JPH0647803U - Position detector - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a position detector that is mounted on a tool axis or a tool rest of a machine tool and detects the relative positional relationship between the work mounted on the machine tool and the tool shaft or the tool rest. An object of the present invention is to provide a position detector that can always detect the contact between a detection needle and a work with a constant sensitivity regardless of the magnitude of the electric resistance of a machine to be mounted. [Constitution] A battery 4 is built in a main body 1 to be mounted on a machine tool, and the main body 1 mounted on the machine tool is provided with a conducting current between a detection needle 9 held in an electrically insulated state and a work 12 mounted on the machine tool. In the position detector that detects the contact between the workpiece 9 and the workpiece 9, the switching transistor 5 is provided,
A closed loop is formed by connecting the collector-emitter of this transistor, the protection resistor 7, the LED 6 and the battery 4 in series, and the conduction current when the detection needle 9 and the work 12 contact each other is given to the base of the transistor 5. It is characterized by

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a position detector which is mounted on a tool shaft or a tool rest of a machine tool and used to detect a relative positional relationship between a work mounted on the machine tool and the tool shaft or the tool rest. is there.

[0002]

[Prior art]

 The body mounted on the machine tool is equipped with a detection needle that is held in an electrically insulated state, and a potential difference is applied between this detection needle and the machine tool body, and the detection needle is attached to the surface of the workpiece fixed to the machine tool. Position detectors that detect the contact between the detection needle and the work by using the conduction current that flows when they make contact, and thereby detect the relative positional relationship between the work and the tool shaft on which the detection needle is mounted, are known. is there.

In this type of position detector, a battery is built in the main body of the detector, one of the electrodes of the battery is grounded to the main body (and therefore the machine tool side), and the other is electrically insulated via an LED. In this state, it is connected to the detection needle held by the main body, and the LED is caused to emit light by the conduction current that flows when the detection needle comes into contact with the work fixed to the main body. I try to make them aware.

FIG. 3 shows an equivalent circuit of the electric circuit of this conventional position detector. Here, 15 is a contact formed between the detection needle and the work, 6 is an LED, 4 is a battery, 7 is a protective resistance, 10 is an electric resistance inside the machine tool including the resistance of the contact 15 part. is there. That is, when the detection needle comes into contact with the workpiece, the conduction current is generated by the gripping surface between the position detector body and the working machine, the tool shaft bearing, the tool head sliding surface, the table sliding surface, the workpiece and table. It flows through the fixed surface between them and the contact surface between the work and the detection needle, and the electrical resistance between this position detector main body and the detection needle becomes the mechanical internal resistance 10.

[0005]

[Problems to be solved by the device]

 The value of the internal machine resistance 10 shown in the equivalent circuit of FIG. 3 varies greatly depending on the type and structure of the machine tool, and when mounted on a machine tool with a large machine internal resistance 10, the sensitivity of the position detector decreases. was there. That is, in a general-purpose position detector that can be used in various machine tools, the protective resistance 7 must be determined in consideration of the case where the machine internal resistance 10 becomes 0. When a position detector is mounted on a large machine, the sensitivity becomes poor and it is difficult to use. Moreover, if the value of the protection resistor 7 and the specifications of the LED 6 are determined according to the machine internal resistance for each type and structure of the machine tool, not only will the number of position detectors increase, but the management will be troublesome. When a position detector for a machine with a large internal resistance is mistakenly used in a machine with a small internal resistance, problems such as damage to the position detector will occur.

The present invention has been made to solve the above-mentioned problem, and it is a position that can always detect the contact between the detection needle and the work with a constant sensitivity regardless of the electric resistance of the machine to be mounted. It is an object to provide a detector.

[0007]

[Means for Solving the Problems]

 In the position detector according to the present invention, a battery 4 is built in a main body 1 mounted on a machine tool, and a battery 4 is installed between the detection needle 9 held in an electrically insulated state and the work 12 mounted on the machine tool. A position detector that detects the contact between the detection needle 9 and the work 12 by the conduction current is provided with a switching transistor 5, and a closed-loop in which a collector-emitter of this transistor, a protection resistor 7, an LED 6 and a battery 4 are connected in series. Is formed, and a conduction current when the detection needle 9 and the work 12 come into contact with each other is applied to the base of the transistor 5.

[0008]

[Action]

 In the position detector configured as described above, the conduction current that flows when the detection needle 9 and the workpiece 12 come into contact with each other is applied to the base of the transistor 5, which causes conduction between the collector and the emitter of the transistor 5 and causes a current to the LED 6. It flows and makes LED6 emit light. Since the electrical resistance between the collector and the emitter when the switching transistor 5 is conducting is almost constant regardless of the magnitude of the conducting current applied to the base, even when the conducting current changes depending on the magnitude of the internal resistance of the machine, the LED 6 The current flowing through the sensor is almost constant, so that the sensitivity of the position detector of the present invention is maintained constant regardless of the internal resistance of the machine in which it is mounted.

Since the current flowing through the LED 6 does not fluctuate due to the machine internal resistance of the machine tool, the resistance value of the protection resistor 7 and the specifications of the battery 4 and the LED 6 can be appropriately determined, and therefore the sensitivity is excellent, and therefore the sensitivity is excellent. A position detector with good workability can be provided, and damage to the position detector due to incorrect use can be prevented.

[0010]

【Example】

 FIG. 1 is a diagram schematically showing a first embodiment of the present invention. The body 1 of the position detector has a shank 3 which is gripped by the rotary tool shaft of a machine tool indicated by a ground symbol 2, and contains a battery 4, a switching transistor 5, an LED 6 and a protection resistor 7. ing. The LED 6 is provided close to the window 8 provided on the wall surface of the main body, and the blinking state of the LED 6 can be visually recognized. It is possible to provide a plurality of LEDs 6 along the circumference of the main body 1 so that the blinking state of the LEDs 6 can be visually recognized from any direction. The main body 1 is made of a conductive material, and a conductive material detecting needle 9 is held in the main body 1 via a support structure (not shown) in a state of being electrically insulated from the main body 1.

The resistance 10 shown by the dotted lines in FIGS. 1 and 2 is the internal resistance of the machine tool.

The positive electrode of the battery 4 is connected to the main body 1, and the negative electrode of the battery 4 is connected to the emitter of the transistor 5. The collector of the transistor 5 is connected to the cathode of the LED 6, and the anode of the LED 6 is connected to the body 1 via the protection resistor 7. The base of the transistor 5 is connected to the detection needle 9. The main body 1 is grounded to the machine tool 2 by being gripped by the tool shaft of the machine tool, and the work 12 fixed to the machine tool is grounded to the machine tool 2 by the fixing.

In the above structure, when the detection needle 9 comes into contact with the work 12, the anode of the battery 4 and the detection needle 9 are electrically conducted through the machine tool, and the conduction current is from the base of the transistor 5 to the emitter. To flow between the collector and emitter of the transistor 5. When the detection needle 9 is separated from the work 12, the conduction current flowing between the base and the emitter of the transistor 5 disappears, and the collector and the emitter are cut off. Therefore, the LED 6 emits light when the detection needle 9 and the work 12 come into contact with each other, and the LED 6 is extinguished when the detection needle 9 and the work 12 separate from each other, and the electrical resistance between the collector and the emitter of the switching transistor is increased. Is kept substantially constant regardless of the magnitude of the current flowing between the base and the emitter, so that the brightness of the LED 6 is also kept substantially constant.

In the circuit of the first embodiment, the detection needle 9 is connected to the base of the transistor 5, but as shown in FIG. 2, the base of the transistor 5 is set to the ground side, and the closed circuit side including the battery 4 and the LED 6 is set to the ground side. It is also possible to adopt a structure in which the detection needle 9 is connected. The operation of the circuit of the second embodiment is the same as that of the first embodiment (the only difference is that the conduction current flows from the emitter of the transistor 5 to the base and the polarity between the collector and the emitter is opposite). Therefore, the description will be omitted.

[0015]

[Effect of device]

 According to the present invention described above, it is possible to provide a position detector that can always detect the contact between the detection needle and the work with a constant sensitivity regardless of the magnitude of the electric resistance inside the machine to be mounted. It is possible to improve workability and prevent damage to the position detector due to misuse.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a first embodiment.

FIG. 2 is an electric circuit diagram of a second embodiment.

FIG. 3 is a diagram showing an equivalent circuit of a conventional device.

[Explanation of symbols]

 1 Main body 4 Battery 5 Switching transistor 6 LED 9 Detection needle 12 Work

Claims (1)

[Scope of utility model registration request] 1. A battery for a main body (1) mounted on a machine tool.
(4) is built in, and the conduction current between the detection needle (9) held in this body in an electrically insulated state and the work (12) mounted on the machine tool causes the detection needle (9) and the work (12) ), A position detector that detects contact with a switch transistor (5) is provided, and a closed loop is formed by connecting the collector-emitter of this transistor, the protection resistor (7), the LED (6), and the battery (4) in series. The position detector is characterized in that the conduction current when the detection needle (9) and the work (12) come into contact with each other is given to the base of the transistor (5).