Geometrical instruments – Gauge – Coordinate movable probe or machine
Patent
1991-02-25
1992-06-09
Will, Thomas B.
Geometrical instruments
Gauge
Coordinate movable probe or machine
33572, G01B 503, G01B 703, G01B 2104
Patent
active
051195666
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a stationary gantry for a precision coordinate measuring instrument comprising a base, a first and a second upright and a cross-member.
Such gantries are known (cf. brochure PMM 12106 from the firm Ernst Leitz Wetzlar GmbH 810-096, 1981).
In this arrangement, the base, uprights and cross-member form a frame around a rectangle in the x/z-plane, a cuboid in three dimensions. Conventionally, the components are designed and connected to one another in such a way that all the side lengths and all the angles are each individually fixed. The result is that all the connections between the base, uprights and cross-member are constructed flat and these surfaces must be aligned highly precisely in terms of angle. Since the rectangle is overdetermined by four sides and four angles, and thus also the cuboid, the result of the deviations, which cannot be ruled out whatever the outlay, is that it still remains necessary to use adjustment aids as connecting elements at the fourth connection.
A high outlay during parts production and installation of the gantry is thus unavoidable with this method of construction.
German Offenlegungsschrift 3,526,317 discloses a coordinate measuring instrument having a movable gantry, in which the gantry crossarm having adjusting devices and locking stops is connected to the supporting uprights. The design requires a great many precision parts. Geometrically, said gantry design is multiply overdetermined.
With the known embodiments, faults arise from strains and deformations due to installation and to thermal, static and dynamic mechanical stress. Because of the stiff connection of the components, these faults are always transferred to all the components of the design. The result is excessive complication both in the predetermination during construction and in the detection of the faults for correction during operation.
It is known in steel construction, for example, to provide crane gantries with a pendulum support. Again, bridges are fitted with partially elastic joints, cf. Handworterbuch der Technik (Pocket Dictionary of Technology) Koch, Kienzle, DVA Stuttgart + Berlin 1935, page 310, page 487 ff. In accordance therewith, high mechanical and thermal loads are decisive, but the requirement for fixed geometry of the highest precision such as exists in the case of coordinate measuring machines does not obtain.
It is the object of the invention to specify a gantry according to the preamble, which can, by contrast with known embodiments, be produced with substantially less outlay and whose weight is substantially reduced, so that the cost of transport is also reduced and the possibilities of installation are widened, and whose behavior in the presence of disturbing stresses can be substantially more simply detected and described.
This object is achieved with a gantry according to the preamble when three of the four connections between the base, first and second upright and cross-member are rotatably embodied.
Advantageous embodiments are the subject of subclaims 2 to 8.
The invention proceeds from the perception that the problems in the known embodiment of the gantries result from the overdetermination, described at the beginning and regarded as unavoidable, of the rectangle or cuboid that is formed.
The solution is achieved by means of a design in which the rectangle that is formed is uniquely determined by four sides and only one angle. The design is then statically determined.
The invention is explained in more detail with reference to the drawing, wherein
FIG. 1 shows a basic form,
FIG. 2 shows a further embodiment.
FIG. 1 shows a view of a stationary gantry for a precision coordinate measuring instrument, which consists of a base 1, a first upright 2, a second upright 3 and a cross-member 4.
The base 1 has guideways 11, 12, embodied in a known way, for a sample slide (not represented) that can be moved in the x-direction. The cross-member 4 likewise has a known guideway 41 for a y-carriage (not represented), on which in turn a movable z-spindle having a contact
REFERENCES:
patent: 4369581 (1983-01-01), Lenz
patent: 4597182 (1986-07-01), Rinn
patent: 4631834 (1986-12-01), Hayashi et al.
patent: 4908950 (1990-03-01), Bano et al.
Zawistowski, "Compensated guages for big dimensions", Microtecnic, vol. XX, No. 6, 1986, pp. 612-614.
Bogolyubov et al., "Apparatus to Determine Coordinates of Large Curved Surfaces", Measurement Techniques, vol. 20, No. 7, Jul. 1977, pp. 979-982.
Patent Abstracts of Japan, vol. 6, No. 156, p. 135, 1034, Aug. 17, 1982 JP 57-73602.
Brochure entitled "LEITZ PMM 866, LETIZ PMM 12106", for the company Ernst Leitz Wetzlar GmbH, No. 810-096 published in 1981.
Handwoerterbuch der Technik (Pocket Dictionary of Techology) Kock, Kienzle, DVA Stuttgart+Berlin 1935, p. 310 and pp. 487-491.
Lindner Matthias
Schalz Karl-Josef
Leitz Messtecknik GmbH
Will Thomas B.
LandOfFree
Stationary gantry for a precision coordinate measuring instrumen does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stationary gantry for a precision coordinate measuring instrumen, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stationary gantry for a precision coordinate measuring instrumen will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1795888