JPH0345140Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an optical displacement detection device, and in particular,
An index scale unit and a main scale unit each having a corresponding optical grating are moved relative to each other to detect the amount of relative displacement of both scale units, and the main scale unit has a reflective optical grating formed thereon. The present invention relates to an improvement of an optical displacement detection device in which a flexible metal tape is attached to an elongated base.

The main scale unit in the above-mentioned optical displacement detection device is generally formed from a long glass plate with an optical grating, or a flexible metal tape with an optical grating. There is.

When an optical grating is provided on a metal tape, the optical grating is formed on the surface of the metal tape by etching or the like. The metal tape on which the optical grating is formed is generally fixed to an elongated base with an adhesive or by laser spot welding.

In this way, a metal tape fixed to a long and thin base with adhesive or a laser spot can be attached to a machine tool, etc. with an optical displacement detection device, and its optical lattice surface is stable in all postures. However, in recent years, for example, a problem has arisen in three-dimensional measuring machines and the like that they are unable to meet the demands for high measurement precision.

For example, if a metal tape is attached to a long and thin base by laser spot welding, even if the precision of the metal tape is checked over a wide range before welding, thermal deformation will occur due to the laser spot. , the accuracy changes,
There was no way to solve this problem.

This phenomenon becomes more noticeable as the scale becomes longer, exceeding 4 m.In contrast, it is possible that the elongated base itself expands and contracts after the metal tape is attached, but in this case, the metal tape is Since the parts are welded at many spots in different directions, it is difficult to accurately correct the accuracy over a wide range, and pulling the long and thin base requires a huge tension, which is impractical. There was a problem.

This invention has been made in view of the above-mentioned conventional problems, and provides an optical displacement detection device in which a metal tape can be attached to a long and narrow base so that thermal distortion etc. do not occur during installation. The purpose is to

Another object of this invention is to provide an optical displacement detection device that can adjust the measurement accuracy by adjusting the metal tape using a small tensile force even after the metal tape is attached.

This invention also provides an optical displacement detection device that can easily and quickly attach a metal tape to a long and thin base at low cost, and can stably hold an optical grating surface on the surface of the metal tape. With the goal.

This device relatively moves an index scale unit and a main scale unit, each equipped with a corresponding optical grating, to detect the amount of relative displacement of both scale units, and the main scale unit has a reflective optical grating. In the optical displacement detection device, the metal tape is formed of a magnetic material and is formed on the tape mounting surface of the long and thin base, and the metal tape is formed on a tape mounting surface of the long and thin base. a tape guide means for guiding the tape substantially straight in the direction of relative movement of the main scale unit; and a tape guide means disposed on the tape mounting surface of the elongated base and holding the metal tape by suction so that its optical grating surface is straight. The above object is achieved by providing a magnetic body and fixing means for fixing both longitudinal ends of the metal tape guided by the tape guide means and held by the magnetic body to the elongated base. It is something to do.

Further, this invention achieves the above object by constructing the fixing means from a fixing means for fixing one end of the metal tape and a tension fixing means for fixing the metal tape by applying an appropriate tensile force to the other end. .

Further, this invention achieves the above object by making the tape guide means a groove formed in the tape mounting surface of the elongated base and having the same width as the metal tape.

Further, this invention achieves the above object by arranging the magnet body at the bottom of the groove.

In this invention, the metal tape is guided in a straight state to the elongated base by the tape guide means, and in this state is attracted and held straight by the magnet, and further fixed to the elongated base by the fixing means at both ends. The flatness of the optical grating surface can be accurately maintained by the magnet body while allowing expansion and contraction.

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

In this embodiment, as shown in FIGS. 1 to 3, an index scale unit (not shown), each equipped with a corresponding optical grating, and a main scale unit 10 are moved relative to each other, and both scale units are In addition to detecting the amount of relative movement, the main scale unit 10 is an optical displacement detection device in which a flexible metal tape 14 on which a reflective optical grating 12 is formed is attached to an elongated base 16. The metal tape 14 is formed from a magnetic material, and the elongated base 16
A tape guide means 20 is formed on the tape mounting surface 18 of the elongated base 16 and guides the metal tape 14 substantially straight in the direction of relative movement of the main scale unit 10; 14, its optical grating 12
A magnet body 22 that attracts and holds the surface so that it is straight.
and fixing means 24 for fixing both longitudinal ends of the metal tape 14 guided by the tape guide means 20 and held by the magnet 22 to the elongated base 16. .

The fixing means 24 includes a fixing means 26 for fixing one end of the metal tape 14, and a tension fixing means 28 for fixing the metal tape 14 by applying an appropriate tensile force to the other end.

The fixing means 26 includes a screw 32 that tightens and fixes one end (the left end in the figure) of the metal tape 14 to the tape mounting surface 18 of the elongated base 16 via a retainer 30.

The tension fixing means 28 is the metal tape 1
A tensioning means 34 is provided for applying a tensile force in the longitudinal direction to the other end of the metal tape 14, and the other end of the metal tape 14 is stretched into an elongated shape while a constant tension is applied by the tensioning means 34. The tape mounting surface 18 of the base 16 is provided with a screw 38 which is tightened and fixed to the tape mounting surface 18 of the base 16 via a retainer 36.

The through hole 40 through which the metal tape 14 and the screw 38 pass is a long hole that allows the other end of the metal tape 14 to expand and contract with respect to the screw 38. The through hole 41 of the metal tape 14 through which the screw 32 passes is a normal circular hole.

Reference numeral 42 in the figure indicates a screw hole on the elongated base 16 side into which the screw 32 or 38 is screwed, and 31 indicates a through hole for the screws 32 and 38 formed in the retainers 30 and 36, respectively.

The tensioning means 34 includes a lever 48 swingably attached to a housing 44 to which the elongated base 16 is attached by a shaft 46, and a lever 48 attached to one end of the lever 48 and the other end of the metal tape 14.
It is composed of a link 50 that is swingably connected via pins 50A and 50B, and a screw 52 that presses the end of the lever 48 opposite to the link 50 so as to be able to adjust the amount of displacement.

The tape guide means 20 is connected to the elongated base 1.
A groove is formed in the tape mounting surface 18 of No. 6 in the longitudinal direction to have the same width as the metal tape 14 and to have substantially the same depth as the thickness of the metal tape 14.

Further, the magnet body 22 is embedded in the bottom of the groove-shaped tape guide means 20 along its longitudinal direction. Therefore, the surface of the magnet body 22 and the bottom surface of the groove-shaped tape guide means 20 are flush with each other.

Next, the operation of the above embodiment will be explained.

When attaching the metal tape 14 to the elongated base 16, the metal tape 14 is first fitted into the groove-shaped tape guide means 20.

The fitted metal tape 14 is attracted by the magnet 22 placed at the bottom of the groove and held in that state.

In this state, move the metal tape 14 in the longitudinal direction to adjust its position, and attach one end of it to the screw 32.
is tightened and fixed to the elongated base 16 via the retainer 30.

Next, the link 5 of the tensioning means 34 is attached to the other end of the metal tape 14 held within the tape guiding means 20.
0 are connected via pin 50A.

In this state, operate the screw 52 of the tensioning means 34 to apply tension to the other end of the metal tape 14 via the lever 48 and the link 50, and with an appropriate tension applied, tighten the screw 38. The other end of the metal tape 14 is fixed to the elongated base 16 by tightening the retainer 36.

To adjust the precision of the metal tape 14 in the attached state, loosen the screw 38 and adjust the tension applied to the metal tape 14 by the screw 52 of the tension means 34 in this state.

In this case, use a block gauge or the like.

After the adjustment, the other end of the metal tape 14 is tightened and fixed with the screw 38 via the retainer 36.

Here, the tension means 3 is attached to the other end of the metal tape 14.
4, the metal tape 14 expands in its longitudinal direction, but this is absorbed by making the through hole 40 at the other end of the metal tape 14 into a long hole.

In this embodiment, when installing the metal tape 14, the straightness of the metal tape 14 can be easily determined by simply fitting the metal tape 14 into the tape guide means 20, which is a groove having the same width. According to experiments, the straightness was within 0.1 per meter.

Further, at the bottom of the groove-shaped tape guide means 20,
The magnet body 22 is arranged, and the metal tape 14
Since the metal tape 14 is made of a magnetic material, the metal tape 14 is attracted and held by the magnet 22 within the tape guide means 20, and therefore, the metal tape 14 does not fall off during the installation operation.

Further, since the bottoms of the magnet body 22 and the tape guide means 20 are flush with each other, the surface of the optical grating 12 of the metal tape 14 can be maintained straight.

Furthermore, during installation, the metal tape 14 is moved in its longitudinal direction within the tape guide means 20,
One end of the metal tape 14 can be tightened and fixed with a screw 32 via a retainer 30.

Also, via the retainer 36 by the screw 38,
Before tightening and fixing the other end of the metal tape 14,
A tensile force is applied to the metal tape 14 by the tensioning means 34, and the metal tape 14 can be tightened and fixed in this state, so there is an advantage that accuracy correction is easy.

Furthermore, since the metal tape 14 is attracted and held by the magnet 22, the optical grating 12 surface of the metal tape 14 is always maintained regardless of the orientation of the displacement detection device when it is attached to a machine tool or the like. can be kept straight.

Further, even after the metal tape 14 is attached to the edge of the elongated base 16, the accuracy can be corrected by adjusting the tensile force as described above.

Furthermore, when replacing the metal tape 14 due to damage to the optical grating 12, etc., there is no need to replace the entire elongated base 16 as in the conventional case.
Since only 4 pieces need to be replaced, the cost is reduced.

Furthermore, when transferring the optical grating 12 onto the metal tape 14, the metal tape 14 is generally transferred with a high degree of straightness. Therefore, by attaching it to the elongated base 16 in a state of high straightness, the reproducibility of its accuracy is greatly improved.

Furthermore, the unreasonable stress of spot welding etc.
Since it does not overlap the metal tape 14, narrow range accuracy is improved, and furthermore, even if the metal tape 14 is curved in its width direction, there is no curvature or distortion in its longitudinal direction, which affects measurement accuracy. There is no.

In the above embodiment, the tape guide means is a long and narrow groove whose cross section is substantially the same as that of the metal tape 14, but the present invention is not limited to this. Any material that can guide the tape in a straight state on the tape mounting surface 18 of the elongated base 16 may be used.

Therefore, for example, the tape guide means 20 may be an appropriate number of projections, pins, etc. attached to the tape mounting surface 18 of the elongated base 16.

Furthermore, the magnet body 22 is provided at the bottom of the groove-shaped tape guide means 20;
The mounting location is not limited as long as it can attract and hold the metal tape 14 held straight by the tape guide means 20.

Furthermore, the magnets do not necessarily have to be provided over the entire length of the metal tape 14, but may be provided at appropriate intervals.

Further, the fixing means 24 of the metal tape 14 in the above embodiment includes the fixing means 26 and the tension fixing means 2.
8, which may both be simple fastening means. In this case, it is not possible to apply tensile force to the metal tape 14, but
Since the metal tape 14 is attracted and held within the tape guide means 20 by the magnet 22 while maintaining its straight state, a certain degree of straightness can be maintained even when no tensile force is applied.

That is, the straightness of the metal tape 14 is maintained in the thickness direction by the magnet 22 and in the longitudinal direction by the tape guide means 20, respectively.

The measurement accuracy is shown in FIG. 4 when the metal tape 14 is measured with no tensile force applied to it and when it is attached to the elongated base 16 with a tensile force applied by the tension means 34. It can be done.

This figure shows that a certain degree of measurement accuracy is maintained even when no tensile force is applied to the metal tape 14, whereas when a tensile force is applied, the measurement accuracy can be further improved. I understand.

Further, as shown in FIG. 4, the metal tape 14
When a tensile force is applied to , the characteristics of measurement error are
The tape exhibits a certain tendency in the length direction. Therefore, this characteristic curve is stored in advance in an electronic computer (e.g., the computer of a three-dimensional measuring machine), and the measured value is corrected using the stored value, and the optical The measurement accuracy of the displacement detection device can be further improved.

Although such correction using an electronic computer has not been impossible in the past, it has a large burden on hardware in terms of storage capacity and the like. However, in the case of the present invention, the variation in measurement error is small and its characteristics are relatively clear, so even if the characteristic curve in the figure is slanted as a whole, the burden on hardware is reduced. It can be stored in memory.

Since the present invention is constructed as described above, it is possible to maintain high precision without causing thermal distortion when attaching a metal tape to a long and thin base, and to easily and quickly attach the metal tape to a long and thin base at a low cost. It has the excellent effect of being able to be attached to the base.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the main parts of an embodiment of the optical displacement detection device according to the present invention, and FIG.
FIG. 3 is an enlarged exploded perspective view showing essential parts of the same embodiment, and FIG. 4 is a diagram showing the relationship between measurement accuracy and scale length according to the same embodiment. DESCRIPTION OF SYMBOLS 10... Main scale unit, 12... Optical grating, 14... Metal tape, 16... Elongated base, 18... Tape mounting surface, 20... Tape guide means, 22... Magnet, 24... Fixed means, 2
6... Fixing means, 28... Tension fixing means, 34...
...Tension means.

Claims (1)

[Claims for Utility Model Registration] (1) An index scale unit and a main scale unit each having a corresponding optical grating are moved relative to each other, and the amount of relative displacement of both scale units is detected, and the main scale The unit is an optical displacement detection device in which a flexible metal tape on which a reflective optical grating is formed is attached to an elongated base, in which the metal tape is made of a magnetic material, and
tape guide means formed on the tape mounting surface of the elongated base to guide the metal tape approximately straight in the direction of relative movement of the main scale unit; and tape guide means disposed on the tape mounting surface of the elongated base to guide the metal tape; The optical lattice plane is
a magnet body that attracts and holds the metal tape so that it is straight; and a fixing unit that fixes both longitudinal ends of the metal tape guided by the tape guide means and attracted and held by the magnet body to the elongated base; An optical displacement detection device characterized by being provided with. (2) The fixing means comprises a fixing means for fixing one end of the metal tape and a tension fixing means for fixing the metal tape by applying an appropriate tensile force to the other end. Optical displacement detection device as described in . (3) The optical type according to claim 1 or 2, wherein the tape guide means is a groove formed on the tape mounting surface of the elongated base and having the same width as the metal tape. Displacement detection device. (4) The optical displacement detection device according to claim 3, wherein the magnet body is disposed at the bottom of the groove.