JPH0446165Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a detection device for measuring the position of the cutting edge of a cutting tool in a machine tool, and more specifically, the invention relates to a detection device for measuring the position of the cutting edge of a cutting tool in a machine tool. This relates to a device that detects when the cutting edge of a tool is located at a certain distance from a reference surface such as a table, chuck, or workpiece, and notifies the operator by emitting light.

(Prior art and its problems) NC machine tools, machining centers, etc.
It is necessary to know the position of the cutting edge of the tool attached to these spindles relative to the workpiece. As a detection device for that purpose, for example,
As is known from Japanese Patent Publication No. 7655 and Japanese Patent Publication No. 56-48042, devices are known that electrically detect when a touch sensor or the like attached to the main shaft of a machine tool comes into contact with a workpiece.

However, in the former device disclosed in Japanese Utility Model Application Publication No. 55-7655, a dedicated detection coil for detecting the electrical closed circuit formed when the workpiece side and the spindle side come into contact is installed concentrically with the spindle side. In the latter device disclosed in Japanese Patent Publication No. 56-48042, it is not only necessary to attach a dedicated detection electrode to the spindle in an electrically insulated state from the spindle (workpiece). Either device must be used by electrically connecting the device attached to the machine tool and the detection circuit device.

In other words, all conventional devices require a dedicated machine to be installed on the machine tool side or an electrical connection to a device used in conjunction with the machine tool, which requires a lot of time and effort to prepare for the tool position detection function. Not only is it time consuming, but it is also substantially difficult and uneconomical to use one detection device for multiple machine tools.

In order to solve these conventional problems, a detection device shown in FIG. 5 was devised.

That is, in the same figure, the detection device 1 has a base portion 2 having a reference bottom surface 2a that can be placed on the flat surface of the workpiece W, and a head portion 3 having a reference top surface 3a, which are made of an intermediate portion made of an insulating material. A battery 5 and a light emitting diode 6 are connected in series between the base part 2 and the head part 3. The reference bottom surface 2a and the reference top surface 3a have a certain distance, and the dimensions thereof are accurately known.

To use this, the detection device 1 is placed, for example, on the workpiece W, and when the tool T attached to the main shaft of the machine tool is manually lowered without rotating, the tip of the tool T comes into contact with the reference top surface 3a. At this point, an external closed circuit C is formed through the tool T, the frame of the machine tool, the bed, the workpiece W, etc., and current flows through the light emitting diode 6, causing it to light up. Therefore,
The operator stops moving the tool T when the light emitting diode 6 lights up, reads the scale built into the machine tool, and measures the tool position, installation length, or the position of the machined surface of the workpiece. This is possible.

However, if we look at the contact process between the cutting edge of the tool T and the reference top surface 3a from a microscopic perspective, the contact pressure changes depending on the positional relationship between the two, which changes the contact resistance. The current flowing through the light emitting diode 6 also changes gradually, and the brightness of the light emitting diode 6 changes even after it starts emitting light. Therefore, the point at which the light emitting diode 6 should be turned on differs depending on the subjectivity of the worker, and even for the same worker, it varies depending on the surrounding brightness and other environments. This appears as a measurement error. This error can be as high as 5 μm at most, and can only be compensated for by the experience and skill of the operator. Such a detection device 1
However, there were practical problems as a measurement jig for precision machining.

(Technical means for solving the problems) The present invention has been made to solve the above-mentioned problems. A tool position detection device for a machine tool includes: a base portion 12 having a reference bottom surface 12a that can be placed on a flat surface and serves as an electrical terminal; a head portion 13 connected to the base portion 12; A reference top surface 14 is held in the head portion 13 so as to be movable within a certain range in a direction perpendicular to the bottom surface 12a, is biased in the projecting direction by a spring 17, and has an electrical terminal at its tip.
A detection device 11 is provided with a movable body 14 having a height of 1.a, a light emitting body (such as a light emitting diode 21) visible from the outside, and has a built-in battery 20 and light emitting circuits 22, 26, 29. The reference top surface 14a refers to the battery 20 and the light emitting circuit 2.
2, 26, and 29, and the light emitting circuits 22, 26, and 29 are connected to the light emitting body (such as the light emitting diode 21) when the current flowing through the light emitting circuit reaches a certain level. It is characterized in that it is provided with a switching circuit that allows the current flowing through it to rapidly increase.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with

In FIG. 1, the detection device 11 includes a base portion 12 having a flat reference bottom surface 12a, a head portion 13 holding a movable body (rod) 14 that can be raised and lowered in the center, and an intermediate member 15 made of an insulating material. Therefore, it is integrally formed into a substantially cylindrical shape. An annular magnet 16 is embedded in the base portion 12, and is adapted to be attracted to the surface of a table, chuck, or workpiece of a machine tool, so that the reference bottom surface 12a is brought into close contact with those surfaces.

The movable body 14 has a reference top surface 14a at its upper end that is parallel to the reference bottom surface 12a, and is biased in the protruding direction by the spring 17 so that when it is at the upper limit position as shown in the figure, the reference top surface 14a and the reference top surface 14a are parallel to each other. The distance from the reference bottom surface 12a is a constant and accurate dimension. The pin 18 is used to prevent the movable body 14 from rotating. The detection device 11 includes a built-in battery 20, a light emitting diode 21, and a light emitting circuit 22, which can be replaced by removing the lid 19.

FIG. 2 shows the electrical circuit of the detection device 11. To explain the structure of the light emitting circuit 22 along with its operation, a light emitting diode 21, a switching transistor 23, and the battery 20 are connected in series between the reference bottom surface 12a of the base portion 12 and the reference top surface 14a of the movable body 14. The base of the transistor 23 is connected to a resistor 24, 2 of an appropriate value.
5 is connected and the base current flowing from the reference top surface 14a through the resistor 24 into the transistor 23 increases to a certain value, the transistor 23 is switched into operation and the collector current increases rapidly, causing the light emitting diode 21 to light up. I'm starting to let them do it.

The detection device 11 configured as described above uses the magnet 16 to attract, for example, the surface or side surface of a workpiece, and causes a tool attached to a machine tool to approach the reference top surface 14a from a direction perpendicular to the reference top surface 14a and come into contact with it. As a result, an external closed circuit C is formed that connects the reference top surface 14a and the reference bottom surface 12a through the workpiece, tool, frame, table, etc. of the machine tool. At that time, the tool and the reference top surface 14
The current flowing through the light emitting diode 22 changes depending on the contact resistance between the resistor 24 and the resistor 24.
Current flows through the side.

As the contact resistance decreases, transistor 2
When the base voltage of transistor 3 rises to a certain extent, switching is activated by the amplification effect of transistor 23.
The current of the light emitting diode 21 increases rapidly, causing it to light up brightly. In this way, since the time point at which the light emitting diode 21 is turned on is clear, there is no difference in the judgment of the lighting due to differences in the operator or the environment, and measurement errors caused by these are eliminated.

By adjusting the values of resistors 24 and 25,
The lighting point of the light emitting diode 21 can be adjusted. It is possible to freely select a resistor for current limiting of the light emitting diode 21, the type of transistor, the circuit, the voltage of the battery, etc. Note that since the movable body 14 can be lowered against the biasing force of the spring 17, problems caused by overtravel of the tool are prevented.

FIG. 3 shows a light emitting circuit 26 of another embodiment. In this case, a thyristor 27 is connected in place of the transistor 23, and a resistor 28 is connected thereto to allow the gate current to flow therethrough. Since no current flows through these light emitting circuits 22 and 26 when the detection device 11 is not in use, the battery 20
It is convenient because it lasts a long time.

FIG. 4 shows a light emitting circuit 29 of still another embodiment. This is because the input voltage to the Schmitt element 30 changes depending on the contact resistance between the tool and the reference top surface 14a, the resistance values of other external closed circuits, the resistance values of the resistors 32 and 33, etc. When the value exceeds 0, the Schmitt element 30 turns on and the light emitting diode 21 lights up. Resistor 31 is for current limiting. Other suitable logic elements may be used in place of Schmitt element 30.

In the above embodiments, other suitable light emitters may be used in place of the light emitting diode 21, and the light emitting circuit can be changed as appropriate depending on the light emitter used. The reference bottom surface 12a may be not a flat surface but a leg-shaped surface that stably contacts the flat surface.

(Operations and Effects of the Invention) As described above, the tool position detection device of the present invention uses the reference bottom surface of the base to place the workpiece on the surface of the workpiece, moves the spindle, and attaches the spindle. Simply bring the tip of the tool that is attached to the reference top surface into contact perpendicularly to the reference top surface, and the point at which the tip of the tool comes into contact with the reference top surface, that is, the point at which the tip of the tool is a certain distance away from the reference bottom surface. You can easily know when this point has been reached by turning on the light emitter. Therefore, the position of the spindle at the time the light emitter is turned on can be read from the scale provided in the machine tool, and the tool position etc. can be determined from this read data.

According to the tool position detection device of the present invention, there is no need to install special equipment or electrical wiring on the machine tool side, and when tool position detection is required, the device of the present invention can be mounted on a workpiece, etc. Put it down,
Tool position can be detected instantly and inexpensively by simply moving the spindle with the tool attached. Therefore, it is extremely easy to use the device of the present invention for multiple machine tools.
Very economical.

Furthermore, according to the device of the present invention, the reference top surface, which serves as an electrical terminal against which the tip of the tool comes into contact, is provided at the tip of the movable body that can retreat against the spring, so overtravel of the tool may occur. Even though
By moving the movable body backward, overtravel of the tool can be absorbed, and problems such as overload and damage to the device can be avoided.

Furthermore, according to the device of the present invention, the light emitting body suddenly emits light when the contact resistance between the tool and the reference top surface approaches a certain value, making it clear when the light emitting body turns on, and eliminating individual differences and environmental factors. Errors in the timing of lighting decisions due to differences can be prevented, and highly accurate tool position detection can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the detection device of the present invention;
FIG. 2 is an electric circuit diagram of the detection device shown in FIG. 1, FIGS. 3 and 4 are electric circuits showing other embodiments of the light emitting circuit, and FIG. 5 is a diagram explaining the basic configuration of the detection device of the present invention. It is. 11...detection device, 12...base part, 12a
... Reference bottom surface, 13 ... Head part, 14 ... Movable body, 14a ... Reference top surface, 20 ... Battery, 21 ...
...Light emitting diode (light emitter), 22, 26, 29
... Light emitting circuit, 23 ... Transistor (switching circuit), 27 ... Thyristor (switching circuit), 30 ... Schmitt element (switching circuit), W ... Work, C ... External closed circuit.

Claims (1)

[Scope of utility model registration request] a base portion that can be placed on a flat surface and has a reference bottom surface that serves as an electrical terminal; a head portion that is connected to the base portion; and a head portion that is movable within a certain range in a direction perpendicular to the reference bottom surface The movable body is held in the head part and biased in the protruding direction by a spring, and has a reference top surface that serves as an electrical terminal at the tip, and a light emitting body that is visible from the outside, and has a built-in battery and a light emitting circuit. In the detection device, the reference bottom surface and the reference top surface are electrically connected through the battery and the light emitting circuit, and the light emitting circuit is provided with a detection device in which a current flowing through the light emitting circuit exceeds a certain level. A tool position detection device for a machine tool, which is provided with a switching circuit that sometimes causes a sudden increase in the current flowing through the light emitting body.