JPS5929383B2 - Contact detection device between a cutting tool and a workpiece in a machine tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contact detection device between a cutting tool and a force-receiving object in a machine tool.

Conventionally, in machine tools, devices for detecting whether or not a cutting tool has come into contact with a workpiece have been magnetostrictive, which magnetically detects the cutting force applied to the cutting tool, that is, the strain on the spindle exerted by the cutting tool. Torque detection devices are known.

However, with the above-mentioned conventional device, unless the cutting tool is cutting into the workpiece by cutting into the workpiece considerably, that is, unless an extremely high level of cutting torque is applied to the cutting tool, it is difficult to determine whether the cutting tool has contacted the workpiece or not. It was difficult to detect.

In addition, as a device for detecting whether or not a cutting tool has come into contact with a workpiece, an electrical insulator is interposed between the table on which the workpiece is placed and the workpiece, and the cutting tool and the workpiece are interposed between the table and the workpiece. Attempts have been made to develop a device equipped with means for applying a voltage from the outside between the cutting tool and the workpiece and detecting the values of both flows flowing between the cutting tool and the workpiece.

However, in this device, an electrical insulator that is generally more easily deformed than metal is interposed between the workpiece and the table, which reduces the rigidity of the workpiece relative to the table, resulting in a reduction in machining accuracy. have.

Furthermore, as a detection device for detecting whether or not a cutting tool has come into contact with an object to be subjected to force, there is known a device described in Japanese Patent Publication No. 48-40861.

In this device, the movable body is mounted on the upper side of the column so as to be able to slide up and down, and the movable body is fitted with a holder having a cutting tool fixed to the end thereof.

However, in such a machine tool, the holder is usually rotatably supported by a movable body by a bearing, and is configured to be rotationally driven by power from a rotational drive source.

In this machine tool, the equivalent circuit of the detection device described in Japanese Patent Publication No. 48-40861 is shown in FIG.

1 is a tool, 2 is a workpiece, 4 is a column and movable body, 13
14 is a detection coil wound around an iron core, and 15 is the above-mentioned bearing.

Therefore, in this detection device, since most of the circuit current flows through the column 4 due to the bearing 15, no current flows between the tool 1 and the workpiece 2, resulting in a situation where detection is almost impossible. had.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a workpiece that can reliably and quickly detect contact between a cutting tool and a workpiece even if the workpiece slightly contacts the cutting tool. An object of the present invention is to provide a contact detection device between a cutting tool and an object to be subjected to force in a machine.

That is, in order to achieve the above-mentioned object, the present invention provides a rotating shaft for attaching a cutting tool or a workpiece to the ground and rotationally driven;
A table having a force-receiving object or a cutting tool attached thereto, and a support member rotatably supporting the rotating shaft on one end side and movably supporting the table on the other end side, the rotating shaft and the table , in a machine tool in which the supporting member is formed of an electrically conductive member, an electromagnetic coil that is excited so as to generate an induced current in the electrically conductive supporting member is disposed close to the electrically conductive supporting member; A means for detecting the amplitude and phase of a current flowing between two points, a part between the cutting tool and the electromagnetic coil and a part between the workpiece and the electromagnetic coil, is provided, and the cutting tool comes into contact with the workpiece. A contact detection device between a cutting tool and a workpiece in a machine tool is characterized in that the change in the amplitude and phase of the current that occurs when the contact between the cutting tool and the workpiece is detected by the means described above.

Further, the present invention is characterized in that an AC power source is connected in series to the above means, and changes in the amplitude and phase of the current are made noticeable to improve detection sensitivity.

The present invention will be specifically explained below with reference to embodiments shown in the drawings.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.

That is, 1 is a cutting tool of a machine tool, 2 is a workpiece placed on a table 3 of the machine tool, and 4 is a column of the machine tool.

The "cutting tool" is rotatably supported by the upper head of the column 4, and is attached to the lower end of a rotary shaft driven to rotate.

Further, the table 3 is supported by a head provided at the bottom of the column 4 so as to be movable in the horizontal direction.

The cutting tool 1 and the workpiece 2 are connected via a column 4 with a conductive member so that a current flows therethrough.

Reference numeral 5 denotes an electromagnetic coil connected to an AC power source and excited by the AC voltage, and is arranged so as to surround the central portion of the column 4 formed of the above-mentioned conductive material.

7 indicates two points (a,
b) Use a resistor to detect the current flowing between them, that is, the potential difference generated between two points (a, b), and connect both ends to the two points (a, b) in column 4.
a, b).

The electromagnetic coil 5 is excited by the AC power supply 6, and an induced current is generated on the column 4 formed of a conductive member.

When the cutting tool 1 comes into contact with the workpiece 2 in this state, an electrically closed loop is formed in the machine tool, and the induced current changes, causing the current generated between the two points (a, b) of the column 4 to change. Changes also occur in the amplitude (potential difference) and phase of the current.

By detecting the amplitude (potential difference) of the current between these two points (a, b) and the change in the phase of the current using the resistor 7, the moment when the cutting tool 1 contacts the workpiece 2 is detected.

That is, when the detection device shown in FIG. 2 is shown as an equivalent circuit, FIG. 3 a
, b.

By the way, E shown in FIG. 3 is the E knee 50 amount Io.

Therefore, in the equivalent circuit shown in Figure 3, becomes.

Therefore, the imaginary part of the composite impedance can be made close to 0, and the real part also becomes small.

The waveform IO applied to the electromagnetic coil 5 at this time is as shown in FIG. 4a.

On the other hand, before the cutting tool 1 contacts the workpiece 2, (a, b
The voltage (Vout) detected between ) is as shown in FIG.
The voltage (Vout) detected between a and b) is as shown in Figure 4 CV
It will be as shown in C.

In this way, before and after contact, changes are seen in the amplitude (voltage) of the current and its phase, making it possible to detect whether or not contact has occurred.

In the above embodiment, one closed circuit is formed in the bamboo, so changes in the induced current can be reliably detected, and contact between the cutting tool and the workpiece can be detected with high sensitivity. .

FIG. 5 is a block diagram showing another embodiment of the present invention.

That is, the power supply 8 is the same as that shown in FIG. 1 except for the AC power supply 8, which is connected in series between one point a of the column 4 and one end of the resistor 7.

An alternating voltage is applied from an alternating current power source 8 between two points (a, b) of the column 4, which is a conductive member, and an alternating current flows.

Furthermore, the electromagnetic coil 5 is excited by the alternating current power source 6, and an induced current is induced on the column 4 in a form superimposed on the alternating current.

When the cutting tool 1 comes into contact with the workpiece 2 in this state, a closed loop is formed in the electric plate, and the two points on the column 4 (
A change occurs in the amplitude (potential difference) and phase of the current generated between a and b), and the current waveform (amplitude and phase) flowing through the resistor 7 becomes different.

Therefore, by detecting the current waveform flowing through this resistor 7, it is possible to detect the moment when the cutting tool 1 contacts the workpiece 2.

With this configuration, the detection effect is even better than that of the embodiment shown in FIG.

Next, a specific example of the electromagnetic coil 5 will be explained based on FIGS. 6-7.

That is, as shown in FIG. 3, the electromagnetic coil 5 has an iron core 9 formed into a mouth shape, and the coil is integrally made and wound around a column. There are two types of coils that can be installed by winding them around the column 4 of a machine tool, and others that are formed so that the coils 12 are wound around each core 11 consisting of four pieces as shown in Fig. 4 so that they can be placed around the column 4 of a machine tool. .

As explained above, according to the present invention, it is possible to detect the moment when a cutting tool contacts a workpiece quickly and with high sensitivity without impairing the inherent performance of the machine tool.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an equivalent circuit of a conventional detection device for detecting contact between a cutting tool and a workpiece in a general machine tool, and Figure 2 is a diagram showing the contact between a cutting tool and a workpiece in a machine tool of the present invention. 3A and 3B are diagrams showing an equivalent circuit of the contact detection device shown in FIG. 2, and FIGS. 5 is a diagram showing the current and voltage waveforms obtained from the equivalent circuit shown in FIG. 5, a schematic configuration diagram showing another embodiment different from the embodiment shown in FIG.
This figure is a perspective view showing one embodiment of the electromagnetic coil shown in FIGS. 2 and 5, and FIG. 7 is a plan view showing another embodiment of the electromagnetic coil different from the embodiment shown in FIG. 6. 1... Cutting tool, 2... Workpiece, 4
... Column, 5 ... Electromagnetic coil, 6.
...AC power supply, 7...Resistance, 8...
·AC source.

Claims (1)

[Scope of Claims] 1. A rotary shaft to which a cutting tool or a workpiece is attached and which is rotationally driven; a table to which the workpiece or cutting tool is attached; the rotary shaft rotatably supported on one end side; A workpiece including a supporting member movably supporting the table on the other end side, and in which the rotating shaft, the table, and the supporting member are made of a conductive material, is excited so that an induced current is generated in the conductive supporting member. An electromagnetic coil to be processed is placed close to the electroconductive support member, and two points on the electroconductive support member are located at a portion between the cutting tool and the electromagnetic coil and a portion between the workpiece and the electromagnetic coil. A machine tool characterized in that the machine tool is provided with means for detecting the amplitude and phase of a current flowing therebetween, and the means detects changes in the amplitude and phase of the current that occur when a cutting tool contacts a workpiece. contact detection device between a cutting tool and a workpiece. 2. A rotating shaft to which a cutting tool or a workpiece is attached and rotationally driven, a table to which a force-receiving object or cutting tool is attached, the rotating shaft rotatably supported on one end, and a rotating shaft on the other end. A machine tool comprising: a support member movably supporting the table, and wherein the rotating shaft, the table, and the support member are made of conductive members; disposed proximate to the conductive support member, on the conductive support member,
An alternating current power source connected to flow an alternating current between two points, a portion between the cutting tool and the electromagnetic coil and a portion between the workpiece and the electromagnetic coil, and connected in series to the alternating current power source; A means for detecting the amplitude and phase of the current flowing between two points is provided, and the change in the amplitude and phase of the current that occurs when the cutting tool contacts the workpiece is detected by the means. A contact detection device between a cutting tool and a workpiece in a machine tool.