JPH0237962B2 - HENISOKUTEIKI - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a displacement measuring device, and in particular, is suitable for use in a linear displacement measuring device equipped with a long main scale, connected to one of two objects to be measured whose relative displacement is to be measured. A frame body, a main scale held by the frame body and made of a material having a coefficient of thermal expansion different from that of the frame body, and an index scale connected to the other of the object to be measured and moved along the main scale. The present invention relates to an improvement in a displacement measuring device, which measures the relative displacement between the two objects to be measured from the relative movement of the main scale and the index scale.

[Conventional technology]

Generally speaking, in a measuring machine that measures the length of an object, when measuring the amount of 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, which has a complicated shape, is generally formed of a pressed aluminum material, and the frame body is Since the main scale used for measurement is made of glass, there will be a difference in the amount of thermal expansion when the temperature changes, causing the main scale to deform and reduce measurement accuracy, or in severe cases, destroy the main scale. However, there were some problems. Therefore, conventionally, as shown in FIG. 1, for example, the main scale 10 is adhesively fixed to the frame 14 using an elastic adhesive 12 with the surface opposite to the scale surface 10A on which the vertically striped scale is formed. Alternatively, as shown in FIG.
The main scale 10 was held fixed. 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 configured to
The main scale 10 is fixed to the surface facing the
The index scales 26 and 28 on which vertical striped scales similar to those shown in FIG. be.

[Problems to be solved by the invention]

However, in the former case, in order to improve the mounting accuracy of the main scale 10, it is necessary to make the layer of the elastic adhesive 12 thin and bring it into close contact with the surface 14A, which is the mounting reference surface of the main scale 10.
The effect of absorbing the difference in the amount of thermal expansion is reduced.
Furthermore, the adhesion work itself is difficult. On the other hand, in the latter case, if the mounting reference surface 14A is deformed or deformed due to the pressing force of the rubber rod 18,
Main scale 10 alone has low rigidity, so
The main scale 10 itself is deformed following the curvature of the mounting reference surface 14A. Furthermore, it is difficult to adhesively fix the lower end of the main scale 10. Furthermore, in any case, the mounting reference surface 14A of the frame 14 must be processed with high precision, and the frame 1
4 is difficult to process. Further, there are other problems such as difficulty in locating the main scale 10, which has relatively low rigidity, within the narrow frame 14. The present invention was made to solve the above-mentioned conventional problems, and can absorb the difference in thermal expansion between the main scale and the frame, and also facilitates positioning and mounting of the main scale with respect to the frame. The purpose of the present invention is to provide a displacement measuring device that can perform highly accurate measurements.

[Means to solve the problem]

The present invention provides a frame body connected to one of two objects to be measured whose relative displacement is to be measured, a main scale held by the frame body and made of a material having a coefficient of thermal expansion different from that of the frame body; and an index scale connected to the other of the objects to be measured and moved along the main scale, so that relative displacement between the two objects to be measured is measured from relative movement between the main scale and the index scale. In the displacement measuring device, the main scale is adhered to a reference member made of a linear bar having a coefficient of thermal expansion between that of the frame and the main scale with an elastic adhesive, and the back surface of the main scale is The above object is achieved by guiding the reference member in contact with the mounting reference plane of the frame and by bonding the reference member to the frame using an elastic adhesive. Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 3, this embodiment consists of a frame body 14 made of, for example, an aluminum extrusion, which is fixed to one of two objects to be measured whose relative displacement is to be measured, for example, to the bed of a machine tool; A main scale 10 made of a material such as glass that has a coefficient of thermal expansion different from that of the frame 14 and is held by a body 14, and a main scale 10 that is connected to the other object to be measured, such as a workpiece or a tool, and that is A linear displacement measuring machine having a movable index scale (not shown), etc., and measuring the relative displacement between the two objects to be measured from the relative movement of the main scale 10 and the index scale,
The main scale 10 is attached to a reference member 40 made of a linear bar having a coefficient of thermal expansion between that of the frame 14 and the main scale 10, using an elastic adhesive 4.
2, the main scale 10 is bonded with parallelism, the back surface (right side in FIG. 3) of the main scale 10 is brought into contact with and guided by the mounting reference plane 14A of the frame 14, and the reference member 40 is attached to the frame 1 with an elastic adhesive 44 to ensure straightness.
4. In this way, the main scale 10 and the reference member 40 can be bonded outside the narrow frame 14 independently of bonding to the frame 14, so that parallelism can be easily achieved. Can be bonded, improving measurement accuracy. In addition, the main scale 10 integrated with the reference member 40 has higher rigidity as a whole than the main scale 10 alone, so even if the main scale 10 is pressed against the mounting reference plane 14A of the frame 14 and glued, Not only is it less susceptible to the effects of bending of the frame 14, making it easier to attach to the frame 14, but the straightness in the work of adhering to the frame 14 is good, regardless of the bend of the frame 14. Measurement accuracy is improved. Furthermore, since the main scale 10 is directly engaged with the frame body 14, the mounting accuracy of the main scale 10 can be improved. In this case, each mounting surface of the frame body 14 only has a temporary fixing function, and therefore does not need to be processed with high precision. Also, the reference member 40 is attached to the frame body 1.
4, the reference member 40 can be lifted from the frame 14 via the main scale 10, so that the elastic adhesive 44 is guaranteed to penetrate. Furthermore, even if external force or thermal stress is applied to the frame 14 during use, it is absorbed in two stages: between the frame 14 and the reference member 40 and between the reference member 40 and the main scale 10, so that it is not applied directly to the main scale 10. The influence is less likely to occur, and the measurement accuracy will not be reduced and the main scale 10 will not be damaged. In 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, and other It is clear that the present invention can be similarly applied to a linear displacement measuring machine using a frame and a main scale made of the same material, or to a general displacement measuring machine.

【Effect of the invention】

As explained above, according to the present invention, not only can the difference in thermal expansion between the main scale and the frame be absorbed, but also the positioning and mounting of the main scale with respect to the frame is facilitated, and measurement accuracy is also improved. have an effect.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a main scale holding structure in an example of a conventional displacement measuring device, FIG. 2 is a cross-sectional view showing a main scale holding structure in another conventional example, and FIG. FIG. 2 is a sectional view showing a main scale holding structure in an embodiment of the displacement measuring device according to the present invention. 10...Main scale, 14...Frame body, 40
...Reference member, 42, 44...Elastic adhesive.

Claims (1)

[Claims] 1. A frame connected to one of two objects to be measured whose relative displacement is to be measured;
a main scale made of a material having a coefficient of thermal expansion different from that of the frame; and an index scale connected to the other of the object to be measured and moved along the main scale; In a displacement measuring device configured to measure the relative displacement between the two objects to be measured from movement, the main scale is attached to a reference member made of a linear bar having a coefficient of thermal expansion between that of the frame and the main scale. , the main scale is bonded with an elastic adhesive, the back surface of the main scale is guided in contact with a mounting reference plane of the frame, and the reference member is bonded to the frame with an elastic adhesive. Displacement measuring device.