JPS5837503A - Measuring apparatus for lead error of screwtype cutting tool by noncontacting type optical filler - Google Patents

Abstract

PURPOSE:To improve accuracy and to measure the lead errors of a screw type cutting tool continuously at a real time by using a noncontacting type optical detector. CONSTITUTION:A gear hob 7 to be measured is rotated around a shaft 7a by a driving arm 9. The angle L of rotation is detected by a rotary encoder 13. A moving board 4 moves in the direction of A along a fixing board 1 at a sending speed equal to the leading pitch of a gear 7 in accordance with the rotation of the shaft 7a and the moving distance E is detected by an interference type measuring instrument consisting of a laser source 15, three mirror sets 20-22 and a photodetector 26. The position Ve of a cutting tooth of a gear 7 is detected by a detector 5 for the rotational angle of the cutting tooth from the reflected light of the cutting tooth. The extent of movement lL of a flank image is detected by an optical filler mechanism 6 from the quantity of light of the projected image of the screw. A lead error epsilon is obtained by finding a sending error DELTAE=E-L and adding the value of lL in every Ve input, i.e. epsilon-DELTAE to the found sending error.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead error measuring device for a threaded cutting tool using a non-contact optical tween.

A conventional measuring device uses a contact type tween to measure the cutting edge lead error of a screw-shaped cutting tool such as a gear hob or tap.

However, conventional contact-type tweens have problems such as malfunctions due to wear of the contacts and difficulty in measuring small module hobs. -2 Accuracy is as low as 2 to 3 μm, making it impossible to perform sufficiently precise measurements.

Furthermore, since conventional equipment uses devices such as optical microscopes to measure small-lead hobs, it takes a long time to measure and organize the data, making it difficult to perform continuous measurements. There was a problem.

The present invention aims to solve these problems all at once, and by using a non-contact optical detector, it is possible to improve measurement accuracy and derive lead errors continuously and in real time. An object of the present invention is to provide a lead error measuring device for a screw-shaped cutting tool using a non-contact optical tween.

For this reason, (1) the lead error measuring device of the present invention is provided with a rotation mechanism that rotates a thread-shaped cutting tool as a sample around its axis on a fixed base, and a rotating mechanism that rotates a thread-shaped cutting tool as a sample around its axis; A movable base that moves in the axial direction of the shaft and a movable base drive mechanism that drives the movable base are provided.

A light wave interference type feed amount measurement mechanism that measures the feed amount in the axial direction of the thread-shaped cutting tool by light wave interference, a shaft rotation angle measurement mechanism that measures the shaft rotation angle of the shaft, and a cutting edge of the thread-shaped cutting tool. A non-contact optical cutting blade rotation angle detection mechanism that detects the cutting blade rotation angle corresponding to the position, and a non-contact type that measures the amount of relative movement of the cutting blade of the screw-shaped cutting tool in the axial direction with respect to the movable table. An optical tween mechanism is provided, which calculates a signal corresponding to the feed amount measured by the light wave interference type feed amount measurement mechanism and a signal corresponding to the shaft rotation angle measured by the shaft rotation angle measurement mechanism. a first calculation that calculates the feed error of the movable table by inputting a signal corresponding to the cutting blade rotation angle measured by the optical cutting blade rotation angle detection mechanism as a calculation control signal; A signal corresponding to the relative movement of the cutting blade in the axial direction with respect to the movable table measured by the optical tween mechanism is input as an input signal for calculation, and a signal corresponding to the rotation angle of the cutting blade is input for calculation. a second computing unit that inputs as a control signal and calculates the difference between the feed error of the moving table and the IJ-do error of the screw-shaped cutting tool, and each of the signals from the first and second computing units; The present invention is characterized by being provided with a third arithmetic unit that receives an output signal and calculates the read error.

Hereinafter, a lead error measuring device for a thread-shaped cutting tool using a non-contact optical tween as an embodiment of the present invention will be explained with reference to the drawings.
Figures (a) and (b) are explanatory diagrams showing the operation of the optical cutting blade rotation angle detection mechanism, Figure 3 is an explanatory diagram showing the optical tween mechanism, and Figure 4 is the optical tween mechanism. 5 is a graph showing the measurement state of the optical cutting blade rotation angle detection mechanism, and FIG. 6 is a block diagram showing the main parts of the optical cutting blade rotation angle detection mechanism.
Fig. 7 is a waveform diagram showing the action of the optical cutting blade rotation angle detection mechanism, Fig. 8 is a graph showing the indexing error during measurement, and Fig. 9 is the output for the axial displacement in the optical tween mechanism. A graph showing the voltage, and FIG. 10 is a graph showing the read error at the time of measurement.

As shown in FIG. 1, the lead error measuring device of the present invention includes:
It has a structure similar to a lathe, and is provided with a bed 1 and a headstock 2 that constitute a fixed base.

A gear hob 7 as a thread-shaped cutting tool to be measured is attached to an arbor 8, and is provided between the centers of the headstock 2 and tailstock 3, and is connected to a rotating mechanism disposed on the headstock 2 side. It is adapted to be rotated about its axis 7a by a drive arm 9 as a.

A shaft 7a is mounted on the bed 1 in proportion to the angle of rotation of the shaft 7a.
A movable base drive mechanism (not shown) is provided to move the movable base 4 in the axial direction A, and the movable base 4 is moved in the axial direction A by a feed screw and replacement gear (not shown). The combination of alternating gears is selected so that the feed amount per revolution is equal to the amount of feed.

For the plate 2a and the movable table 4 that constitute the identification table.

A light wave interference type feed amount measuring mechanism is provided to measure the feed amount of the gear hob 7 as a screw-shaped cutting tool in the axial direction A by light wave interference, and is adapted to measure the feed amount of the movable table 4.

The light wave interference type feed amount measuring mechanism divides a laser beam 16 emitted from a laser generator 15 provided on the plate 2a into laser beams 18 and 19 by a nof mirror 17 fixed to the bed 1. One laser beam 18 is moved to the moving table 4.
Three plane mirrors 20 with a special right-angled three-sided spear 10 fixed on top
．． 21 and 22 to form a laser beam 1ij 23, this laser beam 1ij 23 is caused to interfere with the laser beam 19 by a nof mirror 24 fixed to the bed 1, thereby creating interference fringes.

The interference fringes are magnified by a magnifying glass 25 and converted into an electric signal by a bin photodiode 26 as the amount of feed in the longitudinal direction of the moving table 4 .

This electric signal is transmitted to the converter 27 by the moving table 47) 0.1 μ-
This becomes a pulse signal E of the feed amount for each feed amount, and is supplied to the first arithmetic unit 14 as an input signal for calculation.

Further, a D rotary encoder 13 is provided on the headstock 2 as a shaft rotation angle measuring mechanism for measuring the shaft rotation angle θ, which is the rotation angle of the shaft 7a of the gear hob 7.

The pulse train corresponding to the shaft rotation angle θ from the rotary encoder 13 is input to a converter (not shown), and is multiplied by a coefficient k to correspond to the nominal lead of the gear hob 7. The feed amount is required.

This multiplied signal is converted into a pulse signal of %0.1μ and then sent to the first arithmetic unit 14 as an input signal for calculation.

The rotary encoder 13 is designed to generate 43,200 pulses per rotation of the shaft 7a, and the resolution of the shaft rotation angle θ is 30 seconds.

FIGS. 2(a) and 2(b) show the structure of a non-contact type optical cutting blade rotation angle detection mechanism 5. FIG.

This cutting blade rotation angle detection mechanism 5 uses a reflective optical sensor 11 to detect the cutting blade position B [
The pulse is output at the position shown in FIG. It is now possible to measure effectively.

The reflective optical sensor 11 receives the reflected light from the cutting blade 12 at the rotation angle θ (deg, ) of the gear hob 7, and
A voltage Va (see FIG. 7(a)) proportional to the amount of light is outputted, and this voltage Va is applied to the first differentiator 43 (see FIG. 6) in order to find its inflection point. supplied to

In Fig. 5(b), the rotation angle θ (de g,
The experimental results are shown on the horizontal axis. At this time, Fig. 5 (a
In the positional relationship between the sensor 11 and the cutting blade 12 shown in ) (that is, the cutting blade position B), the output voltage Va' shown by the symbol C in FIG. 5(b) is observed. (Figure 5(a) shows sensor 1
Spot 1 shows the position halfway to the cutting edge.

) As shown in FIGS. 6 and 7, the first differentiator 43 inputs and differentiates the signal voltage Va from the optical sensor 11, and converts this first-order differential signal vb into the first-order differential signal vb. The signal is supplied to the differentiator 44 of No. 2.

The second differentiator 44 inputs the first-order differential signal vb, further differentiates it, and outputs a second-order differential signal, and this second-order differential signal Vc is used to configure the pulse generator 45. The water is supplied to the seamit trigger 45a.

The Schmitt trigger 45a receives the second-order differential signal Vc and outputs a pulse signal Vd when the second-order differential signal Vc is at a positive voltage, as shown in FIGS. 7(c) and (d). This pulse signal Vd is supplied to the monostable multivibrator 45b.

The monostable multi-high flake 45b receives the pulse signal Vd and at its falling edge, that is, when the first-order differential signal vb is at the set level of positive voltage and the second-order differential signal Vc
is zero, the cutting edge position pulse Ve is calculated by the first calculator 14
The signal is then supplied to the second arithmetic unit 29 as a calculation control signal corresponding to the cutting blade rotation angle.

When the gear hob 7 has, for example, 12 cutting edge grooves, the cutting edge rotation angle detection mechanism 5 detects the cutting edge at every 30 degrees of rotation angle.

The detection state at this time is shown in FIG.

In FIG. 8, the white circles are due to the device of the present invention.

This is a graph showing the indexing error with respect to the number of leads, and the black circles indicate a similar graph obtained using a universal measuring machine manufactured by Shipp.

The measurement shown in FIG. 8 is repeated three times, and the measurement accuracy of the cutting edge rotation angle detection mechanism 5 is 20 seconds in standard deviation.

A non-contact type optical feeler mechanism 6 is provided to measure the amount of relative movement in the axial direction A of the cutting blade of the gear hob 7 as a screw-shaped cutting tool with respect to the movable table 4.

FIG. 3 shows the configuration of the optical feeler mechanism 6.
For ease of understanding, the measurement of screw pinch is taken as an example.

The light coming from the light source 30 is divided into two parts by transmission and reflection by a half mirror 31 in order to compensate for variations in brightness of the light source 30, and the transmitted light is directed to a bin photodiode 32 as a first sensor. ing.

On the other hand, an optical system 42 is configured to irradiate the reflected light perpendicularly to the axial direction A of the screw 33 to be measured.

Among the light emitted from the optical system 42, that is, among the light reflected from the half mirror 31.

The passing light that has hit the screw to be measured 33 has the positional information of the thread of the screw to be measured 33, and the objective lens 34
The actual image of the thread of the screw 33 to be measured is connected onto a mask 36 having a circular pinhole 35 (see FIG. 4).

Note that the symbol P in FIG. 4 indicates the pitch of the thread.

In the mask 36, only the light passing through the pinhole 35 is supplied to a bin photodiode 37 as a second sensor of the light receiving section via a lens and a mirror.

The light received by the first and second sensors 32 and 37 is converted into an electrical signal corresponding to the amount of light, and each of the converted light amount signals is supplied to a photoelectric signal amplifier 39 as a differential amplifier. It has become.

This photoelectric signal amplifier 39 is designed to differentially amplify the light intensity signals from each sensor 32, 37, and therefore all brightness fluctuations and noise occurring in the optical system from the light source 30 to the half mirror 31 are eliminated. The signal from which this fluctuation and noise has been removed is the second signal.
The data is supplied to the arithmetic unit 29 of.

Since the optical feeler mechanism 6 is configured in this manner, when the movable table 4 moves in the axial direction A, the image of the screw to be measured changes, the amount of light passing through the pinhole 35 changes, and the pin photodiode 37 The output voltage of will begin to change.

In particular, as shown in FIG. 9, in the vicinity where the image of the flank of the thread passes through the center of the pinhole 35, the change in the amount of light passing through the pinhole (output voltage eL) is proportional to the amount of movement (axial displacement XR).

That is, in the range of axial displacement XR of ±70 μ-, the graph in FIG. 9 is a straight line.

At this time, the straight lines overlap when increasing the axial displacement XR (indicated by white circles and X marks in the figure) and when decreasing the axial displacement XR (indicated by black circles in the figure), and hysteresis is also First, it has good and stable linearity.

When the output voltage eL is 5 mV, the axial displacement XR corresponds to 0.1 μ-, and the fluctuation of the output voltage e is ±0.
．． It can be made 2μ or less.

Therefore, the resolution of the optical feeler mechanism 6 is ±0.2 μm.
becomes.

The process of calculating the lead error based on the electrical signals from the light wave interference type feed amount measuring mechanism, the shaft rotation angle measuring mechanism 13, the optical cutting blade rotation angle detecting mechanism 5, and the optical feeler mechanism 6 is shown in FIG. The following description is based on the block diagram shown in .

The first computing unit 14 inputs a signal E corresponding to the feed amount measured by the light wave interference type feed amount measuring mechanism and a signal E corresponding to the shaft rotation angle measured by the shaft rotation angle measuring mechanism for calculation. In addition to being input as a signal, a signal Ve corresponding to the cutting blade rotation angle measured by the optical cutting blade rotation angle detection mechanism 5 is also input as a calculation control signal.

That is, when the cutting edge position pulse Ve is input, if the signals input to the first computing unit 14 are L and E, △E
=EL is output.

This feed error ΔE is: The feed error ΔE is supplied as an electric signal to one input terminal of the third computing unit 28.

The second computing unit 29 inputs an analog signal eL corresponding to the amount of relative movement of the cutting blade in the axial direction A with respect to the movable table 4 measured by the optical feeler mechanism as an input signal for calculation, and also inputs the cutting blade rotation angle as an input signal for calculation. A signal Ve corresponding to the calculation is inputted as a calculation control signal.

The second arithmetic unit 29 is composed of an A and -D converter, and converts the analog output voltage cL from the optical feeler mechanism 6 into a digital signal every time the control signal Ve is input.
It is designed to be converted into D and output.

This output signal is equal to the difference (ε-ΔE) between the lead error ε of the cutting edge to be determined and the feed error ΔE of the moving table 4.

The difference between this lead error and feed error (ε-△E) is the third
The signal is supplied to the other input terminal of the arithmetic unit 28 in the form of an electric signal.

The third arithmetic unit 28 includes the first and second arithmetic units 14.2.
Each error output signal ΔB, (ε−ΔE) from 9 is input and added, and the read error ε, which is the result of the addition, is supplied to the digital printer 40 and pen recorder 41 and recorded. It is supposed to be done.

Therefore, as shown in Fig. 10, the lead error ε of each cutting edge
is required.

Here, the open circles indicate the results of measuring the lead error ε determined by the apparatus of the present invention, and the black circles indicate the lead errors determined by a universal measuring microscope made by Nobu.

The accuracy of the read error εO observed value measured by the device of the present invention is 0.6 μm in standard deviation.

It is expressed as a close-up.

This is the result of summing up three measurements for each cutting edge.

The measurement procedure is to visually determine the position in the axial direction A so that the image of the flank of the thread of the gear hob 7 is at the upper center of the pinhole 35, and then automatically determine the lead error ε.
It is designed to output . In the case of the hob used as an example to measure each lead error from this positioning, the required time is 2 minutes, and the data is processed extremely quickly.

Although this embodiment is directed to a gear hob, the lead error can also be measured with a cutting tool such as a tap by performing similar operations.

In addition, each arithmetic unit 14, 28, 29 and conversion i27 are
Almost the same effect can be achieved by using a computer such as a microcomputer.

As described in detail above, the lead error measuring device for threaded cutting tools using a non-contact optical tween has the following effects and advantages.

(1) By shortening the time required for measurement and significantly reducing the time required to organize data,
Lead errors can be measured in real time,
Moreover, it can be done automatically and easily.

(Resolution of 210.1 μm and accuracy of 0.6 μm with standard deviation were achieved, greatly improving measurement accuracy.

(8) Accurate lead error measurement is possible regardless of the size of the cutting tool.

[Brief explanation of drawings]

The figures show a lead error measuring device for threaded cutting tools using a non-contact optical tween as an embodiment of the present invention.
Fig. 3 is an explanatory diagram showing the operation of the optical cutting blade rotation angle detection mechanism, Fig. 3 is an explanatory diagram showing the university-style feeler mechanism, and Fig. 4 [A] is an explanatory diagram showing the measurement situation in the optical tween mechanism. Figure 6 is a graph showing the main parts of the optical cutting blade rotation angle detection mechanism, and Figure 7 is a graph showing the optical state of the optical cutting blade rotation angle detection mechanism. Waveform diagram showing the type cutting blade rotation angle detection mechanism for cattle, No. 8
The figure is a graph showing the indexing error during the measurement.
The figure is a graph showing the output voltage with respect to the axial displacement in the optical tween mechanism, and the 10th section is a graph showing the lead error at the time of measurement. 1. Bed constituting the fixed base, 2... Headstock constituting the identification base, 2a... Plate constituting the fixed base, 3... Tailstock, 4... Moving base, 5... Optical cutter. Blade rotation angle detection mechanism, 6
...Optical tween mechanism, 7. Gear hob as screw-shaped cutting tool, 7a.. Axis, 8. Arbor, 9. Drive arm as rotation mechanism, 10. Special right-angled trihedral blunt, 11.
- Reflective optical sensor, 12... Cutting blade of gear hob, 13... Rotary encoder as shaft rotation angle measuring mechanism, 14... First computing unit, 15... Laser generator,
16... Laser beam, 17... Half mirror 118, 1
9...Laser beam, 20,21.22...Plane mirror, 23
... Laser beam, '24... Half mirror 125... Magnifying glass, 26... Pin photodiode, 27... Converter, 28... Third computing unit, 29... Second computing unit, 30
...Light source, 31.. Half mirror 132, ... Pin photodiode as first sensor, 33.. Screw to be measured, 34.. Objective lens, 35.. Circular pinhole.
36... Mask, 37... Pin photodiode as 27th) sensor, 39... Photoelectric signal amplifier as differential amplifier, 40... Dintal printer, 41... Pen encoder, 42... Optical system, 43 ...first differentiator, 4
4...Second differentiator %45...Pulse generator, 45a...
・Schmitt Trigger-145b: Monostable multivibrator, A: Axial direction, B: Cutting edge position. Agent Patent Attorney Yoshihiko Iinuma Figure 6 14.29 Figure 7 □I Figure 8 Lead Autumn Figure 9 Figure 10

Claims (1)

[Claims] (1) A rotation mechanism for rotating a screw-shaped cutting tool as a sample around its axis is provided on a fixed table, and
A moving table that moves in the axial direction of the shaft in proportion to the rotation angle of the screw-shaped cutting tool, and a moving table drive mechanism that drives the moving table are provided, and the feed amount in the axial direction of the screw-shaped cutting tool is provided. a light wave interference type feed rate measuring mechanism that determines the rotation angle of the shaft by light wave interference; a shaft rotation angle measuring mechanism that measures the shaft rotation angle of the shaft; A non-contact optical cutting blade rotation angle detection mechanism is provided, and a non-contact optical tween mechanism is provided to measure the amount of relative movement of the cutting blade of the screw-shaped cutting tool in the axial direction with respect to the moving table. A signal corresponding to the feed amount measured by the light wave interference type feed amount measuring mechanism and a signal corresponding to the shaft rotation angle measured by the shaft rotation angle measuring mechanism are input as calculation input signals, and the optical a first arithmetic unit that calculates a feed error of the movable table by inputting a signal corresponding to the cutting blade rotation angle measured by the cutting blade rotation angle detection mechanism as a calculation control signal; A signal corresponding to the measured amount of relative movement of the cutting blade in the axial direction with respect to the moving table is input as an input signal for calculation, and a signal corresponding to the rotation angle of the cutting blade is input as a control signal for calculation to perform the above movement. A second computing unit calculates the difference between the feed error of the table and the lead error of the threaded cutting tool, and each output signal from the first and second computing units is inputted to calculate the lead error. 1. A lead error measuring device for a thread-shaped cutting tool using a non-contact optical tween, characterized in that a third computing unit for calculating is provided. (2) The optical cutting blade rotation angle detection mechanism is disposed on the movable table, and is provided with an opposite type optical sensor for detecting the cutting blade position, and inputs a signal from the optical sensor and calculates the differential thereof. Input the first-order differential signal from the first differentiator and further differentiate it.
a second differentiator that outputs a first-order differential signal, and the first-order differential signal is at a set level of either positive or negative, and
When the above second differential signal is zero, output a pulse ・2
A lead error measuring device for a screw-shaped cutting tool using a non-contact optical tween according to claim 1, comprising a pulse generator. (8) The optical fee 2 mechanism includes a light source, a no-f mirror that transmits and reflects light from the light source, and the same...
a first sensor that receives the transmitted light from the mirror; an optical system that irradiates the reflected light from the No.-7 mirror perpendicularly to the axial direction of the screw-shaped cutting tool; and the light irradiated from the optical system. a mask that transmits a portion of the passing light having the positional information of the thread of the thread-like cutting tool; a second sensor that receives the light that passes through the mask; and a second sensor that receives the light that passes through the mask; A thread-shaped cutting tool using a non-contact optical tween according to claim 1 or 2, comprising a differential amplifier that receives each light amount signal, differentially amplifies the signals, and outputs them. lead error measuring device. (4) According to any one of claims 1 to 3, wherein the movable stage is configured to move by the lead amount of the thread-shaped cutting tool during one rotation of the thread-shaped cutting tool. A lead error measuring device for threaded cutting tools using the described non-contact optical tween.