JP4982032B2 - Divided support holder - Google Patents

Description

  The present invention relates to a holding unit for a divided support of a position measuring device. In the holding portion, the split support is formed to be flexible.

  It is adhesion that fixes a widely used type of divided support to the holding part. However, it is clear that adhesion does not guarantee good stability in positioning the split support on the holding part. Drift of the divided support can be confirmed based on the shrinkage of the adhesive over time, the high temperature coefficient of the adhesive, and the change of the humidity capacity.

  Therefore, in the high-accuracy position measuring apparatus, the adhesion is abandoned and the divided support body is fixed to the holding portion by tightening. A holding part of this type of divided support is known from EP 264801 (Patent Document 1). In order to fix the split support so as to be stable and reproducible for a long time, the split support is pushed to the surface of the holding part via a spring acting on the narrow face. The sphere between the spherical surface of the holding part and the divided support body enables the rolling support of the divided support body with respect to the holding part.

Nevertheless, it was clear that this arrangement led to measurement errors when changing temperature. The cause is a friction force generated when the temperature is changed between the holding portion and the divided support.
European Patent Application No. 264801

  An object of the present invention is to create a holding portion in which a divided support is stably fixed over a long period of time and stably with respect to temperature.

  This problem is solved by the elastic element (11-16, 110-180) in which the characteristic part of claim 1, that is, the split support (2, 20) acts on the peripheral surface (6, 60) of the split support (2, 20). ) Is fixed to the holding portion (3, 30) via the elastic member (11-16, 110-180), and the divided support (2, 20) is firmly held in a plurality of directions X, Y. At least one other elastic element (11-16, 110-180) is attached to each elastic element (11-16, 110-180) that exerts a force in one direction on the support (2, 20). This is solved by the elastic element exerting a force in the opposite direction on the split support (2, 20) to keep the split support (2, 20) in balance.

  The holding part constituted by this invention has the advantage that it does not lead the friction between the holding part and the divided support when the holding part and the divided support are subjected to different temperature changes. There is no forcing that can lead to a change or replacement of the split support and thereby lead to measurement errors.

  Preferred embodiments of the invention are listed in the dependent claims.

Embodiments of the present invention will be described in detail with reference to the drawings. 1 shows in plan view a holding part with a scale, FIG. 2 shows the holding part with a scale according to FIG. 1 in cross section II-II, FIG. 3 shows an enlarged sectional view A according to FIG. FIG. 5 shows the holding part according to FIG. 4 in cross section VV, and FIG. 6 shows an enlarged cross-sectional view B according to FIG.

1 to 3 show a first embodiment of the present invention. In order to measure the displacement of the first mechanical member 1 (shown in FIG. 5) relative to the second mechanical member 10, the split support in the form of the scale 2 is fixed to the first mechanical member 1 by the holding part 3. Yes. The scale 2 is a bend-resistant plate-like object made of glass, and has an increased section 4 extending in the measuring direction X on the surface thereof and a reference mark 5 arranged in the center in relation to the progress of the section 4. The augmentation section 4 is a phase grid that can be scanned with penetrating light.

The scale 2 has a circular peripheral surface 6. The holding part 3 has at least three elastic elements 11 to 16, and these elastic elements act on the peripheral surface 6 of the scale 2 to fix the scale. The spring forces of all the elastic elements 11 to 16 are of the same magnitude and are directed to the mass center of gravity M1 of the scale 2. Since this scale is firmly held by the elastic elements 11 to 16 in a plurality of directions X and Y, the scale 2 is clamped in the center on the XY plane. In order to generate a centering clamping force, the elastic elements 11 to 16 can be deflected radially. The direction of deflection is determined by the connecting line of the center of gravity M1 of the scale 2 and the contact surface between the respective elastic elements 11 to 16 and the peripheral surface 6 of the scale 2.

  In the illustrated example, the six elastic elements 11 to 16 are uniformly distributed over the peripheral surface 6 of the scale 2, and each elastic element 11, 13, 15 has another elastic element 14, 16. , 12 are attached in the radial direction. The elastic elements 11 to 16, which are respectively positioned in the radial direction, exert the same clamping force on the scale 2, and the scale 2 is kept in balance in the center.

  In order to generate a force balance, two other elastic elements can be inserted into the elastic element to generate a reaction force that occurs as needed. The minimum arrangement for this is an arrangement of elastic elements that are offset by three 120 degrees around the scale.

  Since the elastic elements are cut in order to easily finish the elastic elements 11-16, the elastic elements are manufactured from hollow cylinders of a small material thickness. The web between the cuts forms elastic elements 11-16 in the form of radial resilient tongues. Centering of the scale 2 to the holding unit 3 is performed by pushing the hollow cylinder into the tube. As a result, the elastic elements 11 to 16 are expanded in the radial direction, and the scale 2 is clamped and held. After pushing, the balance of the elastic elements 11-16 via the spring force adapts to the scale 2 based on the force and reaction force exercised. Since the deformation of the elastic elements 11 to 16 is in the elastic range when the temperature is changed during pushing or later operation, this balance remains obtained.

  Even in the case where the holding unit 3 and the scale 2 have different expansion coefficients, the elastic elements 11 to 16 move only in the radial direction when the temperature is changed. If the contact surface between the elastic elements 11 to 16 in the periphery 6 of the scale is small, particularly in the form of a dot, no relative movement between the contact surface of the scale 2 and the elastic elements 11 to 16 occurs. This ensures that no frictional force is generated between the scale 2 and the holding part 3 on the basis of different expansions of the scale 2 and the holding part 3 due to temperature changes. No force that can cause the displacement of the scale 2 is generated.

  As shown in an enlarged view in FIG. 3, since these elastic elements have a convex surface O1 facing inward, the elastic elements 11 to 16 are formed in a spherical shape in order to create a convex contact surface. The convexly curved surfaces O1 of the elastic elements 11 to 16 bring the scale 2 into contact with the center of its thickness, so that the contact surface or point is in the XY plane extending through the center of gravity M1 of the scale 2.

  The scale 2 is made of, for example, glass or glass ceramics, and the holding portion 3 is made of metal, particularly steel.

  In FIG. 1, it is shown in a plan view that an upwardly facing surface of the scale 2 is provided with an photoelectrically scanable incremental section 4 extending in the measuring direction X. In addition, a reference mark 5 is provided in the center of the measuring range for absolute positioning. The holding unit 3 is provided with a fixing surface F for fixing the holding unit 3 to the object 1 to be measured, and the holding unit is fixed to a plane containing the center of gravity M1 of the scale 2 and the reference mark 5. This plane extends perpendicular to the measuring direction X.

  In a form not shown, if the position is retrieved by Teilungspur, for example because the fiducial mark 5 is integrated into the incremental section 4 or a single line absolute code is used, the scale surface It is preferable when the center of gravity of the surface is located at the center of this one section mark.

  In measuring the position of the first mechanical member 1 relative to the second mechanical member 10, the scale 2 is scanned by the scanning unit. The scanning unit has a scanning plate 20 with a scanning structure 40 adapted to the increment section 4 and the reference mark 5. The present invention includes the configuration of the holding unit 3 of the scale 2 and / or the configuration of the holding unit 30 of the scanning plate 20 of the position measuring device.

4 to 6 show the configuration of the holding unit 30 including the scanning plate 20 according to the present invention. The elastic elements 110 to 180 are formed so as to coincide with the elastic elements 11 to 16 of the holding portion 3 of the scale 2. In FIG. 6, the dotted surface 02 of the elastic element 130 is shown enlarged so that the scanning plate 20 contacts the center of the thickness in a dotted manner.

  The scanning plate 20 is held in balance in the center by the radial elastic elements 110-180. Preferably, the holding part 30 also serves to accommodate the imaging lens 8. The optical axis of the imaging lens 8 extends through the center of gravity M2 of the scanning plate 20 in the Z direction. The imaging lens 8 is held by a socket, and this socket is pushed into a part of the hollow cylinder of the holding part 30, and there is no cut surface forming the elastic elements 110 to 180 in this part.

The holding part with a scale is shown in plan view, The holding part with the scale according to FIG. 1 is shown in cross section II-II, 2 shows an enlarged sectional view A according to FIG. The other holding part provided with the scanning plate is shown in a plan view, The holding part according to FIG. 4 is shown in cross section VV, 6 shows an enlarged sectional view B according to FIG.

Explanation of symbols

1 ..... First machine part
2 ..... Scale
3 ... Holding part 4 ..... Incremental division 5 ..... Reference mark 6 ..... Scale peripheral surface 8 .... Imaging lens 10 ..... No. Two mechanical members 11-16 ... Elastic element 20 .. Scanning plate
30 ..... Holding part 40 ..... Scanning structure 60 .... Scale peripheral surface 110-180 ... Elastic element O1 .... Convex surface O2 ..... Convex surface M1 ..... Center of gravity M2 ..... Center of gravity

Claims (8)

In the holding unit comprising scale or bending resistance of the split support is a scanning plate (2, 20) of the position measuring device, the divided support (2, 20) by elastic elements (11-16,110-180) a plurality of directions (X, Y) because it is pinched in, the split support (2, 20) is the elastic element acting on the peripheral surface (6,60) of said split support (2, 20) (11- 16,110-180) is fixed to the holding portion (3, 30) through, said split support (2, 20) a force in one direction on the elastic element (11-16,110-180) each the elastic element (11-13,110-140), at least one other elastic elements of the elastic element (11-16,110-180) (14-16,150-180) is supplied with on the other elastic elements the divided support 2,20) exerts a force in the opposite direction on the split support (2, 20) maintained in equilibrium, the divided support (2, 20) has a single circular peripheral surface (6,60) and characterized in that said elastic element (11-16,110-180) has been arranged at the same intervals over the periphery, each elastic element (11-16,110-180) can be deflected in the radial direction To hold. The elastic element (11-16,110-180) the individual, the divided said elastic element (11-16,110-180) and said each divided into a center of gravity (M1, M2) of the support (2, 20) 2. Holding part according to claim 1, characterized in that it can be deflected in one direction determined by the connecting line between the support (2, 20) and the contact point with the peripheral surface (6, 60). The circumferential surface of the split support (2, 20) (6, 60), the holding portion according to claim 2, in the contact, characterized in that it extends tangentially with respect to the bond line. Wherein the said respective elastic element of the elastic element (11-16,110-180) (11-13,110-140), said one of the other elastic elements of the elastic element (11-16,110-180) ( 14-16,150-180) is disposed against radially, the elastic elements positioned against the radial directions on each respective (11-16,110-180) is same, but opposite The holding part according to any one of claims 1 to 3, wherein a force directed toward the center is exerted on the divided support body (2, 20). The holding according to any one of claims 1 to 4, wherein the elastic element (11-16, 110-180) is an elastic tongue formed by cutting a hollow cylinder. Department. Said elastic element (11-16,110-180) is to have a circumferential surface (6, 60) convexly curved in contact with a respective one of the surfaces (O1, O2) of the divided support (2, 20) The holding part according to any one of claims 1 to 5, wherein Retention according to any one of claims 6, respectively one surface which is curved in the convex (O1, O2), characterized in that the contacting to the center of the thickness of the split support (2, 20) Department. The said holding | maintenance part (3, 30) consists of a metal, especially steel, and the said division | segmentation support body (2, 20) consists of glass or glass-ceramics as described in any one of Claim 1 thru | or 7 characterized by the above-mentioned. Holding part.

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