The invention relates to a stylus for a coordinate and
a coordinate measuring machine with a
such stylus, wherein the coordinate is in particular a hand-held coordinate.
Coordinate measuring machine comprises a
for holding a workpiece to be scanned and a relative to the workpiece base
movable probe with a stylus tip. For the determination of
Coordinates of a surface
of the workpiece
the probe is relative to
the workpiece base
shifts until the probe tip is in touching contact with the surface of the workpiece
comes. For this purpose, the stylus tip is on the surface of the
moved until the touch
of the workpiece
through the probe tip of the probe, for example via a
Deflection of the probe tip from its rest position registered with respect to the probe
or a user who moves the probe, a corresponding signal,
for example, by pressing
a key or the like.
become the relative position of the probe with respect to the workpiece base
and thus the coordinates of the Werkstückoberfäche in a suitable coordinate system
determined. It can
to similar ones
Way further coordinates of surface points of the workpiece determined
become. For this purpose, the probe tip is as continuously as possible over the
of the workpiece
Probe tip includes
a probing structure for contact with the workpiece to be measured. The
Probe structure is common
for example, designed as a sapphire ball. Sapphire is a smooth,
Hard material that moves with low friction along workpieces
to be deformed yourself. The shape of the sphere is a mathematical one
simple shape, and it is accordingly easy to get out
the measured coordinates of the measuring head relative to the workpiece base
at a touch contact
on the coordinates of the place on the ball and thus on the place
to close the workpiece surface
which the touch contact
Probe structure is particularly suitable for installation on large workpieces. Should
however, faces of a plate material, such as one
Sheet metal, to be measured, so it is difficult for a user
the ball so on the end face
lead the plate material along that a meaningful measurement
the coordinates at a touch contact
is. Due to the curved surface of the
Probing structure arise inaccuracies in that the user
can that the
Front side of the plate material not at the curved surface at least a piece
slides off and thus of the coordinate measuring an inconclusive coordinate measurement
Therefore, for measuring end surfaces of thin plate materials cylindrical detent structures
used, with the cylinder jacket brought into abutting contact with the end face
becomes. Inaccuracies are here, however, conditioned by the fact that often not
is that the
is also aligned substantially parallel to the end face. Especially
in bent sheets or the like, which are from a horizontal plane
of the coordinate measuring machine,
is it for
a user difficult by pivoting the probe tip to a
pivotable probe a corresponding orientation of the probing structure
to the frontal area
DE 197 35 772 A1
proposes to use also for the measurement of end faces obliquely to an axis of the stylus oriented plate materials spherical probing structures and these, however, provided with markings on the surface, which help the user, the ball with reproducible same surface areas in touching contact with the To bring face.
Such a stylus has also proven to be inadequate in practice
proved, as he especially high in thin plate materials
Demands on the care and eyesight of the user.
is accordingly an object
of the present invention to provide a stylus which
to touch thin ones
Plate materials and in particular of their faces is suitable.
According to the invention is a
a coordinate measuring machine is provided,
which a holding area for fixing to a probe
of the coordinate measuring machine.
The holding portion may be formed as a cylinder or the like
be, which tuned to a tool holder of the probe
The stylus further comprises a mounted on the support portion probe structure for contact with a workpiece to be measured. The Antast Structure has a defined surface shape such that this plant surface areas provides for reproducible contact with the workpiece to be measured. In particular, the probing structure comprises two spaced-apart convex abutment surface areas which are oriented relative to one another such that in each of the two abutment surface areas there is a surface normal thereof extending from the surface, these two surface normals being spaced away from the abutment Cut surface areas. In such an embodiment of the probing structure, it is possible with a corresponding adjustment of dimensions of the probing structure to a thickness of a plate material to be scanned, the end face reproducible and, with some care, scan substantially error-free or meaningful. For this purpose, a first of the two abutment surface areas is preferably brought into contact with the end face of the plate material, and a second of the two abutment surface areas is brought into contact with a main surface of the plate material adjoining this end face. In this way, the stylus with respect to the plate material at a displacement of the stylus along the end face in the direction of located between the end face and the main surface edge of the plate material well, so that a reproducible contact of the stylus with the plate material can be maintained continuously. With knowledge of the orientation of the system surface areas, it is then in particular easily possible to measure coordinates of this edge of the plate material with comparatively high accuracy.
the first and second surface normals intersect at an angle of
about 90 degrees.
of orientations of the stylus about an extension direction
its holding area to be essentially inde pendent, is the first
or the second or even the first and second abutment surface areas
in terms of
a main axis rotationally symmetric, with such a rotational symmetry
around at least a partial circumference, in particular around an entire circumference,
met around the main axis
indicates the first or the second or even the first and the second
Plant surface area
a shape of a part of a sphere, in particular a spherical layer,
With regard to scanning end surfaces of a plate material
are radii of curvature
of the two plant surface areas
different from each other and are related to each other in a relationship, which
than 1.5, in particular greater than
2.0 and more preferably greater than
3.0. Here, preferably, the contact surface area, which is the smaller
radius of curvature
has, provided for abutment with the end face of the plate material,
the plant surface area
with the larger radius of curvature
for attachment to the main surface
the plate material is provided.
the stylus with both main surfaces of the
Plate material easy to bring in, these three in
a series arranged plant surface areas of the foregoing
described type, with the middle of these three plant surface areas
for contact with the face
of the plate material is provided and then optionally one of
both plant surface areas
with one or the other major surface of the plate material in
Plant contact is brought.
in this connection
is preferably the radius of curvature
of the middle plant surface area
smaller than the curvature radii of the
two other plant surface areas,
which are preferably in turn equal to each other.
Antaststruktur can, for example, by sapphire body, in particular
be provided in the form of partial spheres.
According to the invention is also
a coordinate measuring machine with a
and a relative to the workpiece holder
displaceable probe provided which carries a stylus, such as
this has been described above.
The invention will be explained in more detail with reference to drawings. in this connection
1 a coordinate measuring machine according to the invention with a stylus according to an embodiment of the invention,
2 a detailed view of the stylus of 1 and
3 another enlarged view of the stylus of 1 for explaining geometric terms for describing the stylus.
In 1 a hand-held coordinate is shown schematically. The coordinate measuring machine 1 is hand-guided in the sense; that a user at a probe 17 the coordinate can attack and this probe 17 can move freely in space. This includes the coordinate 1 a base which can be arranged on a floor of a workshop or the like 3 which egg NEN table as a workpiece base for holding a workpiece 7 wearing. The workpiece 7 is in this case a bent sheet metal with an end face 6 and an upper and a lower main surface 8th . 10 , Coordinates of the surfaces 6 . 8th . 10 or edges between these surfaces 6 . 8th . 10 should be measured in a measuring task. This is a Tastspitze 11 one on the probe 17 supported stylus 13 in contact with the surfaces 6 and 8th respectively. 6 and 10 brought and guided along these surfaces, with a controller 15 continuously merges measuring signals of a plurality of sensors explained below and from these coordinates of the surfaces 6 . 8th respectively. 6 . 10 and determined by edges between these surfaces in a suitable coordinate system xyz and to a computer 17 transmitted.
This includes the coordinate 1 a chain of support members which the probe 17 bear relative to the workpiece base.
Details of this coordinate measuring machine 1
as far as it has been described so far are in US 5,396,712
and US 5,909,938
whose disclosure in the present application is fully incorporated by reference.
A description of the coordinate measuring machine 1 takes place here only as far as necessary for the understanding of the present application.
A vertical support member 21 is with the pedestal 3 firmly connected and carries a translationally movable in the z-direction carrier member 23 , To shift the limb 23 in the z-direction is an engine 25 with a gear 27 provided to a spindle 29 to turn, causing the limb 23 is moved in z-direction. A position of the limb 23 in terms of a scale 33 is from a sensor 31 detected and sent to the controller 15 transfer.
When a user releases the stylus 13 or the probe 17 detected and pushed up, this is from the probe 17 detected and sent to the controller 15 which then sends the engine 25 for rotation of the spindle 29 in the direction that drives the link 23 and thus the probe 17 moved upwards. Does the user on the probe 17 or stylus 13 a downward force, this is also registered by the probe, transmitted to the controller and this leaves the spindle 29 turn in the direction that the limb 23 shifted downwards in the z-direction.
On the support member 23 is a first pivotable carrier member 25 around a pivot axis 37 pivotally supported, wherein a pivotal position between the links 23 and 35 through one on the limb 23 moored sensor is detected, which has a circumferential position with respect to a member 35 coupled scale disk 37 read out and to the controller 15 transmitted.
At the first pivotable support member 35 is a second pivotable support member 43 one to the axis 37 parallel offset pivot axis 25 pivotally supported, wherein the second pivotable member 43 finally the probe 17 wearing. With a dial 47 and a sensor 49 is also a pivotal position between the links 35 and 43 detected and sent to the controller 15 transmitted.
From the ones from the sensors 31 . 41 and 49 determined measuring signals, the controller 15 thus after suitable calibration, the position of the stylus 13 in the coordinate system. The user can thus use the stylus 13 grab by hand and along the surfaces 6 . 8th respectively. 6 . 10 lead, with the control coordinates of the surfaces 6 . 8th . 10 to the computer 17 which stores these.
The summit 11 of the stylus 13 is in 2 shown enlarged, in a situation in which the stylus 13 the plate material 7 with face 6 and main surfaces 8th and 10 touches. In this case, the plate material extends from bottom left to top right toward the end face 8th ,
With dashed lines is an alternative Antastsituation to a differently oriented plate material 7 shown, which is towards his face 6 extends from top right to bottom left.
The probe tip 11 includes an upper mounting area 51 , which turns out to be a pen 52 along a major axis 53 extends. On the pen 52 are three ruby balls, which is one the diameter of the pin 52 have corresponding central bore, postponed and glued to the pin. These are an upper big ball 54 , a medium smaller ball 56 and a bottom big ball 58 , The surfaces of the balls are at a small distance from each other, which is why between the balls 54 and 56 respectively. 56 and 58 the pencil 52 in 2 is visible.
It is intended, the Tastspitze 11 such with the workpiece 7 bring into abutting contact that the small ball 56 with the face 6 in abutting contact and the lower large ball 58 with the main surface 10 of the workpiece 7 in contact. In the workpiece shown in dashed lines 7 , which extends from top right to bottom left, is again the small ball 56 with the face 6 in contact. However, then the upper big ball 54 in contact with the main surface 8th brought.
In the 2 illustrated realization of the stylus with a probing structure comprising three balls, corresponds to a preferred embodiment of the invention. However, the design with three balls is a special case of a more general design of the probing structure, as determined by the 3 will be explained below.
Accordingly, the probing structure comprises 61 a first plant surface area 63 and a second abutment surface area spaced therefrom 65 , The plant surface areas 63 . 65 are each convex and oriented to each other so that on the plant surface area 63 a surface normal away from it 67 exists, which one in the plant surface area 65 existing surface normals that are away from it 69 in one point 71 cuts. The intersection angle between the two surface normals 67 . 69 is in particular 90 degrees.
In 3 are the plant surface areas 63 and 65 each as part surfaces of a relative to the main axis 53 shown rotationally symmetrical shape, which extend over a circumferential angle φ around the main axis. In 2 are the plant surface areas 63 and 65 the parts of the balls 54 and 56 respectively. 56 and 58 in which the intersecting surface normals 67 and 69 exist.
Such an embodiment of the geometry of the probing structure is
it, as explained above,
to touch which end faces of comparatively thin plate materials
becomes a stylus for
proposed a coordinate measuring machine,
which is a probing structure of at least two convex contact surface areas
in which surface normal
exist, which intersect. In particular, the plant surface areas are on
provided several balls.