JP2019181606A - Machine tool - Google Patents

Abstract

To provide a machine tool in which fluctuation in a load added to a blade tool can be detected with high accuracy.SOLUTION: A machine tool 1 having: a spindle 3 which grips a work-piece W; a cutter holder 10 which moves blade tools 11a to 11c in an X-axis direction to cut into the work-piece W, and moves the blade tools 11a to 11c in a Z-axis direction parallel to an axis of the spindle 3 relatively to the spindle 3, and thereby cutting the work-piece W; a Y-axis motor 15a which moves the cutting holder 10 in a Y-axis direction perpendicular to the Z-axis direction and the X-axis direction; and current detection means 30 which detects a current value of the Y-axis motor 15a. The machine tool 1 has monitoring means 20c which monitors the current value of the Y-axis motor 15a which is detected by the current detection means 30 when processing the work-piece W, which has been cut with a prescribed cut depth, with a cut depth same as the prescribed cut depth.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a machine tool for cutting a workpiece gripped by a spindle with a cutting tool mounted on a tool post.

  For example, a machine tool such as a CNC lathe has a spindle for gripping a workpiece and a tool rest on which a tool is mounted. The tool rest is moved in the X-axis direction to cut the tool to a predetermined cutting position. In addition, the workpiece is cut by moving it relative to the workpiece in the Z-axis direction (feeding direction), and a detection function that detects the occurrence of damage such as chipping (defects) in the cutting tool. The thing of the structure provided is known.

  For example, Patent Document 1 includes a load detection unit that monitors the behavior of a motor current of a drive system that drives a tool post, and detects a change in load applied to the cutting tool from a fluctuation state of the motor current during cutting. A machine tool is described that detects the occurrence of damage, such as chipping, on a cutting tool based on fluctuations.

  In Patent Document 2, a dedicated command code is inserted before and after a desired machining command in the machining program, so that the motor current is reduced during machining performed based on the machining command in the section specified by the command code. A machine tool that monitors behavior is described.

Japanese Patent Laid-Open No. 60-90659 Japanese Patent No. 5987062

  In the above conventional machine tool, the load fluctuation applied to the cutting tool is detected from the fluctuation state of the Z-axis motor current, etc. related to the machining during the machining of the workpiece in which a high load is applied to the cutting tool. There is a problem that it is difficult to detect the image with high accuracy.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a machine tool capable of detecting a load fluctuation applied to a cutting tool with high accuracy.

  The machine tool of the present invention is equipped with a spindle for gripping a workpiece and a cutting tool, and moves in the X-axis direction for cutting the cutting tool into the workpiece. A turret for cutting the workpiece by relative movement, a Y-axis motor for moving the turret in a Y-axis direction perpendicular to the Z-axis direction and the X-axis direction, and current of the Y-axis motor A current detecting means for detecting a value, wherein the current is processed when the workpiece cut by the predetermined cutting amount is processed by the same cutting amount as the predetermined cutting amount. It has a monitoring means for monitoring the current value of the Y-axis motor detected by the detecting means.

  In the machine tool of the present invention, the cutting process is preferably a threading process in the above configuration.

  The machine tool of the present invention comprises a storage unit storing a machining program including a machining command for the machining and a machining command for machining with the same cutting amount as the predetermined cutting amount in the above configuration, Control means for controlling the operation of the machine tool based on the monitoring program, and in the machining program, a monitoring section where the monitoring means monitors the current value of the Y-axis motor is designated by a dedicated command code, and the control Preferably, the means controls the operation of the machine tool based on the current value of the Y-axis motor detected in the monitoring section.

  In the above-described configuration, the machine tool according to the present invention is preferably configured such that the operation is performed by stopping the process of machining with the same cutting amount as the predetermined cutting amount until the process can be stopped.

  ADVANTAGE OF THE INVENTION According to this invention, the machine tool which can detect the load fluctuation | variation added to a blade tool with high precision can be provided.

It is explanatory drawing which shows schematic structure of the machine tool which is one embodiment of this invention. It is explanatory drawing which shows the principal part of the machine tool which is performing the wiping process. It is explanatory drawing which shows the state which the cutting tool contacted the process defect part of the workpiece | work in the wiping process. It is a characteristic diagram which shows the fluctuation | variation of the load current of a Y-axis motor.

  A machine tool 1 according to an embodiment of the present invention is configured as a CNC lathe and has a spindle 3 arranged on a base 2.

  The spindle 3 is rotatably supported by a spindle base 4 fixed to the base 2 and can hold the workpiece W with a chuck provided at the tip. The main shaft 3 is rotationally driven by a drive source such as an electric motor, for example, and rotates together with the workpiece W.

  As the workpiece W gripped by the main shaft 3, for example, a member formed in a rod shape having a circular cross section can be used.

  The head stock 4 is mounted on the base 2 via a Z-axis guide rail 5 arranged along the Z-axis direction parallel to the axis of the main shaft 3. A Z-axis moving mechanism using a Z-axis motor as a driving source is provided between the headstock 4 and the base 2, and the main shaft 3 is driven by the Z-axis moving mechanism together with the headstock 4, and the Z-axis guide rail 5 is driven. Along the Z axis.

  As described above, in the machine tool 1, the direction parallel to the axis of the main shaft 3 is the Z-axis direction. In addition, the direction perpendicular to the Z-axis direction and perpendicular to the upper surface of the base 2 is the X-axis direction (vertical direction in FIG. 1), and the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction. (Left-right direction in FIG. 1).

  The machine tool 1 includes a tool post 10. The tool post 10 is equipped with three cutting tools 11a, 11b, and 11c. The three cutting tools 11a, 11b, and 11c are each in a posture in which the blade tips are directed downward, and are arranged side by side in parallel with each other at an interval in the Y-axis direction.

  A support base 12 is fixed to the base 2, and a moving member 14 is attached to the support base 12 via a Y-axis guide rail 13 extending along the Y-axis direction. A Y-axis moving mechanism 15 using a Y-axis motor 15 a as a drive source is provided between the support base 12 and the moving member 14, and the moving member 14 is driven by the Y-axis moving mechanism 15 to move against the support base 12. Can be moved in the Y-axis direction.

  For example, an electric motor such as a servo motor is used as the Y-axis motor 15a. By using a servo motor as the Y-axis motor 15a, the moving member 14 can be accurately positioned at a predetermined position by the Y-axis moving mechanism 15, and the moving member 14 can be held at the predetermined position.

  The tool post 10 is attached to the moving member 14 via an X-axis guide rail 16 extending along the X-axis direction. An X-axis moving mechanism 17 using an X-axis motor 17 a as a drive source is provided between the tool post 10 and the moving member 14, and the tool post 10 is driven by the X-axis moving mechanism 17 to move the moving member 14. Can be moved in the X-axis direction.

  The machine tool 1 is provided with a control unit 20 as control means. The control unit 20 is configured as a microcomputer including a calculation unit 20a such as a CPU (Central Processing Unit) and a storage unit 20b such as a memory. The storage unit 20b stores a machining program including a machining command for machining and a machining command for machining with the same cutting amount as a predetermined cutting amount.

  The control unit 20 integrates the rotation of the spindle 3, the operation of the Z-axis movement mechanism, the Y-axis movement mechanism 15 and the Z-axis movement mechanism 17 based on the machining command of the machining program stored in the storage unit 20b. By controlling automatically, the cutting process of the workpiece | work W by any blade 11a, 11b, 11c is performed.

  For example, the control unit 20 rotates the spindle 3 that grips the workpiece W at a predetermined rotation number, and automatically moves the tool post 10 in the X-axis direction by the X-axis moving mechanism 17 to move the cutting tool 11a to a predetermined cutting depth. The workpiece W is cut into the workpiece W, and the workpiece W is cut by the cutter 11a by moving the spindle 3 relative to the cutter 11a in the Z-axis direction (feeding movement) by the Z-axis moving mechanism.

  In the present embodiment, the machine tool 1 can thread the workpiece W under predetermined threading conditions (pitch interval, depth of cut, etc.) as cutting. In the thread cutting process, the cutting of the workpiece W by the cutting tool 11a is performed in a plurality of times instead of a single processing (pass), and the cutting depth of the cutting tool 11a with respect to the workpiece W is set in each processing. By increasing the depth stepwise, a screw S having a desired screw bottom depth is processed on the workpiece W as shown in FIG.

  In FIG. 2, the shape of the cutting tool 11 a is schematically shown. As the cutting tool 11 a, for example, a tool having a cutting edge portion having a shape corresponding to the thread groove of the screw S to be formed is used.

  By controlling the operation of the Y-axis motor 15a, the control unit 20 can automatically move the tool rest 10 along with the Y-axis guide rail 13 in the Y-axis direction together with the moving member 14 by the Y-axis moving mechanism 15. it can. By moving the tool post 10 in the Y-axis direction, the cutting tools 11a, 11b, and 11c for cutting the workpiece W can be selectively switched to any one of the three.

  After the cutting of the workpiece W, the control unit 20 rotates the spindle 3 based on a machining command for machining with the same cutting amount as the predetermined cutting amount of the machining program stored in the storage unit 20b. By controlling the operations of the Z-axis moving mechanism, the Y-axis moving mechanism 15 and the X-axis moving mechanism 17 in an integrated manner, machining is performed with the same cutting amount as the predetermined cutting amount of the workpiece W by any of the cutting tools 11a, 11b, and 11c. The processing to be performed is executed. Machining with the same cutting amount as the predetermined cutting amount is also referred to as “scraping” or “zero-cutting”, and the cutting tools 11a, 11b, and 11c are cut in the same path as the cutting of the workpiece W. Is selected and moved, and is performed by the selected cutting tool 11a, 11b, or 11c with the same cutting amount as that of the cutting process. Hereinafter, this process will be described as a wiping process.

  For example, when the screw S is formed on the workpiece W by cutting, the control unit 20 rotates the spindle 3 that grips the workpiece W at a predetermined rotation number, and moves the tool rest 10 by the X-axis moving mechanism 17. The X-axis direction of the cutting tool 11a is made to coincide with the X-axis direction position in the last machining (pass) of the threading process, and the spindle 3 is moved by the Z-axis moving mechanism with the same feed from the same phase as the last machining (pass). 2 is moved relative to the cutting tool 11a in the Z-axis direction (feed movement), so that the cutting tool 11a has the same phase as the last machining (pass) of the threading process with respect to the workpiece W as shown in FIG. The workpiece is moved by the cutting depth, and the wiping process is executed following the portion of the workpiece W that has been processed with the screw S by the cutting tool 11a. In the wiping process, the blade 11a relatively moves along the screw S without cutting the workpiece W.

  The machine tool 1 is provided with an ammeter 30 as current detection means for detecting the current value of the Y-axis motor 15a. The ammeter 30 is connected between the Y-axis motor 15a and the control unit 20, and in addition to the current value of the drive current supplied from the control unit 20 toward the Y-axis motor 15a, the turret 10 is supplied with Y. It is possible to detect the value of the load current generated in the Y-axis motor 15a when a load directed in the axial direction is applied.

  The control unit 20 has a monitoring unit 20c as monitoring means. The monitoring unit 20c monitors the current value of the Y-axis motor 15a detected by the ammeter 30 when the workpiece W is being wiped after the cutting by the blade 11a. When the current value of the Y-axis motor 15a detected by the ammeter 30 changes more than a predetermined threshold value, the monitoring unit 20c detects that the load on the cutting tool 11a has changed, and displays the detection information. An operator or the like is notified by displaying on a notifying means such as a display (not shown). Based on the fact that the load variation occurs in the cutting tool 11a, the operator can detect a processing defect such as a processing residue R of the workpiece W or damage such as chipping of the cutting tool 11a.

  For example, in the cutting process of the workpiece W by the cutting tool 11a, chipping (deletion) occurs in the cutting tool 11a, or positional deviation of the cutting tool 11a occurs between a plurality of repeated passes in the threading process. As shown in FIG. 2, when the workpiece W having the machining residue R generated at the bottom of the thread groove of the screw S is subjected to a scouring process, the load on the cutting tool 11a in the Y-axis direction is applied to a portion where there is no machining residue R. Is not added, and the load does not fluctuate. Accordingly, the current value (load current value) of the Y-axis motor 15a monitored by the monitoring unit 20c is a linear, substantially constant small current value in FIG. 4, and the load variation of the cutting tool 11a is not detected by the monitoring unit 20c. .

  As shown in FIG. 3, when the cutting tool 11 a comes into contact with the remaining machining R in the sweeping process, a load in the Y-axis direction is applied to the cutting tool 11 a due to a cutting resistance for cutting the remaining machining R. When a load in the Y-axis direction is applied to the blade 11a, the Y-axis motor 15a is controlled by the control unit 20 so as to hold the blade 11a in its original position against the load. As a result, when the cutting tool 11a is in contact with the machining residue R in the sweeping process, the load current of the Y-axis motor 15a increases as shown in FIG. If the increase in the load current of the Y-axis motor 15a is greater than or equal to a predetermined threshold, the monitoring unit 20c detects that the load on the blade 11a has changed, and displays the detection information on a notifying means such as a display (not shown). . Moreover, it is also possible to stop after performing the process which can stop the wiping by the control unit 20.

  As described above, in the machine tool 1 of the present embodiment, in the sieving process in which a high load is not applied to the cutting tool 11a basically in any of the X axis direction, the Y axis direction, and the Z axis direction, Since the load variation applied to the blade 11a is detected by monitoring the current value of the Y-axis motor 15a that does not perform the moving operation, the accuracy of detection of the load variation applied to the blade 11a can be improved.

  In addition, by detecting the load fluctuation applied to the cutting tool 11a with high accuracy, it is possible to detect with high accuracy processing defects or chipping of the cutting tool 11a in cutting of the workpiece W.

  Furthermore, when performing threading on the workpiece W as cutting by the cutting tool 11a, a position shift of the cutting tool 11a occurs between a plurality of repeated passes in the threading process, thereby processing the bottom of the screw groove of the screw S. Although there is a possibility that the remaining R may be generated, it is possible to detect the occurrence of the remaining machining R or damage such as chipping of the cutting tool 11a with high accuracy while removing the remaining machining R by wiping.

  In the machining program stored in the storage unit 20b, a monitoring section in which the monitoring unit 20c monitors the current value of the Y-axis motor 15a is designated by a dedicated command code. That is, the machining program includes a machining command for cutting and a machining command for scouring, but after the machining command for cutting, and in front of the machining command for scouring, the Y axis by the monitoring unit 20c. A dedicated command code serving as a monitoring start command for starting monitoring of the current value of the motor 15a is inserted, and the monitoring end for ending the monitoring of the current value of the Y-axis motor 15a by the monitoring unit 20c is performed behind the machining command for wiping. Dedicated command code is inserted as a command.

  In this way, by inserting these command codes before and after the machining command for the wiping machining in the machining program, the monitoring of the current value of the Y-axis motor 15a by the monitoring unit 20c is performed by cutting the workpiece W by the cutting tool 11a. It is not performed while the workpiece W is being performed, but is performed only while the workpiece W is being wiped after the workpiece W has been cut. Accordingly, it is possible to prevent erroneous processing of the workpiece W or damage to the blade 11a from being erroneously detected based on the load fluctuation of the blade 11a that occurs when the workpiece W is being cut.

  Further, the control unit 20 controls the operation of the machine tool 1 based on the current value of the Y-axis motor 15a detected in the monitoring section in which the monitoring unit 20c monitors the current value of the Y-axis motor 15a. When the monitoring unit 20c detects an increase in the current value of the Y-axis motor 15a detected by the ammeter 30 in the monitoring section during the sieving process, the control unit 20 executes the process until the sieving process can be stopped and then the machine tool. Control to stop 1 is performed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  In the above-described embodiment, the case where the cutting process of the workpiece W by the cutting tool 11a is the threading process has been described as an example. However, the cutting process is not limited to the threading process and may be a normal turning or the like.

  In the embodiment described above, the three blades 11a to 11c are mounted on the tool post 10, but the number can be arbitrarily changed as long as at least one blade 11a is mounted.

  The machine tool 1 may have another tool rest on which a tool is mounted in addition to the tool rest 10 that can move in the Y-axis direction.

DESCRIPTION OF SYMBOLS 1 Machine tool 2 Base 3 Spindle 4 Spindle 5 Z-axis guide rail 10 Tool post 11a Cutting tool 11b Cutting tool 11c Cutting tool 12 Supporting base 13 Y-axis guide rail 14 Moving member 15 Y-axis moving mechanism 15a Y-axis motor 16 X-axis guide rail 17 X-axis moving mechanism 17a X-axis motor 20 control unit (control means)
20a arithmetic unit 20b storage unit 20c monitoring unit (monitoring means)
30 Ammeter (Current detection means)
W Work S Screw R Processing remaining

Claims (4)

A spindle for gripping the workpiece,
A tool post that is mounted with a cutting tool and moves in the X-axis direction for cutting the cutting tool into the workpiece and moves relative to the main shaft in the Z-axis direction parallel to the axis of the main shaft to cut the workpiece. When,
A Y-axis motor that moves the tool post in a Y-axis direction perpendicular to the Z-axis direction and the X-axis direction;
A current detection means for detecting a current value of the Y-axis motor, and a machine tool comprising:
Monitoring that monitors the current value of the Y-axis motor detected by the current detecting means when the workpiece cut by the predetermined cutting amount is being processed by the same cutting amount as the predetermined cutting amount. A machine tool comprising means.   The machine tool according to claim 1, wherein the cutting is threading. A control unit that includes a storage unit that stores a machining program including a machining command for the cutting process and a machining command for machining with the same cutting amount as the predetermined cutting amount, and controls operation of the machine tool based on the machining program Having means,
In the machining program, a monitoring section in which the current value of the Y-axis motor is monitored by the monitoring means is designated by a dedicated command code,
The machine tool according to claim 1 or 2, wherein the control means controls the operation of the machine tool based on a current value of the Y-axis motor detected in the monitoring section.   4. The machine tool according to claim 3, wherein the operation is to stop by executing a process capable of stopping the machining with the same cutting amount as the predetermined cutting amount.

Images