JPS6116582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic measuring device that is inserted into the main shaft of a machine tool, particularly a machining center, and measures an object to be measured.

BACKGROUND ART Conventionally, with measurement tools that are used by being inserted into a tool insertion hole of a spindle that rotates like a tool, how to extract a measurement signal has been a problem.
As an example, a measurement tool is provided with an output socket, and a plug that can move forward and backward is provided at the front end of the spindle head.
After inserting the measuring tool into the tool insertion hole, there are some tools that take out the measurement signal by inserting a plug into the socket, but since the plug is located near the machining area, it may get contaminated by coolant or chips. However, there were problems with durability.

Additionally, there is a non-contact type device that detects the light from a lamp installed on a measuring tool using a light receiving element installed at the front end of the spindle head, but the detection may be hindered by disturbances such as lighting. There was also the problem that the light receiving element was contaminated by coolant, chips, etc.

The present invention solves the above-mentioned problems of the conventional automatic measuring device, and provides the above-mentioned replaceable measuring tool, which emits light when the measuring tip of the measuring tool detects the position of the object to be measured. Provide a luminous body,
A through hole is formed in the center of the spindle parallel to the axis of the spindle in order to transmit the light from the light emitting body to the rear of the spindle, and a photoreceptor is provided at the fixed part behind the spindle to detect the light passing through the through hole. , to provide automatic measuring devices for machine tools.

In other words, since the automatic measuring device of the present invention uses a system in which the light from the emitter is transmitted to the photoreceptor through the inside of the spindle, it is completely unaffected by external disturbances such as other lighting, and as a result, the light from the front of the spindle to the rear of the spindle is transmitted. This enabled the transmission of light over long distances.
Furthermore, since the light emitter and photoreceptor are not exposed to the outside, they are not adversely affected by coolant, chips, etc., and durability is also improved.

In the automatic measuring device of the present invention, the light from the light emitter of the measuring tool is transmitted through the center of the spindle to the light receiver on the fixed side. It becomes possible to transmit the light to the fixed side photoreceptor. Thereby, the probe of the measurement tool can be indexed to the most appropriate measurement angle position for measurement, and the measurement results can be transmitted to the photoreceptor. As shown in Figures 6 and 7, this method of indexing the spindle and indexing the probe to an arbitrary angular position is difficult due to the manufacturing error between the spindle center and the measurement center, and the measurement tool This makes it possible to employ a measurement method that compensates for the installation error that inevitably occurs when inserting into the insertion hole.

In addition, in the automatic measuring device of the present invention, compressed air is effectively supplied to the vicinity of the measuring section of the measuring head through the through hole for transmitting the light of the light emitting body, and chips and coolant adhering to the measuring surface are removed. Blow away,
It becomes possible to perform accurate measurements. For this purpose, in the present invention, the cylinder for tool unclamping provided at the rear of the spindle is of a three-position type (unclamping position, measuring position, clamping position), and in the measuring position, the measuring tool is inserted into the tool insertion hole. The tip of the piston lightly contacts the rear end surface of the pull rod of the main shaft, so that compressed air is effectively supplied to the through hole formed in the pull rod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic measuring device for a machine tool according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall side view of a horizontal machining center incorporating an automatic measuring device of the present invention. A table 2 is slidably placed on the bed 1, and an index table 3 placed on the table 2 has a
Workpiece W is attached. A column 5 is placed on a bed 4 connected to the bed 1 so as to be slidable in a horizontal direction perpendicular to the sliding direction of the table 2. A spindle head 6 is supported on the side surface of the column 5 so as to be slidable in the vertical direction, and a tool storage magazine 7 that can be rotated and indexed is placed on the top surface of the spindle head 6, into which required tools are inserted. After the tool socket is removed from the tool storage magazine 7 by the intermediate transfer device 8 and positioned parallel to the spindle axis, the tool in the spindle and the tool in the intermediate transfer device 8 are exchanged by the tool exchange arm 9.

The measuring tool 10 used in the present invention has exactly the same structure as a normal cutting tool, and is stored in a tool storage magazine 7, and is connected to the intermediate conveyance device 8 and the tool exchange arm as needed. 9, it is inserted into the main shaft. In order to detect the position where the probe 11 at the tip of the measuring tool 10 contacts the work W, a linear scale 12 is fixed to the lower rear surface of the column 5, and a slider 13 paired with the linear scale 12 is mounted on the bed 4. Fixed on the side.
Further, a linear scale 14 is fixed to the side surface of the column 5, and a slider (not shown) paired with the linear scale 14 is fixed to the spindle head 6 side. Similarly, although not shown, a pair of linear scales and sliders are also fixed to the bed 1 and the table 2.

2 and 3 are longitudinal sectional views of the spindle head 6. FIG. In the spindle head 6, the spindle 15 has bearings 16A to 16.
A tool insertion hole 17 is formed at the tip of the main shaft 15 to receive a cutting tool and a measuring tool 10. Main shaft 15
A tension rod 19 is inserted into the through hole 18 formed at the axis of the main shaft so as to be slidable back and forth parallel to the axis of the main shaft, and is constantly pulled rearward by a disc spring 20. Three steel balls 21 are incorporated into the tip of the pull rod 19 so as to be movable in the radial direction, and cooperate with the inner cam surface of the cam sleeve 22 into which the tip of the pull rod 19 is slidably fitted. The action moves the steel ball 21 in and out. That is, as the pull rod 19 reciprocates, the steel balls 21 are moved in and out in the radial direction to engage and disengage the pull stud 23 at the rear end of the tool. A rod 25 that is always urged forward by a spring 24 is inserted into the front part of the tension bar 19, and the tool is inserted into the tool insertion hole 1.
When the steel ball 21 is taken out from the steel ball 7, it moves forward and prevents the steel ball 21 from falling. Further, the tension bar 19 and the rod 25 have through holes 19A and 2 in the axial direction, respectively.
5A is drilled.

As shown in FIG. 3, a cylinder 26 is fixed to the rear of the spindle head 6, and the cylinder 26 has a large diameter cylinder chamber 26A on the front side and a small diameter cylinder chamber 26B on the rear side. . cylinder chamber 2
A hollow piston 27 is fitted into 6A so as to be slidable in the axial direction. Further, a piston 28 is fitted into the cylinder chamber 26B so as to be slidable in the axial direction, and a piston rod 28A integrated with the piston 28 is inserted into the cylinder chamber 26B so as to be slidable in the axial direction.
is slidably inserted into the hollow portion of the piston 27. The cylinder 26 includes a pressure oil passage 29A communicating with the front cylinder chamber of the piston 27, a pressure oil passage 29B communicating with the cylinder chamber between the pistons 27 and 28, and a pressure oil passage communicating with the rear cylinder chamber of the piston 28. 29C are perforated, and by selectively supplying pressure oil to each pressure oil passage 29A, 29B, and 29C, the stop position of the piston 28 can be controlled in three stages.

A pressing rod 30 is screwed onto the tip of the piston rod 28A, and the tip of the pressing rod 30 has a
A sleeve-shaped bearing metal 31 is slidably fitted, and is always urged forward by a spring 32. Furthermore, a bearing metal 33 is fixed to the rear end of the above-mentioned tension rod 19, with which a bearing metal 31 comes into contact. In order to confirm the three stop positions of the piston 28, dogs D-1 and D-2 are screwed into the rear threaded part of the push rod 30, and limit switches LS-1, LS-2, and LS-3 are stepped on. The operation is confirmed by

A sleeve 34 is screwed into the rear end of the pressing rod 30. Attached to the sleeve 34 are an adapter 36 into which a photoreceptor (such as a phototransistor) 35 is inserted and bonded, and an output connector 37 connected to an output terminal of the photoreceptor 35.
Further, a compressed air supply hose 38 is screwed into the sleeve 34 from a direction perpendicular to the axis. Since a through hole 30A is bored in the axis of the pressing rod 30, the measuring tool 1 can be inserted as described later.
When the light emitter inside 0 emits light during measurement, the through hole 2
The light passing through 5A, 19A, and 30A is detected by the photoreceptor 35.

The unclamping cylinder 26 described above performs different operations depending on whether it is a cutting tool used in normal machining operations or when it is used as a measuring tool 10.
That is, when a normal cutting tool is also inserted into the tool insertion hole 17 of the spindle, if pressure oil is supplied to the pressure oil passage 29C and the pressure oil passages 29A and 29B are connected to the tank side, the piston 28 moves to the most advanced position and pushes the pull rod 19 against the disc spring 20 with the front end face of the push rod 30, releasing the steel ball 21 from the pull stud 23. At this time,
Compressed air is supplied from the compressed air supply hose 38, and the compressed air cleans the tool insertion hole 17 through the through holes 30A, 19A, and 25A. When a new cutting tool is inserted, the pressure oil passage 29A remains connected to the tank side, pressure oil is supplied to the pressure oil passage 29B, and the pressure oil passage 29C is connected to the tank side, so that the piston 28 is moved to the most retracted position shown in FIGS. 2 and 3, and the pull rod 19
is retracted by the disk spring 20 to clamp a new cutting tool into the tool insertion hole 17. At this time, a gap is created between the bearing metals 33 and 31, so even if the main shaft 15 rotates next time and machining starts,
There is no need for fever etc.

When the measuring tool 10 is inserted into the tool insertion hole 17, the pressure oil passage 29B remains on the tank side, pressure oil remains supplied to the pressure oil passage 29C, and pressure oil is supplied to the pressure oil passage 29A. Therefore, piston 2
Due to the difference in pressure receiving area between 7 and 28, piston 2
8 retreats to the intermediate position. As a result, the tension rod 19 is moved back by the disc spring 20 and the measuring tool 10 is clamped in the tool insertion hole 17. At this time, the bearing metal 31 is moved by the spring 32.
The through hole 3 is pressed lightly against the bearing metal 33.
0A and 19A are communicated to prevent the diffusion of light from the light emitter and the influence of disturbances, and also to prevent leakage of compressed air supplied during measurement. Further, even if the shaft 15 is rotated at a low speed during measurement, there will be no problem since the contact portion is made of bearing metal.

Next, the measuring tool 10 shown in FIGS. 4 and 5
The internal structure of is explained in detail. Figure 4 shows
When the measuring ball 39 at the tip comes into contact with the work W, an electric circuit is formed between the measuring ball 39, the work W, and the machine body, and the measuring tool emits light from a light emitting body. Tool holder 40 of measurement tool 10
A pull stud 23 screwed into the rear end of the pull stud 23 has a through hole 23A bored in its axial center. Furthermore, an adapter 42 to which a light emitter (such as an infrared light emitting diode) 41 is adhered is attached to the center of the tool holder 40 .

An insulating socket 4 is provided on the front end surface of the tool holder 40.
The body 44 is bolted through 3,
A battery 45 is built into the body 44. A rod 46 is fitted into the axial center of the body 44 so as to be slidable in the axial direction, and is always urged forward by a spring 47. A sleeve 48 is screwed into the front end of the rod 46, and the probe ball 39 is pulled by a spring 49 and held at the front end of the sleeve 48. One terminal of the battery 45 described above is connected to one terminal of the light emitter 41 via a resistor 50 with an electric wire, and the other terminal of the light emitter 41 is grounded to the tool holder 40. The other terminal of the battery 45 is connected to the probe ball 39 which is insulated from the tool holder 40 by the insulating socket 43.

Therefore, when the measuring ball 39 comes into contact with the measurement surface of the work W, the measuring ball 39, the work W, the machine body,
An electric circuit is formed with the tool holder 40,
The light emitter 41 emits light, and the through holes 23A, 25A, 1
The light passing through 9A and 30A is detected by the photoreceptor 35. The gauge head ball 39 is held in the sleeve 48 by a spring 49, but if the gauge head ball 39 comes into contact with the measurement surface of the workpiece W from a direction perpendicular to the axis, and then travels too far, the gauge head The ball 39 is able to escape against the spring 49 and returns to its original position once it leaves the measurement surface. Further, since the rod 46 has a margin of retreat in the axial direction, this measuring tool is capable of making several types of measurements in the direction of the spindle axis and in the direction perpendicular to the spindle axis.

The device shown in FIG. 5 has a built-in micro switch 51 and a battery 45, and when a probe 52 is pressed, the micro switch 51 turns on and the light emitting body 41 emits light. This measuring tool 10 has a measuring point 5
When 2 receives a force perpendicular to the axis, the spherical bearing 5
3, the rod 56 guided by the linear motion bearing 55 is pushed through the steel ball 54, and the micro switch 51 is activated.
Turn it on. Furthermore, when the probe 52 receives a force in the axial direction, the probe 52 is guided by the linear motion pairing 57 and pushed in, pushing the rod 56 through the steel ball 54 and turning the micro switch 51.
Turn it on. When the force is no longer applied to the probe 52, the spring 58 returns the probe 52 to its original position.

As shown in FIGS. 4 and 5, each measuring tool 10 is provided with an air circulation hole 59 that opens near the measuring tip 39 and the measuring tip 52, so that the pull stud 23 can pass through the measuring tool 10 during measurement. The compressed air supplied through the hole 23A is blown onto the measurement surface near the probe, effectively cleaning the measurement surface and helping to perform accurate measurements.

6 and 7 show a measuring method in which the automatic measuring device of the present invention is used to compensate for the error between the center of the main axis and the center of the probe. In other words, Fig. 6-A shows a rough measurement method, and there is always a unique manufacturing error between the center of the spindle and the center of the probe 11, and there is always a possibility that the measurement tool should not be inserted into the tool insertion hole of the spindle. There is an installation error that changes slightly each time it is inserted, and the sum of these two types of errors is Δ. Touch the probe 11 to one end of the hole 60 and read the P ₁ value on the linear scale, then touch the probe 11 to the other end of the hole 60 and read the P ₂ value on the linear scale. , when the center P _s of the hole 60 is determined, P _s =P ₁ +P ₂ -P ₁ /2, and there is a defective point that is measured deviated from the actual center by Δ. In order to solve this problem, Figure 6-B shows that after reading the value of P ₁ on the linear scale, the probe 11 was moved slightly away from the inner wall of the hole 60, and the main shaft 15 was rotated 180 degrees and stopped. rear,
When the measuring element 11 is brought into contact with the other end of the hole 60 and the value of P ₂ is read on a linear scale, the center P _s of the hole 60 is determined as P _s = P ₁ + P ₂ − P ₁ /2. The value matches the actual center of the hole exactly.

Figure 7 shows a method for accurately measuring the wall position of the work W. As shown in Figure 7-A,
Once the probe 11 is brought into contact with the wall of the workpiece W, P ₁
Read the value on the linear scale, then read the value in Figure 7 -
As shown in B, move the measuring head 11 away from the wall and move the main shaft 1.
5 is rotated 180 degrees to position it, and as shown in Fig. 7-C, the contact point 11 is brought into contact with the wall again, and the value of P ₂ is read on the linear scale, then the actual wall position P _x is P _x = P ₁ + P ₂ /2 + r (where r is the radius of the probe), which is obtained as an accurate value that compensates for the error Δ.

FIG. 8 is a control block diagram for controlling the automatic measuring device of the present invention. When the machine tool is moved by the tape command and the probe 11 comes into contact with the workpiece W,
When the light emitter 41 emits light and the light receiver 35 detects the light, the relative position between the linear scale 12 and the slider 13 at that time is read by the scale reader 61 and stored in the memory 62. The measuring ball diameter setting section 63 is used to preset the diameter dimension _D1 of the measuring ball by measuring it in advance, and uses that value and the value in the memory 62 to set the diameter of the measuring ball in the data calculation section 64.
performs necessary calculations and issues a correction signal to the NC device 65.

For example, when measuring the inner diameter dimension and misalignment of a hole shown in Fig. 9, first move the measuring tip 11 to the center position A of the hole specified in the drawing, and then read the linear scale D. _A is stored in the memory 62. Next, move the measuring head 11 in the C direction,
The linear scale reading D B when the probe 11 contacts the inner surface of the workpiece at point _B is stored in the memory 62. Next, the measuring stylus 11 is moved in the E direction, and the linear scale reading D _D when it makes contact at point D is stored in the memory 62, and the data calculating section 64 calculates it based on the following formula.

Hole diameter=D _B −D _D +D ₁ Misalignment=D _A −D _B +D _D /2 FIG. 10 is an example of measuring the deviation of the end face from the reference position. The end face dimension _D2 from the reference position is preset in the end face reference value setting section 66 shown in FIG. At first, the measuring tip 1 is placed at the reference position F.
1 and read the linear scale at that time D
_F is stored in the memory 62. Next, the gauge head 11 is moved in the H direction, and the linear scale reading D _G when the gauge head 11 contacts the end surface of the workpiece at point G is stored in the memory 62, and the data calculation unit 64 calculates the value based on the following formula. and calculate.

End face deviation = (D _F - D _G ) - D ₂ As described in detail above, the present invention has a structure in which neither the light emitting body nor the light receiving body is exposed to the outside, so it is less susceptible to the influence of dust such as chips and coolant. I didn't receive it at all,
Furthermore, since it is not affected by external disturbances such as lighting, it is possible to obtain a highly durable and reliable automatic measuring device. In addition, since the method detects the light from the light emitter through the center of the main axis, the light from the light emitter can be detected externally without being restricted by the indexing angle position of the main axis, so measurements can be made while indexing the main axis. The effect is that the method can be adopted.

As described above, the present invention is not limited to the configurations shown in the embodiments, and modifications are expected without departing from the technical idea of the present invention as described in the claims.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of a machining center equipped with the automatic measuring device of the present invention, Figs. 2 and 3 are partial vertical sectional views of the spindle head, and Figs. 4 and 5 are illustrations of an implementation of the measuring tool. Cross-sectional views showing examples, Figures 6 and 7
The figure is an explanatory diagram showing an effective measurement method using the automatic measuring device of the present invention, FIG. 8 is a control block diagram of the automatic measuring device of the present invention, and FIGS. 9 and 10 are explanatory diagrams showing the measurement order. It is a diagram. In the figure, 10...Measurement tool, 11...Measure head, 12, 14...Linear scale, 13...Slider, 15...Main shaft, 17...Tool insertion hole, 19...Tension rod, 26...Cylinder, 35...Photoreceptor, 41... Luminous body, 45... Battery.

Claims (1)

[Claims] 1. A spindle rotatably provided on the spindle head and having a tool insertion hole at its tip; a measuring tool that can be inserted into the tool insertion hole and has a measuring tip at its tip; a light emitter that emits light when the measuring head detects the position of the object to be measured; a through hole formed in the center of the spindle parallel to the axis of the spindle for transmitting light from the light emitting body to the rear of the spindle; An automatic measuring device for a machine tool, comprising a photoreceptor provided on a fixed part behind the spindle to detect light passing through the through hole.