JPH0929577A - Method for preventing center deviation of tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the center of a tool from deviating during change of tools in a machine tool in which a plurality of tools are automatically changed so as to successively carry out given working steps. SOLUTION: In an automatically controlled machine tool in which tool holders 5 each having a tapered part 5b adapted to be fitted in and positioned at a tapered part 5a formed on the inner surface of a spindle 2 are automatically changed so as to successively carry out given working steps, there are provided a measuring means 8 for measuring rotational oscillation of the outer periphery of a tool holder 5 which is fitted to the spindle, and a means for cleaning the tapered part of the spindle. Oscillation of the tool holder 5 is measured by the measuring means 8, and when the degree of the oscillation exceeds a predetermined value, the tool holder 5 is removed from the spindle, and the tapered part of the spindle is cleaned by the cleaning means under the control of an operation control program.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically preventing misalignment of a replacement tool in a machine tool for automatically changing tools.

[0002]

2. Description of the Related Art In a machining center or an NC machine tool, a conventional cutting tool is mounted by fixing a cutting tool 6 to a tool holder 5 as shown in FIG.
The conical tapered portion 5b of the tool holder 5 is fitted and positioned to the tapered portion 2a of the spindle 2, and the pull stud 5a at the tip of the tool holder 5 is positioned.
Is pulled in the direction of the arrow and fixed. Machining centers include drills, taps, mills,
There is a feature that various processing can be performed while automatically exchanging cutting tools such as boring tools. When exchanging tools, the pull stud 5a is opened and the tool exchange arm shown in the V groove of the tool holder 5 is shown by a chain line. The tool holder 5 is pulled out from the main shaft 2 by engaging 10 and then the tool holder 5 to which another tool is fixed is inserted into the main shaft 2 and fixed in the same manner.

Japanese Unexamined Patent Publication No. 3-35952 discloses a device for exchanging a cutting tool which uses the tool holder 5 having a tapered portion as described above, which occurs during machining because the tool holder is not properly fitted to the spindle. For the vibration, mechanical vibration of the spindle is measured using a vibrometer such as an acceleration converter, and when the measured value exceeds a predetermined value, the position of the tool holder with respect to the spindle is re-installed at an index position that differs by 180 degrees. A tool mounting device is described.

Japanese Patent Application Laid-Open No. 57-194852 discloses a cleaning tool having a brush or leather attached to the surface of a conical body having an outer shape similar to that of a tool holder as a device for cleaning the inner conical portion of a machine spindle. , The cleaning tool is attached to the taper portion of the main shaft and is rotated by a motor driven by compressed air. The publication also states that
Attach a rotating mass to one end of the cleaning tool, rotate the main shaft,
Another embodiment in which the internal conical taper portion of the main shaft is cleaned by utilizing the deviation of the rotation speed from the rotating mass when stopped, and the lever is fixed to this rotating mass, and this lever serves as a stopper. It is disclosed that the cleaning tool and the taper portion on the inner surface of the main shaft are caused to move relative to each other.

[0005]

Cutting oil is often used at the time of machining, and cutting oil and chips adhere to the periphery of the spindle 2. When exchanging tools, chips and dust are generated. It is attached to the taper portion of the holder 5 or the inner surface taper portion of the main shaft 2. When the tool holder 5 is attached and fixed to the spindle 2 as it is by the automatic tool exchanging device using the tool exchanging arm 10, as shown in FIG. 3, the tapered portions of the spindle 2 and the tool holder 5 are clogged with chips and dust D, The center line of the tool holder 5 is eccentric or twisted with respect to the center line of the spindle 2. When machining is performed with the tool having such a misalignment attached, problems occur that the hole diameter becomes large or the hole is machined into an elliptical hole, for example, in drilling.

Japanese Patent Laid-Open Publication No. 3-35952 discloses an apparatus that measures mechanical vibration of a spindle by using a vibrometer such as an acceleration converter, and can detect that a tool holder is not correctly fitted to the spindle. Although described, there is no suggestion of removing chips and dust from the taper fitting portion of the spindle and the tool holder. Further, the above-mentioned Japanese Patent Laid-Open Publication No. 57-194852 discloses a device for cleaning the inner conical portion of the machine spindle, but in combination with a machining center for automatically changing the tool, misalignment of the tool to be replaced is performed. There is no suggestion of automatic prevention.

In a machine tool that automatically operates a tool change or the like according to a program, conventionally, even if the tool change has a misalignment, the machining is continued as it is according to the program, resulting in a large number of defective products. However, in order to prevent these defective products from being sent to the subsequent process, it was necessary to perform 100% inspection. The present invention measures the misalignment of a tool when exchanging the tool, and when the misalignment of a predetermined value or more is detected, the taper fitting portion of the spindle is automatically cleaned so that there is no misalignment of the tool. It is intended to solve the above-mentioned problems by shifting to the processing after confirming.

[0008]

According to the present invention, a taper portion is formed on the inner surface of a main shaft, and a tool holder having a taper portion for fitting and positioning the taper portion is automatically replaced to perform predetermined machining in sequence. In an automatically controlled machine tool, the tool holder is attached to a main shaft, the measuring means for measuring the rotational runout of the outer periphery of the tool holder, and the means for cleaning the inner surface taper portion of the main spindle are provided. A tool as an operation control program for measuring the deflection of the tool holder by the measuring means, and removing the tool holder from the spindle and cleaning the taper portion of the spindle by the cleaning means when the deflection exceeds a predetermined value. In the method for preventing the misalignment of the main shaft, the taper fitting portion of the main shaft is cleaned by using a cleaning tool having an outer shape similar to that of a tool holder with a taper and a brush formed on the taper portion. Can. When the tool misalignment is measured when the tool is changed and a misalignment of a predetermined value or more is detected,
Since the taper fitting part of the spindle is cleaned and it is confirmed that there is no misalignment of the tool before processing is started, in machine tools that automatically change tools, a large amount of defective products due to misalignment of the replacement tool To prevent the occurrence of.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of an embodiment of the present invention and shows a part of a state in which a tool holder 5 is attached to a spindle 2 as a cross section. In FIG. 1, the tool holder 5 to which the cutting tool 6 is fixed is inserted into the conical taper fitting portion 2a of the main spindle 2 by engaging the V-shaped groove 5c of the tool holder 5 with the tool exchanging arm 10 indicated by a chain line. The conical taper portion 5b of the tool holder 5 is positioned and fitted, and the pull stud 5a at the tip of the tool holder 5 is clamped by the chuck 3 and is pulled in the left direction in the figure to be fixed, and 4 is the tool holder 5 is removed. It is an extruding tool that is sometimes used. The above configuration is the same known cutting tool exchanging device as described in the above-mentioned Japanese Patent Laid-Open No. 3-35952.

FIG. 2 is a front view showing an example of the cleaning tool used in the present invention. The cleaning tool 11 has an outer shape similar to that of the tool holder 5, and a brush 12 is formed on the surface of the conical part thereof. The pull stud 11a and the V groove 11c are provided, and the taper portion 2a of the main spindle 2 is formed by the chuck 3, the pushing tool, and the tool exchange arm 10 like the tool holder 5.
It is to be automatically attached and detached. Also, this cleaning tool 11
An anti-rotation pin 13 extending in the axial direction is provided on the shaft 1, and the anti-rotation pin 13 is fitted into the hole 1a of the machine body 1 when the cleaning tool 11 is attached to the main shaft 2.

In FIG. 1, an NC device 7 issues a machining command and a tool replacement command to the machine tool, and a movement control command between the standby position of the shake measuring instrument 8 and the measurement position close to the cutting tool 6. The controller 9 determines whether or not the shake measurement value of the shake measuring device 8 exceeds a predetermined value, and receives a signal from the controller 9 to issue a command to replace the tool holder 5 and the cleaning tool 11. As the shake measuring device 8, an electric micrometer, an eddy current displacement sensor, a visible light laser displacement sensor, or the like can be used.

A method for preventing misalignment of a tool using the above-mentioned device will be described below. The outer circumference of the tool holder 5 rotating with the spindle 2 is measured by the shake measuring device 8. The outer peripheral portion of the tool holder 5 is finished and processed concentrically with the tapered portion 5b. When the shake measurement value exceeds a predetermined value, the controller 9 discriminates this and the NC device receiving the signal issues a command to replace the tool holder 5 and the cleaning tool 11, and sets the shake measuring device 8 to the standby position. Returning, the tool change arm 10 removes the tool holder 5 from the spindle 2 and mounts the cleaning tool 11 instead. At this time, the detent pin 13 of the cleaning tool 11 is fitted into the hole 1a of the machine body 1. After the cleaning tool 11 is replaced, the main shaft 2 is rotated at a low speed for one to two revolutions, and the cleaning tool 1
In No. 1, since the detent pin 13 is stopped by the machine body 1, the taper portion 2 a of the main shaft 2 is cleaned with the brush 12. After cleaning, the cleaning tool 11 is replaced with the original tool holder 5, and the shake measuring device 8 measures again. After confirming that the shake measured value is within a predetermined value, the processing operation is started.

FIG. 4 shows a flowchart of a program operation for preventing misalignment of the tool. When changing tools
The shake measurement device is moved to the measurement position, and the main shaft is rotated once in # 1 to measure the shake amount. If the shake amount of # 2 is within the predetermined value, the shake measuring device is returned to the standby position, and the machining operation is immediately started in # 3. If the shake amount of # 2 exceeds the predetermined value, it is determined whether or not the shake measurement is the first time in # 4.
At the time of the first turn, replace it with a cleaning tool and loosen the main shaft by 1-2.
Rotate to clean the fitted taper surface, then replace with tool holder and repeat # 1 runout measurement. If the shake amount of # 2 at this time also exceeds the predetermined value, it is determined that there is an abnormality in # 4, and the machine is stopped and checked.

As the shake measuring device, the above-mentioned contact type electric micrometer, non-contact type commercially available eddy current displacement sensor, visible light laser type displacement sensor or the like can be used, but it is a digital type electric micrometer ( The "Digital Runout Checker M-400" manufactured by Mitutoyo Co., Ltd. is equipped with a switch for setting the upper limit value and the lower limit value of the shake and a lamp for determining the tolerance, and is suitable as the shake measuring device of the present invention. Further, the cleaning tool is not limited to the one shown in FIG.
An automatic air blow can also be adopted.

[0015]

According to the present invention, when tool misalignment is measured during tool replacement, and when a misalignment of a predetermined value or more is detected, the taper fitting portion of the spindle is automatically cleaned, After confirming that there is no misalignment, the process shifts to machining.Therefore, in machine tools that automatically change tools, it is possible to prevent the occurrence of a large number of defective products due to misalignment of the replacement tool, and to perform unattended operation even at midnight. It will be possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory view of a cleaning tool used in the present invention.

FIG. 3 is a partial cross-sectional view showing a conventional problem.

FIG. 4 is a diagram showing a flowchart of a program operation of the present invention.

[Explanation of symbols]

1 Airframe 2 Spindle 5 Tool holder 6 Cutting tool 7 NC device 8 Run-out measuring device 9 Controller 11 Cleaning tool 12 Brush 13 Lock pin

Claims (2)

[Claims] 1. An automatic control machine tool for forming a tapered portion on an inner surface of a spindle and automatically exchanging a tool holder having a tapered portion for fitting and positioning the tapered portion to sequentially perform predetermined machining. A measuring means for measuring the rotational runout of the outer periphery of the tool holder with the holder attached to the spindle, and means for cleaning the taper portion of the inner surface of the spindle.
The operation of measuring the deflection of the tool holder by the measuring means at the time of exchanging the tool, and removing the tool holder from the spindle when the amount of the deflection exceeds a predetermined value, and cleaning the taper part of the spindle by the cleaning means. A method for preventing misalignment of a tool, which is characterized by a control program. 2. A cleaning tool having an outer shape similar to that of the tapered tool holder and having a brush formed on the tapered portion,
The tool misalignment prevention method according to claim 1, wherein the taper portion of the spindle is automatically cleaned.