JPH0213242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a linear displacement measuring machine, and particularly relates to a method for manufacturing a linear displacement measuring machine, and particularly relates to a method for manufacturing a linear displacement measuring machine, and particularly relates to a method for manufacturing a linear displacement measuring machine, and in particular, a method for manufacturing a linear displacement measuring machine. a main scale holding member, which has two guide surfaces corresponding to two surfaces of the frame, and is adhesively fixed at a predetermined pitch in the longitudinal direction of the frame while maintaining the straightness of the guide surfaces; A main scale made of materials having different coefficients of thermal expansion and adhesively fixed to the main scale holding member while being pressed against the guide surface by a pressing means; an index scale that is moved;
The present invention relates to a method for manufacturing a linear displacement measuring machine that measures the relative displacement between the two objects to be measured based on the relative movement of the main scale and the index scale.

Generally speaking, in a measuring machine that measures the length of an object, when measuring the amount of relative movement of something that moves relative to the main body, such as the amount of movement of the probe relative to the main body, the amount of movement of the slider relative to the column, etc., the main scale is held on one side. A displacement measuring device is known in which a frame body is fixed to the other side and a detector including an index scale is fixed to the other side, and the relative displacement between the frame body and the detector is read by, for example, an optical method or an electromagnetic method. There is.

In such displacement measuring machines, especially in linear displacement measuring machines equipped with a transmission-type displacement detecting device, the frame body is generally complicated in shape, and is designed to improve sealability, nonflammability, and weight reduction of the detection part. Because the main scale is made of extruded aluminum, and the main scale held in the frame is made of glass, there is a difference in the amount of thermal expansion due to temperature changes, which deforms the main scale and reduces measurement accuracy. However, in severe cases, the main scale may be destroyed.

Therefore, conventionally, for example, as shown in FIG.
While being pressed against the guide surfaces 14A and 14B of the frame 14, the main scale 10 is directly adhesively fixed to the frame 14 using an elastic adhesive 16 or the like, so that the main scale 10 is held elastically. was.

In FIG. 1, 20 is moved in the longitudinal direction of the main scale 10 while maintaining a predetermined positional relationship with the main scale 10 by a sliding piece 22 that slides on the surface of the main scale 10. The slider 24, which is configured as shown in FIG. A light emitting element and a light receiving element are fixed to the slider 20, sandwiching the main scale 10 and the index scale 24, respectively.

However, due to the manufacturing method, the aluminum extruded material forming the frame 14 is already, for example, about 0.03 mm per 300 mm of length, that is,
For example, bending, twisting, waviness, etc. of about 30 times the scale resolution of 1 μm occur irregularly, and it is practically difficult to correct this and achieve the same level of precision as the main scale 10. Furthermore, during use, thermal deformation occurs due to temperature changes. Therefore, in the past, no matter how highly precisely the main scale 10 is finished in order to obtain a scale resolution of about 1 μm, for example, when the main scale 10 is adhesively fixed to the frame 14, the main scale 10 is There was a problem in that the frame body 14 would be deformed by adapting to the bending, etc., and the scale would be enlarged or reduced, resulting in a significant decrease in measurement accuracy.

Now, when estimating the effect on measurement accuracy when the main scale 10 is bent due to the bending of the frame 14, for example, as shown in FIG. If the main scale 10 is formed symmetrically with respect to A, no error will occur when the main scale 10 bends in the height direction as shown by arrow B. However, normally, the scale face 10 on which the scale 10B is formed
A does not coincide with the neutral plane C of the main scale 10, so as shown in FIG.
When a bend of 0 occurs in the thickness direction, the radius of the bend is R, the prospective angle Δθ of the unit section for which the error should be evaluated, and the length before the bend occurs, that is, the length of the neutral plane C, is L. , the length of the scale surface 10A is Lo, the error ε between the two is approximately expressed by the following equation.

ε=Lo−L...(1) Lo≒(R+t/2)Δθ...(2) L≒RΔθ...(3) Here, t is the thickness of the main scale 10.

By the way, the maximum deformation amount δ at the center of the neutral plane C is approximately expressed by the following equation.

δ=R−Rcos(Δθ/2) ≒R[1−{1−(1/2!) ×(Δθ/2) ² }] =R(Δθ) ^2/8 =LΔθ/8 ……(4) Therefore, the error ε is expressed by the following equation using this δ.

ε≒(t/2)Δθ ≒(1/2)×(8δ/L) ≒4tδ/L ……(5) Therefore, the length L of the error evaluation unit section of the main scale 10 is 300 mm, and the thickness t is 5mm, δ is 0.06mm
When , the error ε is approximately 4 μm. Therefore, for example, in the case of a main scale with a total length of 900 mm, an error of 12 μm will occur, which is a fatal flaw in a linear displacement measuring machine that requires measurement accuracy of 1 μm or less.

In order to alleviate such problems, when fixing the main scale 10 to the frame 14 by adhesive, for example, a test indicator or an electric micrometer, etc., may be used to touch the two sides of the main scale 10. It is also possible to position the main scale 10 by measuring the accuracy in the longitudinal direction and inserting shims between the main scale 10 and the frame 14 according to the unevenness. This has the problem that it is not only extremely inefficient, but also that accurate positioning is extremely difficult.

In order to solve the above-mentioned conventional problems, the main scale has two guide surfaces corresponding to the two intersecting surfaces, and is glued at a predetermined pitch in the longitudinal direction of the frame while maintaining the straightness of the guide surfaces. It is conceivable to use a fixed main scale holding member to adhesively fix the main scale to the main scale holding member, but it is difficult to maintain the straightness of the guide surfaces of a large number of main scale holding members accurately. In this state, it is not easy to glue and fix the frame at a predetermined pitch in the longitudinal direction of the frame.

The present invention has been made to solve the above-mentioned problems, and has the purpose of holding the main scale straight regardless of bending of the frame, and absorbing the difference in thermal expansion between the main scale and the frame. An object of the present invention is to provide a method for manufacturing a linear displacement measuring device that can extremely easily manufacture a linear displacement measuring device that can perform highly accurate measurements.

The present invention has a frame connected to one of two objects to be measured whose relative displacement is to be measured, and two guide surfaces corresponding to two intersecting surfaces of a main scale, and the straightness of the guide surfaces. a main scale holding member that is adhesively fixed at a predetermined pitch in the longitudinal direction of the frame, and a main scale holding member that is made of a material having a coefficient of thermal expansion different from that of the frame, and is pressed against the guide surface by a pressing means. , comprising a main scale adhesively fixed to the main scale holding member, and an index scale connected to the other of the object to be measured and moved along the main scale,
When manufacturing a linear displacement measuring device that measures the relative displacement between the two objects to be measured based on the relative movement of the main scale and index scale, at least the position corresponding to the installation position of the main scale holding member is provided. A step of suctioning and fixing a main scale holding member made of a magnetic material at a predetermined pitch to a positioning jig including a magnet portion having a shape corresponding to two intersecting surfaces of the main scale, which is provided as a positioning jig; The method includes the steps of adhesively fixing the frame to a main scale holding member suction-fixed to a tool, and removing the positioning jig and instead adhesively fixing the main scale to the main scale holding member. , the above objective has been achieved.

According to the present invention, the positioning jig, which is provided at least in correspondence with the installation position of the main scale holding member and includes a magnet portion having a shape corresponding to two intersecting surfaces of the main scale, is made of a magnetic material. Since the frame body is adhesively fixed to the main scale holding member while the main scale holding member is suctioned and fixed at a predetermined pitch, the straightness of the guide surfaces of a large number of main scale holding members can be easily and reliably maintained. can be maintained.

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

A first embodiment of the present invention is a method of applying the present invention to one of two objects whose relative displacement is to be measured, for example, an extruded aluminum molding, which is fixed to the bed of a machine tool, as shown in FIG. Frame body 1 consisting of
4, and two guide surfaces 30A, 30B corresponding to the two orthogonal surfaces of the main scale 10, and with the straightness of the guide surfaces 30A, 30B maintained, a predetermined pitch is formed in the longitudinal direction of the frame 14. The main scale holding member 30 is made of a material having a thermal expansion coefficient different from that of the frame body 14, such as glass, and is pressed against the guide surface 30A by the rubber rod 12 serving as a pressing means. The main scale 10 is adhesively fixed to the holding member 30, and the main scale 1 is connected to the other object to be measured, for example, a workpiece or a tool.
A linear displacement device that includes an index scale (not shown) that moves along the 0 axis, and measures the relative displacement between the two objects to be measured from the relative movement between the main scale 10 and the index scale. This is applied to the manufacturing of measuring instruments.

As shown in detail in FIG. 5, the main scale holding member 30 is approximately L-shaped, and a guide protrusion 30C is formed at the center of one guide surface 30B in the thickness direction of the main scale. This means that even if there is a slight error in the bending angle θ of the main scale holding member 30, the main scale
This is to ensure that the bottom surface of the guide surface 30B comes into contact with the guide surface 30B. Note that if the main scale holding member 30 can be bent with high precision, the guide protrusion 30C may be omitted.

The contact area of the rubber rod 12 with the main scale 10 is made smaller than the contact area of the main scale 10 with the main scale holding member 30. This is to prevent an unbalanced moment from occurring.

The ratio of the guide surface length l of the main scale holding member 30 to the main scale holding member arrangement interval P is in the range of 1:7 to 1:11 (see FIG. 6). This consists of the main scale 10 and the frame body 14.
absorbs the difference in the amount of thermal expansion of the main scale 10, prevents damage to the main scale 10 due to thermal stress, and reduces hysteresis in measured values due to temperature changes during measurement.
Furthermore, this is to prevent problems such as misalignment of the main scale due to rough handling during transportation.

That is, as the applicant has already proposed in Japanese Patent Application No. 57-57604, the main scale 10 is, for example,
In the case of a long scale of approximately 1,500 mm to 4,500 mm, the pitch and pitch are determined in the longitudinal direction of the main scale 10 by the materials of the main scale 10, the frame 14, and the elastic joint member, and the length of the main scale 10. By providing a long elastic member non-bonded portion to reduce the thermal stress applied to the main scale 10 through the elastic bonding member during temperature changes, damage to the main scale 10 due to thermal stress can be prevented, and It is possible to reduce hysteresis in measured values due to temperature changes. Therefore, when the main scale 10 is a long object of 1500 mm or more, for example, the ratio of the guide surface length l of the main scale holding member 30 to the main scale holding member arrangement interval P is 1:15 to 1:15. It can be in the range of 1:20. On the other hand, if the length of the main scale 10 is relatively short, for example, 1500 mm or less, it is light and easy to carry, so it is easy to be handled roughly during transportation. The maximum allowable external force needs to be increased from about 12G for long scales to about 20G to 50G for short scales. Therefore, in this case, the main scale holding member 30
The ratio of the guide surface length l to the main scale holding member arrangement interval P is in the range of 1:7 to 1:11.

In this first example, as shown in FIG. Almost the same shape as the main scale 10, including the magnet part,
The main scale holding member 30 made of a magnetic material is suctioned and fixed to the precision positioning jig 40 at a predetermined pitch. The magnet portions provided in the positioning jig 40 may be continuous or may have a constant pitch. Furthermore, by forming the magnet portion with an electromagnet, the positioning jig 40 can be easily removed from the main scale holding member 30 when the main scale 10 is adhesively fixed.

Next, as shown in FIG. 6, the frame body 14 is adhesively fixed to the main scale holding member 30, which is suction-fixed to the positioning jig 40, using an elastic adhesive 42. At this time, the frame 14 is attached to the main scale holding member 30 which is suction-fixed to the positioning jig 40.
A guide may be provided to guide the frame 14 so that it is in a convenient position for bonding.

Next, the positioning jig 40 is removed, and the main scale 10 is replaced with an elastic adhesive 44.
Adhesive and fix it to the main scale holding member 30 using.

In this way, the main scale holding member 30
The main scale holding member 30 can be adhesively fixed by pressing the frame 14 against the main scale holding member 30 without pressing the frame 14 against the guide surface of the frame 14. The main scale holding member 30 no longer follows.

Next, a second embodiment of the present invention will be described in detail.

This second embodiment incorporates the present invention, as shown in FIG. and a main scale holding member 50, which has a main scale locking portion 50C and is adhesively fixed at a predetermined pitch in the longitudinal direction of the frame 14 while maintaining the straightness of the guide surfaces 50A and 50B; The main scale holding member 50 is made of a material having a coefficient of thermal expansion different from that of the body 14, such as glass, and is pressed against the guide surface 50A by the rubber rod 12, which is a pressing means using the main scale locking portion 50C. It has a main scale 10 that is fixed with adhesive, and an index scale (not shown) similar to the first embodiment, and the relative movement between the main scale 10 and the index scale determines the relative movement between the two objects to be measured. This is applied to the manufacture of a linear displacement measuring machine that measures displacement.

The main scale holding member 50 is approximately U-shaped.

The other points are the same as those of the first embodiment, so the explanation will be omitted.

In this embodiment, the frame body 14 is not used as a position reference for the main scale 10, so that it can be held with extremely high precision.

Next, a third embodiment of the present invention will be described in detail.

This third embodiment incorporates the present invention, as shown in FIG. A main scale holding part 60C has a main scale locking part 60C having spring characteristics, and is adhesively fixed at a predetermined pitch in the longitudinal direction of the frame 14 while maintaining the straightness of the guide surfaces 60A and 60B. member 60 and the frame 14
The main scale 10 is made of a material, such as glass, and has a coefficient of thermal expansion different from that of the main scale 10, and is adhesively fixed to the main scale holding member 60 while being pressed against the guide surface 60A by the main scale locking portion 60C itself; A linear displacement measurement device having an index scale (not shown) similar to the first embodiment, and measuring the relative displacement between the two objects to be measured from the relative movement between the main scale 10 and the index scale. This is applied to the manufacture of machines.

The main scale holding member 60 is approximately U-shaped.

The other points are the same as those of the first embodiment, so the explanation will be omitted.

Also in this third embodiment, as in the second embodiment, since the frame 14 is not used as a positional reference, highly accurate holding can be performed. Furthermore,
The structure is simple.

In addition, in each of the above embodiments, the frame 1
4 and main scale holding members 30, 50, 60, and main scale holding members 30, 5
When bonding 0.60 and main scale 10,
Since both use elastic adhesives 42 and 44, they are particularly effective in absorbing the difference in thermal expansion between the main scale 10 and the frame 14. Note that the type of the adhesive is not limited to this, and for example, it is also possible to use an adhesive that does not have elasticity for one or both of the adhesives.

Furthermore, in each of the above embodiments, the present invention was applied to a linear displacement measuring machine that used an aluminum frame and a glass main scale, but the scope of the present invention is not limited to this. It is obvious that the present invention is not limited to this, and can be similarly applied to manufacturing a linear displacement measuring machine using a frame made of other materials or a main scale.

As explained above, according to the present invention, the main scale can be held straight regardless of the bending of the frame, and the difference in the amount of thermal expansion between the main scale and the frame can be absorbed. The present invention has an excellent effect in that a linear displacement measuring machine that can obtain accuracy can be manufactured extremely easily.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a main scale holding structure in an example of a conventional linear displacement measuring machine, FIG. 2 is a front view showing an example of the relationship between the scale forming position and the bending direction on the main scale, Figure 3 is
Figure 4 is a plan view for calculating measurement errors caused by bending of the main scale in the thickness direction.
First method of manufacturing a linear displacement measuring device according to the present invention
FIG. 5 is a sectional view showing the main scale holding structure of a linear displacement measuring machine to which the embodiment is applied, and FIG. 6 is a sectional view showing the shape of the main scale holding member used in the embodiment. FIG. 4 is a cross-sectional view taken along the line ``--'' showing the adhesion state of the main scale holding member in the embodiment, and FIG. FIG. 8 is a cross-sectional view showing the main scale holding structure of a linear displacement measuring device to which the third embodiment is also applied. 10...Main scale, 12...Rubber bar, 14...
Frame body, 24... Index scale, 30,5
0,60...Main scale holding member, 30A,3
0B, 50A, 50B, 60A, 60B...Guide surface, 40...Positioning jig, 42, 44...Elastic adhesive.

Claims (1)

[Claims] 1. It has a frame connected to one of two objects to be measured whose relative displacement is to be measured, and two guide surfaces corresponding to the two intersecting surfaces of the main scale, and the straightness of the guide surfaces is maintained. In this state, the main scale holding member is adhesively fixed at a predetermined pitch in the longitudinal direction of the frame, and the main scale is made of a material having a coefficient of thermal expansion different from that of the frame, and is pressed against the guide surface by a pressing means. The main scale is adhesively fixed to the scale holding member, and the index scale is connected to the other of the object to be measured and is moved along the main scale. When manufacturing a linear displacement measuring machine that measures the relative displacement between two objects to be measured,
A main scale holding member made of a magnetic material is attached to a positioning jig that is provided at least in correspondence with the arrangement position of the main scale holding member and includes a magnet portion having a shape corresponding to two intersecting surfaces of the main scale. A step of fixing the frame by suction at a predetermined pitch, a step of adhering and fixing the frame to the main scale holding member suction-fixed to the positioning jig, and a step of removing the positioning jig and fixing the main scale to the main scale in its place. A method for manufacturing a linear displacement measuring device, comprising the step of adhesively fixing it to a scale holding member.