JPH0631593A - Counterbore work and device therefor - Google Patents

Abstract

PURPOSE:To carry out the counterbore work having a proper depth where manual reworking is unnecessary by using an NC machine tool, even for a cast article having each dispersion in the surface state and thickness. CONSTITUTION:In the counterbore working for carrying out counterbore working a bolt seat, etc., the electric current value of an electric motor which revolution- drives a main spindle which supports a grinding tool is detected, and the counterbore work is carried out by NC-controlling the cutting tool from the time point when the electric current value reaches a stationary value to the reach up to a prescribed depth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterboring method and an apparatus therefor, and in particular, it is used for counterboring (including backing) using a numerically controlled machine tool on a surface having irregularities such as a casting surface. And a device therefor.

[0002]

2. Description of the Related Art Conventionally, when a bolt or nut seat is machined (counterbore machining) on a cast product using a numerically controlled machine tool, the cast product has a dimensional variation, and therefore a numerical command value is not available. The casting surface may remain on the counterbore surface, or the counterbore surface may become too deep. This is because no matter how accurately the numerical control is performed on the cutting tool, the casting surface, which is the machined surface, has irregularities.

Therefore, in order to finish as a product, in addition to the counterbore processing by the numerically controlled machine tool, reprocessing by hand is generally performed.

[0004]

However, in addition to counterboring by a numerically controlled machine tool, manual re-machining leads to an increase in machining man-hours, resulting in an increase in cost. There was a point.

In view of the above, the present invention uses a numerically controlled machine tool to perform counterboring with an appropriate depth that eliminates the need for manual re-machining, even for a cast product having variations in surface condition and thickness. It is an object of the present invention to provide a spot facing method and an apparatus therefor capable of performing the above.

[0006]

In order to achieve the above object, a counterbore processing method according to the present invention is a counterbore processing method for counterboring a bolt seat or the like, in which an electric current of an electric motor for rotationally driving a spindle supporting a cutting tool is used. It is characterized in that the cutting tool is numerically controlled until the predetermined depth is reached from the time when the current value reaches a steady value and the counterbore processing is performed.

Further, the counterbore machining device is a counterbore machining device for counterboring a bolt seat or the like, in which a main shaft for supporting a cutting tool, an electric motor for rotationally driving the main shaft, and a current value of the electric motor have reached a steady value. Detection means for detecting that,
The present invention is characterized by comprising a numerical control means for performing counterboring to a predetermined depth from the time when the current value reaches a steady value.

[0008]

According to the present invention configured as described above, by monitoring the current value of the electric motor for rotationally driving the cutting tool and detecting that the current value has reached the steady value, the cast surface with unevenness can be obtained. After confirming that the machined surface such as the surface has become flat, it is possible to perform counterboring with an appropriate depth.

[0009]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a block diagram of a current detecting device for detecting a current value of a motor for driving a spindle of a numerically controlled machine tool.

In FIG. 1, the load current value of the motor for driving the spindle is detected by a current detector 10 of the motor for driving the spindle which monitors the cutting state. As the current detector 10, for example, a measuring instrument AC is used.

Further, the current detecting device includes a detector 10
Amplification / RMS conversion circuit 11 for amplifying and RMS value conversion of the output of A, an A / D converter 12 for converting an analog signal into a digital signal, and a logic circuit for calculating and processing the digital signal. 13 and an operation display unit 14 displayed by a signal processed by the logic circuit 13.
And an input / output interface 15 interposed between the logic circuit 13 and the numerically controlled machine tool.

That is, the detector output (current value) detected by the detector 10 such as an instrument AC converter is converted into a digital signal by the A / D converter 12 after passing through the amplification / effective value conversion circuit 11. After being taken into the logic circuit 13 and processed, it is displayed by the operation display unit 14.

FIG. 2 shows the state of changes in the main current value in the motor for driving the spindle of the numerically controlled machine tool, which is measured using the current detecting device shown in FIG. When the change of the main current value over time is divided into sections up to, as shown in the figure, the contents of each section are as follows.

Spindle stop state During this period, the additional current value becomes zero.

During spindle activation When the spindle is activated by M03 or M04, an additional current corresponding to the activation torque flows.

Spindle no-load rotation state No-load current (INUL) until cutting is actually started
Flows.

During cutting When cutting is started, the load current gradually increases and then reaches a steady value. Therefore, from the time when this steady value is reached, the cutting tool is numerically controlled until the predetermined cutting depth is reached, and counterboring is performed.

Spindle no-load rotation state When cutting is completed, the load current decreases and then becomes no-load current (INUL) again.

When the spindle stop command is issued during the spindle stop, a no-load current corresponding to the stop torque flows.

Spindle stop state When the spindle is stopped, the load current becomes zero again.

In the case of determining the backlash, such a change in the load current is detected, and the current state of the spindle (which section it belongs to) is automatically determined, and the required section is determined. Make a decision only in.

The main current value is input via the A / D converter 12, but in the case of erratic, an average current value obtained by sampling the input value (current value) several times can be used. . That is, as shown in FIG. 3, if Ii is the average value sampled several times, and I is the average value obtained by sampling this average value Ii several times (N times), The average current value I can be used as an input value (current value).

Then, the numerically controlled machine tool constantly monitors the cutting state via the current value, checks the steady cutting determination for each cutting at a constant pitch, and after the steady cutting is determined,
For example, a certain cutting amount is counterbored until a counterbore depth of 2 to 3 mm from the black skin surface is secured.

Here, in the backside boring, which is a special example of the backside boring, the boring face cannot be processed by abutting the tool from the front, and as shown in FIG. The tool 2 in which the cutting tool 1 is fixed in the opposite direction to the hole H is passed through the hole H and stopped at the R point position,
After that, it is a method in which cutting feed is performed up to, for example, the Z coordinate position.

Then, until the steady cutting is determined, the cutting is repeated at a predetermined feed rate so that the predetermined cutting amount is obtained after the steady cutting is determined, that is, the cutting is performed while the cutting tool 1 reaches the Z coordinate value. Then, the processing ends.

[0027]

As described above, according to the method and apparatus of the present invention, when a seat of a bolt or a nut is machined on a machined product such as a cast product having a concavo-convex surface by using a numerically controlled machine tool, Since it is possible to perform counterbore processing while constantly monitoring the cutting state by measuring the current value of the electric motor that drives the tool, even if it is a cast product, regardless of the state of the casting surface, it has an appropriate depth. It is possible to perform counterboring, including back-counting, and thereby eliminate the need for manual reprocessing.

[Brief description of drawings]

FIG. 1 is a block diagram of a current detection device for detecting a main current of a motor for driving a spindle of a numerically controlled machine tool.

FIG. 2 is a diagram showing a change state of a main current detected by the current detection device of FIG.

FIG. 3 is a diagram showing a sample average current average current value.

FIG. 4 is a side view showing an example of a backgripping method.

[Explanation of symbols]

 10 current detector 11 amplification / effective value conversion circuit 12 A / D converter 13 logic circuit 14 operation display section 15 input / output interface

Claims (2)

[Claims] 1. In a counterboring method for counterboring a bolt seat or the like, a current value of an electric motor for rotationally driving a spindle supporting a cutting tool is detected, and a predetermined depth is reached from the time when the current value reaches a steady value. The spot facing method is characterized by performing the spot facing by numerically controlling the cutting tool until it becomes. 2. A counterboring device for counterboring a bolt seat or the like, a main shaft for supporting a cutting tool, an electric motor for rotationally driving the main shaft, and a detection for detecting that a current value of the electric motor has reached a steady value. A counterbore processing apparatus comprising: means and a numerical control means for performing counterbore processing to a predetermined depth from the time when the same current value reaches a steady value.