71 to move the tool in the Z-axis direction and rotating the main shaft 52 in synchronization therewith. In this embodiment, the method of driving the Z-axis servo motor 50 in synchronization with the rotation of the main shaft 52 by operating the manual pulse generator 74 of the main shaft 52 is considered. To use.
[0036]
When positioning is performed with thin paper sandwiched, it may be better to retract the tool in the positive direction of the X axis in advance and remove the thin paper. However, the movement of the tool in the X axis direction may be performed as described above. It may be arbitrarily performed independently of the synchronous operation of the main shaft and the Z axis.
[0037]
The processing shown in steps S9 to S24 is a flowchart showing an outline of processing performed by the processor 11 in accordance with the operation of the manual pulse generators 73 and 74 by the operator in the steps so far (Z-axis manual pulse generator). 71 is not operated).
[0038]
The processor 11 first determines whether or not a value 0 for requesting the detection of the amount of displacement is set in the flag F (step S9). At this stage, the value of the flag F is 0. It is determined whether or not the manual pulse generator 74 is operated to input the manual spindle pulse ΔS (step S10). If there is no input, the process proceeds to step S19. If it is input, the spindle is moved by the input pulse ΔS. Drive (step S11). When the spindle 52 rotates, a feedback signal is fed back from the position coder 63. Based on the feedback signal ΔS, the Z-axis servomotor 50 is driven in synchronization with the rotation of the spindle motor 52 to send the tool (step S12). If the screw lead is ZR, the feedback pulse from the position coder 63 is ΔS, and the number of pulses for one rotation of the spindle is Sc, the feed of the tool in the Z-axis direction is ZR · ΔS / Sc.
[0039]
Next, the processor 11 determines whether or not one rotation signal is input from the position coder 63 (step S13). If a single rotation signal is not input, the process proceeds to step S19. If a single rotation signal is input, the processor 11 stores the Z-axis current position Zn of the tool in the single rotation signal detection position storage register Z2 (step S14). Then, the magnitude relationship between the value of the positioning completion position storage register Z1 and the value of the one rotation signal detection position storage register Z2 is compared (step S15), and if the value of the one rotation signal detection position storage register Z2 is larger, the value of Z1 The value of Z2 is subtracted from the value, and the value is stored as the correction amount Z3 (step S 16 ).
[0040]
In this case, as shown in FIG. 5, this means that the operator has moved the tool in the direction of + Z from the positioning completion position Z1 to detect one rotation signal of the spindle 52, and the correction amount Z3 (in FIG. 7B) (corresponding to β) is a negative value. That is, the tool feed in the −Z direction is started by detecting one rotation signal of the spindle 52 starting from the same position as the Z-axis coordinate of the threading start position set before removing the workpiece from the chuck (described later). If the tool movement is preceded by Z3 in the Z-axis direction (if it is preceded by β (= Z3) as shown in FIG. 7 (b)), FIG. This means that the tool can be moved along the same spiral trajectory as the previous time through the position of Z1 shown, in other words, through the valley of the screw cut in the previous machining (if the correction by Z3 is Otherwise, the tool will pass through the position Z2 in FIG.
[0041]
Further, if Z1 = Z2, it means that the attachment state in the same state as that at the time of the removal is reproduced by the work remounting operation, and the value of the correction amount Z3 is zero.
[0042]
If the value of the one-rotation signal detection position storage register Z2 is smaller than the value of the positioning completion position storage register Z1, the processor 11 subtracts the value of Z2 from the value of Z1 (to α in FIG. 7B). The value of the screw lead ZR is further subtracted from (corresponding), and the value is stored as the correction amount Z3 (step S17).
[0043]
In this case, as shown in FIG. 6, it means that the operator has moved the tool in the direction of -Z from the positioning completion position Z1 to detect one rotation signal of the spindle 52, and Z1-Z2 <ZR. Inevitably, the correction amount Z3 is a negative value. That is, the tool feed in the −Z direction is started by detecting one rotation signal of the spindle 52 starting from the same position as the Z-axis coordinate of the threading start position set before removing the workpiece from the chuck (described later). If the movement of the tool is preceded by Z3 in the Z-axis direction, the position of Z1 shown in FIG. 6, in other words, the thread valley cut by the previous machining is passed. This means that the tool can be moved along the same spiral trajectory as the previous time (if the correction by Z3 is not performed, the tool will pass through the position of Z2 in FIG. 6).
[0044]
Note that the processing is performed so that the correction amount Z3 becomes negative because the tool moves in the + Z direction when tailoring is corrected collectively in the initial stage of threading processing described later, and the tailstock is corrected. If there is a sufficient margin between the threading start point and the tailstock, there is no problem even if the value of the correction amount Z3 becomes positive. Therefore, the processing of step S15 and step S17 is unnecessary. In this case, under the situation of FIG. 6, the value of Z3 becomes positive, and one rotation signal of the spindle 52 is detected starting from the same position as the Z-axis coordinate of the threading start position set before removing the workpiece from the chuck. Thus, the tool movement is delayed by Z3 in the Z-axis direction with respect to the tool feed in the -Z direction (thread cutting processing described later) started.
[0045]
Of course, if the determination result in step S13 is false, that is, if a single rotation signal is not input, the processing in steps S14 to S18 is not performed. When the correction amount Z3 is obtained in the process of step S16 or step S17, a value 1 indicating that the detection of the positional deviation amount is completed is set in the flag F (step S18), and the correction amount Z3 is obtained. To complete the process.
[0046]
Therefore, the process for obtaining the correction amount Z3 is not performed every time the rotation signal of the main shaft 52 is detected, but is executed once when the first rotation signal is detected. Only. Therefore, the absolute value of the correction amount Z3 is smaller than the screw lead ZR.
[0047]
As described above, the tool movement in the X-axis direction is free, and when a movement command is input by operating the manual pulse generator 73 (step S19), the processor 11 determines the tool according to the movement command ΔX. To the X-axis direction (step S20).
[0048]
Next, the processor 11 determines whether or not the threading start button on the operation panel has been operated (step S21). If the threading start button has not been operated, the process proceeds to step S9 again. The subsequent processing is repeatedly executed. The operator operates the manual pulse generator 74 without touching the threading start button, executes the rotation of the spindle 52 and the tool feed in the Z-axis direction in synchronization, and until one rotation signal of the spindle 52 is detected. The movement amount of the tool in the Z-axis direction is obtained, and the value is stored as the correction amount Z3.
[0049]
Once the correction amount Z3 is obtained and the flag F is set to 1, it is not always necessary to synchronize the rotation of the spindle 52 and the tool feed in the Z-axis direction, but the process proceeds from step S9 to step S22. When the manual pulse generator 74 is operated, the same processing as steps S10 to S12 (steps S22 to S24) is executed, the Z axis is driven in synchronization with the main shaft, and the process proceeds to step S19. If the manual pulse generator 74 is not operated, the process proceeds from step S22 to step S19.
[0050]
Therefore, the operator can appropriately operate the X-axis manual pulse generator 73 and the spindle manual pulse generator 74 without touching the threading start button, and can start the automatic threading operation by the fixed cycle. That is, the tool is moved to the vicinity of the Z-axis coordinates of the threading start position set before removing the workpiece from the chuck.
[0051]
The general operation is set before operating the X-axis manual pulse generator 73 to release the tool to the outside in the radial direction of the workpiece and then operating the spindle manual pulse generator 74 to remove the workpiece from the chuck. Further, the tool is moved to the vicinity of the Z-axis coordinate of the threading start position. Naturally, the threading start position is offset in the + Z direction from the workpiece tip. Further, the cutting for the follow-up machining is made by operating the X-axis manual pulse generator 73 at this stage.
[0052]
When the operator operates the thread cutting start button, the processor 11 detects this operation in the process of step S21, drives the Z-axis servo motor 50, and sets the screw set before removing the workpiece from the chuck. The tool is moved to the Z-axis coordinate position of the cutting start position (step S25), and the rotation of the spindle motor 52 is started at the set rotational speed RC (rpm) (step S26).
[0053]
However, as already described, if the one-turn signal of the spindle 52 is detected as it is and the tool feed in the Z-axis direction is started, the tip of the tool passes through the position Z2 shown in FIGS. Therefore, it becomes impossible to perform threading along the same spiral trajectory as before the workpiece is removed from the chuck.
[0054]
This is because when the work is remounted on the chuck, the relative rotational position of the chuck and the work and the amount of protrusion of the work with respect to the chuck change from the state before removal. Strictly speaking, Z1 = Z2 is true when the workpiece is reattached by chance, and when the attachment state in exactly the same state as when the workpiece is removed is reproduced. There are cases in which both the relative rotational position and the amount of protrusion of the workpiece with respect to the chuck change, and the spiral trajectory overlaps in the same state as when it is removed due to the combination of two kinds of deviations. There is no problem with the former, but in the latter case, a fixed cycle of threading is performed using the same coordinates as the Z-axis coordinates of the threading start position set before removing the workpiece from the chuck. In this case, there is a problem that the effective length of the screw changes. Therefore, it is desirable to adjust the amount of protrusion of the workpiece with respect to the chuck in the same manner as before removal. Of course, even if there is a slight difference in the protruding amount, the spiral trajectories themselves are completely coincident with each other, so there is no problem unless a strict machining tolerance is set for the effective length of the screw.
[0055]
As a result, if the tool position is shifted in the Z-axis direction by the correction amount Z3 from the preset threading start position to the tip of the workpiece, the chuck and Even if there is a change in the rotation position relative to the workpiece or the amount of protrusion of the workpiece relative to the chuck, threading processing starts from the screw shape start point set before removing the workpiece from the chuck, It is possible to perfectly match the trajectory obtained by machining performed before removing the workpiece from the chuck.
[0056]
As a method of adding a feed corresponding to the correction amount Z3 until the tool moves from the threading start position to the tip of the workpiece, a feed in the Z-axis direction for every predetermined period required for synchronous operation with the spindle There are a method of adding and outputting a movement command in which the correction amount Z3 is distributed to each of the commands, and a method of starting the synchronous operation after correcting the amount corresponding to the correction amount Z3 first in advance. However, as already mentioned, the amount of protrusion of the workpiece with respect to the chuck may change from the state before removal, and distribution of the correction amount Z3 is completed in what distance section after the Z-axis feed is started. In this embodiment, the latter method is applied because there is a case where it is not exactly known whether or not to do so.
[0057]
Therefore, first, the processor 11 moves the tool in the Z-axis direction by the correction amount Z3 (step S27), first corrects the feed in the Z-axis direction, and detects one rotation signal from the spindle 52. (Step S28), the programmed automatic threading process is started. In other words, the tool lead in the Z-axis direction is started at a speed of RC · ZR / 60 in synchronism with the spindle rotation speed RC (rpm) so that the screw lead becomes ZR. In the same manner as described above, one thread cutting process is performed.
[0058]
As described above, by moving the tool by Z3 in the Z-axis direction with respect to the tool feed in the -Z direction started by detecting one rotation signal of the main shaft 52, FIGS. The tool can be moved along the spiral trajectory exactly the same as the spiral trajectory engraved before the workpiece is removed through the position of Z1 shown in FIG. it can.
[0059]
As described above, as an embodiment, a change in the relative rotational position of the chuck and the workpiece and the amount of protrusion of the workpiece relative to the chuck before the workpiece is removed from the chuck and after the retransmission is detected as a deviation of the tool position in the Z-axis direction. By adjusting the feed of the tool with the same coordinate position as the Z-axis coordinate of the threading start position set before removing the workpiece from Although the description has been made with respect to the later spiral locus, the amount of deviation may be detected not by the amount of tool displacement in the Z-axis direction but by the amount of spindle rotation.
[0060]
In this case, when the determination result in step S6 becomes true, in step S7, the value of the current position storage register of the main shaft 52 (when switching to C-axis control, the feedback pulse from the position coder is counted and the rotational position of the main shaft is counted. Is stored in the current position storage register), the rotational position (c1) of the main spindle is stored, and when one rotation signal is detected in step S13, the current position of the main spindle 52 is replaced with the processing in steps S14 to S17. If the value (c2) of the storage register is read and the rotation direction of the main shaft is screwed in the positive direction, if c2 ≧ c1, the deviation amount of the main shaft rotation amount corresponding to α in FIG. Then, a value obtained by subtracting the rotation pulse amount of one rotation of the main spindle from (c2-c1) (a negative value with a rotation amount corresponding to β in FIG. 7B) is stored as a deviation amount to be corrected. When c2 <c1 (rotation amount corresponding to β), (c2−c1) is stored as a rotation amount to be corrected. In step S27, the stored correction fee is converted into a Z-axis movement amount to correct the tool position.
[0061]
Further, instead of correcting the tool position, the tool movement may be started at a timing when one rotation signal is received from the threading start position Ps and fed by α in FIG. In this case, in steps S15 to S17, when c2 ≧ c1, (c2−c1) is stored as a delay amount for correcting, and when c2 <c1, (c1-c2) ) Is stored as a correction delay amount, and at the time of re-machining, after one rotation signal is detected, the movement of the tool is started with a delay by the stored delay amount.
[0062]
【The invention's effect】
According to the present invention, even when the relative rotational position between the chuck and the workpiece and the amount of protrusion of the workpiece with respect to the chuck change due to the workpiece detaching operation for measurement or the like, before the workpiece is removed from the chuck. Thus, accurate threading can be performed along the spiral trajectory of the screw.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a lathe control device according to an embodiment to which a screw reworking method in a lathe according to the present invention is applied.
FIG. 2 is a flowchart showing an outline of processing in a rework mode by the control device of the embodiment.
FIG. 3 is a continuation of the flowchart showing an outline of processing in the rework mode.
FIG. 4 is a continuation of the flowchart showing an outline of processing in the rework mode.
FIG. 5 is a conceptual diagram showing an operation principle of the embodiment.
FIG. 6 is a conceptual diagram showing an operation principle of the embodiment.
FIG. 7 is a diagram illustrating the principle of the present invention.
[Explanation of symbols]
11 processor
12 ROM
13 RAM
14 CMOS memory
15 interface
16 Programmable machine controller
17 I / O unit
18 interface
19 Interface
20 interfaces
21 Bus
22 interface
23 changeover switch
30 axis control circuit
31 axis control circuit
32 Spindle control circuit
40 Servo amplifier
41 Servo amplifier
42 Spindle amplifier
50 Servo motor
51 Servo motor
52 Spindle motor
63 position coder
70 CRT / MDI unit
71 Manual pulse generator
72 External equipment
73 Manual pulse generator
74 Manual pulse generator
100 Control device
T tool
W Work

Claims (2)

Automatic synchronization feed of the spindle axis of the tool to match the thread lead Upon detection of a single revolution signal of the spindle a threaded by lathe so as to start from the threading start point, once performed threaded, it is threaded In the re-machining method of the screw that removes the workpiece from the lathe, re-attaches it and performs screw machining,
Spindle axis direction until the spindle rotation signal is detected by rotating the spindle and feeding the tool in the spindle axis direction after manually aligning the tip of the tool with an arbitrary screw groove by manual operation. The amount of tool movement is calculated, and when the tool is retracted and a cut is made for reworking to start automatic synchronous feeding of the tool, at least until the tool contacts the workpiece and reaches the screw shape start point A method of reworking a screw in a lathe, characterized in that a tool feed correction corresponding to the amount of movement is given in the spindle axis direction. Automatic synchronization feed of the spindle axis of the tool to match the thread lead Upon detection of a single revolution signal of the spindle a threaded by lathe so as to start from the threading start point, once performed threaded, it is threaded In the re-machining method of the screw that removes the workpiece from the lathe, re-attaches it and performs screw machining,
The amount of spindle rotation until the spindle rotation signal is detected by manually rotating the spindle and feeding the tool in the spindle axis direction after manually aligning the tip of the tool with an arbitrary screw groove. When the tool is retracted and a cut is made for reworking to start automatic synchronous feed of the tool, the spindle rotation amount is obtained by moving the tool in the cutting feed direction. After detecting the rotation signal, the spindle rotates by the amount of spindle rotation, and then automatic synchronous feed of the tool is started from the threading start point, and the spindle rotation amount is obtained by moving the tool in the direction opposite to the cutting feed direction. In this case, after detecting the spindle rotation signal, the spindle rotates by an amount obtained by subtracting the spindle rotation amount from the spindle rotation amount, and then automatic synchronous feed of the tool is started from the threading start point. Turning the screw Re-processing method of the screw in.

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