JPH03185501A - Origin restoration method of numeral controller - Google Patents

Abstract

PURPOSE:To improve positioning accuracy by stopping a main spindle after detecting a Z phase, moving the main spindle at an approach speed until a pulse change in an A or B phase is detected, finding out a inertia traveling distance obtained after detecting the Z phase, finding out the residual distance based upon the inertia traveling distance, and then positining a work based upon the residual distance. CONSTITUTION:After detecting the Z phase, the main spindle is temporarily stopped and then moved at the approach speed and the interia traveling distance is calculated by an inertia traveling distance calculating means 40 based upon the change pulse of the A or B phase. Then the residual distance up to a positioning position (specifying a prescribed position such as the succeeding Z phase) is calculated by a residual distance calculating means 41 based upon the inertia traveling distance and the number of pulses obtained by a main spindle encoder(ENC) 34. Finally, a speed pattern 4 is found out by the positioning operation of a positioning calculating means 42 based upon the residual distance and the speed of the main spindle 32 is rapidly positioned based upon the speed pattern 4. Consequently, the positioning accuracy can be improved without fixing a dog to the main spindle side.

Description

[Detailed description of the invention]

[Industrial Application Field] This invention describes the origin (hereinafter referred to as R point) of a numerical control device that uses a spindle encoder to return to the origin without using a near-point dog.
This is related to the return method. [Prior Art] FIG. 8 is a timing chart of a method for returning to the R point using a conventional spindle encoder, which is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-260201. In the figure, the vertical axis shows the feed rate, and the horizontal axis shows the position. (1),
(la) (The code using the auxiliary code is the feed rate when the feed rate is different) is the feed rate of the R point return axis, and (2)
, (2a) is the R point return position. Furthermore, the timing of the output pulses of the main shaft encoder is illustrated at the bottom of the figure. FIG. 9 is a flowchart showing the operation of the R point return method using the above-mentioned spindle encoder, and the operation will be explained below according to this flowchart. First, by R point return fast forward processing (81), movement is started in the commanded direction at a constant speed (R point return fast forward speed). When two phases are detected (S2), it is then decelerated and stopped by a stop operation (S2).
3>, and that position is defined as the R point return position (2), (2a).

[Problem to be solved by the invention]

In the conventional R point return method using a spindle encoder, the speed of the feed rate (size of droop) (1), (
la), there is a problem that the stop position differs depending on the distance from the movement start point to the second phase (the relationship between the amount of one interpolation and the position of the second phase in the interpolation cycle), the feeding direction, etc. Also, JP-A-63-66608 and JP-A-63-
Although Japanese Patent No. 67607 also discloses a technique regarding return to the R point, it has the same problems as above. This invention was made in order to solve the above-mentioned problems, and is an R-point return method for a numerical control device that enables positioning accuracy (1/pulse of the main shaft encoder) to be obtained that is higher than the accuracy of the main shaft encoder. The purpose is to provide a method.

[Means to solve the problem]

The R-point return method of a numerical control device according to the present invention includes a step of detecting two phases of a spindle encoder that rotates as the spindle moves, decelerating and stopping the movement of the spindle, and then slowing the spindle at a low approach speed. and move the spindle encoder A.
The process of decelerating and stopping the main shaft again at the falling or rising timing of the phase or B phase pulse, and the main shaft encoder pulse from the timing when two phases are detected to the falling or rising timing of the A or B phase pulse. A process of calculating the coasting distance based on the number, a process of calculating the remaining distance based on the distance from the position where two phases are detected to a predetermined fixed point and the coasting distance, and controlling the acceleration/deceleration of the main shaft based on the remaining distance. and positioning at the origin position.

[Effect]

In this invention, after detecting two phases, the spindle is stopped, and then the spindle is moved at approach speed until a pulse change in phase A or B is detected, and the amount of coasting after detecting two phases is determined. Then, the remaining distance is determined based on this coasting amount, and positioning is performed based on this remaining distance. Embodiment FIG. 1 is a block diagram showing the configuration of a numerical control device that implements a method according to an embodiment of the present invention. In the figure, (21> is the CPU, (22) is the ROM in which the control program is stored, and (23) is the R in which the program is stored and functions as a working memory.
It is AM. (24) is an input/output device for human output such as NC program data, (25> is a manual data input device, (2B) is an operation panel, (27) is a display device, (28) is an interface, (29)
is a servo drive circuit. (30) is a machine tool, (31) is a servo motor that drives its main shaft, and (31a) is an encoder that detects the rotation of the servo motor (31). (32) is the main axis,
(34) is a main shaft encoder (hereinafter referred to as ENC) that detects the rotation of main 9IA (32). (35), (8
B) is a gear, and (37) is a workpiece. Gear (8
5) and (3B), the rotation of the workpiece (37) is controlled by the main shaft (32) or the servo motor (31) (rotating shaft). (40) is a coasting amount calculation means, (41) is a remaining distance calculation means, and (42) is a positioning calculation means, and these are ROM
The control program stored in (22) is transferred to the CPU (22).
1) is realized by executing, and is illustrated together with the hardware configuration for convenience of explanation. FIG. 2 is a timing chart showing the operation timing of main shaft feed control when returning to the R point. In the figure, (1
), (3), (4) and <la), (3a)
, (4a) is a speed pattern for each stage of spindle feed control during return to R point. (3), (3jl) are the speed patterns of the approach speed, (4), (3jl) are the speed patterns of the approach speed;
4a) is a velocity pattern formed by the positioning calculation means (42). Figure 3 shows the speed pattern (3) and (!la) in Figure 2.
FIG. 2 is an enlarged timing chart of FIG. FIG. 4 is a flowchart showing the operation of the R point return method of the apparatus shown in FIG. 1, and the operation will be explained below based on this flowchart. First, movement is started by R point return fast forward processing according to the modification program stored in RAM (23) (S1), and the fast forward processing is repeated (S2) until two phases from ENC (34) are detected. It will be done. ENC(34
) is taken in through the interface (27), the servo motor (31) is connected to the servo drive circuit (29).
1 and η via the servo motor (31) to decelerate and stop (S3). The deceleration pattern at this time is shown in Figures 2 and 3 with the symbol (1).
) and (la). The speed control up to this point is the same as the conventional one. Next, check whether there is a change in the A-phase or B-phase output pulse of the ENC (34), and if the pulse has not reached a pulse joint (rising or falling), feed processing using the approach speed ( The accuracy of this invention is determined by the variation in the amount of coasting at the time of positioning stop due to approach feed) is repeated until the pulse seam (pulse change) is reached (S5>. Then, when the seam is detected, the servo motor (31> The movement of the main shaft (32> is stopped by decelerating and stopping the main shaft (32) (S6). The coasting amount calculation means (40) calculates the coasting amount based on the change pulse of the A phase or B phase after the 2-phase. (S7). This is because the pulse amount per revolution is determined by E N C (34), so the coasting amount can be calculated from the pulse change amount from the second phase using the following formula: xENc Travel amount per revolution ( (usually 360° in the case of a rotating shaft) As mentioned above, by stopping at the joint of the pulses, variations in one pulse of the ENC (34) are eliminated.Control by the coasting amount calculation means (40) in Fig. 3 As shown in the enlarged view of the section, the variation in the coasting amount of the approach speed indicated by Δl determines the control accuracy.Next, the remaining distance calculating means (41) determines the positioning position (predetermined position such as the next two phases). Calculate the remaining distance to the specified position) based on the coasting amount and the number of pulses of ENC (34).With the 2-phase passing position as zero, it is determined by the following formula: Remaining distance - Coasting amount - If the calculated value of the return position is negative, the amount of movement per rotation of ENC (34) is added in order to keep the return rotation direction constant.Finally, positioning processing by the positioning calculation means (42>) The speed pattern (4) is determined based on the above remaining distance, and based on this speed pattern (4), the main shaft (32) is moved at high speed to complete positioning (S9). The return operation has been completed and the positioning position has been set to the R point return position.In addition, in order to resolve the difference in the R point return position due to the difference in the feed direction, the speed pattern (3) of the approach speed during cradle and straight The moving directions in (3a) and the speed patterns (4) and (4a) during positioning processing were the same. Fig. 5 is a timing chart showing the operation during cradle operation. In this example, the rotation axis and main axis are In a machine that can be connected, the ENC is used to return the rotating shaft to the R point and position the main shaft. Figures 6 (when straight) and 7 (when in cradle) are explanatory diagrams when the main shaft is a rotating shaft. , in these figures, each velocity pattern (1)
, (3). (4> assumes that the feed rate increases as it moves away from the main shaft (32) in the radial direction. Even if the main shaft (32) is a rotating shaft as in these examples, the above-mentioned linear axis As in the case, the two phases of the ENC rotating with the rotational movement of the main shaft are detected, and the main shaft (3
The rotation movement in step 2) is decelerated and stopped, and then the main shaft is moved at a low approach speed, and the main shaft (32) is decelerated and stopped again at the timing of the falling or rising edge of the A-phase or B-phase pulse of the ENC. Then, the remaining distance is determined from the distance from the position where two phases are detected to a predetermined fixed point and the coasting distance, and the main shaft (32) is accelerated or decelerated based on the remaining distance to position it at the home position. [Effects of the invention] As described above, according to the present invention, after detecting two phases, it is stopped, then moved at approach speed, and at this time Z
The amount of coasting from the phase to the joint of the A-phase or B-phase pulses is determined, and then the remaining distance to the positioning position is determined based on this amount of coasting, and the main shaft is moved to perform positioning. Therefore, the positioning accuracy can be improved without attaching a dog to the main shaft side, and this has a remarkable effect, for example, in machining (drilling, etc.) the side surface of a cylindrical cut object by switching between the main shaft and the rotary shaft.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a numerical control device that implements a method according to an embodiment of the present invention, and FIG. 2 is a timing chart showing speed changes of the R point return method in the above embodiment (when straight). , FIG. 3 is an enlarged view of the approach speed portion of FIG. 2, FIG. 4 is a flowchart showing the operation of the R point return method in the above embodiment, and FIG. 5 is an R point return method according to another embodiment of the present invention. FIG. 6 is an explanatory diagram when the main shaft is used as a rotating shaft, and FIG. 7 is an explanatory diagram when the main shaft in FIG. 5 is used as a rotating shaft. FIG. 8 is a timing chart showing speed changes in the conventional method, and FIG. 9 is a flowchart showing processing in the conventional method. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A step of detecting the Z phase of the spindle encoder that rotates with the movement of the spindle and decelerating and stopping the movement of the spindle, and then moving the spindle at a low approach speed and adjusting the A of the spindle encoder. The process of decelerating and stopping the spindle again at the falling or rising timing of the phase or B phase pulse, and the process of decelerating the spindle and stopping the spindle again from the timing when the Z phase is detected to the falling or rising timing of the A or B phase pulse. a step of calculating a coasting distance based on the number of pulses; a step of calculating a remaining distance based on the distance from the position where the Z phase is detected to a predetermined fixed point and the coasting distance; and a step of calculating the remaining distance based on the remaining distance. A method for returning a numerical control device to an origin, the method comprising: controlling the acceleration and deceleration of the controller to position it at the origin.