JP2770110B2 - NC machine tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC machine tool.

[0002]

2. Description of the Related Art In general, a conventional NC machine tool performs various operations continuously while automatically changing tools when moving from one processing to the next processing. Before performing the next machining, change the length of the tool to NC.
Machine tools need to measure and understand. for that reason,
In a conventional NC machine tool, the main shaft equipped with a tool is lowered at a constant speed by a Z-axis feed means, and it is detected that the tip of the tool has come into contact with an automatic tool length measuring device arranged below at a predetermined pressure. Then, the length of the tool is calculated based on the output from the measuring device and stored in the memory. In still another conventional example
Is a way to feed a tool that is rapidly traversed to make measurements quickly.
Detecting means for detecting the tip position of the tool is provided inside
(Eg, Japanese Utility Model Application No. 60-165)
No. 115).

[0003]

In the above prior art,
The tool whose length is measured is fed at a constant speed by the Z-axis feed means. If the feed speed is too fast, the tool may break due to the impact when it comes into contact with the measuring instrument when the diameter of the tool is small. May bend. Therefore, it is necessary to set a low feed rate so that even a tool having a small diameter will not be damaged by an impact. However, if the feed rate is set to be low, there is a problem that it takes too much time to measure the tool length. Therefore, by measuring and inputting the approximate length of the tool to shorten the tool length measurement time,
There is a method of increasing the feed speed by the Z-axis feed means up to a point where there is a margin more than the measured value. However, this method is very difficult because the length of each tool must be measured and input to the program. It takes time. Also
In the case where the detecting means for detecting the tip position of the tool is provided,
The fact that the oil droplets dripped and crossed the optical path depends on the tool tip.
Was mistaken, and it caused a malfunction.

Therefore, an object of the present invention is to eliminate malfunctions,
An object of the present invention is to shorten the machining time of an NC machine tool by enabling a tool length to be measured in a short time without breaking a tool of any diameter.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a spindle on which various tools are mounted, a Z-axis feed means for moving the spindle up and down, A measuring device that outputs a signal when the tip of the measuring device hits the sensing unit, a Z-axis control unit that controls the Z-axis feed unit, and a tool length calculating unit that calculates a tool length based on a signal from the measuring device. in an NC machine tool having has an optical sensor for outputting a detection signal when the tool path is blocked by the tip of the tool is lowered to the sensing unit near the meter, above the light sensor
It starts the counting from the serial detection signal is output,
While the detection signal is being output from the optical sensor,
Has a timer means for continuing the counting, and the Z-axis control unit controls the Z-axis feed means at a fast feed speed counting means until it completes counting of the predetermined time, timer means
Is configured to control the Z-axis feed means by switching to a slower speed suitable for the tool having the smallest diameter when the clocking of the predetermined time is completed .

[0006]

The optical sensor detects that the tool has descended and has reached a predetermined position, and the timing means continues to count for a predetermined time after the detection.
Since line, faster feed rates of up to complete the counting of a predetermined time, subsequent feed speed control the speed so as not to damage the tool in response to most diameter slender tool out of the tool is set It becomes possible to do. Clocking of a predetermined time
Excludes cases where the light path is temporarily blocked by oil etc.
To do that.

[0007]

An embodiment of the present invention will be described with reference to the drawings. The spindle head 1 is located above, and the main shaft 1a projecting downward is moved up and down by a Z-axis feed means 10 (FIG. 3). The tool 2 is attached to the main shaft 1a. A measuring device 3 is provided directly below the tool 2 at a predetermined interval. The measuring device 3 is of a pressure sensing type, and outputs a signal when the tip of the tool 2 comes into contact with a sensing portion 3a on the upper surface thereof, thereby automatically measuring the tool length. It is fixed to. On both sides of the measuring device 3, support plates 6 a and 6 b are opposed to each other on the base 4.
It is erected in.

The optical sensors 7 are opposed to the support plates 6a and 6b.
a and 7b are attached. One of the optical sensors is a light emitting unit 7
a, the other is a light receiving unit 7b, and the light emitting unit 7a
The optical path L reaching b is mounted at a position passing above near the sensing unit 3a.

A U-shaped mounting plate 8 is fixed to the support plates 6a and 6b, and the blowers 9a and 9a are attached to the mounting plate 8.
9b is attached. The blowers 9a and 9b are air blowing means for blowing dust on the light emitting portion 7a and the light receiving portion 7b of the optical sensor to remove dust and the like, thereby preventing the optical sensor from malfunctioning.

As shown in FIG. 3, the NC machine tool has a Z
A Z-axis control unit 11 for controlling the axis feed means 10;
Length calculation unit 1 that calculates the tool length based on the signal from
And 2. When the optical path L of the optical sensors 7a and 7b is interrupted by the tool 2, the detection signal output from the light receiving section 7b of the optical sensor is a set time variable type
Input to the camera 17 and keep time from when this detection signal is input.
To start. A predetermined time is set in the timer 17 in advance.
Therefore, the optical path L is continuously interrupted for the predetermined time.
When the detection signal is output from the optical sensor
Input to the skip signal processing unit 13 for
The signal is input to the Z-axis controller 11. The detection signal output from the measuring device 3 when the tool 2 comes into contact with the tool 2 is processed by the tool measuring device skip signal processing unit 14 and input to the Z-axis control unit 11.

The Z-axis control section 11 controls the Z-axis feed means 10 at a high feed rate until a signal is output from the optical sensor skip signal processing section 13. When a signal is output from the signal processing unit 13 for the optical sensor, the Z-axis feed unit 10 is controlled to a slow feed speed suitable for a tool having the smallest diameter. And a skip signal processing unit 1 for a tool measuring instrument.
When the signal is output from the control unit 4, the Z-axis feed unit 10 is stopped.

According to the output of the Z-axis feed means 10, the Z-axis coordinates
When the coordinates are detected by the calculation unit 15 and the output of the Z-axis feed unit 10 stops, the tool length is calculated by the tool length calculation unit 12, and the output is stored in the tool length memory unit 16.

FIGS. 4A and 4B show the steps from when a new tool 2 is mounted on the spindle 1a until the tool length is measured. FIG. 4A shows the operation when the tool 2 is mounted on the spindle 1a. The coordinates of the origin are detected by the Z-axis coordinate calculator 15. Therefore, a high feed rate from the Z-axis control unit 11,
For example, a control signal of 3000 mm / min
And the tool 2 descends. As shown in (b)
Then, when the tool 2 interrupts the optical path L, the optical sensor 7b detects it.
The output signal is output and input to the set time variable timer 17,
Here, when the measurement of the predetermined time is completed, the output of the optical sensor skip signal processing unit 13 is input to the Z-axis control unit 11, so that the Z-axis control unit 11 sends a low feed rate,
Since a control signal of about min is supplied to the Z-axis feed means 10, the tool 2 descends slowly. As shown in FIG .
As described above, when the tool 2 gently comes into contact with the sensing unit 3a, the output of the tool measuring instrument skip signal processing unit 14 is output to the Z-axis control unit 1.
As a result, the control signal is not output from the Z-axis control unit 11 and the Z-axis feed unit 10 is stopped. The Z-axis coordinate at this time is detected by the Z-axis coordinate calculator 15 and the tool length calculator 1
In step 2, the Z-axis descent distance is calculated from the Z-axis descent coordinate and the origin coordinate, and the tool length is calculated. This tool length is stored in the tool length memory unit 16, and the NC machine tool performs machining based on the data in this memory unit.

As an example, when measuring the length of a drill having a diameter of 0.3 mm, assuming that the distance from the tip of the drill to the sensing portion 3a is 400 mm, a conventional measuring method for lowering this distance at a constant speed is used. 50mm /
If it is lowered at a feed rate of min, the measurement will take 480 seconds. On the other hand, in the case of the present invention in which the optical sensor is arranged so that the optical path L passes 20 mm above the sensing unit 3a, the section of 380 mm up to the optical path L is 3000 mm
/ Min feed rate and the subsequent 20mm section is 50mm
When sent at / min, the measurement takes only 31.6 seconds, which is 448.4 seconds shorter than the conventional measurement time.

Here, a timer 17 is provided as time measuring means.
To explain the point in more detail, as shown in FIG.
Since the NC machine tool operates continuously, the spindle 1a is always supplied with oil. Therefore, when the tool length is measured, the oil droplet 5 may drop and cross the optical path L, and the light sensors 7a, 7
If b responds and outputs a signal from the optical sensor skip signal processing unit 13, a measurement malfunction may occur. Similar malfunction may occur when dust such as chips attached to the main shaft 1a falls and crosses the optical path L. Therefore, in the present invention , a signal is output only when the optical path L is interrupted by the tool 2.

That is, if the predetermined time set in the timer 17 is set to about 0.1 second, even if the light path L is interrupted by the oil droplets 5 or dust, the detection signal is sent to the Z-axis controller 11 immediately. Is not input, and no malfunction occurs. When the optical path L is interrupted by the tool 2, the interrupted state continues for a longer time than the predetermined time. In this case, the detection signal is reliably input to the Z-axis controller 11 after the elapse of the predetermined time.

After measuring the tool length as described above, machining of the work starts. At this time, since the tool length to be used is known, it is difficult to move the tool on the work. The tool 2 may be raised by the Z-axis feed means 10 to the minimum necessary height position where the tip of the tool 2 does not contact the work. If the tip of the tool is separated from the work surface of the work by a certain distance, machining can be continued safely enough, so that the tool does not need to be raised to an unnecessary height, and the time required for machining can be reduced Becomes

In this embodiment, a pressure sensing type measuring device 3 is used as the tool length measuring device 3, but an electric conduction type measuring device may be used as the measuring device.

In this embodiment, the optical sensors 7a, 7b
After the optical path L is blocked by the tool 2, the Z-axis feed means 1
0 is controlled to a slow feed rate suitable for the tool with the smallest diameter, but if the optical sensor to be used is of a type that can measure the tool diameter, by controlling the feed rate suitable for the tool diameter, In this case, it is not necessary to control the feed rate to a slow speed suitable for the tool having the smallest diameter, and the time required for measuring the tool length can be reduced.

[0020]

As described above, malfunction does not occur even if oil or dust temporarily interrupts the optical path.
Ku can perform accurately and in a short time for the measurement of the tool length, thereby improving the rate of operation of unmanned continuous operation.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of the present invention.

FIG. 2 is a plan view of a main part of the above.

FIG. 3 is a block diagram illustrating a configuration of a drive control unit according to the embodiment.

FIGS. 4A, 4B, and 4C are front views for explaining a step of measuring a tool length.

FIG. 5 is a front view for explaining the necessity of providing a timing unit.

[Explanation of symbols]

 Reference Signs List 1a Main shaft 2 Tool 3 Measuring device 3a Sensing unit 7a Optical sensor (light emitting unit) 7b Optical sensor (light receiving unit) 10 Z-axis feeding unit 11 Z-axis control unit 12 Tool length calculating unit 17 Clocking unit L Optical path

Claims (1)

(57) [Claims] 1. A spindle on which various tools are mounted, Z-axis feed means for moving the spindle up and down, and a measuring device for outputting a signal when the spindle is lowered and the tip of the tool hits a sensing unit. An NC machine tool comprising: a Z-axis control unit that controls the Z-axis feed means; and a tool length calculation unit that calculates a tool length based on a signal from the measurement device. lowered to close has a light sensor for outputting a detection signal when the optical path is blocked by the tip of the tool, the detection signal is outputted from the light sensor
After the time measurement is started,
While the detection signal is being output, keep the timer for a predetermined time.
And the Z-axis control unit includes a timer.
With stage controls the Z-axis feed means until it completes counting of the predetermined time at a high feed rate, the time measuring means is predetermined
An NC machine tool, wherein when the time measurement is completed, the Z-axis feed means is controlled by switching to a slow speed suitable for a tool having the smallest diameter.