JPH07132436A - Origin conforming method in numerical control - Google Patents

Abstract

PURPOSE:To easily and correctly confirm whether the reference point of a movable part is reset normally into an origin by combining an origin sensor, an over-travel sensor and an area sensor, and advancing/retreating a numerically controlled movable part by the specified/distance. CONSTITUTION:The position of a movable part 1 where a reference point 11 coincides with one position (n) among numerous positions n+2-n-2 is set as an origin. After being reset to the origin (n), the movable part 1 is moved by the specified distance D in the (-) direction from the origin (n) and then moved by the specified distance C in the (+) direction from the origin (n). In the case of the reference point 11 being shifted into the position n-1, an over-travel sensor (b) is operated upon moving the movable part 1 in the (-) direction so as to detect the abnormality of origin reset. In the case of the reference point 11 being shifted into the position nil due to the abnormality or the like of an origin sensor (d), the operation of an area sensor (a) is stopped upon moving the movable part 1 by the specified distance D in the (+) direction so as to detect the abnormality of origin reset.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for confirming, when a NC-controlled movable part is returned to the origin, whether the returned position is the originally set origin.

[0002]

2. Description of the Related Art In a machine tool, for example, a movable part such as a work head may be driven by a servomotor via a ball screw to perform NC control based on preset data. In such NC control, each data is set with reference to the origin, the movable part returns to the origin when a series of operations is completed, and the next operation is performed with reference to the origin. Therefore, if the origin return position of the movable portion deviates from the initially set normal origin position, all the subsequent operations will deviate from the normal operations, causing defects such as machining defects and interference.

Incidentally, in order to accurately return the movable part to the origin position, for example, a linear scale may be attached so as to cover the entire operating range of the movable part.
High cost. Further, if an emergency stop is performed during the operation of the movable part, the data of the position where the emergency stop is performed will be cleared and the origin cannot be returned. Therefore, conventionally, one ball screw is used as a signal generating means every one rotation. A rotary encoder that outputs the rotation signal is connected, and an origin sensor that turns on and turns off before the origin when the moving part returns to the origin is provided.When the origin sensor turns on, the moving part first retracts in the direction of the origin. After decelerating the speed and reducing the inertial force, stop the moving part at the position where the rotation signal is output only after the origin sensor turns off, and set this position as the origin so that the moving part can be accurately returned to the origin. I have to.

If the movable part is further retracted beyond the origin, it may deviate from the mechanical movement range of the movable part or interfere with the fixed part. Therefore, the movable part moves at the limit position of the retractable range of the movable part. An overtravel sensor (hereinafter referred to as an OT sensor) for stopping the movement is provided.
On the other hand, if the origin returning operation is performed in a state where the movable part is located closer to the origin than the operating range of the origin sensor, the movable part retreats until the OT sensor is operated. As described above, when the position is near the origin, it is necessary to move it once and then perform the origin return operation. For this reason, an area sensor is provided to detect that the movable portion is located near the origin.

[0005]

If the deceleration after the origin sensor is turned on is made large and the moving speed of the movable part after the deceleration is made too slow, the moving part retreats from the position where the origin sensor is turned on to the origin. There is a problem that the time becomes long, the cycle time is extended, and the productivity is lowered. In such a case, it is not necessary to make the moving speed of the movable part too slow after the origin sensor is turned on, but the inertial force of the movable part increases as the moving speed of the movable part increases, and even if a rotation signal is output. There is a case where it cannot stop and goes past the origin position, and the position at which the next rotation signal is output is erroneously recognized as the origin and stops. Further, if the off position of the origin sensor shifts due to foreign matter such as chips, the origin position may shift. If a ball screw with a pitch of 10 mm is used, for example, if the rotation signal deviates by one, the origin will deviate by 10 mm from the initial position, and all subsequent operations will be deviated by 10 mm.

In view of the above problems, the present invention provides a method for confirming the origin in NC control, which can confirm whether or not the movable portion returned to the origin is at the initially set origin position. With the goal.

[0007]

In order to achieve the above object, the present invention is directed to a signal generating means for outputting a signal each time an NC-controlled movable part moves a certain distance, and a direction of returning the movable part to the origin. Is the backward direction, the origin sensor that detects that the movable part exists within a predetermined range in front of the origin, the overtravel sensor that detects that the movable part has retracted the first predetermined distance beyond the origin, and the movable part An area sensor that detects a position beyond the second predetermined distance ahead of the origin and is located on the origin side is provided, and after retracting beyond the detection range of the origin sensor, a signal is first output from the signal generating means. In the method for confirming whether the position where the movable part is stopped at the position is the origin that is initially set, the movable part is moved by a distance obtained by subtracting a distance shorter than the predetermined distance from the first predetermined distance from the position where the movable part is stopped. A step of retracting the, from the position where the movable part is stopped, characterized in that a step of advancing the only moving part a distance obtained by subtracting the distance shorter than the predetermined distance from the second predetermined distance.

[0008]

The present invention utilizes the OT sensor and the area sensor that have been conventionally provided for performing NC control, and when the origin return operation of the movable portion is completed, the OT sensor is left with a distance shorter than the above-mentioned fixed distance. Is moved forward from the operating position, and is also moved backward from a position outside the detection range of the area sensor, leaving a distance shorter than a certain distance. If the movable portion has been returned to the original set position, the OT sensor does not operate and the area sensor maintains the operating state. However, if the movable part is displaced to the retracted side, the distance to the OT sensor is short, and therefore the OT sensor operates by retracting. On the contrary, if the movable part is displaced toward the forward side, it will be out of the operating range of the area sensor when the movable part is advanced. In this way, it is possible to detect whether the movable part is displaced to the front or back, and there is no need to add any new sensors to the conventional configuration.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, reference numeral 1 denotes a movable part such as a work head of a machine tool, and an embodiment of the present invention will be described based on the position of a reference point 11 of the movable part 1. In the figure, the movable part 1 moves to the left to perform machining and other work, and the origin return moves to the right in the figure, where the left direction in the figure is the + direction and the right direction is the-direction. The movable portion 1 is moved by the rotation operation of a ball screw (not shown), and a rotary encoder (not shown) is attached to the ball screw. The rotary encoder outputs one rotation signal for each rotation of the ball screw, and the position of the reference point 11 at the time when each rotation signal is output is n + 2 to n−.
2, the position of the movable portion 1 in the state where the reference point 11 coincides with n is set as the origin. Further, in the case of the present embodiment, three sensors for detecting the position of the movable portion 1 are attached. One is an area sensor, the operating range of which is indicated by a, and it operates when the reference point 11 is closer to the origin than the position a1 which is a predetermined distance A away from the origin position in the + direction, and the reference point 11 is It continues to operate unless a1 is exceeded to the + side. Further, the other one is an OT sensor, the operating range of which is shown in b, and the reference point 11 is greater than the position b1 which is a predetermined distance B away from the origin position in the-direction.
Will continue to operate as long as it goes away from the origin, unless it exceeds b1 to the + side. The last one is an origin sensor, whose operating range is shown in d, and operates when the reference point 11 is closer to the origin than the position d1 which is a predetermined distance away from the origin position in the + direction. The operation is stopped when the position is closer than the position d2 which is a predetermined distance away from the + direction.

In such a configuration, the reference point 11 is a
When the origin return operation is performed in a state where the movable portion 1 is located on the + side of 1, the movable portion 1 moves in the -direction in a fast running manner. When the reference point 11 reaches the operation start position d1 of the origin sensor, the moving speed of the movable portion 1 is reduced, and the reference point is set at the position n where the first rotation signal is output after passing the operation end position d2 of the origin sensor. The origin return is performed by stopping in the state where 11 is matched. When the origin return is performed with the reference point 11 located between b1 and d2, the movable part 1
Is moved to the position where the OT sensor operates, the area sensor is provided, and when the origin is returned while the area sensor is operating, the movable portion 1 is moved until the area sensor stops operating. After moving in the + direction once-
The above-mentioned inconvenience does not occur by moving it in the direction.

When the movable part 1 is returned to the origin in this way,
First, the movable part 1 is moved by a distance D in the − direction from the origin, and further, the movable part 1 is moved by a distance C in the + direction from the origin. The C is set to be x shorter than the A, and the D is set to be y shorter than the B. Incidentally, both x and y are n + 2 to n-2.
Is set to be shorter than the pitch p. Therefore, the movable part 1
If the reference point 11 coincides with n, the OT sensor does not operate even if the movable part 1 is moved in the -direction and the + direction respectively, and the area sensor operates. Stay in the state. However, if the reference point 11 is displaced to the position of n−1 during the origin return, the OT sensor is activated at the time when the movable portion 1 is moved in the − direction, and the origin return is normally performed. It is detected that it was not. On the contrary, the reference point 1
When 1 is shifted to the position of n + 1, no abnormality is detected at the time when the movable portion 1 is moved in the -direction by D, but C is detected in the + direction.
The operation of the area sensor is stopped at the time of the movement, and it is detected that the origin return is not normally performed.

[0012]

As is apparent from the above description, according to the present invention, it is possible to surely confirm whether or not the movable portion is accurately returned to the home position by the home position return operation in the NC control without adding a new sensor. can do.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

[Explanation of symbols]

 1 Moving part 11 Reference point a Operating range of area sensor b Operating range of OT sensor d Operating range of origin sensor C Moving amount of moving part D Moving amount of moving part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nagai 1-10-1 Shin-Sayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd.

Claims (1)

[Claims] 1. A signal generating means for outputting a signal each time an NC-controlled movable part moves a certain distance, and a movable part within a predetermined range in front of the origin, with a returning direction of the movable part to the origin being a backward direction. The origin sensor that detects that the moving part has moved, the overtravel sensor that detects that the movable part has retracted beyond the origin by the first predetermined distance, and the movable part is located at the origin side beyond the position that is the second predetermined distance ahead of the origin. Area sensor to detect the movement of the moving part, and after moving backward beyond the detection range of the origin sensor, the position where the moving part is stopped at the position where the signal is first output from the signal generating means is the origin that was initially set. In the method for confirming whether there is any, a step of retracting the movable part from a position where the movable part is stopped by a distance obtained by subtracting a distance shorter than the predetermined distance from the first predetermined distance, and a step where the movable part is stopped. And a step of advancing the movable portion by a distance obtained by subtracting a distance shorter than the predetermined distance from the second predetermined distance, the origin returning method in NC control.