JP3361119B2 - Small diameter drilling method in lathe - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing small-diameter drilling on a work using a lathe having a feature in a control means of a feed motor of a turret tool post. . [0002] A tool post of a lathe controlled by an NC device is
Usually, the spindle (Z) is controlled by a feed motor controlled by a servo controller.
(Axial direction) and a direction perpendicular to the main axis (X-axis direction). The servo control device controls the speed and position of the tool post during movement and stop based on a difference signal between a position command given from the NC device and a position feedback signal detected by a pulse encoder or the like. When drilling a small hole in a work held by a spindle of a lathe, a small-diameter drill 12 mounted on a tool holder 11 of a turret tool rest 5 is opposed to a work 14 and the turret tool rest 5 is advanced toward the work. It is done by letting you do. [0004] In the drilling of a small diameter, when the tip of the drill 12 bites into the work 14, the drill 12 bends, the tip of the drill dances, and the tip of the drill is oblique to the work. There is such a problem that a bent hole is made by digging into the hole, and sometimes chipping may occur. In order to prevent this phenomenon, the advance speed of the drill 12 when the tip of the drill 12 abuts on the surface of the work 14 needs to be extremely slow, and there has been a problem that the processing time becomes long. [0005] The present invention has a task to be able to process the correct orientation of the small holes in the correct position of the workpiece to prevent chipping of the drill when small-diameter drilling by lathes. Means for Solving the Problems The present invention is applied to a processing method of the present invention .
The lathe is equipped with a Z-axis direction feed motor 7 of the turret tool post 5.
And / or servo control device 21 for X-axis direction feed motor 8
Output torque control means 27 for setting the output torque of the feed motors 7 and 8; position command a given to the servo control device 21 of the feed motor;
Position deviation detecting means 3 for detecting a position deviation c, which is a difference signal from a position feedback signal b detected by, for example,
1 is provided. [0007] Generally, the output torque control means and the position are provided to the bidirectional feed motors 7 and 8 of the turret tool rest 5.
Although a deviation detecting means is provided, for example, in a lathe in which the processing of the following small holes is performed only in one direction of the main axis direction or the direction perpendicular to the main axis, only the feed motor 7 or 8 in either the Z axis direction or the X axis direction is provided. It is also possible to provide the output torque control means, the position deviation detection means and the comparison means. When drilling a small hole in the work 14 using the above-mentioned lathe, the tip of the small-diameter drill 12 mounted on the turret tool post 5 is brought close to the surface of the work 14 gripped by the main shaft 1 to move the drill 12. After rotating, turret tool post 5
The above-described positional deviation is obtained in a state where the output torque of the X-axis direction feed motor 8 (when a small hole in the direction perpendicular to the main axis is formed in the work) or the Z-axis direction feed motor 7 (when the small hole in the main direction is formed in the work) is limited While monitoring c, the turret tool post 5 is made to approach the work 14 at a low speed, and when the increase in the position deviation c is detected, the position command a given to the feed motor 8 or 7 is fixed. The control waits until c decreases, and then the output torque of the feed motor 8 or 7 is increased to advance the turret tool post 5 to a desired processing position. The servo control device 21 provides a difference signal (position deviation) between a position command a given from the NC device 22 and a position feedback signal b given from the pulse encoder 13 or the like.
The feed motors 7, 8 are driven so that c becomes zero.
Therefore, when the load exceeds the output torque of the feed motors 7 and 8 and the feed motors 7 and 8 stop or slow down, the position feedback signal b from the NC device 22 continues to change even though the position command a from the NC device 22 keeps changing. It becomes impossible to follow, and the position deviation (absolute value) c rapidly increases. At this time, an acting force corresponding to the output torque limited by the output torque control means 27 is applied to the tool rest 5 in a direction facing the load. In this state, when the stop command is given to the feed motors 7 and 8 to fix the position command a, the above-described acting force is continuously applied, and when the load is released or the tool rest 5 moves against the load, the position is changed. The deviation (absolute value) c decreases. The small diameter drilling method of the present invention utilizes the above-described operation, and the tool post 5 is fed by a small force capable of cutting the surface of the work 14 without causing the small diameter drill 12 to whirling or bending. The output torque of the feed motors 7 and 8 is limited so as to be controlled. Therefore, when the tip of the small-diameter drill 12 comes into contact with the work 14, the feed speed of the small-diameter drill 12 stops or decreases to a speed near the stop. Then, by fixing the position command a and waiting until the position deviation c decreases, it waits for the tip of the small diameter drill 12 to drill a small hole in the surface of the work 14 under a weak pressing force. When the movement and inclination of the tip of the small-diameter drill 12 are prevented by the small hole, the positional deviation c decreases. Thereafter, the hole is formed with a regular feed force and feed speed. As described above, according to the method of the present invention, a drilling operation is realized in accordance with the conventional small-diameter drilling by manual operation. Particularly, at the start of cutting of the cutting edge, regardless of the active feed from the NC device 22, Processing is performed at a passive feed speed according to the state of the cutting edge of the drill and the surface hardness of the work, and the processing is performed by an operation close to processing performed by a skilled operator. FIG. 1 is a block diagram showing an embodiment of a lathe used in the present invention. The spindle 1 is supported by a headstock 2 which is substantially integral with a bed (not shown), and a chuck 3 is mounted on the tip thereof. A tool rest 5 having a turret 4 is mounted on a slide base 6 slidable in the main shaft direction (Z-axis direction) so as to be slidable in a direction perpendicular to the main shaft (X-axis direction). Feed screws 9 and 10 driven forward and reverse by a Z-axis direction feed motor 7 and an X-axis direction feed motor 8, respectively, are screwed into the table 5. Turret 4 is the rotary tool holder 1
The tool holder 11 is provided with a small-diameter drill 12 in the X-axis direction. Z-axis and X-axis direction feed motors 7, 8
Are controlled by the servo controller 21. FIG.
2 shows only the servo control system of the X-axis direction feed motor 8. The servo control device 21 includes a difference detector 24, a compensation circuit 25, and a power amplifier 26.
The difference signal (position command) c between the position command a given from 2 and the position feedback signal b given from the pulse encoder 13 mounted on the feed motor 8 is given to the compensation circuit 25, and the compensation circuit 25 is based on the position deviation c. The speed command is calculated and a difference signal from the speed feedback signal is given to the power amplifier 26. The current output from the power amplifier 26 is limited by the set value of the maximum current setter 27. N
The C device 22 increases or decreases this set value at necessary timing. The position deviation c output from the difference detector 24
Are detected by the position deviation detecting means 31. On the other hand, the set value d to be compared when detecting an increase or decrease in the position deviation is:
The values are set in the position deviation setting means 32, and the set values + d and -d on the plus side and the minus side are individually set. Comparator 33
Outputs a control output e when the detected position deviation c reaches the set value d. The position deviation detecting means 31, the position deviation setting means 32 and the comparing means 33 are actually configured as a program of the NC unit 22. When the position deviation c cannot be extracted from the servo control device 21, the NC device 2
The position command a and the position feedback signal b of the pulse encoder 13 and the like are input to the position deviation detecting means 31, and a position deviation c is detected as a difference therebetween. FIG. 2 is a flowchart showing a small-diameter drilling method according to the method of the present invention. After the tool rest 5 is moved at high speed in the Z-axis and X-axis directions, the small-diameter drill 12 is opposed to the hole drilling position of the workpiece. The tool post 5 is advanced at a low speed while the X-axis direction feed motor 8 is torque-restricted, and the small-diameter drill 12 approaches the work 14. When the increase of the position deviation c is detected, the position command a given to the servo controller is fixed and the feed is stopped.
Wait until is reduced. When a decrease in the positional deviation is detected, that is, when the tip of the small-diameter drill 12 completely bites into the work 14 during the standby operation, the torque limit is released, the tool post 5 is advanced at a predetermined speed by a predetermined amount, and the hole bottom is moved. Work up to. In the above embodiment, the case where a small hole in the direction perpendicular to the main axis is machined in the work has been described. However, when a small hole in the main axis direction is machined in the work, a small-diameter drill in the main axis direction is mounted on the turret 4. What is necessary is just to control the Z-axis direction feed motor 7 in the same procedure as the above. When small diameter drilling is performed by the method of the present invention, the waiting time from the stop of the feed of the tool post 5 to the reduction of the positional deviation c differs depending on the sharpness of the drill. Processing time becomes longer. By utilizing this, advanced tool life management is possible. That is, the machining time when the tool counter indicates 0 immediately after the exchange of the tool is stored, and when the machining time is longer than the machining time by a set amount or a percentage or more, the tool life is determined. In other words, by setting the tool life when the machining time reaches, for example, 120%,
It is not necessary to change the life data even if the processing conditions change, and accurate tool life management can be performed with simpler work. The operation after step 35 in FIG. 2 is for managing the tool life. After the machining to the bottom of the hole is completed, the elapsed time from the time clear at the start of machining is stored. If it is 0, the time is stored as a set value, and the process proceeds to the next cycle. If the tool counter is not 0, the measured machining time is compared with the set value to determine whether the machining time is longer than the set%, and if not, the process proceeds to the next machining and becomes longer. If so, an alarm is issued and the operator is requested to change tools. As described above, according to the present invention, small-diameter drilling, which has conventionally had problems such as chipping or a long processing time, can be performed manually by humans. In other words, the tip of the drill is slowly applied to the workpiece, the drill is pressed against the workpiece with a small force until the small hole is clear, and when the small hole is drilled, the drill is pressed to the end and drilling is completed automatically. And
There is an effect that small-diameter drilling can be performed accurately and quickly without causing whirling or bending of the tool. Further, the tool life can be more easily managed by measuring the processing time of the processing by the method of the present invention.

[Brief description of the drawings] FIG. 1 is a block diagram showing an embodiment. FIG. 2 is a flowchart of a small diameter drilling method. [Explanation of symbols] 5 Turret turret 8 X-axis direction feed motor 12 Small diameter drill 14 Work 21 Servo control device 27 Maximum current setting device 31 Position deviation detection means 33 means of comparison a Position command b Position feedback signal c Position deviation d Set value e Control output

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B23Q 15/00-15/28 B23B 47/18 G23Q 17/00-23/00

Claims (1)

(1) A small diameter drilling method for a lathe in which a small hole is drilled in a work (14) with a small diameter drill (12) mounted on a turret tool post (5). 12) Work the tip
After rotating the drill (12) close to (14), the output torque of the feed motor (8) for moving the turret tool post (5) in the axial direction of the drill (12) is limited, Position command (a) given to the feed motor servo controller (21)
Position feedback signal (b) and the turret tool post while monitoring the position deviation which is a difference signal (c) of (5) was close to the word over click (14), the increase in the position deviation (c) is detected and At this point, the position command (a) given to the turret tool post (5) is fixed, and in this state, the system waits until the position deviation (c) decreases, and then increases the output torque of the feed motor (8) to a desired value. A small-diameter drilling method for a lathe, wherein the turret tool post (5) is advanced to a machining position.