JP2853307B2 - External thread precision measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the precision (lead accuracy, roundness, bending, etc.) of a male screw, and more particularly, to measuring with the male screw horizontally supported. In the apparatus for performing the measurement, a measurement error due to the deflection of the male screw under its own weight or the like is removed.

[Conventional technology]

As shown in FIGS. 6 (a) and 6 (b), when the horizontally supported male screw 1 is deformed by its own weight and displaced to the position shown by the broken line, the radial displacement and the axial displacement of the thread groove surface 1a are performed. The relative positional relationship between the contact 2 of the measuring device and the thread groove surface 1a of the measuring device deviates, so that the measurement result of the measuring device has a radial error.
E will contain _R and the axial error E _L, accurate measurement of the external thread 1 there is a problem that not correctly performed.

As a conventional technique for solving such a problem, for example, there is a technique described in Japanese Patent Publication No. 52-31187. This conventional technique measures at two positions 180 degrees out of phase. Then, the measurement error is removed by using the two measured values.

[Problems to be solved by the invention]

However, in the above conventional solution, since the axial error appears in the opposite directions at the two measurement points, the measurement error is removed if the average value of the two measurement values is obtained, but the obtained measurement values are two. The average value of the read accuracy at the measurement point is obtained, and the read accuracy at one desired point cannot be obtained. Further, the above-described conventional technique cannot remove radial errors.

The present invention has been made in view of such unresolved problems of the conventional technology, and can eliminate both the radial error and the axial error due to the deflection of the male screw's own weight from the measured value, and can accurately perform the measurement. It is an object of the present invention to provide a device for measuring the accuracy of a male screw capable of performing accurate measurement.

[Means for solving the problem]

In order to achieve the above object, the invention according to claim (1) includes a rotating unit for rotating the male screw while supporting the male screw horizontally, a rotation angle detecting unit for detecting a rotation angle of the male screw,
First displacement measuring means for measuring a radial displacement and an axial displacement of a thread groove surface at an intermediate point in the vertical direction of the horizontally supported male screw; and about 90 degrees from a measurement position of the first displacement measuring means.
A second displacement measuring means for measuring a radial displacement of the thread groove surface separated by a degree phase, and capable of being displaced in the axial direction and the vertical direction with respect to the male screw supported horizontally, A support for supporting a second displacement measuring means, a first driving means for changing an axial relative position between the male screw and the support in proportion to a rotation angle and a lead of the male screw; Second driving means for changing the relative position in the vertical direction between the male screw and the support base so that the measured value of the displacement measuring means maintains a predetermined value.

Further, the invention described in claim (2) provides the invention according to claim (1).
In the invention described above, there is provided a third displacement measuring means for measuring a radial displacement of a thread groove surface which is supported by the support table and is separated from the first displacement measuring means by a phase of about 180 degrees, and a second driving means. Is such that the measured value of the second displacement measuring means maintains an average value of the radial displacement measured by the first displacement measuring means and the radial displacement measured by the third displacement measuring means. The relative position in the vertical direction between the male screw and the support table is changed.

[Action]

According to the invention described in claim (1), the rotating means rotates the male screw which is horizontally supported, the rotation angle detecting means detects the rotation angle of the male screw, and the first driving means comprises:
The relative position of the male screw and the support in the axial direction is changed in proportion to the rotation angle of the male screw and the lead.

Then, the relative position in the axial direction between the male screw and the first displacement measuring means supported by the support table also changes in proportion to the rotation angle of the male screw and the lead.

Further, the second displacement measuring means is located at a position separated by about 90 degrees from the measurement position of the first displacement measuring means, that is, the diameter of the thread groove surface at the highest point or the lowest point of the horizontally supported male screw. The directional displacement is measured, and the second driving means changes the vertical relative position between the male screw and the support base so that the measured value of the second displacement measuring means maintains a predetermined value.

Then, the radial displacement of the thread groove surface measured by the second displacement measuring means is equal to the vertical displacement of the male screw, that is, the deflection of the male screw supported horizontally. If the relative position in the vertical direction changes, the relative position in the vertical direction between the male screw and the first displacement measuring means supported by the support base also changes following the deflection of the male screw.

That is, the measurement position of the first displacement measuring means is synchronized with the rotation of the male screw by the first driving means and moves in parallel with the male screw, and is vertically moved following the deflection of the male screw by the second driving means. Because they will move,
The first displacement measuring means always measures the radial displacement and the axial displacement of the thread groove surface at the midpoint in the vertical direction of the horizontally supported male screw.

Further, according to the invention described in claim (2), the third displacement measuring means is located at about 18 degrees from the measurement position of the first displacement measuring means.
The radial displacement of the thread groove surface at a position separated by 0 degree (about 90 degrees from the measurement position of the second displacement measuring means) is measured, and the second driving means measures the measured value of the second displacement measuring means. However, since the relative position between the male screw and the support base is changed so as to maintain the average value of the radial displacement measured by the first and third displacement measuring means, the diameter of the male screw may change. However, the first displacement measuring means always measures the radial displacement and the axial displacement of the thread groove surface at the midpoint in the vertical direction of the horizontally supported male screw.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 show a first embodiment of the present invention.

First, the configuration will be described. As shown in FIG. 1 and FIG. 2, the accuracy measuring device 3 has a work stock 5 and a tail stock 6 constituting a rotating means on a bed 4, and these work stocks 5 The male screw 1 is horizontally supported between the tail stock 6 and the male screw 1, and the male screw 1 can rotate by receiving a rotational force via a rotational force transmission mechanism 7 composed of a gear train.

Below the male screw 1, there is provided a main carriage 8 which can move in parallel with the male screw 1 along guide rails 4a, 4b formed on the bed 4. The main carriage 8 is moved by a driving device (not shown) in proportion to the output of a rotary encoder 5a as a rotation angle detecting means for detecting the rotation angle of the male screw 1 and the lead of the male screw 1.

On the main moving table 8, an up-down fine moving table 9 is installed. The vertical fine moving table 9 is displaced in a direction perpendicular to FIG. 2 by a wedge 10 interposed between the main moving table 8 and the vertical fine moving table 9 receiving the torque of the electric motor 11 via a feed screw mechanism (not shown). By doing so, it is possible to displace in the vertical direction with respect to the main moving table 8.

Then, a first displacement measuring device for measuring the radial displacement and the axial displacement of the thread groove surface of the male screw 1 is provided on the vertical fine movement table 9.
15, a second displacement measuring device 16 for measuring only the radial displacement of the thread groove surface of the male screw 1, a position detector 17 for detecting the position in the width direction (vertical direction in FIG. 1) of the vertical fine moving table 9, Is installed. The vertical displacement of the vertical fine movement table 9 is measured by a detector (not shown) incorporated in the vertical fine movement table 9, and the axial displacement (horizontal direction in FIG. 1) of the vertical fine movement table 9 is as follows.
It is measured by a laser interferometer (not shown).

As shown in FIGS. 3 (a) and 3 (b), the first displacement measuring device 15 has its contact 15a in contact with the thread groove surface 1a at the vertically intermediate point of the horizontally supported male screw 1. Is installed on the vertical fine movement table 9 as described above, and the second displacement measuring device 16
As shown in FIGS. 3A and 3B, the contact 16a
Is mounted on the vertical movement table 9 so as to be in contact with the lowest thread groove surface 1a of the male screw 1 separated by about 90 degrees from the contact position of the contact 15a.

That is, the radial displacement of the thread groove surface 1a measured by the first displacement measuring device 15 is a displacement in the left-right direction in FIG. 3 (a), and the displacement of the thread groove surface 1a measured by the second displacement measuring device 16 is The radial displacement is a displacement in the vertical direction in FIG.

Then, the electric motor 11 changes the height position of the second displacement measuring device 16 by moving the vertical fine movement table 9 up and down,
The measured value of the second displacement measuring device 16 is maintained at a predetermined value.

Further, the position detector 17 has a contact thereof in contact with the straight edge 18 parallel to the moving direction of the main moving table 8, and measures the contact position based on, for example, a change in electric resistance and the like. 9 is detected in the width direction.

 Next, the operation and effect of this embodiment will be described.

That is, when the main carriage 8 moves in parallel with the male screw 1 in proportion to the rotation angle of the male screw 1 detected by the rotary encoder 5a and the lead of the male screw 1, the vertical fine movement set on the main carriage 8 Since the table 9 also moves integrally, the first and second displacement detectors 15 and 16 also move.

On the other hand, the male screw 1 supported horizontally bends under its own weight, and the deflection appears as a measured value of the second displacement detector 16.

Therefore, when the electric motor 11 moves the vertical fine movement table 9 up and down so that the measurement value of the second displacement detector 16 maintains a predetermined value, the first displacement detector 15 also moves up and down integrally.

That is, the first displacement detector 15 moves in the axial direction in proportion to the rotation angle of the male screw 1 and the lead, and also moves in the vertical direction following the deflection of the male screw 1.
The contact position 15a is always located at the middle point in the vertical direction of the horizontally supported male screw 1 as shown in FIGS. 3 (a) and 3 (b).

When the male screw 1 bends due to its own weight, the lead contracts on the upper side due to compressive stress, and the lead extends on the lower side due to tensile stress. In the present embodiment, the male screw 1 Leads can be measured.

Therefore, even if the lead error, roundness, bend, and the like of the male screw 1 are measured based on the radial displacement and the axial displacement of the thread groove surface 1a measured by the first displacement detector 15, the measurement results may be different. Does not include an error component due to the deflection of the male screw 1, and accurate accuracy measurement is performed.

Here, in the present embodiment, the first displacement measuring device 15 corresponds to the first displacement measuring device, the second displacement measuring device 16 corresponds to the second displacement measuring device, The fine moving table 9 corresponds to the supporting table, the driving device for displacing the main moving table 8 in the axial direction corresponds to the first driving means, and the electric motor 11 corresponds to the second driving means.

FIGS. 4 (a) and 4 (b) are views showing a main part of a second embodiment of the present invention, and correspond to the invention described in claim (2).

That is, in the present embodiment, a third displacement measuring device as third displacement measuring means is provided on the vertical fine movement table 9 together with the first and second displacement measuring devices 15 and 16, and the contact 20a is provided. ,
Thread groove surface approximately 180 degrees away from the contact position of contact 15a
1a.

The radial displacement of the thread groove surface 1a measured by the first displacement measuring device 15 is R ₁ , and the screw groove surface measured by the third displacement measuring device 15 is R ₁ .
If the radial displacement of 1a was R _3, the electric motor 11, the second
Measurements R ₂ displacement measuring device 16 is moved up and down the vertical fine table 9 so as to satisfy the following equation (1).

R ₂ = (R ₁ + R ₃ ) / 2 (1) That is, since the output of the second displacement detector 16 also changes due to the change in the diameter of the male screw 1, the male screw is not used in the configuration of the first embodiment. The contact 15a of the first displacement detector 15 moves up and down with the increase and decrease of the diameter of 1, and the contact position of the contact 15a changes.

Then, as in the present embodiment, when the electric motor 11 moves the vertical fine moving table 9 up and down so that the measured value R2 of the _second displacement measuring device 16 satisfies the above equation (1), Reference numeral 9 denotes a value obtained by removing the increase or decrease in the diameter of the male screw 1 from the value measured by the second displacement measuring device 16, that is, the vertical movement follows only the deflection component of the male screw 1.

That is, in the present embodiment, even if the diameter of the male screw 1 changes, the contact position of the contact 15a is always located at the middle point in the vertical direction of the male screw 1 supported horizontally. The same effects as in the first embodiment can be obtained.

Here, as shown in FIG. 5, when the horizontally supported male screw 1 bends, its axial length also changes, so that the measurement result of the above embodiment also includes the change in its axial length. However, if the following processing is performed, the change can be removed.

That is, as shown in the enlarged view in the lower part of FIG. 5, in the extremely short section, the axis of the bent male screw 1 can be regarded as a straight line, and the vertical length of the horizontal male screw 1 in the section is dx
₁ , when the axial length of the bent external thread 1 is dx, the change Δx
Can be expressed as in the following equation (2).

Δx = dx−dx ₁ (2) Then, this change Δx is obtained from the measurement start point of the male screw 1 to the measurement point, and the total change ΔX is subtracted from the measurement result to obtain the axis due to the deflection of its own weight. Measurement results with no change in length are obtained.

Therefore, as shown in FIG. 5, the angle between the horizontal male screw 1 and the bent male screw 1 in the minute section is θ, and the length of the perpendicular drawn from the horizontal male screw 1 to the bent male screw 1 is
When dy, the _{Δx = dx-dx 1 = (} 1-cosθ) dx = (θ 2/2) dx ...... (3). Then, since θ = dy / dx, the total change ΔX can be expressed as the following equation (4).

In each of the above embodiments, the second displacement measuring device 16 is configured to measure the radial displacement of the thread groove surface 1a on the lowest point side of the male screw 1, but the present invention is not limited to this. A configuration for measuring the radial displacement of the thread groove surface 1a on the point side may be adopted.

〔The invention's effect〕

As described above, according to the invention described in claim (1), the radial error and the axial error due to the self-weight deflection of the male screw can be removed from the measurement result, and the result that accurate accuracy measurement can be performed is obtained. Can be

According to the invention described in claim (2), even if the diameter of the male screw changes, the measurement position of the first change measuring means does not move up and down, so that the measurement result may fluctuate due to the change in the diameter of the male screw. There is no.

[Brief description of the drawings]

FIG. 1 is a plan view showing the structure of a first embodiment of the present invention, and FIG.
Fig. 3 is a side view of Fig. 1, Fig. 3 (a) is a front view showing a relationship between a male screw and a contact, Fig. 3 (b) is a side view showing a relationship between a male screw and a contact, Fig. 4 (A) is a front view showing the relationship between a male screw and a contact according to the second embodiment of the present invention.
FIG. (B) is a side view showing the relationship between a male screw and a contact according to the second embodiment of the present invention, FIG. 5 is a diagram showing a change in axial length due to deflection of a male screw, and FIGS. 6 (a) and (b). () Is a diagram showing a conventional problem. 1 ... external thread, 3 ... accuracy measuring device, 5 ... work stock, 6 ... tail stock, 8 ... main carriage, 9 ...
Vertical movement table, 11: electric motor, 15: first displacement detector, 16: second displacement detector

Claims (2)

(57) [Claims] A rotating means for rotating the male screw in a horizontally supported state; a rotation angle detecting means for detecting a rotation angle of the male screw; and a screw groove surface at a vertically intermediate point of the horizontally supported male screw. First to measure radial displacement and axial displacement
A displacement measuring means, a second displacement measuring means for measuring a radial displacement of a thread groove surface separated by a phase of about 90 degrees from a measurement position of the first displacement measuring means, and the male screw supported horizontally. A support base that is relatively displaceable in the axial direction and the vertical direction, and supports the first and second displacement measuring means, and a distance between the male screw and the support base in proportion to a rotation angle and a lead of the male screw. A first driving means for changing a relative position in the axial direction of the first screw and a vertical relative position between the male screw and the support base such that a measured value of the second displacement measuring means maintains a predetermined value. And a second driving means. And a second drive means for measuring radial displacement of the thread groove surface supported by the support base and spaced from the first displacement measurement means by about 180 degrees in phase. Is such that the measured value of the second displacement measuring means maintains an average value of the radial displacement measured by the first displacement measuring means and the radial displacement measured by the third displacement measuring means. The apparatus for measuring the accuracy of a male screw according to claim 1, wherein the relative position in the vertical direction between the male screw and the support base is changed.