JPH0233123Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a measuring device that measures, for example, the diameter of a hole in an object to be measured from the moving position of a detection means in contact with the object.

Conventionally, when adding an automatic measurement function to a machining center, if a contact type detector was used as a detector, the contact signal generated when the detector came into contact with a workpiece to be measured would cause the sensor to be attached to the machine. It is necessary to read the values of the coordinate scale, such as inductosin and resolver. This contact signal is generated while the machine is moving, so if there is a delay in the signal transmission system (delay in electrical signals, delay in recognition when taking in the contact signal to the arithmetic processing unit, etc.), the point at which the machine has gone too far may be detected. The coordinates will be read. This error increases as the machine feed speed increases.

For this reason, in order to perform highly accurate measurements, it is sufficient to make the machine feed speed as slow as possible, but if the machine feed speed is slowed down,
The problem arises that measurement takes too much time and is not practical.

An object of the present invention is to provide a measuring device that improves measurement efficiency without reducing measurement accuracy.

Therefore, the present invention includes a detection means that generates a detection signal upon contact with and separation from an object to be measured, a drive means that relatively moves the detection means and the object to be measured, and a command regarding the relative movement to the drive means. a command means for outputting value data; a position detection means for detecting the relative position between the detection means and the object to be measured and outputting the relative position data; and control means for measuring the contact position with the detection means. and,
The control means includes a contact state indicating means that outputs a contact state signal when receiving a detection signal associated with the contact, and a contact state indicating means that outputs a detachment state signal when receiving a detection signal associated with the detachment while the contact state signal is present. detachment state indicating means for outputting; measurement position output means for outputting the relative position data as a measured position when receiving the detachment state signal; and measurement position output means for outputting the relative position data as a measured position when receiving the contact state signal; braking distance storage means for storing a difference from the data as a braking distance; movement correction value storage means for storing a preset constant movement correction value; and moving the object to be measured and the detection means in an approaching direction at a first speed a first movement command means for relatively moving the object by the braking distance in the same direction when receiving the contact state signal; a second movement command means for relatively moving the object in the opposite direction at a second speed by a distance obtained by subtracting the movement correction value from the braking distance; and third movement command means for relatively moving the means again in the opposite direction at a third speed lower than the first speed and the second speed.

With such a configuration, the object to be measured and the detection means are first approached at a first speed, and after making contact, they travel a predetermined distance in the same direction, and are returned a predetermined distance in the opposite direction at a second speed. Subsequently, it is moved in the opposite direction at a third slow speed, and the contact position is measured at the time when it leaves during this movement. In other words, accuracy is ensured by setting the third speed at a low speed when performing position measurements, and the distance traveled at the third speed is limited to short sections, increasing the moving speed in other sections to speed up the overall process. By realizing the operation,
This aims to achieve the above objective.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire system of this embodiment. The system uses a contact type sensor as a detection means mounted on a machining center, for example, in the measurement direction of the workpiece W as the object to be measured, that is, in the diameter direction of the hole H in this example (hereinafter referred to as the x direction). Alternatively, a contact detector 1 made of a piezoelectric element or the like can be moved back and forth by the operation of a drive device 2. The detector 1 is equipped with a probe 1A at its tip that is in contact with the workpiece W, and while the probe 1A is in contact with the workpiece W, a detection signal is transmitted through a signal detection circuit 3 as a control means, which is the main part of the present invention. It is given to the control section 4. The control section 4 includes the signal detection circuit 3
Based on the detection signals given through the NC device 5, various control signals are given to the NC device 5 according to preset processing procedures,
The data input to the NC device 5 is taken in. The NC device 5 includes the detector 1
Position data (Position Feedback Signal, hereinafter referred to as PFS) from the position detection device 6 attached to the drive device 2 that indicates the movement position of the
The driving device 2 is driven based on the difference between the command value data and the command value data, and the driving is controlled according to a control signal from the control section 4.

FIG. 2 shows the circuit configuration of the control section 4 and the NC device 5. In the figure, the NC device 5 is
First and second storage means 51 and 52, and an NC that also serves as a command means and first to third movement command means.
Device main section 53, addition section 54, and difference register 55
and a constant movement correction value α as a movement correction value storage means.
A constant register 56 that stores .
The first storage means 51 is composed of a feedback counter that sequentially stores position data from the position detection device 6. The second storage means 52 is
It is composed of a command value counter that sequentially adds and stores the movement command value (Δx/Δt) given from the interpolation calculation section 53A of the NC device main section 53 at fixed time intervals. In addition, these first and second storage means 5
The difference between 1 and 52 is given to the difference register 55 via the adder 54 as a so-called servo error amount (SVE). Incidentally, the addition section 54 and the difference register 55 can be configured as reversible counters. In addition to the interpolation calculation section 53A, the HC device main section 53 includes a sequence section 53B that handles sequence information, a decoding section 53C that decodes data from the tape reading section 7, and the like. The movement correction value d of the constant register 56 is given. Further, the output of the difference register 55 is provided to the drive device 2 including a D/A converter.

The control section 4 includes third and fourth storage means 41,
42, a timer circuit 43 that outputs a clock signal every fixed time Δt, and a flip-flop 44.
An AND circuit 45A receives the clock signal from the timer circuit 43, the signal from the set output terminal Q of the flip-flop 44, and the detection signal provided through the signal detection circuit 3; an AND circuit 45B which receives as input a signal from the reset output terminal and a signal obtained by inverting the detection signal by an inverter 46; When the output of the AND circuit 45B and the output of the AND circuit 45B reaches H level, the position data of the first storage means 51 is displayed, for example. the fourth storage means 42 for outputting to a device etc.
The drive circuit 2 includes a gate circuit 47B for inputting data into the drive circuit 2, and controls the drive circuit 2 according to a preset procedure.

The flip-flop 44 is reset when the output of the AND circuit 45A becomes H level,
It is set when the output of the AND circuit 45B becomes H level. Moreover, the flip-flop 44 is
The set state is set in advance by a command SS from the sequence section 53B of the NC device main section 53.The NC device main section 53 includes an AND circuit 45A.
A signal is given as a signal STP for stopping the distribution of the command value Δx/Δt to the second storage means 52, and a signal from the third storage means 41 transferred through the gate circuit 47A is given as a signal STP for stopping the distribution of the command value Δx/Δt to the second storage means 52. The value is set to probe 1 after the value of difference register 55 is once zeroed.
A signal ΔX _SVE for moving A in the opposite direction is given.

Here, the AND circuit 45A and the flip-flop 44 constitute contact state indicating means, and the H output of the AND circuit 45A becomes the contact state signal. Also, an AND circuit 45B, an inverter 46
The flip-flop 44 constitutes detachment state indicating means, and the H output of the AND circuit 45B becomes the detachment state signal. Further, the gate circuit 47A and the third storage means 41 constitute a braking distance storage means, and ΔX _SVE stored in the third storage means 41 becomes the braking distance. In addition, the gate circuit 47
B and the fourth storage means 42 constitute a measured position output means, and the position data stored in the fourth storage means 42 becomes the measured position.

Next, the operation of this embodiment will be explained with reference to FIG.

First, after setting the flip-flop 44 as an initial condition, in response to a command from the NC device main section 53, the detector 1 is moved via the drive device 2 from the reference position _P0 , which is the measurement start point, at a high first speed _V1. When it is moved (see FIG. 3), position data PFS is provided from the position detection device 6 attached to the drive device 2, and the position data PFS is sequentially stored in the first storage means 51.

On the other hand, in the process of the detector 1 moving at a speed V ₁ , when the probe 1A reaches the position P where it contacts the workpiece W, an H level detection signal (contact signal) is transmitted through the signal detection circuit 3 to the AND circuit of the control unit 4. 45
given to A. Since the flip-flop 44 is in the set state, that is, the AND circuit 45A is in a state where an H level signal is applied from its set output terminal Q, when the clock signal from the timer circuit 43 is applied, the AND circuit 45A outputs an H level signal. occurs. The H level output from the AND circuit 45A is applied as a reset signal to the flip-flop 44, and at the same time the flip-flop 44 is reset, it is applied to the NC device main section 53 as a stop signal STP, and is sent to the second storage means 52. The distribution of the command value Δx/Δt is prevented, and furthermore, the H level output from the AND circuit 45A is
7A is also applied to open the gate circuit 47A. By opening the gate circuit 47A, the difference between the position data PFS in the second storage means 51 and the command value data in the second storage means 52 (servo error amount
SVE), that is, the value of the difference register 55 is stored in the third storage means 41. After this, the detector 1 is moved by the driving means 2 to the position where the servo error amount becomes zero.
It is moved to P ₁ and stopped (see Figure 3).

Here, the overtravel amount l of the detector 1 from when the probe 1A of the detector 1 comes into contact with the workpiece W and the corresponding detection signal is output until it stops is: l=servo error amount SVE+V ₁ · Δt ₁ ... It is expressed as (1). Here, V ₁ · Δt ₁ is the amount of deviation of the stop position due to the delay error Δt ₁ that occurs during braking, and Δt 1 is the amount of deviation of the stop position due to the delay error Δt 1 that occurs during braking, and Δt ₁ is the amount of deviation of the stop position due to the delay error Δt 1 that occurs during braking. This is the time from the time when the clock signal is applied to the timer circuit 43, that is, the delay until the control section 4 recognizes the detection signal, and is smaller than at least the cycle Δt of the clock signal.

Next, from the position P ₁ where the detector 1 stopped, the detector 1 is moved at a relatively high speed in the opposite direction to the above.
Move with V ₂ . At this time, the NC device main part 53
commands movement in the opposite direction given from the third storage means 41, that is, a value obtained by subtracting the movement correction value α of the constant register 56 from the servo error amount SVE. Note that this movement correction value α is set in advance as a distance at which the probe 1A will not separate from the workpiece W when moving in the opposite direction, even if a foreign object is present, for example. Furthermore, the position where the movement was completed
Move in the same direction from P ₂ at a third speed V ₃ , which is a low or minute speed.

In the process of detector 1 moving at speed V ₃ ,
Position P where the probe 1A leaves the workpiece W
When the detection signal reaches the inverter 4 of the control section 4, an L-level detection signal (a signal of failure) is transmitted through the signal detection circuit 3.
After being inverted at step 6, it is applied to an AND circuit 45B. The AND circuit 45B is a flip-flop 44
Since it is in a reset state, that is, a state where an H level signal is applied from the reset output terminal, when the clock signal from the timer circuit 43 is applied, it generates an H level output. This H level output from the AND circuit 45B opens the gate circuit 47B, and at this time, the position data PFS of the first storage means 51 is stored in the fourth storage means 42, and at the same time, the flip-flop 44 is set. is set to the initial state. Thereafter, the data stored in the fourth storage means 42 can be displayed as measured values on, for example, a display.

Here, Δt ₂ is (<
The amount of overshoot of the detector 1 at Δt), that is, the error δ, is expressed as δ=V ₃ ·Δt ₂ (2). Therefore, if the speed V ₃ is set to a low speed or a very small speed, the error δ can be made extremely small. In addition, the speed V ₂ is unrelated to the measurement, so it is set as a fast feed, and the speed V ₁ is allowed to have some error, so if the allowable speed of the fastest detector 1 is set, then the speed V ₃ is set as a slow or slow feed. Even at very low speeds, the distance traveled is limited to a small range, so there is no loss in measurement accuracy.
Moreover, it is possible to increase measurement efficiency.

Although the diameter of the contact end of the probe 1A has been ignored in the above description, it is actually necessary to correct the diameter of the contact end. In addition to measuring hole diameters, it can also be used for hole core measurement, automatic centering, concentric hole machining, etc.

Although FIG. 2 in the above embodiment shows the configuration of the control unit 4 as a logic circuit as hardware, recently, CNC (Computerized
In the case of a numerical control device of the numerical control device type, the control section 4 does not need to be configured as a specific logic circuit, and can be replaced with a group of program commands.

Such a program command group is read out and executed as a subprogram in the CNC device in response to an interrupt signal every Δt.

The main steps of this program command will be explained below.

Now, when the machine (detector) is moving at a speed of V ₁ and an interrupt signal is given, the signal detection circuit 3
The presence or absence of the output of the signal detection circuit 3 is checked, and when the output of the signal detection circuit 3 is "present", the interpolation calculation within the CNC device is stopped, and the servo error amount at this time is stored in the register for braking distance storage (the above-mentioned implementation). (corresponding to the third storage means 41 in the example). Eventually, when the machine is stopped after moving by the servo error, the value obtained by subtracting the movement correction value α from the contents of the register is given to the machine's drive system as a command value, and the machine is moved in the direction of movement at the speed V ₁ . command to move at a speed of V ₂ in the opposite direction.

Then, when the movement corresponding to the servo error minus the movement correction value α is completed, a movement command is given at a low (fine) speed V ₃ in the same direction as the speed V ₂ . While moving at this low speed _V3 , check that the output of the signal detection circuit 3 changes from "present" to "absent".
If it is “None”, command pulse (Δx/Δt)
supply will be stopped. Then, the content of the first storage means at this time is transferred to the register for outputting the measured position, and if necessary, an instruction is given to display the value.

The main program commands have been explained above, but a skilled programmer can easily create a series of programs that operate in response to interrupt commands by referring to Figure 2. It is.

Further, in the above embodiment, the present invention is mounted on a machining center, but the present invention is not limited to this, and can also be mounted on, for example, an NC horizontal boring machine.
For example, it can be applied to a coordinate measuring device.

As described above, the present invention has the effect of providing a measuring device that can improve measurement efficiency without reducing measurement accuracy.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention; Fig. 1 is an explanatory diagram showing the entire system, and Fig. 2 is an explanatory diagram showing the control unit.
A circuit diagram showing the circuit configuration of the NC device, and FIG. 3 is an explanatory diagram showing the movement of the detector. DESCRIPTION OF SYMBOLS 1...Detector as detection means, 2...Drive device as drive means, 4...Control unit as control means, 5...NC device, 6...Position detection device as position detection means, 41... ...Third storage means as braking distance storage means, 42...Fourth storage means as measured position output means, 45A, 45B, 44...
...AND circuit and flip-flop constituting contact state indicating means and release state indicating means, 51
...first storage means, 52...second storage means,
53...Main part of the NC device which also serves as a command means and first to third movement command means, 56...A constant register which is a movement correction value storage means.

Claims (1)

[Claims for Utility Model Registration] A detection means that generates a detection signal upon contact with and separation from an object to be measured, a drive means for relatively moving the detection means and the object to be measured, and a drive means for moving the relative movement of the detection means and the object to be measured. command means for outputting command value data related to the object to be measured; position detection means for detecting the relative position between the detection means and the object to be measured and outputting the relative position data; control means for measuring the contact position between the object and the detection means, the control means comprising: contact state indicating means for outputting a contact state signal when receiving a detection signal accompanying the contact; and a contact state indicating means for outputting a contact state signal when the contact state signal is detected. detachment state indicating means for outputting a detachment state signal when receiving a detection signal associated with detachment during a certain period; measured position output means for outputting the relative position data as a measured position when receiving the detachment state signal; , braking distance storage means for storing the difference between the command value data and the relative position data as a braking distance when receiving the contact state signal; and a movement correction value storage for storing a preset constant movement correction value. means, first movement command means for relatively moving the object to be measured and the detection means in a proximal direction at a first speed, and for causing the object to be relatively moved by the braking distance in the same direction when receiving the contact state signal; a second movement command means that is activated subsequent to the first movement command means and relatively moves the object to be measured and the detection means in opposite directions at a second speed by a distance obtained by subtracting the movement correction value from the braking distance; a third movement command means that is activated subsequent to the second movement command means and relatively moves the object to be measured and the detection means in the opposite direction at a third speed lower than the first speed and the second speed; A measuring device comprising: .