JPH0114882Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves attaching a contact detection head with a contact surface formed on the outer peripheral surface of the tip to the spindle of a numerically controlled machine tool. This invention relates to a centering device that is used to center a spindle.

[Prior Art] In recent years, a contact detection head is attached to the spindle of a numerically controlled machine tool, and this contact detection head is inserted into a hole formed in a workpiece, etc., and the contact detection head or workpiece is , in the Y-axis direction to bring the contact surface provided on the outer peripheral surface of the tip of the contact detection head into contact with the side surface of the hole, and determine the center position of the hole from the amount of movement when the contact surface contacts the side surface of the hole. Devices have been developed to detect and center the spindle. In order to perform accurate centering on such outer materials, it is required that the centering of the contact detection head and the center of rotation of the spindle coincide completely.

However, in reality, there is a slight misalignment between the center of the spindle's fitting hole and the spindle's rotation center, and there is a problem in changing tools, especially between the spindle's fitting hole and the fitting surface of the contact detection head. Foreign matter such as chips may get caught in between, causing misalignment. For this reason, it has been difficult to accurately center the apparatus as described above.

In order to eliminate the influence of such misalignment and perform highly accurate centering, a method has been devised in which the error is compensated for while the contact detection head mounted on the spindle is rotated.

[Problems to be solved by the invention] However, when the spindle is rotated and the contact detection head is rotated, there is a drawback that the contact surface of the contactor of the head is worn out.

Furthermore, due to the eccentricity of the axis of the contact detection head with respect to the center of rotation of the spindle, the contact surface becomes partial with respect to rotation and therefore discrete with respect to time, so that the feed of the contact detection head can be made faster. In this case, the timing of contact becomes uncertain, resulting in an error.

The present invention has been made to improve the above-mentioned drawbacks, and its object is to perform centering without rotating the contact detection head.

[Technical means and effects for solving the problem] The present invention has a contact detection head attached to the spindle of a numerically controlled machine tool, and a contact surface provided on the outer peripheral surface of the tip of the contact detection head. a contact detection circuit that detects contact with a surface to be measured of a workpiece and outputs a contact detection signal; and a contact detection circuit that detects contact with a surface to be measured of a workpiece and outputs a contact detection signal; an arithmetic control means for moving the contact detection head along a predetermined route using a control signal and performing centering control by detecting the amount of movement of the contact detection head; , a spindle control circuit that rotates the spindle by half a rotation so that when relative movement is made on a straight line, the contact surfaces of the contact detection head are at the same point at both end contact points on the straight line; This is a centering measuring device using a commercial head.

The feature of this invention is that the contact detection head is not brought into contact with the surface to be measured of the workpiece while rotating, but is brought into contact with the surface to be measured while remaining stationary, and the contact detection head is brought into contact with the surface to be measured while moving in a straight line. When making a relative movement, the spindle should be rotated half a turn so that the contact surfaces of the contactors of the contact detection head are at the same location when contact is made at both ends.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

Figure 1 is an overall diagram showing the configuration of a numerically controlled machine tool that has the function of automatically centering a hole formed in a workpiece W etc. and measuring the hole diameter, etc., and shows the machine body 1 and the numerical control device. 2, a contact detection circuit 3, an arithmetic and control unit 4, and a main control circuit 5.

10 is the bed of the machine body 1, and this bed 10
On the top, a table 11 on which a workpiece W is placed is guided so as to be movable in a direction perpendicular to the plane of the paper (X-axis direction), and a column is provided that guides a spindle head 12 so as to be movable in the vertical direction (Y-axis direction). 13 is guided so as to be movable in the left-right direction (Z-axis direction). The table 11 is moved in the X-axis direction by a servo motor 14 fixed to the bed 10, and the spindle head 12
is controlled in the Y-axis direction and Z-axis by a servo motor 15 attached to the rear end of the bed 10 and a servo motor 16 attached to the upper part of the column 13.
It is adapted to be moved in the axial direction. These servo motors 14 to 16 are connected to the numerical control device 2 via the drive unit 6, and are driven to rotate by distribution pulses output from the numerical control device 2. The relative position between the object W and the spindle head 12 is controlled.

A spindle 17 is mounted on the spindle head 12 and rotated by a spindle motor 18 attached to the rear end of the spindle head. The contact detection head TS shown in the figure is attached to the contact detection head TS when the contact detection head TS shown in the figure is attached to a tool changer, and when centering a hole machined in a workpiece W or measuring the diameter of the hole.
In addition, a current detection resistor R is installed on the outer periphery of the tip of the main shaft surface 12.
A coil 20 for contact detection is connected to an exchange power supply 19 through a spindle 17.
It generates a magnetic flux that surrounds the . Therefore, when the contact surface formed on the outer peripheral surface of the tip of the contact detection head TS comes into contact with the workpiece W, an induced current flows through the induced current path shown by the broken line in FIG. 1, reducing the impedance of the coil 20. let
When the impedance of the coil 20 decreases, the excitation current increases and the voltage generated across the resistor R1 increases, so that a high voltage signal is given to the contact detection detection 3. The contact detection circuit 3 detects contact between the workpiece W and the contact detection head TS by the increase in this voltage signal, and sends out a detection signal TDS when contact is detected.

The numerical control device 2 distributes pulses to each axis based on numerical control commands programmed on the paper tape 21 read by the tape reader TR, thereby machining the workpiece W. An output terminal for outputting M code and S code data, and a manual operation terminal for receiving manual operation commands from the outside are provided. The S code data output from the numerical control device 2 controls the rotation of the main shaft motor 18 to a speed specified by the S code.

On the other hand, the M code data output from the numerical control device 2 is given to a decoder 22 that decodes the M code.
Various auxiliary function commands corresponding to the M code are output from the M code. Most of the auxiliary function commands output from this decoder 22 are given to a relay control circuit (not shown) to control things such as turning on and off the cutting oil supply valve, but among these auxiliary function commands, centering control and Auxiliary function commands M41 and M42 for instructing measurement of hole diameter, etc., are given to the arithmetic and control unit 4. In this embodiment, M41 is assigned to an auxiliary function command that instructs centering, and M42 is assigned to an auxiliary function command that instructs hole diameter measurement. When these auxiliary function instructions are given to the arithmetic and control unit 4,
The arithmetic and control unit 4 performs operations according to the supplied auxiliary function commands. Further, the arithmetic and control unit 4 outputs signals a and b for rotating the spindle by 1/2 or 1/4 at predetermined timings to the spindle control circuit 5.
This spindle control circuit 5 inputs the a and b signals,
Rotate the spindle 1/2 turn and 1/4 turn, respectively.

The arithmetic control device 4 performs centering control or hole diameter measurement in accordance with the auxiliary function commands output from the numerical control device 2, as described above, and is constituted by, for example, a microcomputer. When this arithmetic and control unit 4 receives an auxiliary function command, it switches the numerical control unit 2 to manual mode and directly sends distribution pulses to the drive unit 6. FIG. 2 is a flowchart showing the operation of the arithmetic and control unit 4 when performing centering control, and the centering operation will be explained below based on this flowchart.

First, stop the tape movement at step 100 and enter manual mode. Next, reset the diameter counter and radius counter provided inside (step 100),
Set the angular position of the main shaft to the original position O. (Step 104). After this, a + pulse is sent to the X-axis, and the contact detection head TS is moved along the X-axis +
direction (step 106). When it is detected that the contact surface TQ of the contact detection head TS has contacted the side surface P1 of the hole formed in the workpiece W (step 108), a pulse is sent to the The TS is moved in the X-axis direction (step 110) and the amount of movement is counted by a diameter counter (step 112).

Here, OS is the rotation center of the spindle 17, and OP is the axis of the contact detection head TS. As shown in Figure 4, unlike OS and OP,
The axis OP is eccentric with respect to the rotation center OS of the spindle 17.

Next, in step 114, when it is determined that the hole has moved away from the side surface P1 by a certain amount, step 1
16, the spindle 17 is rotated 1/2 turn (shown at position b in FIG. 4). Thereafter, the contact detection head TS is further moved in the X-axis direction to detect whether the same contact surface TQ has contacted the side surface P2 of the opposite hole (step 118).

Next, in step 120, 1/2 of the count value of the diameter counter is loaded into the radius counter, in step 122, the radius counter is reset, and in steps 124 and 126,
The radius counter is decremented while moving the contact detection head TS in the +X-axis direction. When the count value of the radius counter becomes zero, it means that the contact detection head TS has been indexed to the center position in the X-axis direction. When the count value of the radius counter becomes zero (step 128)
At step 130, spindle 17 is rotated 90 degrees.
Next, in step 132, the contact detection head TS is moved in the Y-axis direction, and the contact detection head TS is indexed to the center position in the Y-axis direction in the same manner as described above.
132-154). As a result, the spindle 17 is indexed to the center position of the hole, completing the centering. As described above, the present invention is characterized in that the spindle 17 is rotated 180 degrees when moving between the P1 and P2 contacts.

Therefore, even if there is misalignment between the axis OP of the contact detection head TS and the rotation center OS of the spindle 17, this misalignment is corrected and the spindle 17 is accurately indexed to the center position of the hole. It will be done.

[Effects of the invention] As described above, in the centering device of the invention, the contact surface of the contact detection head is kept on the same surface during movement between two contact points during measurement according to the operation command given to the arithmetic and control unit. Since a spindle control circuit is provided to rotate the 1/2 rotation spindle so that the contact detection head and the spindle are misaligned, accurate centering can be achieved. Furthermore, since the main shaft is not rotated for measurement, the contact surface of the contact detection head will not wear out, and detection accuracy will not decrease even if the relative movement speed is increased.

[Brief explanation of the drawing]

Figure 1 shows the configuration of a numerically controlled machine tool equipped with a centering device according to the present invention, and shows a schematic side view of the machine body with an electric circuit, and Figure 2 shows the arithmetic and control unit in Figure 1. Flowcharts for explaining the operation, FIGS. 3 and 4 are diagrams showing the movement locus of the contact detection head. 1... Machine body, 2... Numerical control device, 3... Contact detection circuit, 4... Arithmetic control device, 5... Spindle control circuit,
6...Drive unit, 10...Bed, 11...Table, 12...Spindle head, 14-16...Servo motor, 17...Spindle, 18...Spindle motor, 20
...Coil for contact detection, 22...Decoder, TS...Head for contact detection, W...Workpiece.

Claims (1)

[Scope of claim for utility model registration] A contact detection head attached to the spindle of a numerically controlled machine tool, and a contact surface provided on the outer peripheral surface of the tip of this contact detection head that comes into contact with the surface to be measured of a workpiece. a contact detection circuit that detects the contact detection signal and outputs a contact detection signal; and a contact detection circuit that changes the relative position of the contact detection head and the surface to be measured, and moves the contact detection head along a predetermined route using the contact detection signal as a control signal. arithmetic control means for performing centering control by detecting the amount of movement of the contact detection head; A centering device using a contact detection head, comprising: a spindle control circuit that rotates the spindle by half a rotation so that the contact surfaces of the contact detection head are at the same point at both ends of a straight line.