JPS599805Y2 - Machine tool cutting state detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device for detecting cutting conditions such as cutting width and depth of cut when light cutting is performed intermittently with an end mill or the like in a milling machine of a machine tool or the like.

Conventionally, when measuring the cutting force of a milling machine, it was relatively easy to measure large cutting forces by measuring the power of the spindle motor, but this method is impossible to measure small cutting forces. This method requires a special detector to be installed in each section, which makes the device complicated and has the disadvantage of impairing cutting rigidity.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques, and to detect cutting conditions of machine tools by making it possible to easily detect cutting conditions such as cutting width and depth of cut, which are related to light cutting force in milling machines, etc., using a simple device. We are in the process of providing equipment.

That is, the present invention forms an electric circuit between the cutter or tool of a machine tool and the workpiece, provides a detection means for detecting the current value flowing through this electric circuit, and detects the current value obtained from the detection means. A means for determining the time width of a predetermined reference level is provided, and the cutting condition such as the cutting width or cutting depth when the workpiece is cut by the force ivy or the tool is detected using the time width of the signal obtained by the means. , this detected cutting width,
Or to prevent the cutter or tool from being damaged by preventing the cutting depth from exceeding the maximum allowable cutting width or cutting depth determined by the cutter or tool in accordance with a preset cutting speed. It is characterized by the following.

The present invention will be specifically described below based on embodiments shown in the drawings.

That is, Fig. 1 shows an example of a method of applying voltage between the cutter 1 and the workpiece 8, and it shows an example of how to apply voltage between the cutter 1 and the workpiece 8.
An electrical contact 7 is provided on the bolt 6, and a power source 11 and a resistor 12 for measuring the current of the circuit are provided between this electrical contact and the table 9.
Insert.

Note that 2 is a katsutahonoreda, and 5a and 5b are gears.

FIG. 2 is a schematic diagram of end mill cutting, and when the cutting width is small, the cutting is interrupted.

That is, during one rotation of the end mill, there are states in which the cutter is in contact with the workpiece and states in which it is separated from the workpiece.

When the cutter is away from the workpiece, the current flows through the electrical contact 7, the draw-in bolt 6, the main shaft 3, the bearings 4a, 4b, 4C, and the external framework 1 in the electrical circuit shown in Figure 1.
0, flows to the table 9, but when the main shaft rotates at a constant rotation speed, the electrical resistance of the bearings 4a, 4b, and 4C maintains approximately a certain constant value, so the electrical contact 7 and the table 9 There will be no short-circuit condition.

In the electric circuit shown in FIG. 1, the potential difference Vout across the resistor 12 is measured as shown in FIGS. 3a and 3.
Figure b.

FIG. 3a is an example of measurement when the width of cut shown in FIG. 2 is small, and FIG. 3b is an example of measurement when the width of cut shown in FIG. 2 is large.

When cutting with a 4-blade end mill, the 1rev. corresponds to the time it takes for one rotation of the cutter.

Also, T is the time that one blade of the cutter is in contact with the workpiece,
It is measured as the time that Vout is above a certain reference voltage.

Therefore, for example, in cutting where the depth of cut is constant and only the cutting width changes as shown in Figure 2, the contact state between the cutter and the workpiece can be determined from the value obtained by measuring the time width of T obtained from Vout. This makes it possible to understand the cutting force.

Further, the same applies to the case of cutting in which the cutting width is constant and the cutting depth changes as shown in FIG.

Generally, the width of cut and the depth of cut change at the same time, but when performing adaptive control ACC with constraint conditions in cutting where the workpiece and machining shape are approximately fixed, the range in which the width of cut and depth of cut change is Since it is roughly fixed, it is possible to grasp the cutting force.

That is, as shown in FIG.
ut (current value flowing through the electric circuit) to a predetermined reference voltage Vs
Comparator 13 is used to compare and this comparator 13 is 2
The converted signal is converted into a digital signal through an AND circuit 14 through a clock pulse having a predetermined reference frequency, and this digital signal is converted into an analog quantity by a D/A converter 15, thereby determining the cutting width, cutting depth, etc. The cutting state can be detected and it is possible to control this cutting state so that the cutter or tool is not overloaded.

Note that the predetermined reference voltage Vs is the Vout
A value obtained by integrating and averaging the values, or a value proportional to this average value is preferable.

As explained above, according to the present invention, cutting conditions such as cutting width or depth of cut can be accurately and automatically detected in machine tools such as milling machines that perform light cutting intermittently. , adaptive control with constraint conditions becomes possible, and there is an effect that unmanned automatic driving becomes possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an electric circuit of a cutting force measuring device according to the present invention, and FIG. 2 is a diagram showing an end mill cutting state, for example.
3a is a diagram showing the waveform of the current value Vout flowing through the electric circuit when the cutting width is small; FIG. 3b is a diagram showing the waveform of the current value Vout flowing through the electric circuit when the cutting width is large; FIG. 4 is a diagram showing a schematic structure or circuit for measuring the cutting force from the value of the current flowing through the electric circuit. Explanation of symbols: 1...Cut, 3...Main shaft, 4a, 4b, 4C...Bearing, 6...
...Draw-in bolt, 7...Electrical contact,
8...Work, 9...External framework, 11
...Power supply, 12...Resistance, 13...
···comparator.

Claims (1)

[Scope of utility model registration request] In a machine tool, an electric circuit formed between the cutter or tool of the machine tool and a workpiece, a detection means for detecting the current value flowing in the electric circuit, and an integral of the current value detected by the detection means. and a time width detection means for detecting a time width of a predetermined reference level created by the reference level adjustment means in the current value detected by the detection means. A cutting state detection device for a machine tool, which is characterized by: