JPS6320202Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a measuring head that is detachably attached to the tool spindle of a machine tool.In particular, the contact detection signal detected by the measuring head is transmitted, and the signal is transmitted on the machine tool body side. This invention relates to an improvement in a transmitting/receiving device for a measuring head for a machine tool.

In recent years, when automated machine tools such as machining centers are operated unmanned, one way to improve reliability is to install a removable measuring head on the tool spindle to perform contact detection, automatic measurement,
Techniques for automatic centering, position error correction, etc. have been developed. A machining center grips and rotates a machining tool on the tool spindle, and rotates it in the X, Y direction between it and the workpiece.
and relative movement in the Z-axis direction, and machining progresses while automatically changing tools between the tool magazine and the tool spindle as appropriate. During this machining, the measuring head stored in the tool magazine is automatically attached to the tool spindle as necessary, and contact detection is performed between the measuring head and the workpiece or jig. Various methods have been proposed for transmitting the contact detection signal obtained by the measurement head to the machining center main body, but the present invention modulates the contact detection signal built into the measurement head into a radio wave, and uses the radiated electromagnetic field. A wireless transmission/reception method using radio waves is adopted in which the contact detection signal is received and demodulated by a transmitting antenna that transmits data using the contact detection signal and a receiving antenna provided on the main body of the machining center.

An outline of a conventional transmitting/receiving device for a measuring head for a machine tool that employs this wireless transmitting/receiving method using radio waves will be explained with reference to FIG. The measuring head 1 is attached to a tool spindle 5 that is pivotally supported by the spindle head 3 of the machine tool, and a measuring head 7 provided at the tip of the measuring head 1
The contact detection signal is modulated and transmitted as radio waves from a loop-shaped transmitting antenna in the transmitting device 9. The receiving side is configured to receive these radio waves with a loop-shaped receiving antenna in a receiving device 13 attached to the end face of the bearing holder 11 so as to surround the tool spindle 5. On the other hand, the tool spindle 5 includes a work table on which a workpiece is placed, a column that supports the spindle head, a tool magazine provided on the top or side surface of the column, and an automatic tool change arm.
The work table is surrounded by metal such as a splash guard to prevent chips and cutting fluid from scattering. The measuring head 1 mounted on the tool spindle 5 must transmit and receive radio waves in an environment surrounded by metal. Then, when the tool spindle 5 and the workpiece reach a certain relative positional relationship, the radio waves 1 directly received from the transmitting antenna
5 and radio waves received after being reflected on the work table, splash guard, etc., interfere with each other, and reception sensitivity may be extremely reduced, resulting in the disadvantage that accurate contact detection cannot be performed. this is,
As mentioned above, the measurement head 1 is forced to perform contact detection in an environment surrounded by metal;
Furthermore, during machining, metal chips adhere to the outer surface of the receiving device 13, which is equipped with a loop-shaped receiving antenna and is installed around the tool spindle 5, together with the cutting fluid, which deteriorates the receiving sensitivity. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transmitter/receiver device for a measuring head for a machine tool that is capable of accurate contact detection even in the above-mentioned adverse environments.

According to the present invention, a measuring head is removably attached to the tool spindle of a machine tool, detects contact, transmits the contact detection signal, and receives the contact detection signal on the machine tool main body side. In the head transmitting/receiving device, the contact detection signal is sent from a power supply section provided at a predetermined position of the measuring head to a transmitting antenna, and the signal from the transmitting antenna can be received by a radiated electromagnetic field effect or an electromagnetic induction effect. Thus, there is provided a transmitting/receiving device for a measuring head for a machine tool, in which a helical receiving antenna is provided protruding from the machine tool body near the power feeding section, and the helical receiving antenna is covered with a cover having high radio wave transmittance.

The present invention will be explained in detail below with reference to FIGS. 2 to 4. Fig. 2 is a sectional view of the measuring head of the present invention when it is attached to the tool spindle, and Fig. 3 is a sectional view of the transmitting device taken at - in Fig. 2.
FIG. 4 is a sectional view of the receiving device taken along the line - in FIG. 3. The tool spindle 5 of the machine tool is mounted on the spindle head 3 by a bearing 21 and a bearing retainer 11.
The cutting tool is rotatably attached to the tool, and is normally rotated by holding the processing tool in the tapered hole 23 at its tip. Note that a large number of machining tools are stored in a tool magazine of an automatic tool changer, and this tool magazine and tool spindle 5
Tools are exchanged between them according to the machining program. When a machining tool is attached to the tool spindle 5, the X, Y and Z
By performing three-dimensional relative movement in the axial direction, the workpiece can be machined into a desired shape.

Perform automatic centering of the reference hole of the workpiece,
When a command to measure dimensions is issued to the machine tool via the control device, the processing tool is removed from the tool spindle 5 by the automatic tool changer, and the measuring head 1, which was previously installed in the tool magazine, is removed. It is newly attached to the tool spindle 5. As shown in FIG. 2, the measuring head 1 has a casing 25 with a measuring element 7 at its front end, and a casing 29 with a tapered shank 27 at its rear end. Now, the tapered shank portion 27 of the casing 29 of the measuring head 1 is connected to the tapered hole 27 of the tool spindle 5.
The pull stud 31 inserted into the casing 29 and screwed onto the tool spindle 5 of the spindle head 3 is pulled to the right by engaging with the pull rod 33 provided through the tool spindle 5 from the right. The measuring head 1 is gripped by the tool spindle 5. A V-groove 35 is formed on the outer periphery of the casing 29 so that the measuring head 1 can be replaced by an automatic tool changer. The casing 25 is fixed to the center of the casing 29, and the measuring shaft device of the measuring head 1 is mounted inside the casing 25. This measuring axis device includes a measuring element 7 having a spherical portion 37 at the tip, and a spherical bearing portion 39.
, the cylindrical bearing portion 41 , the ball 43 , and the rod 45
and a spring 47. The above probe 7
has the above-mentioned spherical part 37 at the tip, and also has a spherical part 49 in the center, which is inserted into the spherical bearing part 39 and the cylindrical bearing part 41, while the rear end has a conical part with an apex angle of 90 degrees. It has a recess 51. And as mentioned above,
Since the spherical part 49 of the gauge head 7 is inserted into the spherical bearing part 39 and the cylindrical bearing part 41 of the casing 25, the gauge head 7 is moved relative to the casing 25 in the X, Y, and Z axis directions. It is automatically supported and movable. The rod 45 is attached to a ball bush 53 fixed to the casing 25 so as to be slidable in the axial direction.
A conical recess 55 with an apex angle of 90 degrees is formed on the end face near the tip, and the recess 55 and the recess 51 of the measuring tip 7
A ball 43 is inserted between the recess 55 and a spring 47 that applies an elastic force from the other end opposite to the recess 55 to support the recess 55 . That is, due to this elastic force, the measuring stylus 7 always tries to maintain a posture in which it is in a straight line with the rod 45, and this is the centripetal action acting on the measuring stylus 7. In other words, the measuring axis device is freely supported with respect to the housing 25 with centripetal action. Therefore, the measuring head 7 is
Contact detection is possible in any direction along the Z-axis. On the other hand, a limit switch 59 is attached to a limit switch mounting base 57 fixed to the casing 29, and when the rod 45 is displaced in the axial direction, the limit switch 59 has a pushing action and a releasing action, and is turned on. , is the one that operates off. The casing 29 further includes a signal conversion device 61 that converts the signal detected by the limit switch 59 into a binary encoded pulse train.
, a modulation device 63 that modulates the pulse train obtained by the signal conversion device 61 into a form that can be transmitted wirelessly, and a loop that transmits the output signal of the modulation device 63 to a receiving device 65 attached to the bearing retainer 11 of the spindle head 3. A transmitting device 67 having a shaped transmitting antenna 68, a battery 69 that supplies current to these signal converting device 61, modulating device 63, transmitting device 67, and limit switch 59, and measuring head 1 to prevent consumption of battery 69. A switch 71 is provided so that current is supplied from the battery 69 only when the tool spindle 5 is attached to the tool spindle 5. Note that a cover 73 is provided to protect the signal conversion device 61, modulation device 63, and battery 69 from external impact, dirt, and dust. Also, casing 25
There is a bellows 75 between the most extreme surface of the contact point 7 and the probe 7.
is stretched, and the X, Y and Z of the measuring head 7 mentioned above are
This prevents only rotational movement around the axis without damaging the free support in the axial direction, and also prevents dirt from entering the spherical bearing portion 39.

On the other hand, the helical receiving antenna 8 in the receiving device
The signal received by the signal converter 1 is demodulated by the demodulator 83 into the same binary encoded pulse train as the output of the signal converter 61. The reliability of the received signal is confirmed by a comparator 85 that determines whether the level of the demodulated signal is larger or smaller than a predetermined value, and if it is higher than the predetermined value, sends the signal to the arithmetic and control unit 87 to measure the contact detection position. Further, if the level of the signal received by the comparator 85 is lower than the predetermined value, it means that the contact detection was not performed correctly, and an alarm is displayed.

Here, one of the features of the present invention is that a helical receiving antenna 81 is used as the receiving antenna, the transmitting device 67 and the receiving device 65 are brought closer together than in conventional devices, and the loop provided in the transmitting device 67 is A power feeding unit 91 that feeds a signal to the shaped transmitting antenna 68
However, the antenna is positioned as close as possible to the helical receiving antenna 81 built into the receiving device 65. By shortening the distance between the transmitting and receiving devices, the receiving sensitivity is improved, and the transmission output is the highest near the feeding section 91. By bringing the feeding section 91 and the helical receiving antenna closer together, the reception sensitivity is improved. Sensitivity has improved. The reason for this improvement in reception sensitivity is that in the past, the distance between the transmitting and receiving devices was relatively long, and transmission was carried out only by the effect of the radiated electromagnetic field. This is because the signal could be received by both the electromagnetic field effect and the electromagnetic field effect.

Another feature is that the helical receiving antenna 81 is covered with a cover 93 made of a synthetic resin material with good radio wave transmittance, and the shape of the cover 93 is such that chips and cutting fluid can slide off without accumulating on the top. The upper part is formed into a convex shape by providing a rounded part 97 or an inclined part, and the helical receiving antenna 8
1 is fixed to the lower part of the cover 93 with a filler 95, so that even if chips accumulate on the upper part of the cover 93, the chips are received from the lower part near the power supply part 91.
The configuration is such that the receiving sensitivity of the helical receiving antenna 81 does not decrease.

In the end, as in the case of conventional receiving devices, the radio waves 15 directly received from the transmitting antenna interfere with the radio waves received after being reflected on the work table, splash guard, etc., resulting in reception due to the effect of the radiated electromagnetic field. Even if there is a phenomenon in which the sensitivity is extremely reduced, in the device of the present invention, the receiving sensitivity due to the effect of the induced electromagnetic field is quite large, so it is unlikely that the total receiving sensitivity will become almost zero. Therefore,
Even if contact detection is performed in an environment where the measuring head 1 is surrounded by metal, or even if contact detection is performed after chips or cutting fluid have been scattered, there is an effect that accurate detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing the transmission/reception method of a conventional measuring head for machine tools, Fig. 2 is a sectional view of the measuring head for machine tools according to the present invention, and Fig. 3 is a transmission section taken at - in Fig. 2. FIG. 4 is a cross-sectional view of the receiving device taken along the line - in FIG. 3. 1...Measuring head, 5...Tool spindle, 65...
Receiving device, 67... Transmitting device, 68... Loop-shaped transmitting antenna, 81... Helical-shaped receiving antenna, 91... Power feeding unit.

Claims (1)

[Claims for Utility Model Registration] 1. A measuring head is removably attached to the tool spindle of a machine tool, detects contact, transmits the contact detection signal, and receives the contact detection signal on the machine tool main body side. In a transmitting/receiving device for a measuring head for a machine tool, the contact detection signal is sent from a power supply section provided at a predetermined position of the measuring head to a transmitting antenna, and the signal from the transmitting antenna is transmitted by a radiated electromagnetic field effect or an electromagnetic induction effect. A transmitting/receiving device for a measuring head for a machine tool, wherein a helical receiving antenna is provided protruding from the machine tool body near the power feeding part so as to be able to receive radio waves, and the helical receiving antenna is covered with a cover having high radio wave transmittance. 2 Utility Model Registration Scope of Claim 1. The transmitting/receiving device for a measuring head for a machine tool according to claim 1, wherein the cover of the helical receiving antenna has a convex upper portion.